Question

I’m tinkering around with WCF and MemoryCache. The goal is to host WCF in a Windows Service so different clients can access this cache.

The first part, setting up the host works fine and I’m able to write to and read from the cache via a separate client application. At least, when trying to put very simple objects in the cache, like a string or a value type like int.

When I try a ‘custom’ object, even if it only has a string property, stuff starts to go wrong:

There was an error while trying to serialize parameter http://tempuri.org/:value. 

TheInnerException message was 'Type 'Solution.MyType' with data contract name 
'MyType:http://schemas.datacontract.org/2004/07/MyType' is not expected. 
Consider using a DataContractResolver or add any types not known statically to the list    
of known types 
- for example, by using the KnownTypeAttribute attribute or by 
adding them to the list of known types passed to DataContractSerializer.'.
Please see   InnerException for more details.

Now after some searching I found that I might had to decorate my type with a KnownType attribute, but alas, with no succes. I also tried decorating it with DataContract and DataMember attributes, but no sigar either.

What to do now? Isn’t the WCF DataContractResolver supposed to do this work for me? I find it hard to believe I’d have to write a custom DataContractResolver for every class I want to have serialized. What else are the DataContract and DataMember attributes for?

What am I missing here? Note also that MyType does not inherit from another class (save object).

Answer 1

I’ve solved this by implementing some custom serialisation:

string result = string.Empty;
        Encoding encoding = Encoding.UTF8;
        DataContractSerializer ser = new DataContractSerializer(typeof(MyType));
        MemoryStream stream = new MemoryStream();
        using (XmlDictionaryWriter writer = XmlDictionaryWriter.CreateTextWriter(stream, encoding, true))
        {
            ser.WriteObject(writer, principal);
            writer.Flush();
            result = encoding.GetString(stream.ToArray());
        }

which suffices for my purposes.