JEP-0143: Guidelines for JEP Authors

4.1 Working With JEP Files

The best way to start working on your proposal is to retrieve all of the existing JEPs and associated stylesheets from source control. These files are stored using the CVS system, in a CVS module labelled 'jeps' at the jabberstudio.org CVS repository. Instructions for accessing these files are provided at <http://www.jabberstudio.org/cvs.php>. The document structure is formally defined by both a DTD and an XML schema, but you do not need to understand these in order to author a JEP. In addition, a handy template file is included under the "templates/" directory in the "jeps" module, providing an easy starting point for JEP authoring.

To create your proposal, do a CVS checkout of the 'jeps' module, create a new directory (e.g., 'tmp/') for your JEP within the existing 'jeps/' directory, copy the template file from the 'template/' directory to your new directory, and start editing the file using either a basic text editor or a specialized XML editing application such as XML Spy or XMLmind.

Even if you use a basic text editor, you should be able to view your JEP in most modern web browsers as an XML file as long as you have jep.xsl and jep.dtd in the 'jeps/' directory (i.e., the parent of the directory for your specific JEP). Because of inconsistencies in browser XSLT implementations, certain formatting (e.g., table layouts and the numbering of tables, examples, and footnotes) may not be perfect. Don't panic; it will look fine in HTML. If your XML file doesn't render at all (i.e., it's just one big text blob), you are using the wrong browser. If you see only the bare outline generated by jep.xsl but none of your text, you have an error in your XML. You can check your XML syntax at xml.com [8].

To programatically convert your XML file into HTML, we recommend using Daniel Veillard's xsltproc program, which will give you helpful error messages regarding XML syntax problems. However, the JEP Editor will do the final rendering of XML into HTML as well as posting of your HTML file to the JSF website, so you do not need to generate HTML files for submission to the JEP Editor (in fact, the JEP Editor requires that you submit your proposal in the JEP XML format, not HTML).

Finally, the jep.ent file contains helpful "external entities" that provide shortcuts for including references to JEPs, RFCs, and other common strings. Unfortunately, most browsers do not correctly process external entities, so you cannot include entities from jep.ent if you need to view your XML source file in a browser. However, the JEP Editor reserves the right to convert your markup to external entities, since it makes his life easier. Also, please do not add items to the jep.ent file; instead, ask the JEP Editor to add them for you.

4.2 File Metadata

This section describes the metadata elements contained in the <header/> element of a JEP file (see below for the file contents).

The XML character data of the <title/> element is the title of your JEP. Choose a descriptive title that is less than five words long. The JEP Editor may change this in consultation with the author.

The XML character data of the <abstract/> element SHOULD be one sentence that captures the essence of your proposal (usually beginning "This JEP defines a protocol that..."). The JEP Editor has been known to modify the abstract so that it accurately describes the proposal.

The XML character data of the <legal/> element MUST be as follows:

This Jabber Enhancement Proposal is copyright 1999 - 2004 by the Jabber Software Foundation (JSF) and is in full conformance with the JSF's Intellectual Property Rights Policy (http://jabber.org/jsf/ipr-policy.php). This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/).

Your JEP number will be assigned by the JEP Editor; thus you can just make the XML character data of the <number/> element "xxxx".

The XML character data of the <status/> element SHOULD be "Experimental" since all JEPs start out as Experimental.

The XML character data of the <type/> element SHOULD be either "Standards Track" or "Informational" (there are also Historical and Procedural JEPs, but these are uncommon and usually written by the JEP Editor). A Standards Track JEP is basically any JEP that defines a protocol to be used in the Jabber community. An Informational JEP defines best practices or a usage profile related to an existing protocol (e.g., Invisibility [9]).

The XML character data of the <approver/> element SHOULD be "Council".

The <dependencies/> element is used to specify JEPs, RFCs, and other specifications on which your proposal depends in a normative fashion (i.e., specifications that MUST or SHOULD be implemented in order to implement your proposed protocol). Each specification MUST be identified by a distinct <spec/> child element (see existing JEPs for clues regarding document identifiers, or consult with the JEP Editor).

The <supersedes/>, <supersededby/>, <shortname/>, and <schemaloc/> elements are for use by the JEP Editor; however, if your JEP supersedes an existing JEP, feel free to include a <spec/> child element specifying the document identifier (e.g., JEP-0093) for the protocol that is being superseded.

Include one <author/> element for each co-author. Note well that the <firstname/>, <surname/>, <email/>, and <jid/> elements are all mandatory per JEP-0001.

