WCF: MessageContract, DataContract … Confused?

Question

I\'m writing my first WCF service. I decided to write the service just as a DLL to begin with and then aspect the WCF stuff on afterwards which is where I am now.

I

Answer 1

Re the request/response - a [DataContract] would work just as well. One of the advantages of message-contracts is that you can set privacy against members, but in many cases this isn't necessary. In such cases, I prefer to keep the contract as simple as possible, just as a data-contract.

Re which serializer - that is largely a factor of the configuration. By default over http, for example, it will be DataContractSerializer.

I'm not sure, however, that the list of IMyComplexType is going to work very well. You could try, but generally it wants concrete types. Note that with base-classes you can use [KnownType] to specify the allowed sub-types.

Note that unlike XmlSerializer, it is not a requirement for collection members to have setters - although you might need to add an OnDeserializing callback method to initialize the list if you do that (WCF doesn't call constructors).

Aside: you can also use protobuf-net with data-contracts and WCF (as long as they have an explicit Order); this is more densely packed than the regular xml. It has no support for message-contracts at the moment, though.

Answer 2

Though not a direct answer to your question, it is worth to take a note of the following from MSDN -Using Message Contracts

Each individual message header and message body part is serialized (turned into XML) using the chosen serialization engine for the service contract where the message is used. The default serialization engine, the XmlFormatter, can handle any type that has a data contract, either explicitly (by having the System. Runtime. Serialization. DataContractAttribute) or implicitly (by being a primitive type, having the System.SerializableAttribute, and so on).