%ents; ]>
Internet of Things - Concentrators This specification describes how to manage and get information from concentrators of devices over XMPP networks. &LEGALNOTICE; 0326 Experimental Standards Track Standards Council XMPP Core XEP-0001 XEP-0004 XEP-0030 XEP-0122 XEP-0137 XEP-0141 XEP-0323 XEP-0324 XEP-0331 XEP-0336 sensor-network-concentrators &peterwaher; 0.3 2015-11-09 pw

Updated contact information.

Updated example JIDs to example.org

0.2 2014-03-10 pw

Namespace in dynamic form examples has been changed to urn:xmpp:xdata:dynamic.

Added the following node query events: title, status, beginSection and endSection.

Updated the schema to more strictly validate references to x-data forms.

Updated attribute names so queries and responses are consistent.

Updated the language.

Added section about how to determine support.

Corrected language and examples.

Node Query command type added.

Fixed links to documents with new numbers.

Changed namespace urn:xmpp:sn to urn:xmpp:iot

0.1 2013-05-06 psa

Initial published version approved by the XMPP Council.

0.0.1 2013-03-20 pw

First draft.

Concentrators are devices in sensor networks, concentrating the management of a sub set of devices to one point. They can be small (for example: PLC:s managing a small set of sensors and actuators), medium-sized (for example: mid-level concentrators, controlling branches of the network, islands, perhaps using separate communication protocols), large (for example: entire sub-systems, perhaps managed by a separate child/partner organization) to massive (for example: The entire top-level system, smart-grid, IoT network).

Even though this XEP is generally written and can be used by other implementations not based on sensor networks, much of the requirements used to define this specification comes from requirements used in sensor networks and Internet of Things applications and infrastructure.

This specification will define the following aspects of a general concentrator profile, that can handle all different types of concentrators available in sensor network architectures:

Sensor networks contains many different architectures and use cases. For this reason, the sensor network standards have been divided into multiple XEPs according to the following table:

XEP Description
xep-0000-IoT-BatteryPoweredSensors Defines how to handle the peculiars related to battery powered devices, and other devices intermittently available on the network.
xep-0000-IoT-Discovery Defines the peculiars of sensor discovery in sensor networks. Apart from discovering sensors by JID, it also defines how to discover sensors based on location, etc.
xep-0000-IoT-Events Defines how sensors send events, how event subscription, hysteresis levels, etc., are configured.
xep-0000-IoT-Interoperability Defines guidelines for how to achieve interoperability in sensor networks, publishing interoperability interfaces for different types of devices.
xep-0000-IoT-Multicast Defines how sensor data can be multicast in efficient ways.
xep-0000-IoT-PubSub Defines how efficient publication of sensor data can be made in sensor networks.
xep-0000-IoT-Chat Defines how human-to-machine interfaces should be constructed using chat messages to be user friendly, automatable and consistent with other IoT extensions and possible underlying architecture.
XEP-0322 Defines how to EXI can be used in XMPP to achieve efficient compression of data. Albeit not a sensor network specific XEP, this XEP should be considered in all sensor network implementations where memory and packet size is an issue.
XEP-0323 Provides the underlying architecture, basic operations and data structures for sensor data communication over XMPP networks. It includes a hardware abstraction model, removing any technical detail implemented in underlying technologies. This XEP is used by all other sensor network XEPs.
XEP-0324 Defines how provisioning, the management of access privileges, etc., can be efficiently and easily implemented.
XEP-0325 Defines how to control actuators and other devices in Internet of Things.
XEP-0326 This specification. Defines how to handle architectures containing concentrators or servers handling multiple sensors.
XEP-0331 Defines extensions for how color parameters can be handled, based on &xep0004;
XEP-0336 Defines extensions for how dynamic forms can be created, based on &xep0004;, &xep0122;, &xep0137; and &xep0141;.

Even though there are technologies available in forms of XEPs that solve parts of the above mentioned problem, they do not provide sufficient support. The following paragraphs will take the time to list why different technologies are not applicable.

This XEP defines tree structures for nodes in different data sources. &xep0060; defines a model where a tree structure of nodes is published and users can browse this tree structure. Furthermore, it allows the possibility to publish items on these nodes as well as syndication of this information.

This XEP also defines data sources (in a tree structure). These data sources contain nodes. &xep0248; defines a structure called a node collection, a structure that allows the creation of collections containing loosely coupled nodes.

Even though this document defines tree structures of data, it is not however based on XEP-0060. There are multiple reasons for this:

  • The structures defined in this specification do not include items to publish for each node.
  • We want to be able to use XEP-0060 in parallel to this specification, for the purpose of publishing sensor data. More information about this is found in xep-0000-IoT-PubSub.html.
  • For massive systems (hundreds of thousands, or millions, of nodes behind a concentrator, its vitally important to be able to manage sets of nodes directly (for example: Edit multiple nodes at once). Many of the operations in XEP-0060 only allow for operations of singular nodes. Furthermore, many simple operations require multiple messages per node. This document defines way to operate of sets of nodes simultaneously, as well as ways to perform operations with a smaller number of operations.
  • In this document, nodes have specific functions, controlled by a specific Node Type. Different Node Types have different parameter sets, different options, commands, capabilities, etc. XEP-0060 does not differ between node types. There, nodes are only a structural way to sort data into a tree graph.
  • In this document, nodes have real-time status, like errors, warnings, etc.

XEP-0248 defines the concept of node collections and syndication of information from nodes in these collections. But XEP-0248 is not used in this specification. There are multiple reasons:

  • We want to be able to use XEP-0248 in parallel to this specification, for the purpose of publishing sensor data. More information about this is found in xep-0000-IoT-PubSub.html.
  • Node IDs are not necessarily unique by themselves in the system. This document defines a uniqueness concept based on a triple of data: (Data Source ID, Cache Type, Node ID). This means that Nodes must have IDs unique within a given Cache Type, within a given data source.
  • We need to expand on types of events generated from a data source, to make them adhere to the particulars of nodes as defined in this specification.
  • Data sources own their nodes. XEP-0248 define a loosely coupled structure with references to nodes. In this document, a data source is the owner of all nodes contained in it.

&xep0050; defines how ad-hoc commands can be implemented and how clients can use such commands to interact with underlying logic. But XEP-0050 is not used in this specification. There are multiple reasons:

  • We want to be able to use XEP-0050 for other types of commands, than commands defined in this specification. Generally, XEP-0050 is used to implement system-wide commands.
  • Commands defined in this specification are context sensitive, i.e. they depend on the type of node and the context of the node on which the act.
  • It is a requirement to be able to execute commands on sets of nodes directly.
  • Since commands have to be context sensitive, a large concentrator system may have hundreds or thousands of different commands, making it impossible to create context sensitive GUI's using XEP-0050.
  • Dialog types used for Ad-Hoc-commands are not sufficient. First, dynamic dialogs are required in the general case. (XEP-0326 define how to create dynamic forms.) Furthermore, the wizard style type of dialogs used for more complex dialogs in ad-hoc commands, are difficult to automate.

The following table lists common terms and corresponding descriptions.

