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- SIP Basics and Beyond
- A Lesson in SOA Model-Based Management
- NCSA Spotlights Digital Library Technologies
- OAGi and HR-XML Consortium Announce Architectural Alignment
- VC Firm, Ex-Microsoft Execs Back Internet OS Company
- XML for PHP Developers: Add XSLT to DOM and SimpleXML APIs
- No (Showstopping) Contradictions in OpenXML?
- Microsoft FAT Patent Fails in Germany
SIP Basics and Beyond
Robert Sparks, ACM Queue
Chances are you're already using SIP (Session Initiation Protocol), since it is one of the key innovations driving the current evolution of communications systems. SIP is an open standard developed by the IETF. It has a large and active implementation community: nearly 100 unique implementations were present at each of the recent SIP Forum SIPit (SIP Interoperability Test) events. SIP is a transaction-oriented, text-based protocol. Its messages are similar in syntax to HTTP, but there is little similarity in protocol behavior. SIP endpoints, also known as UAs (user-agents), can both generate and answer requests. SIP URIs appear in several places in SIP messages: the RURI (Request-URI) in the first line of a request determines where the request is going to go—in essence, this is to whom the request is targeted. Some URIs may be GRUUs (Globally Routable User-agent URIs); these URIs are similar to AoRs in that they are long-lived—they could be placed on a business card or in an e-mail signature. SIP also provides a publish-subscribe mechanism called SIP Events that lets elements learn about state changes elsewhere in the network. For example, a service can subscribe to the dialog state of a UA to learn when it becomes available, making it easy to build a camp-on or call-back service. The most powerful event currently available, however, is presence. This event, defined by the IETF's SIMPLE working group (SIP for Instant Messaging and Presence Leveraging Extensions), conveys information about the end user's availability and willingness to communicate. This RPID (rich presence information) ranges from where the user is (geographic location) to what he or she is doing (driving, meeting, or eating, for example) and even what kind of environment he or she is in (such as a movie theater). SIP provides a framework for developing communications systems. It is not just a simple telephony application protocol. It is being used to construct peer-to-peer systems, residential telephony services, PBX replacement systems, and large-scale carrier next-generation networks, such as the IMS (IP Multimedia Subsystem) of the 3GPP (Third Generation Partnership Project).
See also: IETF SIP Working Group
William Vambenepe WS-ResourceTransfer, or WS-RT, plays at the intersection of SOA and model-based management. While its goals are modest and its usage will often be hidden, it meets a critical need in allowing model-driven interactions to be conducted in an SOA. WS-RT defines a set of Simple Object Access Protocol messages that are used to provide flexible access to a model-driven service. It is fully compliant with the WS-Transfer specification (a World Wide Web Consortium submission that is one of the components of WS-Management) on which it is based. But while WS-Transfer allows access to the entire representation of the model of a system that is being accessed (in order to read, update, create or destroy it), WS-RT lets individual parts be specified. This capability is useful when interacting with models of individual resources (such as a server) and is critical in interacting with large models that represent complex systems (such as a data center), in which case interacting with the entire model is impractical. The improvements that WS-RT adds to the WS-Transfer Create operation allows one to specify parts of the model of the system to create. For example, when asking for a server to be provisioned, one might want to specify what operating system it should run and how much memory it should have. But in general the creator doesn't want to have to specify what IP address the server should be assigned (even though this information is part of the model of the server). Rather, the IP address will be assigned automatically at the time of provisioning.
See also: WS-RT references
NCSA Spotlights Digital Library Technologies
Staff, NCSA Digital Library Technologies Group Announcement
NCSA's Digital Library Technologies group, led by Joe Futrelle, develops tools and techniques to manage semantic content for scientific applications. This ranges from digital library technology for managing scientific data to semantic Web technology for integrating distributed, heterogeneous metadata while maintaining its semantic integrity. The group's primary project is the Tupelo Semantic Content Repository, which provides tools for managing data across distributed heterogeneous semantic storage technologies such as RDF triple stores and content management systems. Tupelo is designed for archiving large-scale, complex scientific data and metadata collections; it is also suitable for more conventional digital libraries containing Dublin Core or other standard digital library metadata schemas. Its RDF-based metadata framework can support a wide variety of schemas, from simple, flat-namespace schemas such as Dublin Core, to hierarchical models derived from XML Schema, to more web-like models derived from RDF variants. Futrelle: "Generic tools and techniques that we're developing can enable data management infrastructure to be more easily extended to support specialized use cases without requiring extensive domain-specific development. Semantic Web technologies lend themselves to loosely coupled environments like science cyber-environments, where centralization of data resources is impractical." Futrelle says his group acts in almost a consulting role to a range of NCSA projects and collaborators, assisting them with issues of integrating heterogeneous data and moving from data stovepipes to more flexible, loosely coupled strategies. DLT collaborators include NCSA's Automated Learning Group, which is also using semantic Web technologies; the TRECC visualization group, which is involved with developing interfaces to semantic content repositories for ECID; Tom Habing, a research programmer at Grainger Engineering Library, and other Grainger staff involved with the ECHO-DEP project; and several researchers from the Graduate School of Library and Information Science, including Janet Eke, David Dubin, and J. Stephen Downie.
