First posted at charlesyoung.joeuser.com on 29th March 2004
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BizTalk 2004's XLANG/s language is syntactically reminiscent of C#, and it is natural to assume that it exhibits similar features. In fact, XLANG/s is very different to C#, providing specific support for process flow, whilst offering only a rudimentary set of features for expressing business logic.
It is not really necessary for developers to know the main constructs of XLANG/s because these are produced as a result of drawing orchestration diagrams in Visual Studio .NET. It is unlikely that many developers will wish to create orchestrations by writing XLANG/s directly in an .odx file, though this can be done if wished. Several of the orchestration shapes relate directly to XLANG/s constructs. For example, a ConstructMessage shape generates a 'construct' statement. Others output 'if' and 'while' statements or generate calls to pre-defined functions. From a practical viewpoint, it is, however, important to understand the syntactic differences between C# and XLANG/s when writing expressions.
At the time of writing (March 2004), there is no public documentation for XLANG/s. I have created an article which provides some of this 'missing. information. The document comes with a health warning. It is written in good faith as a result of observation and trial & error. There is no guarantee made in regard to its accuracy or completeness. I have not documented a comparison with every feature of C#, as it is fairly obvious that many features do not apply to orchestrations. For example, you cannot declare your own classes or structs within XLANG/s, and therefore you cannot overload operators or create virtual methods. I have concentrated, instead, on those features that you might expect to be able to use within expressions and message assignment shapes.