Yossi Dahan [BizTalk]


Monday, December 29, 2008

Wish list: optional parameters when using call/start orchestration

I wasn’t sure how bit problem this was, and in any case thought that optional parameters are a VB thing, but I’ve been proven wrong, and not only because optional parameters are soon to become a c# thing :-)

When using call/start orchestration we increasingly, as our solution “matures”, find that we need to add optional parameters to our processes..

In c# I was trained that function overloading is the correct way to implement this, and although I can see the benefit of the slim optional parameters approach I do think that it is much clearer; we’re talking BizTalk though, and you can’t really overload a function, can you? :-)

So we [can] do several things -

When dealing with .net types we can simply break the interface, add the parameter, change all the calling processes to supply one, and – if they don’t actually need to supply a value for this new parameter make them pass one anyway (an empty string, or a 0, or even –1); not elegant to say the least, and quite time consuming which means upsetting both the architect and the project manager.

Same approach works quite well when dealing with optional messages as well, only that now constructing that unnecessary extra parameter, in the same of a content-less message, is even harder (see my post on creating messages from scratch).

Another option, valid for .net types only, is to have a <something>Parameters class which would include all the parameters a process takes as properties; this would allow you to add as many properties as you need, without forcing callers to specify them; there are downsides of course – it is less readable and intuitive in my view, there’s a bit more hassle for the caller (create instance of parameters class, assign members) and now it’s harder to force those non-optional parameters (can be done via the parameter class’ constructor)

But there’s not equivalent option for optional message parameters.

Last, but not least, there’s the closest thing to overloading – you could always create a second process, with the extended set of parameters and have the original process forward the original call while providing this empty parameter, effectively saving the hassle from the original caller.

This is really how a function overloading solution would look like only that a process is not a function; it has a lot more impact in term of compile time, configuration required, deployment so the overall maintenance cost of such an approach is quite enormous for any decent sized project.

So – I can no longer ignore this problem and have to agree – allowing optional parameters with default values, for orchestration is quite important.


2011? :-)

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  • Hi yossi,

    Cant really think where this has been a big problem for me, but wondering about your Parameters class option and if it would support having an XLANGMessage property if you wanted to optionally pass across your message. It would of course not be strongly typed but i think this is always one of those problems where you have to trade off something

    By Anonymous Mike Stephenson, at 02/01/2009, 12:45  

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