moving data between GWT client and App Engine server (Java)

Question

I am creating a client using GWT, and a server using App Engine, where we've got a combination of standard servlets, and Restlet components.

Following some online advice, I've succeeded in using restyGWT on the client side (encode/decode only), and Gson on the server side, to encode an object to JSON, move the data to the other side, and decode the object. In both directions. This is just for a simple class with two public members. I like this approach so far because it appears to not require using annotations.

We're using POST requests.

Is anyone using this approach? Are there pitfalls I should think about? What about private members? Lists/Arrays?

Does anyone prefer a different approach, and what is it?

Obviously we want the client and server to share source code for the objects we're moving back and forth. We'r using JDO annotations, will these conflict with either restyGWT or Gson?

thanks for listening.

Answer 1

me and my team are using restyGWT with jersey and jackson on the serverside. We are pretty happy, apart from the long time jersey takes to start at the beginning of each instance (around 30s). That's for this issue I am starting to look at http://cxf.apache.org/.

In any case working without any REST framework could affect the maintainability of your code: we have around 10 different kind of resources (each one with the 4 different HTTP methods) and it's already difficult to maintain everything.

A suggestion is: pay attention on how long does it take to warm-up an instance. GAE and other PaaS architectures scale well horizontally so the time spent in creating new instances matters (a lot). Just to have an idea: I had JAXB, Jackson and JDO starting-up together and I was already out of 60seconds deadline.

This relates to my suggestion to not use a persistence framework. I am using JDO and I realized all the time I spent understanding how it relates with a NoSql DB could be better spent on creating my own layer (that simply serialize my class to an "Entity" class persisted by low-level API). Without the dealy to initialize all the stuff needed by JDO