[infinispan-dev] Infinispan and Google app engine

[Manik Surtani]

On 30 Nov 2009, at 18:05, Vladimir Blagojevic wrote:

> Hi all,
> 
> Manik asked me to investigate what it would take to deploy Infinispan 
> inside google app engine (GAE). As you might have heard GAE execution 
> environment is somewhat constricted (can not create threads, write to 
> files, open sockets, etc). Right from a get go it was clear that we can 
> not run Infinispan in any mode other than local. However, even if 
> Infinispan is run in local mode GAE users could benefit from 
> Infinispan's JSR-107 cache interface that is backed up with cache store 
> implemented using google datastore api. There probably are use case 
> scenarios where GAE users interact with both google provided JSR-107 
> memcache service [1] and datastore [2] separately where in fact 
> Infinispan's JSR-107 interface that is automatically synced with 
> datastore would make much more sense.

Yup.  It would be good to put together a wiki page on how and why this is a good thing, maybe even with some benchmarks using GAE/J APIs directly and via Infinispan.

> Manik and I went back and forth and decided to put this sub project on a 
> back burner at this moment. Even though we could accommodate GAE's 
> thread restriction it turns out that GAE sandbox restrictions involve 
> several apis that we use (JAXB, JMX, JNDI among others) and retrofitting 
> Infinispan into this tight sandbox would be a headache. There is a 
> strong comunity push to unrestrict these API and it seems pressures from 
> community would eventually be successful.

JAXB is the real headache since our configuration relies on it.  The rest - JNDI, JMX - can all be switched off.  TBH, even JAXB is not *critical* as we could support just programmatic config, but that still is pretty intrusive so I think JAXB is the real blocker.

> Also, I am still awaiting for some feedback from Mircea to see if we can 
> even implement google datastore cache loader to be transactional. Even 
> though GAE datastore supports transactions they are only available in 
> the same entity group [3]. As far as I understand GAE datastore they 
> implement horizontal partitioning which basically involves putting 
> different rows into different tables. Think each Person row entry would 
> have to be in different table unless they are in some owns (say 
> parent-child) relationship.

I don't think we need to worry about transactions and cache stores.  Propagating transaction context to a cache store is entirely optional and only if the underlying store is JTA compliant (e.g., JDBC).  Most of our cache stores are not JTA compliant (file system, S3, etc) but we still work around this quite well - have a look at the FileCacheStore as an example.

Cheers
Manik

> 
> Feedback appreciated,
> Vladimir
> 
> [1] http://code.google.com/appengine/docs/java/memcache/usingjcache.html
> [2] http://code.google.com/appengine/docs/java/datastore/
> [3] http://www.youtube.com/watch?v=2jW2iSKDipY (between 6:45 and 11:40)
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--
Manik Surtani
manik at jboss.org
Lead, Infinispan
Lead, JBoss Cache
http://www.infinispan.org
http://www.jbosscache.org