Include one <revision/> element for each revision of your JEP. The XML character data of the <version/> element SHOULD be "0.0.1" for your initial submission to the JEP Editor, and the <remark/> SHOULD be "Initial version."; for each revision, you will include another <revision/> element (place it before the existing <revision/> elements) and iterate the <version/> element (e.g., "0.2" after "0.1"). The format for the <date/> element is yyyy-mm-dd. Please do not include the characters ' or " in your revision remarks.

4.3 File Contents

Aside from the metadata in the JEP <header/> element (see above), a JEP file is a series of sections, arranged in a hierarchy (<section1/> is a top-level section, within which you can nest <section2/> sections, and so on down to <section4/>). The title of a section is captured in the 'topic' attribute. You may also include an 'anchor' element so that you can link to page fragments from within your JEP. The allowable elements within a section element probably look familiar: <p/> for paragraphs, <ol/> and <ul/> for ordered and unordered lists, and so on.

The <example/> and <code/> elements are used to show protocol snippets; the <example/> element includes a 'caption' attribute so that you can provide a description of the example, whereas the <code/> element does not. Define an XML CDATA section within both of these elements so that you do not need to escape the '<' and '>' characters in your sample XML stanzas, since this makes life much easier for author and editor alike.

The <p/> and <li/> elements can also contain more markup that is familiar from HTML, such as the <img/> element. Note that hyperlinks are of the form <link url='foo'>bar</link> rather than <a href='foo'>bar</a>; the reasons for this are lost in the mists of time and it is too late to change it now, so you'll just have to adjust. If needed, you can also use inline structural and presentational markup such as <em/>, <strong/>, <tt/>, <cite/>, and <span/> within the <p/> and <li/> elements.

You can also include tables (these are helpful for listing error codes and such). The <table/> element also can possess a 'caption' attribute so that you can provide a description of the table's contents. Standard HTML table structure applies (<tr/> defines a row, which contains <th/> elements for header rows and <td/> elements for data rows), and the 'colspan' and 'rowspan' attributes are also available if you need them. Table presentation (such as cellpadding and cellspacing) is handled by the XSLT and CSS stylesheets.

In fact, the jep.xsl file performs all sorts of magic in converting your XML file into HTML, including creation of the front matter, table of contents, section numbering, notes, and revision history. Feel free to submit patches for this file, but do not commit your modified version to CVS.

5.1 Introduction

The introduction to a JEP is quite important since it provides the rationale for considering the proposal. In particular, the introduction SHOULD include information such as the following:

1. Tasks that users currently cannot complete because we are lacking the protocol you propose. (Note: users are not just IM users, but any person, system, or application that could gain value from interacting with other entities over Jabber/XMPP networks.)
2. Other projects or protocols and how Jabber technologies could interface with them because of your proposed protocol (e.g., XML-RPC, SOAP).
3. A comparison between Jabber technologies and "the competition" (e.g., other IM systems or messaging protocols) that describes holes in the Jabber protocols that need to be filled in order to offer similar functionality.
4. The relevant history of thinking within the Jabber community.
5. Real-world examples of problems the protocol can solve.

5.2 Glossary

If your JEP uses terms that may not be familiar to the reader, please define them in a glossary.

5.3 Requirements

Every JEP SHOULD include a section describing the requirements being addressed by the JEP. This information is critically important, because it clearly defines the scope of the proposal as well as any relevant constraints on the protocol design.

5.4 Use Cases

It is recommended that JEP authors structure their proposals according to the use cases that the proposal will address. [11] We have found that use cases force JEP authors to focus on functionality rather than "protocol for the sake of protocol". It is also helpful to sort use cases by actor, as is done in Multi-User Chat [12], for example. Include one subsection for each use case.

When writing use cases and the associated protocols, make sure to:

• Clearly define the successful scenarios as well as alternate flows.
• Include lots of protocol examples.
• Describe the expected behavior of Jabber clients, servers, and components when using this protocol.

We just said so, but we will repeat ourselves: include lots of protocol examples. Examples help not only implementors but also those who will review your proposal in the Standards JIG [13] and Jabber Council [14]. You get extra credit with the JEP Editor if you follow Jabber tradition by using characters and situations from the plays of Shakespeare:

Example 1. An Example from Shakespeare

<message 
    from='juliet@capulet.com/balcony'
    to='romeo@montague.net/garden'
    type='chat'>
  <body>Wherefore art thou, Romeo?</body>
</message>
    

5.5 Error Codes

If your proposal defines a number of error and status codes (as is done in JEP-0045), it is a good idea to include a table of all the codes defined in your document.

5.6 Business Rules

As with implementation notes, you may want to include a section describing various business rules (essentially, a variety of MUSTs, SHOULDs, and MAYs regarding application behavior). This is not required but can be helpful to implementors.

