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Last modified: July 30, 2009
XML Daily Newslink. Thursday, 30 July 2009

A Cover Pages Publication
Provided by OASIS and Sponsor Members
Edited by Robin Cover

This issue of XML Daily Newslink is sponsored by:
Oracle Corporation

XML Media Types: Updated IETF Internet Draft
MURATA Makoto, Dan Kohn, Chris Lilley (eds), IETF Internet Draft

Members of the 'ietf-xml-mime' discussion group and others provide continuing input to a redraft of the IETF Standards Track RFC 3023, originally published in 2001 as XML Media Types. Appendix B of the updated Internet Dtaft presents changes relative to RFC 3023: there are numerous and significant differences between this I-D specification and RFC 3023, which it obsoletes. Appendix B summarizes the major differences only.

The XML Media Types Internet Draft "standardizes three media types: (1) the 'application/xml' type, (2) the 'application/xml-external-parsed-entity' type, and (3) the 'application/xml-dtd' type for use in exchanging network entities that are related to the Extensible Markup Language (XML), while deprecating the IANA-registered 'text/xml' type and 'text/xml-external-parsed-entity' type. This Internet Draft also standardizes a convention (using the suffix '+xml') for naming media types outside of these five types when those media types represent XML MIME entities. XML MIME entities are currently exchanged via the HyperText Transfer Protocol on the World Wide Web, are an integral part of the WebDAV protocol for remote web authoring, and are expected to have utility in many domains.

XML provides a general framework for defining sequences of structured data. In some cases, it may be desirable to define new media types that use XML but define a specific application of XML, perhaps due to domain-specific display, editing, security considerations or runtime information. Furthermore, such media types may allow UTF-8 or UTF-16 only and prohibit other charsets. This document does not prohibit such media types and in fact expects them to proliferate. However, developers of such media types are strongly recommended to use this document as a basis for their registration. In particular, the charset parameter should be used in the same manner [...] for interoperability.

Appendix A "Why Use the '+xml' Suffix for XML-Based MIME Types?" offers answers to sixteen questions commonly asked about the use of the base '+xml'. Appendix B notes the major changes vis-a-vis RFC 3023: "First, 'text/xml' and 'text/xml-external-parsed-entity' are deprecated. Second, XPointer (XPointerFramework, XPointerElement, XPointerXmlns) has been added as fragment identifier syntax for "application/xml", and the XPointer Registry mentioned. Third, XBase has been added as a mechanism for specifying base URIs. Fourth, the language regarding charsets was updated to correspond to the W3C TAG finding Internet Media Type registration, consistency of use with the 2004 memo. Fifth, many references are updated...

Session Initiation Protocol (SIP) Event Package for the Common Alerting Protocol (CAP)
Brian Rosen, Henning Schulzrinne, Hannes Tschofenig (eds), IETF Draft

Members of the IETF Session Initiation Proposal Investigation (SIPPING) Working Group have published a revised I-D for Session Initiation Protocol (SIP) Event Package for the Common Alerting Protocol (CAP). The specification registers an event package ('common-alerting-protocol') and requests IANA Registration of a new MIME/media type and subtype: 'application/common-alerting-protocol+xml'.

The Common Alerting Protocol, both an OASIS Standard and an ITU-T Recommendation, "is an XML document format for exchanging emergency alerts and public warnings. This IETF document defines facilities to allow CAP documents to be distributed via the event notification mechanism available with the Session Initiation Protocol (SIP).

Specifically, this I-D defines a new "common-alerting-protocol" event package. Event Publication Agents (EPA) use PUBLISH requests to inform an Event State Compositor (ESC) of changes in the common-alerting-protocol event package. Acting as a notifier, the ESC notifies subscribers about emergency alerts and public warnings. RFC 3265 ("Session Initiation Protocol (SIP)-Specific Event Notification") defines a SIP extension for subscribing to remote nodes and receiving notifications of changes (events) in their states. It leaves the definition of many aspects of these events to concrete extensions, known as event packages. This document defines such an event package... Additionally, RFC 3903 defines an extension that allows SIP User Agents to publish event state. According to RFC 3903, any event package intended to be used in conjunction with the SIP PUBLISH method has to include a considerations section. This Internet Draft also fills the information for all event packages to be used with PUBLISH requests.

See also: Common Alerting Protocol (CAP) specification references

W3C XML Security Working Group Publishes Six XML Security Documents
Frederick Hirsch, Pratik Datta, Magnus Nystrom (et al. eds), W3C Technical Reports

W3C announced that members of the XML Security Working Group have published six documents related to XML signature and encryption. XML Signatures provide integrity, message authentication, and/or signer authentication services for data of any type, whether located within the XML that includes the signature or elsewhere.

The existing suite of XML security specifications has become a fundamental technology in the XML and Web Service worlds over the last seven years: The joint IETF/W3C XML Signature Working Group specified mechanisms to digitally sign XML documents and other data, and to encapsulate digital signatures in XML. The W3C XML Encryption Working Group specified mechanisms to encrypt XML documents and other data, and to encapsulate the encrypted material and related meta-information in XML. In 2007, the XML Security Specifications Maintenance Working Group took up limited maintenance work of the XML Signature Specification, and the XML Core Working Group prepared the Canonical XML 1.1 Recommendation, on which XML Signature depends.