Actuator
Device containing at least one configurable property or output that can and should be controlled by some other entity or device.
Computed Value
A value that is computed instead of measured.
Concentrator
Device managing a set of devices which it publishes on the XMPP network.
Data Source
A Data source contains a collection of nodes. Three types of data sources exist: Singular, Flat and Tree. Singular data sources only include one object. Flat data sources contain a list of objects and Tree data sources contain nodes formed as a tree graph with one root element.
Field
One item of sensor data. Contains information about: Node, Field Name, Value, Precision, Unit, Value Type, Status, Timestamp, Localization information, etc. Fields should be unique within the triple (Node ID, Field Name, Timestamp).
Field Name
Name of a field of sensor data. Examples: Energy, Volume, Flow, Power, etc.
Field Type
What type of value the field represents. Examples: Momentary Value, Status Value, Identification Value, Calculated Value, Peak Value, Historical Value, etc.
Historical Value
A value stored in memory from a previous timestamp.
Identification Value
A value that can be used for identification. (Serial numbers, meter IDs, locations, names, etc.)
Localization information
Optional information for a field, allowing the sensor to control how the information should be presented to human viewers.
Meter
A device possible containing multiple sensors, used in metering applications. Examples: Electricity meter, Water Meter, Heat Meter, Cooling Meter, etc.
Momentary Value
A momentary value represents a value measured at the time of the read-out.
Node
Graphs contain nodes and edges between nodes. In Internet of Things, sensors, actuators, meters, devices, gateways, etc., are often depicted as nodes whereas links between sensors (friendships) are depicted as edges. In abstract terms, it's easier to talk about a Node, rather than list different possible node types (sensors, actuators, meters, devices, gateways, etc.). Each Node has a Node ID. Nodes belong to a data source, and all nodes have a Node Type. Some nodes have a parent node, and some nodes have child nodes. Nodes with the same parent nodes a called sibling nodes.
Node ID
An ID uniquely identifying a node within its corresponding context. If a globally unique ID is desired, an architecture should be used using a universally accepted ID scheme.
Node Type
Each node has a Node Type. The Node Type defines the functionality of the node in the system.
Parameter
Readable and/or writable property on a node/device. The XEP-0326 &xep0326; deals with reading and writing parameters on nodes/devices. Fields are not parameters, and parameters are not fields.
Peak Value
A maximum or minimum value during a given period.
Precision
In physics, precision determines the number of digits of precision. In sensor networks however, this definition is not easily applicable. Instead, precision determines, for example, the number of decimals of precision, or power of precision. Example: 123.200 MWh contains 3 decimals of precision. All entities parsing and delivering field information in sensor networks should always retain the number of decimals in a message.
Sensor
Device measuring at least one digital value (0 or 1) or analog value (value with precision and physical unit). Examples: Temperature sensor, pressure sensor, etc. Sensor values are reported as fields during read-out. Each sensor has a unique Node ID.
SN
Sensor Network. A network consisting, but not limited to sensors, where transport and use of sensor data is of primary concern. A sensor network may contain actuators, network applications, monitors, services, etc.
Status Value
A value displaying status information about something.
Timestamp
Timestamp of value, when the value was sampled or recorded.
Token
A client, device or user can get a token from a provisioning server. These tokens can be included in requests to other entities in the network, so these entities can validate access rights with the provisioning server.
Unit
Physical unit of value. Example: MWh, l/s, etc.
Value
A field value.
Value Status
Status of field value. Contains important status information for Quality of Service purposes. Examples: Ok, Error, Warning, Time Shifted, Missing, Signed, etc.
Value Type
Can be numeric, string, boolean, Date & Time, Time Span or Enumeration.
WSN
Wireless Sensor Network, a sensor network including wireless devices.
XMPP Client
Application connected to an XMPP network, having a JID. Note that sensors, as well as applications requesting sensor data can be XMPP clients.

To create a complete set of operations supported by all types of concentrators, ranging from PLCs to subsystems to entire systems is very difficult. So, the aim of this document is instead to create a very small reduced set of operations, a common denominator, that would allow for basic maintenance and interoperability of concentrators of different makes and models and of these varying ranges.

This document lists a sequence of commands. Some are very basic, while others are used for managing massive amounts of devices. When developing a small PLC, it might be difficult to motivate the implementation of the more advanced commands. They are simply not necessary for the management of the device. So, clients connecting to the concentrator need a way to learn what operations are available in the concentrator, and as a consequence what operations are not. To do this, the getCapabilities command is sent, as is shown in the following example.

getCapabilities getAllDataSources getRootDataSources getChildDataSources containsNode containsNodes getNode getNodes getAllNodes getNodeInheritance getRootNodes getChildNodes getIndices getNodesFromIndex getNodesFromIndices getAllIndexValues getNodeParametersForEdit setNodeParametersAfterEdit getCommonNodeParametersForEdit setCommonNodeParametersAfterEdit getAddableNodeTypes getParametersForNewNode createNewNode destroyNode getAncestors getNodeCommands getCommandParameters executeNodeCommand executeNodeQuery abortNodeQuery getCommonNodeCommands getCommonCommandParameters executeCommonNodeCommand executeCommonNodeQuery abortCommonNodeQuery moveNodeUp moveNodeDown moveNodesUp moveNodesDown subscribe unsubscribe getDatabases getDatabaseReadoutParameters startDatabaseReadout ]]>

A concentrator without databases, but still contain a rich interface for handling masses of nodes may present itself as follows:

getCapabilities getAllDataSources getRootDataSources getChildDataSources containsNode containsNodes getNode getNodes getAllNodes getNodeInheritance getRootNodes getChildNodes getIndices getNodesFromIndex getNodesFromIndices getAllIndexValues getNodeParametersForEdit setNodeParametersAfterEdit getCommonNodeParametersForEdit setCommonNodeParametersAfterEdit getAddableNodeTypes getParametersForNewNode createNewNode destroyNode getAncestors getNodeCommands getCommandParameters executeNodeCommand executeNodeQuery abortNodeQuery getCommonNodeCommands getCommonCommandParameters executeCommonNodeCommand executeCommonNodeQuery abortCommonNodeQuery moveNodeUp moveNodeDown moveNodesUp moveNodesDown subscribe unsubscribe ]]>

A smaller gateway on the other hand, may have skipped the implementation of the batch commands that are used for larger systems:

getCapabilities getAllDataSources getRootDataSources getChildDataSources containsNode getNode getNodeInheritance getRootNodes getChildNodes getNodeParametersForEdit setNodeParametersAfterEdit getAddableNodeTypes getParametersForNewNode createNewNode destroyNode getAncestors getNodeCommands getCommandParameters executeNodeCommand executeNodeQuery abortNodeQuery moveNodeUp moveNodeDown moveNodesUp moveNodesDown subscribe unsubscribe ]]>

But a small PLC, possibly with a fixed set of nodes, might have support for an even more reduced set of commands:

getCapabilities getAllDataSources containsNode getNode getRootNodes getChildNodes getNodeCommands getCommandParameters executeNodeCommand executeNodeQuery abortNodeQuery ]]>

So, clients who need to interact with different types of concentrators need to be aware of what commands are supported, and limit operations to those commands.

This command will return a flat list of all available data sources on the concentrator. It is not structured hierarchically.

... ]]>

If the client is interested in the hierarchical structure of available data sources, it should request only the root sources, and then ask the client for their corresponding child data sources. If the client wants to present the data sources to a user, presenting them in their hierarchical order may be more intuitive.

... ]]>

Having the ID of a data source that contains child data sources, you can fetch the child sources as follows:

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A client can subscribe to changes made in a data source. It does this by sending the subscribe command to the concentrator, as is shown in the following example:

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Multiple subscriptions to the same source will not result in an error, however the server will still only send one event message for each event in the data source.

Important: Event subscriptions only last for as long as the client and concentrator both maintain presence. The concentrator must not persist event notification subscriptions, and if it goes offline and back online, or if the client goes offline or online again for any reason, the event subscription is removed.

Note: The parameters and messages attributes can be used to retrieve parameter and status message information about the nodes in event messages sent from the concentrator. Note that the xml:lang may be used to select the language used in such events, if the concentrator supports localization of strings.

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The subscribe command has a set of optional attributes, one for each event type available, and with the same names (nodeAdded, nodeUpdated, nodeStatusChanged, nodeRemoved, nodeMovedUp and nodeMovedDown), that the client can use to subscribe to individual events, but not to others. They have the default value of true implying that if not provided, the default action is to subscribe to those events. The attributes parameters and messages can also be used to specify if node parameters and node messages respectively should be available in event messages. The default value for the these later attributes is false, implying that normal events do not include node parameter and node message information.

The following example shows how a client can subscribe to a set of events only:

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For more information on types of events sent, see the Data Source Events section.

A client can unsubscribe to changes made in a data source it is subscribed to. It does this by sending the unsubscribe command to the concentrator, as is shown in the following example:

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An unsubscription made to an existing data source, but where an event subscription does not exist, must not result in an error.

The unsubscribe command has a set of optional attributes, one for each event type available, and with the same names, that the client can use to unsubscribe from individual events, but not from others. They have the default value of true implying that if not provided, the default action is to unsubscribe from those events.

The following example shows how a client can unsubscribe from a subset of events, keeping subscriptions on the others (if subscribed to):

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If a client comes back online and wants to know any changes that have taken place on the concentrator since last time it was in contact with it, it can include a getEventsSince attribute in the subscribe command sent to the concentrator. This will make the concentrator send all event messages since the given timestamp to the client before subscribing the client to events in the given data source.

... Sequence of event messages sent from concentrator to client.]]>

Important: Event subscriptions only last for as long as the client and concentrator both maintain presence. The concentrator must not persist event notification subscriptions, and if it goes offline and back online, or if the client goes offline or online again for any reason, the event subscription is removed.

Note: The parameters and messages attributes can be used to retrieve parameter and status message information about the nodes in event messages sent from the concentrator.

For more information on types of events sent, see the Data Source Events section.

