Welcome to our April newsletter. This has been a busy time for us, with further expansion of the company and plenty of activity on both commercial and development fronts. For those of you not yet involved with web services, we offer a brief introduction to the change control challenges that this much-hyped technology presents. Over the last year there has been a dramatic increase in the number of enquiries we receive concerning web services - it is now a very widely adopted standard.

A clear sign that change control requirements for XML are becoming more complex, and that understanding of the problems involved is becoming more widespread, is the increased interest in our DeltaXML Sync product, with its advanced three-way merge capabilities. Offering an unrivalled solution to the issues raised by concurrent editing and document merging, we are happy to see this work emerging from the world of academia to become a proven product.

The success of both DeltaXML Sync and DeltaXML Core is allowing us to continue our heavy R&D expenditure and to keep our position as clear industry leaders. This is crucially important for us since it allows us great freedom to first discuss with colleagues from industry and academia and then to tackle problems in the "right" way. We have every intention of remaining world leaders in this field, and we know this is only possible with the support of our loyal customers.

If you intend visiting XTech 2005 in Amsterdam next month, do get in touch, we will be attending and would very much like to hear from you. We welcome your feedback, about our products, our newsletter, our website or our services. Please get in touch if there's anything you'd like to suggest or discuss. Evaluation downloads of the DeltaXML Core API, together with full documentation and online demos, are always available at: http://www.deltaxml.com/

    - The DeltaXML Team.

Contents

In this newsletter:

• Recent DeltaXML Customers
• DeltaXML and Web Services
• Diary Dates

Customer Focus: Recent DeltaXML Customers

Recent customers include:

• University of Waikato (NZ) (visit) - pioneering the Semantic Web

[More customers...] 

DeltaXML and Web Services

"Web Services" is a generic term for a set of standards for interoperability of programs written in different programming languages, running on different platforms and at disparate locations. At its simplest, web services allow an application to request some processing by passing a message (typically containing data and details of the request) to a remote server. These messages are XML documents.

Many of the benefits of web services are already available from existing and proven technologies such as CORBA and RMI - so why all the hype? In a nutshell, it seems it is the combination of easy interoperability with transparent messaging which is most appealing. Unlike predecessors such as CORBA it is possible to communicate with a web service entirely by transmitting and receiving text (XML) messages which can tunnel through firewalls, are simple to create and (relatively!) straightforward to debug. In a computing environment where development and maintenance costs are generally high, such a simple approach is attractive even where the trade off is in performance overhead.

Web Services are now seeing widespread adoption, with strong backing from Microsoft, Sun, IBM, BEA and many others. According to its proponents it promises a "uniform computing platform", the preferred choice for many integration projects requiring Microsoft .NET and Java applications to work seamlessly with each other and with legacy systems in C++, Fortran or even COBOL.

At the heart of web services are the messages sent between the client and the server. These messages are represented in XML using SOAP (the Simple Object Access Protocol). Essentially SOAP is a very lightweight way of specifying what you want a server to do and what data you are making available to it. That is, SOAP is the language of communication between clients and web service servers. Associated with SOAP is the Web Services Description Language (WSDL). This is a specification which describes the functionality offered by a web service and the data required. In effect WSDL is for the Web services world what IDL is for CORBA - but unlike IDL text files, WSDL is an XML vocabulary.

As the first generation web services projects evolve and begin to develop serious complexity typical change management issues arise for web services. There are typically two sets of requirements. The first, during the development phase of a project, involves tracking expected changes and identifying unexpected ones as the message definitions are evolved. As web services are defined primarily in terms of the XML based WSDLs, tracking changes to these (XML) documents can prove difficult. Tools such as that offered by DeltaXML can be critical on larger projects and improves manageability even on smaller ones. When the project goes live another of the real benefits of change control becomes evident. For robust deployments in 24x7 environments, the ability to find differences between the expected messages and those actually received is crucial; without it, every failure may require manual intervention. These incoming messages can be monitored, and by distinguishing expected changes (the parameters passed to specific SOAP methods, for example) from unexpected ones, perhaps where the SOAP envelope, while still valid according to its schema, no longer satisfies some business rule, exceptions can be reliably reported. To automate such processing, precise identification of changes is a prerequisite.

DeltaXML is particularly well suited to such requirements. Key features used here are:

• keyed comparisons for guaranteed accuracy
• orderless comparisons to handle changes to element order which can safely be disregarded
• full context comparisons to simplify automated reporting - a single document contains all relevant information

Whether over-hyped or not, web services clearly have a role in the computing landscape which seems likely to grow in importance. For many, the "web services" epithet is used to apply more widely to other XML-based communications protocols such as XML-RPC and those taking the ReSTful "HTTP + TCP/IP + XML" approach. There is also a growing set of applications using "Document Literal" SOAP messages, which do not in fact convey instructions for a remote method call but which use SOAP as a container for a Plain Old XML Document. Given all these developments, the need for powerful XML change control in the web services world seems pressing.

Weblinks:
Wikipedia - http://en.wikipedia.org/wiki/Web_services
Web Services Interoperability Organization: http://www.ws-i.org/

Diary Dates

http://www.xtech-conference.org/ - XTech 2005, Amsterdam, 24-27 May 2005

Weblinks:
DeltaXML news: http://www.deltaxml.com/news/

Please let us know whether this newsletter has been useful to you, we welcome any suggestions about information you'd like discussed in future editions. We'll be back next month with another edition.

Copyright © 2005 DeltaXML and Monsell EDM Ltd.

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