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<!-- Copyright (C) 2004 The Apache Software Foundation. All rights reserved. -->
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<document>
 <header>
  <title>POI 2.0 Vision Document</title>
  <authors>
   <person name="Andrew C. Oliver" email="acoliver2@users.sourceforge.net"/>
   <person name="Marcus W. Johnson" email="mjohnson@apache.org"/>
   <person name="Glen Stampoultzis" email="poi-user@jakarta.apache.org"/>
   <person name="Nicola Ken Barozzi" email="barozzi@nicolaken.com"/>      
   </authors>
 </header>

 <body>
 
 <section><title>Preface</title>
        <p>
                This is the POI 2.0 cycle vision document.  Although the vision
                has not changed and this document is certainly not out of date and 
                the vision has not changed, the structure of the project has
                changed a bit.  We're not going to change the vision document to
                reflect this (however proper that may be) because it would only
                involve deletion.  There is no purpose in providing less
                information provided we give clarification.
        </p>
        <p>
                This document was created before the POI components for 
                <link href="http://xml.apache.org/cocoon">Apache Cocoon</link> 
                were accepted into the Cocoon project itself.  It was also
                written before POI was accepted into Jakarta.  So while the
                vision hasn't changed some of the components are actually now
                part of other projects.  We'll still be working on them on the
                same timeline roughly (minus the overhead of coordination with
                other groups), but they are no longer technically part of the
                POI project itself.
        </p>
 </section>

 <section><title>1. Introduction</title>
  <section><title>1.1 Purpose of this document</title>
	<p>
                The purpose of this document is to
                collect, analyze and define high-level requirements, user needs, 
                and features of the second release of the POI project software. 
                The POI project currently consists of the following components: 
                the HSSF Serializer, the HSSF library and the POIFS library.
	</p>
        <ul>
	        <li>
                        The HSSF Serializer is a set of Java classes whose main 
                        class supports the Serializer interface from the Cocoon 
                        2 project and outputs the serialized data in a format 
                        compatible with the spreadsheet program Microsoft Excel 
                        '97.
                </li>
	        <li>
                        The HSSF library is a set of classes for reading and 
                        writing Microsoft Excel 97 file format using pure Java.
                </li>
	        <li>
                        The POIFS library is a set of classes for reading and 
                        writing Microsoft's OLE 2 Compound Document format using 
                        pure Java.
                </li>
        </ul>  
        <p>By the completion of this release cycle the POI project will also
        include the HSSF Generator and the HWPF library.
        </p>
        <ul>
	        <li>The HSSF Generator will be responsible for using HSSF to read
	        in the XLS (Excel 97) file format and create SAX events. The HSSF
	        Generator will support the applicable interfaces specified by the
	        Apache Cocoon 2 project.
                </li>
	        <li>The HWPF library will provide a set of high level interfaces
	        for reading and writing Microsoft Word 97 file format using pure
	        Java.</li>
        </ul>
        
