I have external library that requires very long initialization time (approx. 2 minutes) and I need to call it in almost every HTTP request that is handled by Play Framework Controller-Action. Is there mechanism to instantiate such Scala object (e.g. put into some global scope, some Configuration bean, some specialized Cache) and retrieve it upon request in Controller-Action?
This object is not fully stateful object. It is stateful in the meaning that it requires some complex initialization. But when it is ready up and running then it is stateless - it can serve any request in any time (of course, some queuing may be necessary, but I can implement it with some tricks), it is common resource in this sense.
My Play application is purely stateless API, so, there is no HTTP session. I was thinking about use of Spring in Play (I guess, it is possible), but Spring session scope is related to HTTP sessions and servlets, so, this is not solution.
I have not managed to find uses cases which uses J2EE session beans in Play, maybe that is not possible.
I am reading about ThreadPools and configuration facility of the Play framework, but currently I feel quite skeptical that Play Framework can have such statful/preinitialized/common-resource.
Context: the mentioned common resource is quite heavy mathematical library that can do some AI/automated reasoning, I plan to use Play framework to create API around it and then use this API from the Python machine learning scripts.
I am considering using Cache API https://www.playframework.com/documentation/2.8.x/ScalaCache . I will expand my answer further when I will be able report results of my efforts.