Service Life Cycle

blog Submitted by GroG on Tue, 09/18/2018 - 08:59

Service Life Cycle

Name Action
Type		  Description  
Runtime.install(service) Method framework will install if not installed  
Runtime.publishStatus Event installationStart &
installationStop - "general" Status msgs		  
Service.getMetaData Method getting "meta" information - dependencies, exclusions, peers  
Runtime.create(name, type) Method  construct a new service - do not start inbox or outbox - do not create peers yet  
Runtime.register(service) Method puts service in Runtime's registry  
Runtime.registered Event publish to any subscribers the newly registered service, can use onRegistered(name)  
Service.startService() Method starts inbox, outbox - and can call startPeer for all peers  
Service.isReady() Method    
Service.isRunning() Method is true at this point  
Service.publishShutdown Event notifies subscribed services of impending shutdown, can use onShutdown()  
Service.preShutdown() Method called on each service from Runtime before stopService & releaseService are called  
Service.stopService() Method stops the inbox and outbox threads of the service
if overriden super.stopService should be called
any additional threads created by the service need to be shutdown		  
Service.releaseService()  Method calls stopService(), detach(), releasePeers(), unregister()  
Service.detach() Method all attached services are detached - possibly should be "before"stop service because with inbox & outbox stopped this service is unreachable, and detach might require action  
Service.releasePeers() Method recursively release all peers a service might have - recently working - Yay!  
Service.purgeTasks() Method Purges all timers for the service added with addTask  
Runtime.unregister(name) Method Final action to remove service from Runtime registry  
Runtime.released Event publishes released service to any subscribers, can use onReleased  
Runtime.uninstall Method doesn't exist yet - TODO  

Rough draft of "what exists" 
Currently these are method calls, and not "events" .. 

register & release are the only official "events" in mrl

OpenCV Filter Life Cycle

     
     
     

 

 

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MaVo's picture

I think we need to

Submitted by MaVo on Tue, 09/18/2018 - 10:04.

I think we need to differentiate what the framework does vs which method is called on the service/which methods a service should override to do custom things at that stage.

e.g. I want to call a custom cleanup method durning stopService(). Do I now need to take care of my inbox and outbox myself as well?

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kwatters's picture

Lifecycle management

Submitted by kwatters on Tue, 09/18/2018 - 11:17.

This is really a subset of the methods on services.  Lifecycle really is having consistent programatic hooks around when certain framework related things happen to services.

https://docs.oracle.com/cd/E19501-01/819-3659/beamc/index.html

Java defines a specific lifecycle for web servers, and if we consider our services to be very similar in nature.. then the following "official" java lifecycles would be as follows:

INIT_EVENT

STARTUP_EVENT

READY_EVENT

SHUTDOWN_EVENT

TERMINATION_EVENT..

This is just one model ... we might find there are other "events" in a service that we want to hook.   Off the top of my head I can think of the following

  • create
  • start
  • ready
  • shutdown

We might want pre/post hooks on each of those events... we might also want to introduce an error event of some sort.

 

 

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