  </section>
  

  <section><title>1.2 Project Overview</title>
        <p>
                The first release of the POI project
                was an astounding success. This release seeks to build on that
                success by:
        </p>
        <ul>
                <li>
                        Refactoring POIFS into imput and
                        output classes as well as an event-driven API for reading.
                </li>
                <li>
                        Refactor HSSF for greater
	                performance as well as an event-driven API for reading
                </li>
                <li>
                        Extend HSSF by adding the ability to read and write formulas.
                </li>
	        <li>
                        Extend HSSF by adding the ability to read and write 
                        user-defined styles.
                </li>
	        <li>
                        Create a Cocoon 2 Generator for HSSF using the same tags 
                        as the HSSF Serializer.
                </li>
	        <li>
                        Create a new library (HWPF) for reading and writing 
                        Microsoft Word DOC format.
                </li>
	        <li>
                        Refactor the HSSFSerializer into a separate extensible 
                        POIFSSerializer and HSSFSerializer
                </li>
                <li>
                        Providing the create excel charts. (write only)
                </li>
        </ul>
  </section>
 </section>
 <section><title>2. User Description</title>
   <section><title>2.1 User/Market Demographics</title>
	<p>
                There are a number of enthusiastic
                users of XML, UNIX and Java technology. Furthermore, the Microsoft
                solution for outputting Office Document formats often involves
                actually manipulating the software as an OLE Server. This method
                provides extremely low performance, extremely high overhead and is
                only capable of handing one document at a time.	
        </p>
        <ol>
                <li>
                        Our intended audience for the HSSF
                        Serializer portion of this project are developers writing reports or
                        data extracts in XML format.
                </li>
                <li>
                        Our intended audience for the HSSF
                        library portion of this project is ourselves as we are developing
                        the HSSF serializer and anyone who needs to read and write Excel
                        spreadsheets in a non-XML Java environment, or who has specific
                        needs not addressed by the Serializer
                </li>
                <li>
                        Our intended audience for the
                        POIFS library is ourselves as we are developing the HSSF and HWPF
                        libraries and anyone wishing to provide other libraries for
                        reading/writing other file formats utilizing the OLE 2 Compound
                        Document Format in Java.
                </li>
                <li>
                        Our intended audience for the HSSF
                        generator are developers who need to export Excel spreadsheets to
                        XML in a non-proprietary environment.
                </li>
                <li>
                        Our intended audience for the HWPF
                        library is ourselves, as we will be developing a HWPF Serializer in a
                        later release, and anyone wishing to add .DOC file processing and
                        creation to their projects.
                </li>
        </ol>        
   </section>
   <section><title>2.2. User environment</title>
        <p>
                The users of this software shall be
                developers in a Java environment on any operating system, or power
                users who are capable of XML document generation/deployment.
        </p>
   </section>
   <section><title>2.3. Key User Needs</title>
	<p>
                The HSSF library currently requires a
                full object representation to be created before reading values. This
                results in very high memory utilization. We need to reduce this
                substantially for reading. It would be preferable to do this for
                writing, but it may not be possible due to the constraints imposed by
                the file format itself. Memory utilization during read is our top
                user complaint.	
        </p>
	<p>
                The POIFS library currently requires a
                full object representation to be created before reading values. This
                results in very high memory utilization. We need to reduce this
                substantially for reading.	
        </p>
        <p>
                The HSSF library currently ignores
                formula cells and identifies them as &quot;UnknownRecord&quot; at the
                lower level of the API. We must provide a way to read and write
                formulas. This is now the top requested feature.
        </p>
        <p>
                The HSSF library currently does not support
                charts.  This is a key requirement of some users who wish to use HSSF
                in a reporting engine.
        </p>
        <p>
                The HSSF Serializer currently does not
                provide serialization for cell styling. User's will want stylish
                spreadsheets to result from their XML.
        </p>
        <p>
                There is currently no way to generate
                the XML from an XLS that is consistent with the format used by the
                HSSF Serializer.
        </p>
        <p>
                There should be a way to read and write
                the DOC file format using pure Java.
        </p>	

   </section>
   <section><title>2.4. Alternatives and Competition</title>
	        <p>
            Originally there weren't any decent <link href="../hssf/alternatives.html">alternatives</link> for reading or writing
            to Excel.  This has changed somewhat.
            </p>
   </section>
 </section>
 <section><title>3. Project Overview</title>
   <section><title>3.1. Project Perspective</title>
	<p>
                The produced code shall be licensed by
                the Apache License as used by the Cocoon 2 project (APL 1.1) and
                maintained on at <link href="http://poi.sourceforge.net/">http://poi.sourceforge.net</link>
                and <link href="http://sourcefoge.net/projects/poi">http://sourcefoge.net/projects/poi</link>.
                It is our hope to at some point integrate with the various Apache
                projects (xml.apache.org and jakarta.apache.org), at which point we'd
                turn the copyright over to them.
	</p>
   </section>
   <section><title>3.2. Project Position Statement</title>
	<p>
                For developers on a Java and/or XML
                environment this project will provide all the tools necessary for
                outputting XML data in the Microsoft Excel format. This project seeks
                to make the use of Microsoft Windows based servers unnecessary for
                file format considerations and to fully document the OLE 2 Compound
                Document format. The project aims not only to provide the tools for
                serializing XML to Excel and Word file formats and the tools for
                writing to those file formats from Java, but also to provide the
                tools for later projects to convert other OLE 2 Compound Document
                formats to pure Java APIs.
	</p>
   </section>
   <section><title>3.3. Summary of Capabilities</title>
	<p>
		HSSF Serializer for Apache Cocoon 2
	</p>
	<table>
		<tr>
			<th>
				Benefit
			</th>
			<th>
				Supporting Features
			</th>
		</tr>
		<tr>
			<td>
				Ability to serialize styles from XML spreadsheets.
			</td>
			<td>
				HSSFSerialzier will support styles.
			</td>
		</tr>
		<tr>
			<td>
				Ability to read and write formulas in XLS files.
			</td>
			<td>
				HSSF will support reading/writing formulas.
			</td>
		</tr>
		<tr>
			<td>
				Ability to output in MS Word on any platform using Java.
			</td>
			<td>
				The project will develop an API that outputs in Word format
			        using pure Java.
			</td>
		</tr>
		<tr>
			<td>
				Enhance performance for reading and writing XLS files.
			</td>
			<td>
				HSSF will undergo a number of performance enhancements. HSSF
			        will include a new event-based API for reading XLS files. POIFS
			        will support a new event-based API for reading OLE2 CDF files.
			</td>
		</tr>
		<tr>
			<td>
				Ability to generate XML from XLS files
			</td>
			<td>
				The project will develop an HSSF Generator.
			</td>
		</tr>
		<tr>
			<td>
				The ability to generate charts
			</td>
			<td>
                                HSSF will provide low level support for chart records as well
                                as high level API support for generating charts.  The ability
                                to read chart information will not initially be provided.
                        </td>
		</tr>
                