If during a subscription request the concentrator is not able to fulfill the request of retrieving previous events using the getEventsSince attribute, perhaps the attribute stretches too far back, or includes too many records, the concentrator can return an error message using a response code of NotImplemented. In this case, the subscription must not be made.

When receiving such an error from the concentrator, the client must make a decision if it should download the data source again, or keep the data source as is, and subscribing again without the getEventsSince attribute.

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This command permits the client to check the existence of a node in the concentrator.

true ]]>

If the client wants to check the existence of multiple nodes on the concentrator, it can use this batch command instead:

true true false true ]]>

The array returned will have one item for each item in the request, in the same order.

This command returns basic information about a node in the concentrator.

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For more information, see Node Information.

This command lets the client get information from multiple nodes at once.

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For more information, see Node Information.

This command returns basic information about a node in the concentrator, as well as node parameters.

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For more information, see Node Information.

This command lets the client get information from multiple nodes at once, including node parameters.

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For more information, see Node Information.

If the device does not manage too many nodes, it could choose to implement this function. It would return all available nodes with one call.

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If the device does not manage too many nodes, it could choose to implement this function. It would return all available nodes with their parameters with one call.

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This command assumes node types exist in a class hierarchy, and allows the caller to retrieve nodes with similar inheritance.

Namespace.BaseClass1 ]]>

This command assumes node types exist in a class hierarchy, and allows the caller to retrieve nodes with similar inheritance. It also returns node parameters directly in the response.

Namespace.BaseClass1 ]]>

Note that the caller can list multiple classes in the request. This would return only nodes having the correct base class(es) and implementing all interfaces.

This command assumes node types exist in a class hierarchy. It allows the caller to get a list of the node class hierarchy and implemented interfaces the node has.

Namespace.BaseClass1 Namespace.AbstractBase ]]>

Note: It is assumed the client already knows the node type of the node, so the response must not contain the type of the node, only its base classes and any implemented interfaces.

This command returns the root node of a data source (in case the source is a tree-shaped data source) or the nodes of a data source (in case the source is flat).

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This command returns the root node of a data source (in case the source is a tree-shaped data source) or the root nodes of a data source (in case the source is flat), and also returns the parameters for the corresponding nodes.

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This command returns the child nodes of a node in a data source.

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This command returns the child nodes of a node in a data source, and also returns the parameters for the corresponding nodes.

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This command returns a list of available indices in a data source. Indices can be used for efficient node look-up.

country region city area street building apartment oid ]]>

This command can be used to get a node or nodes from a data source using an index and an index value.

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This command can be used to get a node or nodes from a data source using an index and an index value, and also returns the parameters for the corresponding nodes.

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This command can be used to get nodes from a set of data source using indices and index values.

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This command can be used to get nodes from a set of data source using indices and index values, and also returns the parameters for the corresponding nodes.

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This command can be used to get a list of available index values, given a data source and an index.

A1-1 A1-2 ... ]]>

In a tree formed data source, all nodes except the root node has a parent node. The getAncestors command allows the client to get a list of all ancestors (parent, grand parent, etc.) of a node, as is shown in the following example:

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Note that the concentrator returns information about the node itself in the response. The parameters and messages attributes are used in the request to control if the concentrator should return node parameters and node status messages in the response as well.

As the order of siblings in a tree can be important, depending on the context and type of nodes involved, the client may be allowed to move nodes up and down among siblings. To move a node upwards among its siblings is done using the command moveNodeUp, as is shown in the following example:

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Note that a node that is first among its siblings will maintain its position. The response to the command must still be OK.

As the order of siblings in a tree can be important, depending on the context and type of nodes involved, the client may be allowed to move nodes up and down among siblings. To move a node downwards among its siblings is done using the command moveNodeDown, as is shown in the following example:

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Note that a node that is last among its siblings will maintain its position. The response to the command must still be OK.

To move a set of nodes upwards among its siblings is done using the command moveNodesUp, as is shown in the following example:

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Note that a node that is first among its siblings will maintain its position. The response to the command must still be OK. If an attempt is performed to move a sequence of nodes that are together first as siblings, none of the nodes move relative to each other.

To move a set of nodes downwards among its siblings is done using the command moveNodesDown, as is shown in the following example:

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Note that a node that is last among its siblings will maintain its position. The response to the command must still be OK. If an attempt is performed to move a sequence of nodes that are together last as siblings, none of the nodes move relative to each other.

Previously described commands can return parameters for a node. But these parameters are for presentational or informational use. If the client wants to edit the parameters of a node, another set of commands must be used. This use case shows how getNodeParametersForEdit can be used to edit available parameters for one node.

Note: When editing parameters for a node, a different set of parameters might be returned compared to the set of parameters available in commands mentioned above. There may be various reasons for this, among other things (but not limited to) user rights, node settings, and parameter type. User rights may restrict the number of parameters the user can access. The node may be configured not to allow editing of certain parameters. Also, some types of parameters may only be available in an edit mode (like long multi-line parameters) and not in a shorter presentation mode.

Node1 009c7956-001c-43fb-8edb-76bcf74272c9 ID of the node. Node1 Type of node. Watchamacallit Temperature Sensor v1.2 Class of node Temperature ... Serial number of node/device. 123456 Meter Location. P123502-2 Bus address 123 Latitude of node. 12.345 Longitude of node. 123.45 ]]>

The following table lists the different XEP's the client should implement to be able to support parameter forms according to this proposal:

XEP Description
XEP-0004 Describes how basic forms are handled.
XEP-0122 Makes it possible to add certain client validation rules to form parameters.
XEP-0137 Makes it possible to publish a file upload parameter.
XEP-0141 Makes it possible to layout parameters into pages and sections.
XEP-0331 Defines extensions for how color parameters can be handled.
XEP-0336 Makes it possible to create dynamic forms, with server-side validation and forms that change dynamically depending on input.

Read-only parameters will be returned with the readOnly element, as defined in XEP-0336. Clients SHOULD support this extension if using this command. However, the server MUST NOT change parameters in a node that are read-only, even if clients happen to try to set them.

After editing the form, the client uses the setNodeParametersAfterEdit command to set the parameters in the node. Note that it is possible to set the same parameters (or a sub-set of the same parameters) to a different node using this command, without the need to get new form parameters. However, after the first successful set operation, any form session used for dynamic validation during edit will not be available on the server anymore and must be ignored by the server.

009c7956-001c-43fb-8edb-76bcf74272c9 Node1 Temperature 123456 P123502-2 123 12.345 123.45 ]]>

Note that validation rules, pagination, etc., can be stripped from the form when submitting it to the server. Also the form type attribute must be set to 'submit'. Note also that as the result attribute is OK, it is assumed the server has dropped any parameter form resources related to the form, which disables any future dynamic validation of the contents of the form. The newly edited node will also be available in the response in a node element.

The following example shows how the server responds when the client tries to set invalid parameters. The response contains detailed information about why, information which the client can use to inform the user (if any) of what went wrong.

009c7956-001c-43fb-8edb-76bcf74272c9 Node1 Temperature 123456 P123502-2 123 12.345 123.45 There already exists a node with this ID. ]]>

As the result attribute is FormError, the server maintains any parameter form resources related to the form, and features such as dynamic validation of the contents of the form will still be available until the parameters have been successfully set, the operation has been explicitly cancelled or a form session time-out has occurred. See XEP-0336 XEP-0336: Dynamic Data Forms <http://xmpp.org/extensions/xep-0336.html> for more information.

Advanced concentrators handling large quantities of nodes may let users edit sets of nodes at once to be practical. This is done by publishing the getCommonNodeParametersForEdit command. It will return a form with parameters that are common for all selected nodes. Since nodes may have different node types it is assumed that different nodes have different sets of parameters. But if this command is used, only parameters matching in IDs, descriptions, validation rules, etc., (but not values) will be returned in a form.

Important: A parameter that exists in multiple nodes, but has different parameter values among the nodes, will be marked with the notSame element, according to XEP-0336. Clients using this command MUST support the extensions defined in XEP-0336.

Node1, Node2, Node3 009c7956-001c-43fb-8edb-76bcf74272c9 Type of node. Watchamacallit Temperature Sensor v1.2 Class of node Temperature ... Serial number of node/device. 123456 Meter Location. P123502-2 Bus address 123 Latitude of node. 12.345 Longitude of node. 123.45 ]]>

Note that parameters that are not available in all selected nodes will have been removed. Also and ID-parameter will have been removed, since they cannot be set for a collection of nodes.

