Cover Pages: XML Daily Newslink: Monday, 01 December 2008

A Cover Pages Publication http://xml.coverpages.org/
Provided by OASIS and Sponsor Members
Edited by Robin Cover

This issue of XML Daily Newslink is sponsored by:
Oracle Corporation http://www.oracle.com

Headlines

W3C Invites Implementations of Service Modeling Language (SML) 1.1
Some Thoughts on the Oslo Modeling Language
NIEM Onboard for Maritime Use: Sharing Notes on Seafaring Scofflaws
Link Relations and HTTP Header Linking: Updated Internet Draft
Amazon SimpleDB: Unlimited Public Beta Announced
Owen Ambur: Work for the U.S. Federal Government, XML, and Standards

W3C Invites Implementations of Service Modeling Language (SML) 1.1
Bhalchandra Pandit, Valentina Popescu, Virginia Smith (eds), W3C Technical Report

W3C has issued a call for implementations of the Candidate Recommendation release of SML Version 1.1, including "Service Modeling Language, Version 1.1" and "Service Modeling Language Interchange Format Version 1.1". The Service Modeling Language specification, developed as part of the W3C Extensible Markup Language (XML) Activity, provides a rich set of constructs for creating models of complex services and systems. Depending on the application domain, these models may include information such as configuration, deployment, monitoring, policy, health, capacity planning, target operating range, service level agreements, and so on. The W3C Service Modeling Language (SML) Working Group expects to request that the Director advance this document to Proposed Recommendation once the Working Group has demonstrated two implementations of each required feature and at least one implementation of each optional feature affecting interoperability. The SML Working Group, working closely with the developer community, expects to show implementations by December 2008. This estimate is based on known implementations. The Working Group does not plan to request to advance to Proposed Recommendation prior to 01-January-2009. No features have been identified as "features at risk" by the SML Working Group. The major substantive change since the previous publication of this specification as a Last Call Working Draft has been the introduction of what are expected to be the final XML namespace names for the SML and SML-IF namespaces; previously each new Working Draft used a new pair of namespace names. Other editorial and cosmetic changes have also been made. The principal SML document ("Service Modeling Language, Version 1.1") defines the SML language, used to model complex services and systems, including their structure, constraints, policies, and best practices. A "model" in SML is realized as a set of interrelated XML documents. The XML documents contain information about the parts of a service, as well as the constraints that each part must satisfy for the service to function properly. Constraints are captured in two ways: (1) Schemas: constraints on the structure and content of the documents in a model. SML uses XML Schema (Part 1: XML Schema Structures, Part 1::XML Schema Datatypes) as the schema language. In addition SML defines a set of extensions to XML Schema to support references that may cross document boundaries. (2) Rules: Boolean expressions that constrain the structure and content of documents in a model. SML uses Schematron (ISO/IEC 19757-3, "Introduction to Schematron, Improving Validation with Schematron") and W3C XPath for rules. One of the important operations on the model is to establish its validity. This involves checking whether all data in a model satisfies the schemas and rules declared. This specification focuses primarily on defining the extensions to XML Schema for references that cross document boundaries, Schematron usage in SML, as well as the process of model validation. The second document describes SMIF ("Service Modeling Language Interchange Format Version 1.1"). It defines the interchange format for Service Modeling Language, Version 1.1 (SML) models. This format identifies the model being interchanged, distinguishes between model definition documents and model instance documents, and defines the binding of rule documents with other documents in the interchange model. This specification defines a standard format called the SML Interchange Format (SML-IF) and a process called interchange model validation. The specification consists of two parts. The first part is an informal description of SML-IF to set the context. This is followed by SML-IF's normative definition.