OAGi and HR-XML Consortium Announce Architectural Alignment
Staff, Open Applications Group and the HR-XML Consortium
A joint announcement from OAGi and HR-XML Consortium reports that work has begun on a project to align the business language standards produced by the two organizations. The planned architectural alignment represents a significant step forward for enterprise application interoperability. The Open Applications Group Integration Specification (OAGIS) is "the world's largest and most implemented business language standard. OAGIS covers a diverse set of enterprise functions, including purchasing, manufacturing, and supply-chain management. The HR-XML Consortium is the recognized authority on, and leading source of, global interoperability standards for human resources management. The architectural alignment by the Open Applications Group and HR-XML promises to give enterprises an expanded and unified business language for wide-ranging integration needs. Once the alignment project is complete, the HR-XML and OAGIS libraries will be packaged separately, but will be structured so enterprises wanting to leverage both libraries will be able to install them together. Other key features planned for the alignment are: (1) Leveraging OAGIS Business Object Documents (BODs) for HR-XML message design; (2) Incorporating the OAGIS implementation of the UN/CEFACT harmonized core components within HR-XML; (3) Adhering to common naming and design rules and a common schema modularity model; (4) Reusing from each library, relevant content from the other.
See also: the OAGi web site
VC Firm, Ex-Microsoft Execs Back Internet OS Company
Elizabeth Montalbano, InfoWorld
A venture capital firm has given a $10 million boost to a Swedish company that could soon be in the competitive crosshairs of Google and Microsoft. Swedish venture company Northzone Ventures will help Xcerion AB emerge from stealth mode to launch its Web-based OS and related marketplace for hosted software later this year, said Xcerion CEO Daniel Arthursson, in an interview with the IDG News Service. Xcerion has developed an OS that works from within a browser, which developers can use to build Web-based versions of existing software or new applications quickly and without having to build separate versions for different computer OSes, he said. The company also will host the applications and make them available in an online marketplace. Users can choose to either run ad-supported versions of the applications for free, or pay a small yearly fee—about $5 or $10 per year—to run them is ad-free, Arthursson said. The company will manage subscriptions for third-party vendors and give them about 80 percent or 90 percent of the subscription revenue, while keeping a small percentage for its hosting and management services, he said. Users also can run applications built on Xcerion's XML Internet OS when they are offline, Arthursson said. Any information saved when they are running the application offline will be immediately updated to the online version when they reconnect to the Internet. Xcerion is hoping to do for Web-based business application development what Microsoft did for applications development on the desktop. From the company Inspiration statement: "We strongly believe in social computing, enabling user participation and that the Internet eventually will become the operating system. All information will eventually be stored in XML format—enabling access from any device or service."