Fields marked with the notSame element only present one value, perhaps the value of the first node. However, the field should be clearly marked in any end-user GUI (for example by graying the field), and MUST ONLY be sent back to the server in a set operation if explicitly edited by the end-user. The parameter will be set in all selected nodes in that case. Unedited fields should be treated as if the end-user accepts the different values for the current set of nodes.

After editing the form, the client uses the setCommonNodeParametersAfterEdit command to set the parameters in the set of nodes. Note that it is possible to set the same parameters (or a sub-set of the same parameters) to a different set of nodes using this command, without the need to get new form parameters. However, after the first successful set operation, any form session used for dynamic validation during edit will not be available on the server any more.

009c7956-001c-43fb-8edb-76bcf74272c9 Temperature ]]>

Note that validation rules, pagination, etc., can be stripped from the form when submitting it to the server. Also the form type attribute must be set to 'submit'. Note also that as the result attribute is OK, it is assumed the server has dropped any parameter form resources related to the form, which disables any future dynamic validation of the contents of the form.

Important: A parameter that exists in multiple nodes, but has different parameter values among the nodes, will be marked with the notSame element, according to XEP-0336. Such parameters MUST NOT be sent back to the server unless they have explicitly been edited or signed by the end-user. The value sent back to the server will be set in all nodes.

The following example shows how the server responds when the client tries to set invalid parameters to a set of nodes. The response contains detailed information about why, information which the client can use to inform the user (if any) of what went wrong.

009c7956-001c-43fb-8edb-76bcf74272c9 Node1 Temperature Parameter not available. ]]>

As the result attribute is FormError, the server maintains any parameter form resources related to the form, and features such as dynamic validation of the contents of the form will still be available until the parameters have been successfully set, the operation has been explicitly cancelled or a form session time-out has occurred. See XEP-0336 for more information.

Each node in the concentrator has a state. This state is a dynamic run-time state, and therefore not presented as a more static property. This state can be any of the following values, in order of increasing importance:

State Description
None Nothing has been reported on the node.
Information There are informative events reported on the node.
WarningSigned There are warnings reported on the node. But these warnings have been viewed by an operator.
WarningUnsigned There are new or unreviewed warnings reported on the node.
ErrorSigned There are errors reported on the node. But these errors have been viewed by an operator.
ErrorUnsigned There are new or unreviewed errors reported on the node.

Other types of "states" are of course possible, such as phase - installation phase, test phase, production phase, etc. - but such "states" are seen as static and presented as parameters on the node. The purpose of the dynamic state attribute of a node, is to give a dynamic runtime state that has the possibility to change during runtime, which operators must be aware of.

The following commands have an optional attribute messages, with which they can ask the server to return any events logged on the node, giving more details of the current state of the node:

  • getNode
  • getNodes
  • getChildNodes
  • getAllNodes
  • getRootNodes
  • getNodesFromIndex
  • getNodesFromIndices
Internal clock is offset more than 7 seconds. ]]>

The messages attribute can be combined with the parameters attribute to provide both node parameters and messages in the response.

Internal clock is offset more than 7 seconds. ]]>

Since nodes are context sensitive, depending on node type and tree structure, before being able to create a new node, it is important to know what types of nodes that can be added to a given node. This is done using the getAddableNodeTypes command, as is shown in the following example:

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When you know what type of node you want to create, you need to get a set of parameters you need to fill in for the new node, before you can create it. This is done using the getParametersForNewNode command, as is shown in the following example:

Metering Topology 0B146517-8EA3-4BEC-A2E9-CF3F209D4A5D ID of the node. ID of the node in the metering topology. ]]>

After editing the form, the client uses the createNewNode command to create the new node using the parameters provided in the form.

0B146517-8EA3-4BEC-A2E9-CF3F209D4A5D Reference to Node1 Node1 ]]>

Note that validation rules, pagination, etc., can be stripped from the form when submitting it to the server. Also the form type attribute must be set to 'submit'. Note also that as the result attribute is OK, it is assumed the server has dropped any parameter form resources related to the form, which disables any future dynamic validation of the contents of the form. The newly created node with corresponding parameters is also returned in the response in a node element.

The following example shows how the server responds when it cannot accept parameters provided when trying to create a node. The response will contain detailed information about why, information which the client can use to inform the user (if any) of what went wrong.

0B146517-8EA3-4BEC-A2E9-CF3F209D4A5D Node2 NodeX There already exists a node with this ID. Referenced node was not found. ]]>

As the result attribute is FormError, the server maintains any parameter form resources related to the form, and features such as dynamic validation of the contents of the form will still be available until the parameters have been successfully set, the operation has been explicitly cancelled or a form session time-out has occurred. See XEP-0336 for more information.

To destroy (remove) a node from the concentrator, the destroyNode command is sent, as is shown in the following example:

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Since the result attribute in the response is OK, the node has been removed.

If the result attribute in the response is other than OK, the node was not removed from the concentrator. The result attribute contains the reason why the operation failed, as is shown in the following example:

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Each node can have a context sensitive set of commands available to it. This is shown using the hasCommands attribute in the Node Information record describing the corresponding node. If the client wants to get a list of available commands, the getNodeCommands command is sent to the concentrator, as is shown in the following example:

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There are three types of commands available: Simple, Parameterized and Query. Simple commands take no parameters, and are therefore simpler to execute. Parameterized commands require the client to get a set of parameters for the corresponding command before it can be executed. Query commands also require a set of parameters to be executed, but return a response after (or during) execution in an asynchronous fashion. Queries can also be aborted during execution. A Query with an empty parameter set is considered to be a simple query, not requiring a parameter dialog to be shown.

For more information about command attributes, see Node Commands.

Executing a simple command is done by sending the executeNodeCommand command to the concentrator, as is shown in the following example:

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To execute a parameterized command or a query on the node, the client first needs to get (and edit) a set of parameters for the command. Getting a set of parameters for a parameterized command is done as follows:

Schedule wake-up call E14E330F-8496-46F0-8F40-178808AB13A7 Time of the wake-up call. Type of wake-up call Soft ]]>

Executing a parameterized command is also done by sending the executeNodeCommand command to the concentrator, but including the edited form parameters, as is shown in the following example:

E14E330F-8496-46F0-8F40-178808AB13A7 04:30:00 Harass ]]>

If an error occurs during the execution of a command or if the server rejects the execution of a command, the server returns a response code different from OK. If the response code is FormError, the server maintains any parameter form resources related to the form, and features such as dynamic validation of the contents of the form will still be available until the parameters have been successfully set, the operation has been explicitly cancelled or a form session time-out has occurred. See XEP-0336 for more information.

E14E330F-8496-46F0-8F40-178808AB13A7 04:30:00 Harass You are not allowed to harass people at 04:30:00! ]]>

Executing a Node Query also requires the client to get a set of parameters for the query. This is done in the same way as for parametrized commands, as is shown in the following example:

Search for events E14E330F-8496-46F0-8F40-178808AB13A7 From what point in time events will be fetched. 2013-04-16T12:58:00 To what point in time events will be fetched. 2013-04-23T12:58:00 Only return events including this text. ]]>

Executing the query is then done by sending the executeNodeQuery command to the concentrator, but including the edited form parameters, as is shown in the following example:

2013-04-16T12:58:00 2013-04-23T12:58:00 Harass ...]]>

After the successful execution of a query command, a sequence of query events will follow. These events will include a queryId attribute to identify to which query the corresponding events correspond. See section about Query Events for more information about this.

Note: Queries with no visible parameters in the command parameter form need not display a parameter form to the user before being executed. However, if a confirmation question is defined for the command, such a confirmation question should always be presented to the user (if possible) before executing the command.

If an error occurs during the reception of a query or if the server rejects the execution of a query, the server returns a response code different from OK. If the response code is FormError, the server maintains any parameter form resources related to the form, and features such as dynamic validation of the contents of the form will still be available until the parameters have been successfully set, the operation has been explicitly cancelled or a form session time-out has occurred. See XEP-0336 for more information.

2013-04-23T12:58:00 2013-04-16T12:58:00 Harass The TO timestamp needs to be later than the FROM timestamp. ]]>

One a query has been accepted and started running, the client can abort it using the abortNodeQuery command, as is shown in the following example.

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Note: The execution of a query is an asynchronous process, with a small delay between the compilation and transmission of query events and the reception of them by a client. A client may thinkt a query is still active when asking to abort it, when the query might actually have been finished and removed on the query side. Therefore, clients should be aware of this when receiving NotFound responses from a concentrator, that the query might already have been finished.

