[infinispan-dev] Executing server tasks that contain POJOs

[Gustavo Fernandes]

On Thu, Mar 30, 2017 at 1:51 PM, Galder Zamarreño <galder at redhat.com> wrote:

> Hi all,
>
> For a demo I'm giving next week, I'd like to show how to use distributed
> streams via a remote server task. All server tasks that we have in
> testsuite rely on primitives but in my case I wanted to use POJOs.
>
> To do that, I needed to get compatibility mode working in such way that
> those POJOs could be unmarshalled for the server task. Since in another
> demo I'm showing Protostream based POJOs, I thought I'd try to use that as
> mechanism to unmarshall POJOs server side.
>
> We have a test for such scenario [1], but the reality (running on a proper
> server) is anything that simple. Here's a list of things I've found out
> while creating a WordCount example that relies on a POJO:
>
> 1. Out of the box, it's impossible to set compatibility marshaller to
> org.infinispan.query.remote.CompatibilityProtoStreamMarshaller [1]
> because "org.infinispan.main" classloader can't access that class. I worked
> around that by tweaking the module.xml to have an optional dependency to
> "org.infinispan.remote-query.server" module.
>
> 2. After doing that, I had to register the protofile and associated
> classes remotely in the server. Again, there's no out of the box mechanism
> for that, so I created a remote server task that would do that [3].
>


AFAICT, you should be able to do that doing a PUT in the Protobuf_Metadata
cache, which entails having auth enabled. This cache should be REPL_SYNC,
so no need to run a server task.



>
> 3. Finally, with all that in place, I was able to complete the WordCount
> test [4] with a final caveat: the return of the word count, and words
> protofile registration, tasks return objects that are not marshalled by the
> compatibility marshaller, so I had to make sure that the remote cache
> manager used for those tasks uses the default marshaller.
>
> Clearly we need to improve on this, and we have plans to address these
> issues (with new upcoming transcoding capabilities), but I thought it'd be
> worth mentioning the problems found in case anyone else encounters them
> before transcoding is in place.
>
> Cheers,
>
> [1] https://github.com/galderz/datagrid-patterns/blob/master/
> server-config/domain/domain.xml#L139
> [2] https://github.com/galderz/datagrid-patterns/blob/master/
> server-config/org.infinispan.main_module.xml#L18
> [3] https://github.com/galderz/datagrid-patterns/blob/master/
> analytics-stream/tasks-server/src/main/java/test/WordsProtoTask.java
> [4] https://github.com/galderz/datagrid-patterns/blob/master/
> analytics-stream/tasks-client/src/test/java/test/WordCountTest.java
> --
> Galder Zamarreño
> Infinispan, Red Hat
>
>
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