Question

I’m a complete neub to working with WCF but have been put on a project that needs it. Although not given as a requirement I want this service to seemlessly work with any client regardless of the technology it is written in (e.g. Java).

Basically, the client will send me a block of XML which I will validate and process. If all is well, I am going to return an XML document with 2 fields in it (an exit code and a message).

If I use DataContracts (with 1 write only and 2 read only properties) will that do the trick or is there more to this than I am seeing.

Thanks much!

Clay

Answer 1

DataContracts are not “the solution”; the DC is one possible approach for message serialization. whether you want to use DC depends on what the XML must look like, or can look like, and also how you want or need to map from objects in program memory to messages (xml documents or fragments).

In particular, if you want or need xml attributes in the messages, then DataContracts is probably not the way to go.

DC can support this kind of input message:

<request>
  <flavor>7</flavor>
  <param>eiueuie</param>
</request>

notice all data is stored as xml elements. DataContract will not work for this kind of message:

<request flavor='7'>
  <param>eiueuie</param>
</request>

…in which any of the message data is stored in xml attributes. If you want to use XML Attributes, then you probably want to use the XML Serializer. If you don’t care one way or the other then DC will probably be fine.

BUT, the Xml Serializer cannot map private fields or properties into XML elements, while DC Can. So, if your object model requires that, then you cannot use XML Serializer and you should use DC.

To find out more on the tradeoff between DC and XMLS, read this.

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Having said all that, the decision on whether to use DC or not is just one part of your design. You will also need to decide whether you want full SOAP Envelope support (which allows for things like message signatures and so on) or whether you want the simpler “REST” message format, which is probably better called “plain old XML” .

And then there are things like instancing, hosting and activation (use IIS or self-host?), logging/auditing, security (authentication and authorization), and so on.

So, WCF can work for you, for any type of client, but the choice to use DataContracts or not is just one piece of the puzzle.