5.7 Implementation Notes

You may want to include a section devoted to implementation notes. Again, this is not required but can be helpful to implementors.

5.8 Internationalization Considerations

If there are any internationalization or localization issues related to your proposal, define them in this optional section.

5.9 Security Considerations

Your proposal MUST include a section entitled "Security Considerations". Even if there are no security features or concerns related to your proposal, you MUST note that fact. For helpful guidelines, refer to RFC 3552 [15].

5.10 IANA Considerations

This section is REQUIRED. The IANA is the Internet Assigned Numbers Authority, the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. Most proposals do not require interaction with the IANA, in which case the text of this section SHOULD read "This JEP requires no interaction with the Internet Assigned Numbers Authority (IANA)." If your proposal requires interaction with the IANA, discuss the matter with the JEP Editor. Do not contact the IANA on your own!

5.11 Jabber Registrar Considerations

This section is REQUIRED. The Jabber Registrar maintains a list of reserved Jabber protocol namespaces as well as registries of parameters used in the context of protocols approved by the Jabber Software Foundation. If your proposal does not require interaction with the Jabber Registrar, the text of this section SHOULD read "No namespaces or parameters need to be registered with the Jabber Registrar as a result of this JEP." Refer to Draft or Final JEPs for appropriate text in other cases, or consult with the JEP Editor.

5.12 XML Schema

An XML Schema is required in order for a JEP to be approved by the Jabber Council. The JEP Editor can assist you in defining an XML Schema for the protocol you are proposing.

5.13 Acknowledgements

Some JEPs end with a section thanking non-authors who have made strong contributions to the specification; if that is true of your JEP, feel free to include this section.

6.1 Attributes

When talking about an attribute by name, refer to it in single quotes. Example: the 'to' attribute.

When talking about an attribute value, refer to it in double quotes. Example: the value of the 'subscription' attribute is "both".

Elements possess attributes and contain character data and/or child elements; do not confuse these terms.

6.2 Code Examples

In examples, use single quotes rather than double quotes; they are more readable.

To show the hierarchy of XML elements, indent two spaces for every level.

If an element possesses a large number of attributes, include a line break before each attribute and indent them by four spaces or so that the attributes are vertically aligned for readability.

If the XML character data of an element is long, include line breaks and indent by two spaces.

Examples are the major source of right-scrolling in our HTML output files. Right-scrolling is evil. Adjust your example layouts accordingly (line widths should be no more than 110 characters or so).

Example:

<iq from='darkcave@macbeth.shakespeare.lit' 
    id='config1' 
    to='crone1@shakespeare.lit/desktop' 
    type='result'>
  <query xmlns='http://jabber.org/protocol/muc#owner'>
    <x xmlns='jabber:x:data' type='form'>
      <title>Configuration for "darkcave" Room</title>
      <instructions>
        Please coomplete this form to make changes to the configuration 
        of your room; to add room owners and administrators, use the 
        appropriate room commands rather than this form.
      </instructions>
      <field
          type='hidden'
          var='FORM_TYPE'>
        <value>http://jabber.org/protocol/muc#owner</value>
      </field>
  </query>
</iq>
    

6.3 Conformance Terms

Conformance terms (e.g,, "MUST" and "SHOULD") are specified in RFC 2119. Use them. When such terms are not in ALL CAPS, the special conformance sense does not apply (this should be obvious but may not be).

6.4 Elements

When talking about an element by name, refer to it as an empty XML element. Example: the <query/> element. There are shortcuts for some common element names in the jep.ent file.

The top-level <message/>, <presence/>, and <iq/> elements are actually XML stanzas (see XMPP Core [17]); refer to them as such. There are shortcuts for stanza names in the jep.ent file.

Elements possess attributes and contain character data and/or child elements; do not confuse these terms.

Do not use the term "tag" when you mean "element".

6.5 Errors

When talking about an error condition, use the XML element names defined in XMPP Core rather than the old HTTP-style code numbers. Example: the <feature-not-implemented/> error. There are shortcuts for the stanza errors in the jep.ent file.

6.6 Namespaces

When talking about a namespace by name, refer to it in single quotes. Example: the 'jabber:iq:roster' namespace.

An element or attribute is qualified by (rather than "scoped by" or "in") a particular namespace.

6.7 Quotes

For precision, the JSF follows IETF usage by placing all punctuation outside the quotation marks unless one is quoting text that includes the punctuation. Example: the port used for Jabber client communications is "5222".

Version 0.3 (2004-10-12)

Version 0.2 (2004-09-16)

Version 0.1 (2004-09-15)