On Thu, Mar 30, 2017 at 3:51 PM, Galder ZamarreƱo <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.
Could the server create the GlobalConfigurationBuilder with a
classloader that has access to the query module instead?
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?
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 ZamarreƱo
Infinispan, Red Hat
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