	</table>   
   </section>
   <section><title>3.4. Assumptions and Dependencies</title>
	<ul>
		<li>
                        The HSSF Serializer and Generator
	                will support the Gnumeric 1.0 XML tag language.
                </li>
		<li>
                        The HSSF Generator and HSSF
                        Serializer will be mutually validating.  It should be possible to
                        have an XLS file created by the Serializer run through the Generator
                        and the output back through the Serializer (via the Cocoon pipeline)
	                and get the same file or a reasonable facimille (no one cares if it
	                differs by the order of the binary records in some minor but
	                non-visually recognizable manner).
		</li>
		<li>
                        The HSSF Generator will run on any
	                Java 2 supporting platform with Apache Cocoon 2 installed along with
	                the HSSF and POIFS APIs.
                </li>
		<li>
                        The HSSF Serializer will run on
                        any Java 2 supporting platform with Apache Cocoon 2 installed along
                        with the HSSF and POIFS APIs.
                </li>
		<li>
                        The HWPF API requires a Java 2
                        implementation and the POIFS API.
                </li>
		<li>
                        The HSSF API requires a Java 2
                        implementation and the POIFS API.
                </li>
		<li>
                        The POIFS API requires a Java 2
                        implementation.
                </li>
                
	</ul>	
   </section>
 </section>
 <section><title>4. Project Features</title>
	<p> 
                Enhancements to the POIFS API will
                include:
	</p>
	<ul>
		<li>
                        An event driven API for reading
                        POIFS Filesystems.
		</li>
		<li>
			A low-level API for
			creating/manipulating POI filesystems.
		</li>
		<li>
                        Code improvements supporting
	                greater separation between read and write structures.
		</li>
	</ul>	
	<p>
                        Enhancements to the HSSF API will
                        include:
	</p>
	<ul>
		<li>
                        An event driven API for reading
                        XLS files.
		</li>
		<li>
                        Performance improvements.
		</li>
		<li>
                        Formula support (read/write)
		</li>
		<li>
                        Support for user-defined data
                        formats
		</li>
		<li>
                        Better documentation of the file
                        format and structure.
		</li>
		<li>
                        An API for creation of charts.
		</li>                                
	</ul>
	<p>
                The HSSF Generator will include:
	</p>
	<ul>
		<li>
                        A set of classes supporting the
	                Cocoon 2 Generator interfaces providing a method for reading XLS
	                files and outputting SAX events.
		</li>
		<li>
                        The same tag format used by the
                        HSSFSerializer in any given release.
		</li>
	</ul>
	<p>
                The HWPF API will include:
	</p>
	<ul>
		<li>
                        An event driven API for reading
	                DOC files.
                </li>
		<li>
                        A set of high and low level APIs
                        for reading and writing DOC files.
                </li>
		<li>
                        Documentation of the DOC file
                        format or enhancements to existing documentation.
                </li>                
	</ul>	
 </section>		
 <section><title>5. Other Product Requirements</title>
   <section><title>5.1. Applicable Standards</title>
	<p>
		All Java code will be 100% pure Java.
	</p>
   </section>
   <section><title>5.2. System Requirements</title>
	<p>
		The minimum system requirements for the POIFS API are:
	</p>
	<ul>
		<li>64 Mbytes memory</li>
		<li>Java 2 environment</li>
		<li>Pentium or better processor (or equivalent on other platforms)</li>
	</ul>	
	<p>
		The minimum system requirements for the the HSSF API are:
	</p>
	<ul>
		<li>64 Mbytes memory</li>
		<li>Java 2 environment</li>
		<li>Pentium or better processor (or equivalent on other platforms)</li>
		<li>POIFS API</li>
	</ul>
	<p>
		The minimum system requirements for the the HWPF API are:
	</p>
	<ul>
		<li>64 Mbytes memory</li>
		<li>Java 2 environment</li>
		<li>Pentium or better processor (or equivalent on other platforms)</li>
		<li>POIFS API</li>
	</ul>	
	
