KeyValuePair value type

[Prageeth Silva]

Looks like GWT doesn't allow Object as a type to be returned or used as method parameters (or used as fields) in classes that go through RPC.

Therefore I was trying to implement Serializable as the value field (and also for the particular getter and setter).

I can't remember why we had a conversation about the client api returning Object instead of Serializable; the head revision contains Serializable in the KeyValueService in the client api.

For now, I'm planning to convert the KeyValuePair (Client wrapper class) to use Serializable for the value field (and the getter/setter).

Any thoughts? Am I missing something that we discussed the other day?

[Prageeth Silva (prageethsilva)]

OK, I think I came across the GWT warnings that complain about using java.io.Serializable and the only work around that worked so far is when I used com.google.gwt.user.client.rpc.IsSerializable instead.

However, what I don't understand is that the client API still uses java.io.Serializable but GWT doesn't complain.

[Scott Ritchie (sritchie)]

The problem was (when i tried to fix it) Is that if you changed the value type to Serializable or IsSerializable, it would throw a warning at compile time that it couldnt find any class of that type - My interpretation of the error message was that it iterated over our class files looking for those marked with the Serializable/IsSerializable interface. So even if the students supplied their own Serializable class, it wouldnt work because it wouldnt be one of the Serializable/IsSerializable classes found at compile time.

[Matt Giuca (mgiuca)]

Is this a duplicate of bug #744035? I feel like we have had this discussion many times (on the mailing list). There wasn't really a good solution.

We can't use com.google.gwt.user.client.rpc.IsSerializable, as that doesn't work for primitive types and requires that the game developers implement that obscure interface. I thought I tried it with students supplying their own java.io.Serializable and that worked, despite the warning. I think it's just a performance issue.

See this Stack Overflow question I asked:
http://stackoverflow.com/questions/5538591/should-a-gwt-rpc-service-use-java-io-serializable-as-a-parameter-type

[Prageeth Silva (prageethsilva)]

@Scott: The way I interpreted was that, by that time, we had an annotation "serialize=true", and that is only valid for concrete classes. That's the reason you kept getting that error. Other than that, I really don't know the solution; the optimised solution rather.