See also: the Xcerion AB web site
XML for PHP Developers: Add XSLT to DOM and SimpleXML APIs
Cliff Morgan, IBM developerWorks
This article "Part 3: Advanced techniques to read, manipulate, and write XML" is the final installment in a three-part series which discusses more techniques for reading, manipulating, and writing XML in PHP5. PHP5 offers the developer a lot more muscle to work with XML. New and modified extensions such as the DOM, SimpleXML, and XSL make working with XML less code intensive. In PHP5, the DOM is compliant with the W3C standard. Most importantly, the interoperability among these extensions is significant, providing additional functionality, like swapping formats to extend usability, W3C's XPath, and more, across the board. The article focuses on the now familiar APIs DOM and SimpleXML in more sophisticated surroundings, and, for the first time in this series, discusses the XSL extension. The examples in this article use Yahoo's search API, PHP5, and REpresentational State Transfer (REST) to illustrate the use of the DOM in an interesting application environment. Yahoo chose REST because of a common belief among developers that REST offers 80% of SOAP's benefits at 20% of the cost. The SimpleXML extension is a tool of choice for manipulating an XML document, provided that the XML document isn't too complicated or too deep, and contains no mixed content. SimpleXML is easier to code than the DOM, as its name implies. It is far more intuitive if you work with a known document structure. Greatly increasing the flexibility of the DOM and SimpleXML the interoperative nature of the libXML2 architecture allows imports to swap formats from DOM to SimpleXML and back at will. PHP5's implementation of the W3C standard supports interoperability with the DOM and XPath. EXtensible Stylesheet Language Transformations (XSLT) is an XML extension based on libxml2, and its stylesheets are XML documents. XSLT transforms an XML source tree into an XML or XML-type result tree. These transformations apply the series of rules specified in the stylesheet to the XML data. XSLT can add or remove elements or attributes to or from the output file. It allows the developer to sort or rearrange elements and make decisions about what elements to hide or display. Different stylesheets allow for your XML to be displayed appropriately for different media, such as screen display versus print display.
No (Showstopping) Contradictions in OpenXML?
Rick Jelliffe, O'Reilly Articles
Erc Lai at ComputerWorld is reporting that JTC1 has accepted Ecma's responses to the recent contradiction review, and that matters are proceding to the next phase of the voting as normal... So the Ecma spec is now at the "Draft International Standard" stage (DIS). In five months time, as I understand it, there will be a ballot of the national bodies that are P-members of SC34 (participating members, rather than observers). In ISO procedure, there are votes for "abstain", "yes", "no" and "no with comments". I expect that OpenXML will have a lot of "No with comments", which happens sometimes. These comments give all the technical (and perhaps IPR) issues that have been found that are showstoppers, together with other misc comments. After this ballot, we all wait two or three months. This gives everyone time to draw their breaths, gird their loins, examine each other's positions, and prepare responses. Then there a ballot resolution meeting, at which all the issues are dealt with; the meeting may respond with a fix to the DIS, or with a comment that this is an issue for further study and enhancement, or they may to decline to fix the problem, or they may say that it is not a problem in their opinion. Then Ecma takes these on board, makes the appropriate changes, and this becomes the FDIS, the "Final Draft International Standard". The FDIS then gets sent around to the national bodies, and a vote is taken after 30 days. So we are talking, 1 month admin review (contradiction) + 1 month (Ecma response) + 5 months (detail review) + 2month (collection) + 2 months (resolution) + 1 month (pre-vote). A Fast Track standard with any controversy actually has about 13 months of review time before the final vote minimum... What is important to realize is that even though JTC1 may have found that Ecma's responses to the contradiction issues are satisfactory enough to let matters proceed, it does not mean that therefore the issues themselves go away. It is not JTC1s job to make technical decisions but procedural ones, is one way to put it. I expect that some of the issues will be re-put at the DIS ballot, some will have been answered by the Ecma response already, and there will probably be some more. The DIS ballot resolution process looks like being a long and difficult job, but it will make the claims that OpenXML had no input from an open process fairly untenable; probably ODF should have had the same amount of scrutiny.
See also: Office Open XML
Microsoft FAT Patent Fails in Germany
Steven J. Vaughan-Nichols, Linux-Watch
While the U.S. courts recently reaffirmed Microsoft's FAT (File Allocation Table) patents, the German Patent Federal Court has just dismissed the patent for use in Germany. According to a report in the German news publication Heise Online, the court has denied the protection that the European Patent Office granted to Microsoft under EP 0618540 for a "common namespace for long and short filenames." This was based on Microsoft's US Patent No. 5,758,352. The German Patent Court stated that the patent claims Microsoft made are "not based on inventive activity." FAT is a file system that Windows and other operating systems use to track the clusters of data that make up files on mass storage devices, such as hard drives or USB memory sticks. In Linux circles, it's best known for its use in the Samba server application. Samba enables Windows PCs to read and write files on Linux servers, and allows Linux desktops to access Windows servers. Microsoft has been willing to license FAT to European vendors for prices ranging from US $0.25 per unit to a one-time payment in full of US $250,000 per company. No Linux distributor, however, has ever admitted to paying such a fee.
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