Using the command getCommonNodeCommands, the client can receive commands that are common for a set of nodes, as is shown in the following example:

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Executing a simple command on multiple nodes is done by sending the executeCommonNodeCommand command to the concentrator, as is shown in the following example:

true true true true true true ]]>

To execute a parameterized command on a set of nodes, the client first needs to get (and edit) a set of parameters for the common command. Getting a set of parameters for a common parameterized command is done as follows:

Schedule wake-up call E14E330F-8496-46F0-8F40-178808AB13A7 Time of the wake-up call. Type of wake-up call Soft ]]>

Executing a common parameterized command is also done by sending the executeCommonNodeCommand command to the concentrator, but including the edited form parameters, as is shown in the following example:

E14E330F-8496-46F0-8F40-178808AB13A7 04:30:00 Harass true true true true true true ]]>

If an error occurs during the execution of a common command or if the server rejects the execution of a common command, the server returns a response code different from OK. If the response code is FormError, the server maintains any parameter form resources related to the form, and features such as dynamic validation of the contents of the form will still be available until the parameters have been successfully set, the operation has been explicitly cancelled or a form session time-out has occurred. See XEP-0336 for more information.

E14E330F-8496-46F0-8F40-178808AB13A7 04:30:00 Harass You are not allowed to harass people at 04:30:00! ]]>

When executing a command, simple or parameterized, on multiple nodes, it might happen that the command fails on some nodes, but not on others, even though any parameters are validated beforehand. Therefore, the client needs to check any result elements in the response, even though the response code is OK.

The following example shows the execution of a parameterized command on multiple nodes that fail on some nodes but are executed on others. Note that individual error messages can be provided as error attribute messages for each node that fails in the corresponding result element.

E14E330F-8496-46F0-8F40-178808AB13A7 04:30:00 Harass true true false true false true ]]>

Executing a Node Query on multiple nodes also requires the client to get a set of parameters for the query common to all nodes. This is done in the same way as for parametrized commands, as is shown in the following example:

Schedule wake-up call E14E330F-8496-46F0-8F40-178808AB13A7 From what point in time events will be fetched. 2013-04-16T12:58:00 To what point in time events will be fetched. 2013-04-23T12:58:00 Only return events including this text. ]]>

Executing the query is then done by sending the executeCommonNodeQuery command to the concentrator, but including the edited form parameters, as is shown in the following example:

2013-04-16T12:58:00 2013-04-23T12:58:00 Harass ...]]>

After the successful execution of a query command, a sequence of query events will follow. These events will include a queryId attribute to identify to which query the corresponding events correspond. They will also include node reference attributes so the receptor can distinguish information from different nodes in the query. See section about Query Events for more information about this.

Note: Queries with no visible parameters in the command parameter form need not display a parameter form to the user before being executed. However, if a confirmation question is defined for the command, such a confirmation question should always be presented to the user (if possible) before executing the command.

If an error occurs during the execution of a common query or if the server rejects the execution of a common query, the server returns a response code different from OK. If the response code is FormError, the server maintains any parameter form resources related to the form, and features such as dynamic validation of the contents of the form will still be available until the parameters have been successfully set, the operation has been explicitly cancelled or a form session time-out has occurred. See XEP-0336 for more information.

2013-04-23T12:58:00 2013-04-16T12:58:00 Harass The TO timestamp needs to be later than the FROM timestamp. ]]>

When executing a query on multiple nodes, it might happen that the query is rejected on some nodes, but not on others, even though any parameters are validated beforehand. Therefore, the client needs to check any result elements in the response, even though the response code is OK.

The following example shows the execution of a query on multiple nodes that fail on some nodes but are executed on others. Note that individual error messages can be provided as error attribute messages for each node that fails in the corresponding result element.

2013-04-23T12:58:00 2013-04-16T12:58:00 Harass true true false true true true ]]>

To abort a query common to a set of nodes you use the abortCommonNodeQuery command, as is shown in the following example:

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Note: The execution of a query is an asynchronous process, with a small delay between the compilation and transmission of query events and the reception of them by a client. A client may thinkt a query is still active when asking to abort it, when the query might actually have been finished and removed on the query side. Therefore, clients should be aware of this when receiving NotFound responses from a concentrator, that the query might already have been finished. In the case of aborting queries on multiple nodes, servers must ignore nodes where the query has already finished executing.

Query events are sent as a response to executing queries on nodes. They are reported asynchronously from the concentrator to the client executing the query. Each event is wrapped in a queryProgress element within a message sent from the concentrator to the client. Each such queryProgress element can include any number of query events, and the client must process them in the order they appear in the message.

Each queryProgress element contains a queryId attribute identifying the query to which the events correspond. They also contain sourceId, nodeId and an optional cacheType to identify from which node in a concentrator the events originated.

Note: A queryProgress element can only contain events from a single query executed on a single node. If a query is executed on multiple nodes, events resulting from different nodes will be sent in different messages.

The following subsections describe each query event in turn.

This event is sent when the query is started on a node. It is sent using a queryStarted event element. This element does not take any attributes.

... ]]>

This event is sent when the query is done on a node. It is sent using a queryDone event element. This element does not take any attributes.

... ]]>

This event is sent when the query has been aborted on a node. It is sent using a queryAborted event element. This element does not take any attributes.

... ]]>

A query result can consist of zero or more data tables. Each data table consists of a set of columns and records containing value items for the these columns. A new table is identified by a query event named newTable. a newTable event contains a sequence of column events each identifying a column in the table.

... ... ]]>

For more information about column definitions, see Table Column definitions in query results.

A set of records in an open table is reported using the newRecords query event.

... 2013-04-24T17:43:15 Harassed ... ... ]]>

For more information about records, see Record Item definitions in query results.

This event is sent when the query is done with a table. It is sent using a tableDone event element. The query must not send any more records to a table that has been closed using this query event.

... ... ]]>

Some queries may want to return other types of data than tables, like images, graphs, etc. These may be combined with table information or not. A query returns such an object using the newObject query event. Each object is MIME encoded, and the MIME Type is sent in the contentType attribute. The object itself is Base-64 encoded.

... ... ... ]]>

During the processing of a query, the query might want to report a message of some kind. This is done using the queryMessage query event.

... 30 events found. ... ]]>

For more information about query messages, see Message definitions in query results.

Enables the executing process of the query to set a custom title for the result. Note that the result only has one title.