Microsoft recently introduced Oslo. Microsoft seems to have designed Oslo to replace some of things it now uses XML for. Since Microsoft have been one of the biggest supporters of XML, I think it's worth looking at what they've come up with. The key part of Oslo is the "M" language, which Microsoft calls a "modeling language"... There's quite a lot about M that I like. Mostly it seems pretty clean. The type system is powerful. Structural typing is clearly the right approach for something like M. I like the way that constraints that can be checked statically are seamlessly blended with constraints that will need to be checked dynamically. Static type checking is good, but there's no need to rub your users faces in the limitations of your static type checker... It's obviously very early days for M, and there's still lots of scope for improvement. Microsoft's initial implementation of M targets SQL and works a bit like a database. But clearly there's potential for using something like M in quite different contexts, e.g. for exchanging data on the Web (like what I talked about some time ago with TEDI). But several aspects of the current design seem to reflect the initial database focus. For example, the current top level wrapper of modules/entities makes sense for a database application of M, but wouldn't work so well if you were using M for exchanging data on the Web. The spec needs some fleshing out. Microsoft's current implementation is a long way from implementing the full language. I am skeptical whether the language as currently specified can be fully implemented. For example, can you implement the test for whether one type is a subtype of another type so that it works in non-exponential time for two arbitrary types? [...] One of the strengths of XML is that it handles both documents and data. This is important because the world doesn't neatly divide into documents and data. You have data that contains documents and document that contain data. The key thing you need to model documents cleanly is mixed text. How are you going to support documents in M? The lack of support for order is a major problem here, because ordered is the norm for documents. A related issue is how M and XML fit together. I believe there's a canonical way to represent an M value as an XML document. But if you have data that's in XML how do you express it in M? In many cases, you will want to translate your XML structure into an M structure that cleanly models your data. But you might not always want to take the time to do that, and if your XML has document-like content, it is going to get ugly. You might be better off representing chunks of XML as simple values in M (just as in the JSON world, you often get strings containing chunks of HTML). M should make this easy. You could solve this elegantly with RELAX NG (I know this isn't going to happen given Microsoft's commitment to XSD, but it's an interesting thought experiment): provide a function that allows you to constrain a simple value to match a RELAX NG pattern expressed in the compact syntax (with the compact syntax perhaps tweaked to harmonize with the rest of M's syntax) and use M's repertoire of simple types as a RELAX NG datatype library... [Note: James Clark served as technical lead for the World Wide Web Consortium's XML activity which developed XML 1.0 Recommendation, and has created several critical XML languages and implementations.]

NIEM Onboard for Maritime Use: Sharing Notes on Seafaring Scofflaws
Joab Jackson, Government Computer News

Law enforcement agencies and the U.S. Defense Department's maritime organizations might soon be able to share more information about seafaring scofflaws, thanks to a recent agreement between DOD and the federal National Information Exchange Model (NIEM) data-sharing initiative. DOD has adopted NIEM for reporting on maritime activities, according to a memo recently signed by NIEM Executive Director Donna Roy. NIEM "is an interagency initiative to provide the foundation and building blocks for national-level interoperable information sharing and data exchange. The NIEM project was initiated on February 28, 2005 as a joint venture between the U.S. Department of Homeland Security (DHS) and the U.S. Department of Justice (DOJ) with outreach to other Government departments and agencies. The NIEM leverages both the Global Justice XML Data Model (GJXDM) reference model and the GJXDM XML-based framework and support infrastructure. The NIEN Version 2.0 release package contains the NIEM reference schemas (Core, code lists, domains, wrappers for external standards, as well as the schemas for those standards, or profiles of, or adaptations of.) It also contains a cumulative change log and the spreadsheet. NIEM provides practitioners and developers with a baseline set of XML Schema components for building Information Exchange Package Documentation (IEPDs)..." From the November 25, 2008 memo of Donna Roy: "Under this agreement, the DoD EA for Maritime will work with the NIEM program to transition the Maritime Information Exchange Model (MIEM) 1.0, developed by the MDA Data Sharing Community of Interest, into NIEM as its maritime information domain component. This partnership furthers the objectives for ensuring that Maritime Domain Awareness situation intelligence is actionable for homeland security and will ensure the long-term stewardship of the maritime model for information exchange... Law enforcement agencies having jurisdiction over ports, inland waterways, bridges, and other connections to maritime environments realize that the ability to share information about the locations, crew, characteristics, and content of vessels is critical to preventing crime or acts of terror, as well as investigating criminal activity. The magnitude of information sharing that is needed to support collaborative efforts among local, state, and federal agencies requires high-speed, automated systems and a standard for computer-based information sharing across domain boundaries. Having the maritime domain as a part of NIEM will expedite information sharing and increase its efficiency..."

See also: the NIEM web site

Link Relations and HTTP Header Linking: Updated Internet Draft
Mark Nottingham (ed), IETF Internet Draft

An updated version -03 Internet Draft has been published for "Link Relations and HTTP Header Linking." The document specifies relation types for Web links, and defines a registry for them. It also defines how to send such links in HTTP headers with the Link header-field. Appendix A presents "Notes on Using the Link Header with HTML", while Appendix B presents "Notes on Using the Link Header with Atom." Editor Mark Nottingham notes: "This is a fairly substantial rewrite of the specification, based upon the observation that the link header really isn't the central concept here; it's link relations themselves. Changes include: inverted focus from Link headers to link relations; specified was a link relation type is; based on discussion, re-added 'rev'; changed IESG Approval to IETF Consensus for relation registrations, i.e., now require a document; updated RFC 2434 reference to RFC 5226; registered relations should conform to sgml-name; cautioned against confusing relation types with media types... I'm particularly interested in feedback regarding registration requirements, as I think that's the biggest remaining sticking point. Also, I believe this still accommodates other standards orgs like the W3C using their processes to publish documents that register entries, just as with media types. Assuming this is acceptable and no serious shortcomings are found in this draft, I think this document is ready to progress; i.e., I believe (speaking as an individual) there is consensus within the Atom community to make the registry modifications, and the feedback I've heard from the HTML community is that it's not necessary to have a tight integration with HTML4 or HTML5..." Background: " A means of indicating the relationships between documents on the Web, as well as indicating the type of those relationships, has been available for some time in HTML, and more recently in Atom (IETF RFC 4287). These mechanisms, although conceptually similar, are separate. However, links between resources need not be format-specific; it can be useful to have typed links that are independent of the format, especially when a resource has representations in multiple formats. This document defines typed link relations, independent of the context they occur in. It does so by clarifying the status of the link relation registry established by Atom, and registering in it the relations that are defined by HTML. Furthermore, an HTTP header-field for conveying typed links was defined in RFC 2068, but removed from RFC 2616, due to a lack of implementation experience. Since then, several use cases for doing so have surfaced. However, because it was removed, the status of the Link header is unclear, leading some to consider minting new application-specific HTTP headers instead of reusing it. This document addresses this by re-specifying the Link header with updated but backwards-compatible syntax..."

