<p>Generic maps provide a way to extending the roster into a general display showing contacts (JIDs) together with further additional information. The further information is provided by the position in the map (and possibly by the dot type - e.g. shape or colour). In addition to showing people belonging to one roster group, it is possible to cluster people, use more detailed inset maps etc. each of these features providing a unique context.</p>
<li>It is faster and easier to find people using a rich graphical view as compared to linear lists/trees</li>
<li>Maps provide easily understandable further information (context) about the contact</li>
<li>Maps show relations among JIDs and give better idea about their distribution in a given space (e.g. geographic region, company, campus)</li>
</ul>
</section1>
<section1topic='Requirements'>
<p>The requirements for the protocol are:</p>
<ul>
<li>General definition of projection based on some attribute(s) of particular JIDs</li>
<li>Scaleability - in display size and size of transmitted data</li>
</ul>
</section1>
<section1topic='Use Cases'>
<p>Generic Map is actually XML description of a graphical display, which can then be sent as a part of <message/> or <iq/> packet together with information about how to obtain attributes needed for its display (other resources required).</p>
<section2topic='Generic Map message'>
<p>Example 1 shows a typical message containing simple Generic Map.</p>
<p>Each map consists of one or more layers. The main purpose of layers is to combine maps and views to deliver information suitable for a particular context, and to offer greater flexibility to the user in respect to customization.</p>
<p>Layers can be defined either inline or by a reference to another map. Each layer has a specified position in the map, a scale and a priority. The maps defined inline contain also projection, underlying image and a list of entities lying inside it (i.e. typically JIDs or clusters of JIDs). The underlying images are sent out of band using the jabber:x:oob namespace or possibly defined in some other way (e.g. xml-based SVG).</p>
<p>The map in Example 1 uses an implicit map projection assuming that attributes x and y are directly the co-ordinates of a particular entity (e.g. buddy1@jabber.org) in the image (ortho_0.gif) expressed in pixels.</p>
<p>A similar map with coordinates specified using geographic latitude + longitude (possibly obtained using Geographic Location Information <note>XEP-0080: Geographic Location Information <linkurl='http://www.xmpp.org/extensions/xep-0080.html'>http://www.xmpp.org/extensions/xep-0080.html</link></note> extension) is shown in Example 2 (only the map tag is shown).</p>
<p>As can be seen in Example 2, the projection can be specified using any parameters either explicitly set in the item tags or obtained for the particular JID from some other source (e.g. JUD or LDAP).</p>
</section2>
<section2topic='Scaleability'>
<p>Another important feature of this proposal is scaleability, which is achieved by grouping the individual JIDs with similar properties (e.g. 'near' locations) into clusters. Cluster is basically a list of constituting entities (JIDs) that share similar values of specified attribute (e.g. JIDs that are co-located in the same town/region/country). The size of clusters may depend on the resolution and intended scale of the map. In the map clusters can be displayed using a distinctive icon.</p>
<examplecaption='Generic map tag with clustered items'><