... ... </queryProgress> </message>]]> </example> </section3> <section3 topic='Status'> <p> Permits the executing process to report the current status. This can change a lot during execution and values should not be persisted, like query messages. Instead, they can be displayed in a status bar, just to give the end-user feedback of the status of a long-running query. </p> <example caption='Status'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <queryProgress xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringGroups' nodeId='Apartment 1-1' cacheType='Apartment' queryId='Query0001'> ... <status message='Processing. 67% done.'/> ... </queryProgress> </message>]]> </example> </section3> <section3 topic='Starting a section or subsection'> <p> Starts a new section in the query result. In large query results, sections can be used to format the result using an intuitive disposition in a visually appealing way. Nested sections should be interepreted as sub-sections. Tables and objects started or reported within a section belong in that section, and should be listed sequentially in the order they are reported to the client. </p> <example caption='Starting a section or subsection'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <queryProgress xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringGroups' nodeId='Apartment 1-1' cacheType='Apartment' queryId='Query0001'> ... <beginSection header='1. Stockholm'/> ... <beginSection header='1.1. Solna'/> ... </queryProgress> </message>]]> </example> <p> Note that the use of sections in a query result is optional. Tables and objects received outside the scope of sections should be placed in a default section by the client. </p> </section3> <section3 topic='Closing a section or subsection'> <p> Closes the current section or sub-section. Tables inside closed sections can still be open and receive fields. Tables are closed using the <strong>tableDone</strong> query event. </p> </section3> <example caption='Starting a section or subsection'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <queryProgress xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringGroups' nodeId='Apartment 1-1' cacheType='Apartment' queryId='Query0001'> ... <endSection/> ... <endSection/> ... </queryProgress> </message>]]> </example> </section2> <section2 topic='Data Source Events' anchor='sourceevents'> <p> Events are asynchronous messages sent from the concentrator to devices registered with the concentrator and having subscribed to events from the concentrator. <link url='#subscribe'>Event subscription</link> can be activated using the <strong>subscribe</strong> command. You can also <link url='#subscribe2'>retrieve historical events</link> using the <strong>subscribe</strong> command. </p> <p> Each event is sent from the concentrator to each subscriber using a <strong>message</strong> stanza. Each such <strong>message</strong> stanza may contain multiple events. The following subsections list the different types of events that can be sent. Even though these examples may list only one element in a message stanza, this is not a limitation. Different types of events may also be mixed within the message stanza. </p> <p> Event subscriptions only last for as long as the client and concentrator both maintains presence. The concentrator must not persist event notification subscriptions, and if it goes offline and back online, or if the client goes offline or online again for any reason, the event subscription is removed. </p> <p> Node events may contain parameters or status messages. This depends on how the subscription was made. The <strong>parameters</strong> and <strong>messages</strong> attributes in the <strong>subscribe</strong> command determine if node parameters and/or status messages should be sent in event messages. </p> <section3 topic='Node added event'> <p> The <strong>nodeAdded</strong> event is sent when a node has been added to a data source which the client subscribes to. The following example shows how such an event message may look like: </p> <example caption='Node added event, without parameters'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeAdded xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1' nodeType='Namespace.NodeType1' cacheType='Node' state='None' hasChildren='false' isReadable='true' isControllable='true' hasCommands='true' parentId='Root' lastChanged='2013-03-19T17:58:01'/> </message>]]> </example> <example caption='Node added event, with parameters'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeAdded xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1' nodeType='Namespace.NodeType1' cacheType='Node' state='None' hasChildren='false' isReadable='true' isControllable='true' hasCommands='true' parentId='Root' lastChanged='2013-03-19T17:58:01'> <string id='id' name='Node ID' value='Node1'/> <string id='type' name='Node Type' value='Watchamacallit Temperature Sensor v1.2'/> <string id='sn' name='Serial Number' value='123456'/> <string id='class' name='Node Class' value='Temperature'/> <string id='meterLoc' name='Meter Location' value='P123502-2'/> <int id='addr' name='Address' value='123'/> <double id='lat' name='Latitude' value='12.345'/> <double id='long' name='Longitude' value='123.45'/> </nodeAdded> </message>]]> </example> <p> <strong>Note:</strong> Moving a node in a data source from one parent to another, possibly between different data sources, is performed by first removing it from the current source (sending a <strong>nodeRemoved</strong> event) and then adding it to the new data source (sending a <strong>nodeAdded</strong> event), in that order. </p> <p> If a node is added to a parent where order of nodes is important, the attributes <strong>afterNodeId</strong> and also optionally <strong>afterNodeCacheType</strong> used to identify the node after which the new node should be inserted. </p> <example caption='Ordered Node added event, without parameters'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeAdded xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node2' nodeType='Namespace.NodeType1' cacheType='Node' state='None' hasChildren='false' isReadable='true' isControllable='true' hasCommands='true' parentId='Root' lastChanged='2013-03-19T17:58:01' afterNodeId='Node1' afterNodeCacheType='Node'/> </message>]]> </example> </section3> <section3 topic='Node removed'> <p> The <strong>nodeRemoved</strong> event is sent when a node in a data source has been removed or destroyed. It does not include status message or parameter information about the node, only the reference to the node. The following example shows how such an event message may look like: </p> <example caption='Node removed'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeRemoved xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1'/> </message>]]> </example> <p> <strong>Note:</strong> Moving a node in a data source from one parent to another, possibly between different data sources, is performed by first removing it from the current source (sending a <strong>nodeRemoved</strong> event) and then adding it to the new data source (sending a <strong>nodeAdded</strong> event), in that order. </p> </section3> <section3 topic='Node updated'> <p> The <strong>nodeUpdated</strong> event is sent when a node has been updated in a data source which the client subscribes to. The following example shows how such an event message may look like: </p> <example caption='Node updated event, without parameters'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeUpdated xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1' nodeType='Namespace.NodeType1' cacheType='Node' state='None' hasChildren='false' isReadable='true' isControllable='true' hasCommands='true' parentId='Root' lastChanged='2013-03-19T17:58:01'/> </message>]]> </example> <example caption='Node updated event, with parameters'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeUpdated xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1' nodeType='Namespace.NodeType1' cacheType='Node' state='None' hasChildren='false' isReadable='true' isControllable='true' hasCommands='true' parentId='Root' lastChanged='2013-03-19T17:58:01'> <string id='id' name='Node ID' value='Node1'/> <string id='type' name='Node Type' value='Watchamacallit Temperature Sensor v1.2'/> <string id='sn' name='Serial Number' value='123456'/> <string id='class' name='Node Class' value='Temperature'/> <string id='meterLoc' name='Meter Location' value='P123502-2'/> <int id='addr' name='Address' value='123'/> <double id='lat' name='Latitude' value='12.345'/> <double id='long' name='Longitude' value='123.45'/> </nodeUpdated> </message>]]> </example> <p> The event has an optional attribute named <strong>oldId</strong>. It is set when the node has been renamed. It must be used, if available, to identify what node has been updated, as the following example shows: </p> <example caption='Node renamed event, without parameters'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeUpdated xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' oldId='OldNode1' nodeId='Node1' nodeType='Namespace.NodeType1' cacheType='Node' state='None' hasChildren='false' isReadable='true' isControllable='true' hasCommands='true' parentId='Root' lastChanged='2013-03-19T17:58:01'/> </message>]]> </example> <example caption='Node renamed event, with parameters'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeUpdated xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' oldId='OldNode1' nodeId='Node1' nodeType='Namespace.NodeType1' cacheType='Node' state='None' hasChildren='false' isReadable='true' isControllable='true' hasCommands='true' parentId='Root' lastChanged='2013-03-19T17:58:01'> <string id='id' name='Node ID' value='Node1'/> <string id='type' name='Node Type' value='Watchamacallit Temperature Sensor v1.2'/> <string id='sn' name='Serial Number' value='123456'/> <string id='class' name='Node Class' value='Temperature'/> <string id='meterLoc' name='Meter Location' value='P123502-2'/> <int id='addr' name='Address' value='123'/> <double id='lat' name='Latitude' value='12.345'/> <double id='long' name='Longitude' value='123.45'/> </nodeUpdated> </message>]]> </example> <p> <strong>Note: </strong>If only the status has changed, and no other parameters have changed, the <link url='#nodeStatusChanged'>nodeStatusChanged</link> event could be sent instead, for somewhat improved performance in this case. </p> </section3> <section3 topic='Node status changed' anchor='#nodeStatusChanged'> <p> The <strong>nodeStatusChanged</strong> event is sent when the <link url='#nodestates'>state of the node</link> has changed, but no other parameters have been changed. If the client has subscribed to state messages, these will also be included in the event. </p> <example caption='Node status changed event, without messages'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeStatusChanged xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1' cacheType='Node' state='ErrorUnsigned'/> </message>]]> </example> <example caption='Node status changed event, with messages'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeStatusChanged xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1' cacheType='Node' state='ErrorUnsigned'> <message timestamp='2013-03-22T12:49:34' type='Error'>Sensor does not respond to read-out requests.</message> </nodeStatusChanged> </message>]]> </example> </section3> <section3 topic='Node moved up'> <p> The <strong>nodeMovedUp</strong> event is sent when a node in a data source has been moved up among its siblings. It does not include status message or parameter information about the node, only the reference to the node. The following example shows how such an event message may look like: </p> <example caption='Node moved up'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeMovedUp xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1'/> </message>]]> </example> <p> <strong>Note:</strong> If issuing a <strong>moveNodeUp</strong> command on a node that is already first among its siblings, the node is not moved and the concentrator must not send a <strong>nodeMovedUp</strong> event. However, if the client receives such an event pointing to a node that is already first among its siblings, it should not move the node. </p> </section3> <section3 topic='Node moved down'> <p> The <strong>nodeMovedDown</strong> event is sent when a node in a data source has been moved down among its siblings. It does not include status message or parameter information about the node, only the reference to the node. The following example shows how such an event message may look like: </p> <example caption='Node moved down'> <![CDATA[ <message from='concentrator@example.org' to='client@example.org/client'> <nodeMovedDown xmlns='urn:xmpp:iot:concentrators' sourceId='MeteringTopology' nodeId='Node1'/> </message>]]> </example> <p> <strong>Note:</strong> If issuing a <strong>moveNodeDown</strong> command on a node that is already last among its siblings, the node is not moved and the concentrator must not send a <strong>nodeMovedDown</strong> event. However, if the client receives such an event pointing to a node that is already last among its siblings, it should not move the node. </p> </section3> </section2> <section2 topic='Field Databases'> <p> A concentrator can often store data from sensors locally (or remotely but controlled locally). Storage is done in <strong>field databases</strong>. A concentrator with only communicative abilities will publish zero such field databases (and support for none of the field database commands), while a pure metering database will publish one or many field databases, but none of the nodes available in any of the different data sources are readable or writable. The nodes in this latter case only acts as placeholders for the data that the concentrator is storing or controlling. </p> <p> The following subsections lists different use cases relating to field databases and how to use them. </p> <section3 topic='Get All Databases'> <p> The client can retrieve the list of available databases on the concentrator using the <strong>getDatabases</strong> command, as is shown in the following example: </p> <example caption='Get All Databases'> <![CDATA[ <iq type='get' from='client@example.org/client' to='concentrator@example.org' id='64'> <getDatabases xmlns='urn:xmpp:iot:concentrators' xml:lang='en'/> </iq> <iq type='result' from='concentrator@example.org' to='client@example.org/client' id='64'> <getDatabasesResponse xmlns='urn:xmpp:iot:concentrators' result='OK'> <database databaseId='LocalDB' name='Local Database'/> <database databaseId='LocalDBTest' name='Local Test Database'/> <database databaseId='LocalDBProduction' name='Local Production Database'/> <database databaseId='RemoteDB' name='Remote Database'/> </getDatabasesResponse> </iq>]]> </example> </section3> <section3 topic='Get Database Readout Parameters'> <p> Before reading data from a database can begin, a parameter form containing database specific search parameters needs to be fetched from the server. This is done using the <strong>getDatabaseReadoutParameters</strong> command, as is shown in the following example: </p> <example caption='Get Database Readout Parameters'> <![CDATA[ <iq type='get' from='client@example.org/client' to='concentrator@example.org' id='65'> <getDatabaseReadoutParameters xmlns='urn:xmpp:iot:concentrators' xml:lang='en' databaseId='LocalDB'/> </iq> <iq type='result' from='concentrator@example.org' to='client@example.org/client' id='65'> <getDatabaseReadoutParametersResponse xmlns='urn:xmpp:iot:concentrators' result='OK'> <x type='form' xmlns='jabber:x:data' xmlns:xdv='http://jabber.org/protocol/xdata-validate' xmlns:xdl='http://jabber.org/protocol/xdata-layout' xmlns:xdd='urn:xmpp:xdata:dynamic'> <title>Database read-out C20D4F0C-8F8A-490F-8188-53017DF2B71A Read values not older that this timestamp. Read values not newer that this timestamp. If specified, only the following fields (include wildcards) will be read out. If checked, momentary values will be read. false If checked, peak values will be read. false If checked, status values will be read. false If checked, computed values will be read. false If checked, identity values will be read. false If checked, historical values (second) will be read. false If checked, historical values (minute) will be read. false If checked, historical values (hour) will be read. false If checked, historical values (day) will be read. false If checked, historical values (week) will be read. false If checked, historical values (month) will be read. false If checked, historical values (quarter) will be read. false If checked, historical values (year) will be read. false If checked, historical values (other) will be read. false Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore Determines how this flag should be treated during readout. Ignore This parameter specifies how multiple status flags are to be treated in the readout. Any ]]>

