--
Galder Zamarreño
Infinispan, Red Hat
On 30 Mar 2017, at 18:33, Dan Berindei <dan.berindei(a)gmail.com>
wrote:
On Thu, Mar 30, 2017 at 3:51 PM, Galder Zamarreño <galder(a)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.
>
I know Sanne also wanted to add one of the query modules as an
optional dependency to the core module for a similar reason, but it
seems really hacky.
Yeah, might be a bit hacky but it's just a configuration change as opposed to a code
change.
Could the server create the GlobalConfigurationBuilder with a
classloader that has access to the query module instead?
Hmmm, not sure. I mean, in theory you could plug any marshaller, even
com.acme.WhateverMarshaller, so it's not really an issue about having access to the
query module, but having access a module that contains that marshaller.
Alternatively, I know ModularClassResolver prefixes class names with
the slot and module name, and can load a class from any module. Maybe
we could also allow a slot:module:class format everywhere the
configuration currently accepts a class name?
That could be handy. I'm about to create a JIRA on this, so I'll add it as an idea
to it.
> 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].
>
> 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/do...
> [2]
https://github.com/galderz/datagrid-patterns/blob/master/server-config/or...
> [3]
https://github.com/galderz/datagrid-patterns/blob/master/analytics-stream...
> [4]
https://github.com/galderz/datagrid-patterns/blob/master/analytics-stream...
> --
> Galder Zamarreño
> Infinispan, Red Hat
>
>
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> infinispan-dev(a)lists.jboss.org
>
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