New and updated documents: (1) "XML Signature Best Practices" describes best practices related to improving security and mitigating attacks, yet others are for best practices in the practical use of XML Signature, such as signing XML that doesn't use namespaces, for example. (2) "XML Signature Syntax and Processing Version 1.1" updates the signature specification. (3) "XML Signature Transform Simplification: Requirements and Design" outlines a proposed simplification of the XML Signature Transform mechanism, intended to enhance security, performance, streamability and to ease adoption. (4) "W3C XML Encryption Syntax and Processing Version 1.1" updates the encryption specification. (5) XML Security Generic Hybrid Ciphers" is a W3C First Public Working Draft that augments XML Encryption Version 1.1 by defining algorithms, XML types, and elements necessary to enable use of generic hybrid ciphers in XML Security applications. (6) The "XML Security Algorithm Cross-Reference" Group Note collects the various known URIs for encryption algorithms (at the time of its publication) and indicates which specifications define them.

W3C's XML Security Working Group is currently chartered through May 2010 to evaluate and act on recommendations in the Workshop report in developing the XML Security specifications on the basis of lessons learned from implementation and deployment experience to date.

See also: XML Security Generic Hybrid Ciphers

Blueprint and BPMN Diagram Portability
Bruce Silver, BPMS Watch Blog

Earlier, "I wrote about Lombardi's efforts to open up Blueprint using XPDL 2.1. A BPMN diagram created in Blueprint can be exported as XPDL and imported into itp commerce Process Modeler for Visio... Even though it is a standard, BPMN is rarely portable between tools, something that baffles users. But I noticed the lanes did not import properly. My investigation into why has increased my understanding of the portability problem... A long time ago, we wasted time talking about the relative merits of BPEL vs XPDL.. I argued at the time that graphics portability was hopeless, since each tool uses different graphics libraries, fonts, connection points, etc. You could never get the graphics to port exactly and remain editable. The truth, as it turns out, is something in between. Portable BPMN graphics is really an approximation of the layout, capturing the arrangement of nodes in swimlanes and connector bendpoints, but not necessarily fonts, precise connection points, etc. Those are still determined by each tool...

I set about writing an XSLT transform that would map the Blueprint export XPDL into something ITP can import, including graphics. I played around to arrive at a scale factor that made the imports look OK. If I had more time, maybe I could figure out how to create multi-page hierarchical models in the XSLT, but to start I just put everything in one page -- which is what the Blueprint export actually provides..."

See also: Standards for Messaging and Transaction Coordination

Modeling Your Data with DBpedia Vocabularies
Bob DuCharme, Blog

About "Broad, useful, vocabularies with plenty of sample data... digging into the vocabularies used in DBpedia's massive collection of RDF triples... how to chain statements together with shared resource references... note two DBpedia vocabularies being used not to query DBpedia, but to model data completely outside of the context of DBpedia, because they offered straighforward, dereferencable URIs for these things...

The Linked Movie Database project team has worked out a specific property vocabulary as part of their project, while the DBpedia one has grown more organically, leading to many more strange edge cases among the well-chosen terms... While the Library of Congress Subject Headings provide a solid, professional taxonomy and a set of URIs for a wide variety of subjects and concepts, they don't have them for places or people. (They might have one for London (England)—History, but they don't have one for 'London (England)'.) So, while they have a URI for the concept of sightings of Elvis Presley since his death, they have no URI for Elvis himself. Nor do they have one for Einstein, and I don't know what well-known vocabulary does, so the RDFa spec's authors went with the DBpedia URI for the famous physicist.

To look for a property name you might need, you can check a DBpedia page for a resource that may have had that property assigned to it. You can also download an ntriples or csv file in your choice of fourteen languages from DBpedia's Download Page.. , plenty of other hard work continues to make the DBpedia predicate vocabulary more valuable to all of us, so it's worth keeping an eye on the work going on around this vocabulary..."

DBpedia: "Knowledge bases are playing an increasingly important role in enhancing the intelligence of Web and enterprise search and in supporting information integration. Today, most knowledge bases cover only specific domains, are created by relatively small groups of knowledge engineers, and are very cost intensive to keep up-to-date as domains change. At the same time, Wikipedia has grown into one of the central knowledge sources of mankind, maintained by thousands of contributors. The DBpedia project leverages this gigantic source of knowledge by extracting structured information from Wikipedia and by making this information accessible on the Web under GNU Free Documentation License. The DBpedia knowledge base currently describes more than 2.6 million things, including at least 213,000 persons, 328,000 places, 57,000 music albums, 36,000 films, 20,000 companies. The knowledge base consists of 274 million pieces of information (RDF triples). It features labels and short abstracts for these things in 30 different languages; 609,000 links to images and 3,150,000 links to external web pages; 4,878,100 external links into other RDF datasets, 415,000 Wikipedia categories, and 75,000 YAGO categories..."

See also: the DBpedia Knowledge Base


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