Once the parameter form has been filled out, a database readout can be started using the startDatabaseReadout command. Data read from the concentrator will follow the same flow of sensor data as that described in &xep0323;. The only difference is that the read-out is started with the startDatabaseReadout command instead of the req command of the sensor data namespace.

The following diagram shows the flow of messages when requesting a readout from a database:

The following example shows a startDatabaseReadout request:

C20D4F0C-8F8A-490F-8188-53017DF2B71A 2013-03-22T00:00:00 2013-03-23T00:00:00 Temperature Pressure Power true false false false false false false false false false false false false false Ignore Ignore Ignore Ignore Ignore Ignore Ignore Ignore Ignore Ignore Ignore Ignore Ignore Any ... Readout messages follow.]]>

The following example shows a response when the concentrator rejects the read-out request:

... ]]>

The error might also be a result of invalid input parameters being sent:

... 2013-03-23T00:00:00 2013-03-22T00:00:00 ... The To timestamp cannot be older than the From timestamp. ]]>

A client can cancel a database read-out using the cancel read-out command, as described in Internet of Things - Sensor Data.

... ... ]]>

If an entity supports the protocol specified herein, it MUST advertise that fact by returning a feature of "urn:xmpp:iot:concentrators" in response to &xep0030; information requests.

]]> ... ... ]]>

In order for an application to determine whether an entity supports this protocol, where possible it SHOULD use the dynamic, presence-based profile of service discovery defined in &xep0115;. However, if an application has not received entity capabilities information from an entity, it SHOULD use explicit service discovery instead.

Several commands return basic node information. The following table lists possible fields with corresponding descriptions.

Attribute Use Default Description
nodeId required   The ID of the node in the data source.
displayName optional   If provided, a string presentable to users. If localization is supported and a correct language attribute was provided, this string will be localized.
nodeType optional   A string representing the type of the node.
localId optional   If provided, an ID for the node, but unique locally between siblings.
logId optional   If provided, an ID for the node, as it would appear or be used in system logs.
cacheType optional   Used to uniquely identify the node in sources where the ID of the node is not sufficient. Example: In a spatial ordering different nodes may represent countries, regions, cities, areas, streets, buildings and apartments in the same source. However, the ID of each node would depend on what type of node it represents. It might be valid to have a region, city and/or area with the same ID. So, to these circumstances, a Cache Type of Country, Region, City, Area, Street, Building and Apartment can be used to allow for non-unique IDs within the source, as long as they are unique within the same cache type. ***
state required   Current overall state of the node.
hasChildren required   If the node has children or not.
childrenOrdered optional false If the children of the node have an intrinsic order (true), or if the order is not important (false). If the order is not important, the client can present the order as it wishes, for example sorted on Node ID or any other parameter available on the child nodes. However, if the children have an intrinsic order, it's important for the client to refresh the child list when necessary whenever the order is unknown, such as after a nodeAdded event or a nodeRemoved event.
isReadable optional false If the node can be read. (*)
isControllable optional false If the node can be controlled. (**)
hasCommands optional false If the node has registered commands or not.
parentId optional   The node ID of the parent node. If not available, the node is considered a root node.
parentCacheType optional   The Cache Type of the parent node.
lastChanged optional   When the node was last changed. Can be used by clients to synchronize content between the concentrator and itself.

(*) See Internet of Things - Sensor Data for more information about how to read nodes.

(**) See Internet of Things - Control for more information about how to control nodes.

(***) Note that cacheType is optional. In some data sources it might be necessary to include a cache type to allow for IDs that are not unique within the source. In these cases, it concentrator must include the cacheType attribute for nodes in the corresponding data source, and clients must use the corresponding cacheType value when referencing the node. But if such a separation of IDs within a source is not required, the concentrator may ignore the cacheType attribute. In these instances clients may also ignore the cacheType attribute when referencing the nodes in the corresponding data source, or use the empty string as value for the cacheType value. The server must ignore empty cacheType values for data sources not using a cache type separation mechanism.

Nodes can report parameters of different types. The following table lists available parameter types.

Element Name Parameter Value
boolean Boolean values. Can be true or false.
color Color values. They are strings containing 6 case-insensitive hexadecimal digits of the form RRGGBB, where RR=Red component, GG=Green component, BB=Blue component.
dateTime Date and time value, with possible time zone information.
double double precision floating point value.
duration A time duration value.
int A 32-bit integer value.
long A 64-bit integer value.
string A string value.
time A time value using a 24-hour clock.

All responses have a response code that the client is required to check. The following table lists possible response codes and their corresponding meanings.

Response Code Description
OK Request is OK and accepted.
NotFound Corresponding object, node, etc., was not found.
InsufficientPrivileges Insufficient privileges to perform the corresponding action or execute the corresponding command. Make sure to provide sufficient credentials in the call (user, service, device tokens) with sufficient privileges to perform the action/command.
Locked The object/node is locked, and operation could not be performed or completed.
NotImplemented Command is not implemented.
FormError The form send to the concentrator contains errors. The response contains detailed error information.
OtherError Another error occurred.

It's important that the concentrator responds to unrecognized commands. This, to make sure future extensions to this document does not produce unexpected results in concentrators implementing a previous version, or in concentrators implementing only a subset of available commands.

When a concentrator receives an element that it does not understand, it must do as follows:

  • If the element is received in a message stanza, the element must be ignored.
  • If the element is received in an iq-result stanza, the element must be ignored.
  • If the element is received in an iq-get or iq-set stanza, an iq-result stanza must be composed containing an element with the same name as the incoming element, but with Response appended to it, having a response code of NotImplemented.