	<p>
		The minimum system requirements for the HSSF Serializer are:
	</p>
	<ul>
		<li>64 Mbytes memory</li>
		<li>Java 2 environment</li>
		<li>Pentium or better processor (or equivalent on other platforms)</li>
		<li>Cocoon 2</li>
		<li>HSSF API</li>
		<li>POI API</li>
	</ul>	
   </section>
   <section><title>5.3. Performance Requirements</title>
	<p>
		All components must perform well enough
		to be practical for use in a webserver environment (especially
		the "killer trio": Cocoon2/Tomcat/Apache combo)
	</p>
   </section>
   <section><title>5.4. Environmental Requirements</title>
	<p>
		The software will run primarily in
		developer environments. We should make some allowances for
		not-highly-technical users to write XML documents for the HSSF
		Serializer. All other components will assume intermediate Java 2
		knowledge. No XML knowledge will be required except for using the
		HSSF Serializer. As much documentation as is practical shall be
		required for all components as XML is relatively new, and the
		concepts introduced for writing spreadsheets and to POI filesystems
		will be brand new to Java and many Java developers.
	</p>
   </section>
 </section>
 <section><title>6. Documentation Requirements</title>
   <section><title>6.1 POI Filesystem</title>
	<p>
		The filesystem as read and written by
		POI shall be fully documented and explained so that the average Java
		developer can understand it.
	</p>
   </section>
   <section><title>6.2. POI API</title>
	<p>
		The POI API will be fully documented
		through Javadoc. A walkthrough of using the high level POI API shall
		be provided. No documentation outside of the Javadoc shall be
		provided for the low-level POI APIs.	
	</p>
   </section>
   <section><title>6.3. HSSF File Format</title>
	<p>
		The HSSF File Format as implemented by
		the HSSF API will be fully documented. No documentation will be
		provided for features that are not supported by HSSF API that are
		supported by the Excel 97 File Format. Care will be taken not to
		infringe on any &quot;legal stuff&quot;.  Additionally, we are 
                collaborating with the fine folks at OpenOffice.org on
                *free* documentation of the format.
	</p>
   </section>
   <section><title>6.4. HSSF API</title>
	<p>
		The HSSF API will be documented by
		javadoc. A walkthrough of using the high level HSSF API shall be
		provided. No documentation outside of the Javadoc shall be provided
		for the low level HSSF APIs.	
	</p>
   </section>
   <section><title>6.5 HWPF API</title>
	<p>
                The HWPF API will be documented by
                javadoc. A walkthrough of using the high level HWPF API shall be
                provided. No documentation outside of the Javadoc shall be provided
                for the low level HWPF APIs.        
	</p>
   </section>   
   <section><title>6.6 HSSF Serializer</title>
	<p>
		The HSSF Serializer will be documented
		by javadoc. 	
	</p>
   </section>
   <section><title>6.7 HSSF Generator</title>
	<p>
		The HSSF Generator will be documented
		by javadoc. 	
	</p>
   </section>      
   <section><title>6.8 HSSF Serializer Tag language</title>
	<p>
		The XML tag language along with
		function and usage shall be fully documented. Examples will be
		provided as well.
	</p>
   </section>
 </section>
 <section><title>7. Terminology</title>
   <section><title>7.1 Filesystem</title>
	<p>
		filesystem shall refer only to the POI formatted archive.
	</p>
   </section>
   <section><title>7.2 File</title>
	<p>
		file shall refer to the embedded data stream within a 
		POI filesystem. This will be the actual embedded document. 
	</p>
   </section>
 </section>
</body>
</document>