See also: Mark Nottingham's note

Amazon SimpleDB: Unlimited Public Beta Announced
Staff, DDJ

Amazon Web Services has announced the unlimited public beta of Amazon SimpleDB. Any developer or business may now sign up and start using the service immediately. Amazon SimpleDB is a web service providing the core functionality of a database, including fast storage and simplified querying of structured data. This service works in close conjunction with Amazon Simple Storage Service (Amazon S3) and Amazon Elastic Compute Cloud (Amazon EC2), collectively providing the ability to store, process and query data sets in the cloud, making web-scale computing available to developers without large capital outlays. Also announced today, Amazon SimpleDB users can take advantage of a free monthly usage tier, and reduced pricing for structured data storage. Amazon SimpleDB is a web service providing the core database functions of indexing and querying... For at least the next six months, Amazon SimpleDB users will enjoy a free tier of usage. Every month, customers receive 25 machine hours, 1 GB of data transfer in and out, and 1 GB of storage at no charge. From the Web site: "Amazon SimpleDB provides a simple web services interface to create and store multiple data sets, query your data easily, and return the results. You organize your structured data into domains and can run queries across all of the data stored in a particular domain. Domains are comprised of items, and items are described by attribute-value pairs. To understand these elements, consider the metaphor of data stored in a spreadsheet table. An Amazon SimpleDB domain is like a worksheet, items are like rows of data, attributes are like column headers, and values are the data entered in each of the cells. However unlike a spreadsheet, Amazon SimpleDB allows for multiple values to be associated with each 'cell' (e.g., for item '123,' the attribute 'color' can have both value 'blue' and value 'red'). Additionally, in Amazon SimpleDB, each item can have its own unique set of associated attributes (e.g., item '123' might have attributes 'description' and 'color' whereas item '789' has attributes 'description,' 'color' and 'material'). Amazon SimpleDB automatically indexes your data, making it easy to quickly find the information that you need. There is no need to pre-define a schema or change a schema if new data is added later... Amazon SimpleDB passes on to you the financial benefits of Amazon's scale. You pay only for resources you actually consume..."

Owen Ambur: Work for the U.S. Federal Government, XML, and Standards
Alice Marshall, Presto Vivace Blog

This is the second of an occasional series of interviews with local technology leaders. Owen Ambur recently retired from the Fish and Wildlife Service. He talks about the Federal XML Work Group, and his current work with AIIM's StratML Committee. "My involvement in XML stems from my long-standing interest in document/records management and forms automation... Early in 2000 I sent a message to George Brundage of GSA highlighting two opportunities for the government to leverage the potential of XML. He posted my message on a listserv he was maintaining relating to information technology architecture. Martin Smith, who was then with the U.S. International Trade Commission (ITC), and more recently has worked at the Department of Homeland Security (DHS), suggested that I bring those ideas to the attention of the CIO Council (CIOC). I did so and Lee Holcomb, who was then CIO at National Aeronautics and Space Administration (NASA) and co-chaired what is now the CIOC's Architecture and Infrastructure Committee (AIC), commissioned Martin and me to form an ad hoc group and come back to his committee with a recommendation. That group recommended that a more formal working group be chartered under the auspices of the CIOC, and our first charter was approved in the fall of 2000. In September 2004, the XML WG was re-chartered as the XML Community of Practice (xmlCoP)... As I told Lee and others in the CIOC, XML was going to happen regardless of whether the CIOC did anything about it or not. It has taken longer than I had hoped and we still have a long way to go to fully capitalize on the potential in an effective and well-coordinated manner on a government-wide basis. However, I do believe the fact that the xmlWG/CoP was formally recognized by the CIOC, met virtually every month for six years straight, and still maintains the xml.gov site has fostered awareness, education, and sharing of experiences and expertise. Hopefully, that has brought greater credibility to what is to most people a pretty esoteric subject and, in turn, has encouraged agencies to act more rapidly than might have otherwise been the case..."


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