The following example shows how unrecognized commands must be handled by the concentrator:

... ]]>

Node commands have a set of attributes. The following table lists available attributes and what they mean.

Attribute Use Description
command required ID of the command. Used to identify the command.
name required A string that can be presented to an end-user. Should be localized if the request contained a language preference.
type required If the command is 'Simple' or 'Parameterized'.
sortCategory optional Should be used (if available) by clients to sort available node commands before presenting them to an end-user. Commands should be sorted by Sort Category, Sort Key and lastly by Name.
sortKey optional Should be used (if available) by clients to sort available node commands before presenting them to an end-user. Commands should be sorted by Sort Category, Sort Key and lastly by Name.
confirmationString optional Should presented to clients (if available) before letting an end-user execute the command. A delete command might have a confirmationString saying 'Are you sure you want to delete the current item?' The confirmation string should be presented as a Yes/No[/Cancel] dialog.
failureString optional Could be presented to end-users (if available) if a command fails. It provides the client with an optionally localized string giving some context to the error message. A delete command might have a failureString saying 'Unable to delete the current item.'. The client could then add additional error information, if available, for instance from the response code.
successString optional Could be presented to end-users (if available) if a command is successfully executed. It provides the client with an optionally localized string giving some context to the message. A delete command might have a successString saying 'Current item successfully deleted.'.

Nodes can be in different states. Even though nodes are free to publish any amount of states as parameters, there are a set of states that are so crucial to the concept of a node state, that they are published using a separate attribute and separate events. These node states are as follows:

State Description
None The node has nothing special to report.
Information The node has informative events reported on it.
WarningSigned The node has warnings reported on it. These warnings have been viewed by an operator.
WarningUnsigned The node has warnings reported on it that have not been viewed by anybody.
ErrorSigned The node has errors reported on it. These errors have been viewed by an operator.
ErrorUnsigned The node has errors reported on it that have not been viewed by anybody.

The following table lists required data sources for concentrators (of sensors, actuators, meters, etc.) in sensor networks:

Data Source Description
MeteringTopology Data Source containing the topology of metering devices, including sensors, actuators, meter, infrastructure components, etc.

More information can be found in the XEP-xxxx: Interoperability Interoperability section.

Table columns in query results can have the following attributes:

Attribute Use Description
columnId Required ID of column
header Optional If provided, a localized name to be displayed instead of the column ID.
alignment Optional Alignment of contents in the column. If provided, the client does not need to guess alignment from the type of data reported.
nrDecimals Optional If floating point data is presented in the column and a fixed number of decimals is desired, this attribute is used to fix the number of decimals used.
dataSourceId Optional If contents of columns contains references to nodes in a data source, this attribute defines the data source ID.
cacheTypeName Optional If contents of columns contains references to nodes in a data source, this attribute defines the cache type.
fgColor Optional If presentation of this column should be done using a specific foreground color.
bgColor Optional If presentation of this column should be done using a specific background color.

Records contain arrays of items, each item correspond to a specific column with the same ordinal index. Each item is specified together with its type. This, so receptors can integrate the result with type information if necessary. The following different type elements are available:

Element Contents
boolean A boolean value, corresponding to the xs:boolean data type.
color A color value. These are strings containing 6 case-insensitive hexadecimal digits of the form RRGGBB, where RR=Red component, GG=Green component, BB=Blue component.
dateTime A Date & Time value, corresponding to the xs:dateTime data type.
double A floating-point value, corresponding to the xs:double data type.
duration A duration value, corresponding to the xs:duration data type.
int A 32-bit integer value, corresponding to the xs:int data type.
long A 64-bit value, corresponding to the xs:long data type.
string A string value, corresponding to the xs:string data type.
time A time value, corresponding to the xs:time data type.
base64 A base-64 encoded object. The object is MIME encoded, and the attribute contentType contains the MIME Type which includes information on how to decode the value.
void Contains no information. This represents a NULL value.

Messages in query results contain apart from a message text, also contain some classification on what the message is using two attributes: The type attribute gives a rough idea about the type of message and level the importance of the message.

Type Description
Information Information message
Warning Message contains a warning. The situation could turn into an error if consideration or action is not taken.
Error Message contains an error. The error message describes the error, and the error has been handled correctly by the device performing the query.
Exception Message contains an exception message. An unforseen and perhaps an unhandled event has occurred during the execution of the query.
Level Description
Minor Minor event. Message describes common tasks.
Medium Medium event. Message might describe a state change, something has been updated, or important information.
Major Major event. Message might describe architectural change or vital information.

Many commands exist in single and batch versions. Large concentrators require efficient ways to manage sets of nodes simultaneously, while for small concentrators, it is sufficient to manage nodes one at a time.

A concentrator is not required to implement both sets of commands if not desired. However, it must report which commands it supports in the getCapabilities command. A caller can then adapt its calls based on what commands are supported.

If a caller wants to call the single item version of a command, but the concentrator only supports the batch version, it should call the batch version, but only include the single node in the list of nodes.

On the other hand, if the caller wants to perform an operation on a set of nodes, but the concentrator only supports the single item version of the command, it needs to manually perform the operation on each node separately, unless failing the request is an option.

Localization of content can be performed if clients provide xml:lang attributes in commands made to the concentrator. If omitted, the default language will be used in responses. If provided, but the concentrator does not support localization, or the requested language, the default language will also be used.

Concentrators of larger sub-systems spanning multiple time-zones should specify all timestamps with time-zone information, so readers can perform comparisons of time information.

Information read from a concentrator that lacks time-zone information should be considered to lie in the same time-zone as the reader, unless not explicitly configured with a time-zone.

For concentrators to be interoperable in sensor networks, they need to adhere to rules and guidelines described in the xep-0000-IoT-Interoperability document.

This document publishes a lot of commands with which to interact with a concentrator. If security and access rights is an issue, it might not be sufficient to allow all friends access to the system. There are many ways in which to restrict access to the contents of the concentrator. Following are some examples:

  • The concentrator can restrict friendships to trusted friends, and then assign access rights internally to the approved contacts.
  • The concentrator can use a provisioning server (see &xep0324;) to delegate trust to a third party responsible for controlling who can get access to the concentrator (isFriend or canAccess commands), and what items can be viewed (hasPrivilege or downloadPrivileges commands).
  • All requests to the concentrator can contain the optional attributes deviceToken, serviceToken and userToken. Clients making requests to the concentrator can use these attributes to forward information about who originated the action (userToken), what service is performing the action (serviceToken) or what device is performing the action (deviceToken). The concentrator can use this information to check with provisioning servers what access rights and user privileges exist before performing the action.

The Internet of Things - Provisioning document describes how trust can be delegated to trusted provisioning servers that can be used to restrict access to and privileges in a network.

If a concentrator has a trusted relationship with a provisioning server, external or internal, the provisioning server must be used to guarantee that the concentrator only allows access according to rules defined by the provisioning server. In order to do this, it's important that clients always provide available tokens (userToken, serviceToken and deviceToken) to the concentrator so that it can forward this information to the provisioning server.

The following subsections show different examples of how such an integration can be performed.

This section shows how a provisioning server can be used to restrict access to data sources to users allowed to access those data sources.

Notice the following:

  • The user has a userToken it received during connection with the service. This user token should be included in all calls made by the user.
  • The service has a serviceToken it received during service registration. This service token should be aggregated by all calls made by the service.
  • The concentrators should cache all calls made to the provisioning server according to available cache rules.
  • The conversion of a Data Source ID to a Privilege ID should be performed according to rules defined in xep-0000-IoT-Interoperability.

This section shows how a provisioning server can be used to restrict access to node parameters that users allowed to access and edit.

  • Not that privileges for all parameters needs to be checked in every call. And if lost from the cache, a new request needs to be made to the provisioning server.
  • The conversion of a Parameter ID (and Page) to a Privilege ID should be performed according to rules defined in xep-0000-IoT-Interoperability.

This section shows how a provisioning server can be used to restrict access to node commands to users allowed to access those commands.

In addition to rules noted above, also notice the following:

  • Not that privileges for all parameters needs to be checked in every call. And if lost from the cache, a new request needs to be made to the provisioning server.
  • The conversion of a Command ID to a Privilege ID should be performed according to rules defined in xep-0000-IoT-Interoperability.

This document requires no interaction with &IANA;.

The protocol schema needs to be added to the list of XMPP protocol schemas.

]]>

For more information, please see the following resources:

Thanks to Joachim Lindborg, Karin Forsell, Tina Beckman and Klaudiusz Staniek for all valuable feedback.