Play 2.0 integrates the Akka framework to provide built-in support for concurrency. It is designed for asynchronous HTTP requests that can be long-lived using streams or sockets. Concurrency is handled through actors instead of threads for a reactive, event-based model. Play 2.0 provides APIs for asynchronous I/O, executing long tasks asynchronously using actors, and handling data streams reactively without buffering.

1. CONCURRENCY
IN
PLAY 2.0
Ola Wiberg
Wednesday, 11 July, 12

2. OVERVIEW
• Background
• Play architecture
• Integrated Akka
• API
• Asynchronous IO
Wednesday, 11 July, 12

3. A PLATFORM FOR
THE FUTURE
"The web has evolved from
static to dynamic to real-time."
"Play is a framework for highly-scalable
real-time applications!"
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4. DESIGN DECISIONS
• Designed for asynchronous HTTP
• Assumes that any request is long-lived (streams/sockets)
• Concurrency using Actors (Akka) instead of Threads
• Reactive (event based) model for IO
• Keep things simple!
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5. BACKGROUND
Threads or Events
• One process/thread per request • Single process for all requests
• Resource intense / upper bound • Less resource intense
limit
• State maintained in program
• State is handled by the stack
• Single event-loop, with event
• Requests handled in "isolation" call-backs
• Easy to track control flow • Difficult to track control flow
• Apache, Tomcat • Lighttp, Nodejs
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6. A BETTER SOLUTION
• Threads are good
• Events are good
• Why not make use of them both?
• To do it well the complete framework stack
needs to support it!
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7. Java EE compared to Play
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8. Play framework stack
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9. PLAY CONCURRENCY
• Integrated support for Akka
• For concurrent, distributed, event-driven solutions
• Asynchronous IO (play specific)
• Reactive model using Iteratee IO
• Event driven, non-blocking IO (streams/sockets)
• Netty for HTTP
• Asynchronous event-driven framework (NIO)
• Stateless architecture
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10. Wednesday, 11 July, 12

11. AKKA
• Akka is used internally for concurrency features in Play
• Built in ActorSystem to be used by the application
• play.api.libs.concurrent.Akka helper object
• Startup new ActorSystems
• Access remote ActorSystems
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12. WHEN TO USE AKKA
• When executing long running tasks.
• Calculations, data crunching, long running queries.
• When accessing web services.
• When accessing remote ActorSystems.
• When scheduling tasks.
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13. CREATE AN ACTOR
Built in ActorSystem
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14. USING AN ACTOR
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15. CREATE AN ACTOR SYSTEM
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16. EXECUTE A TASK
Without creating an Actor
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17. HELPER METHOD
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18. CALLING A WEB SERVICE
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19. REQUEST => RESPONSE
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20. What type of request, stream or regular request?
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21. In-memory request
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22. Stream/socket based request
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23. REACTIVE MODEL
Async IO
• Handling data streams reactively
• Remove IO stream limitation (Blocking, memory, threads)
• “React” to input only at a rate it is needed (no buffering)
• Implemented using Iteratees, Enumerators, Enumeratees
(Consumer/Producer Pattern)
• Topic for another presentation!
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24. Example System Overview
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25. SUMMARY
• Play 2.0 is implemented for high concurrency applications
• Play 2.0 has a simple API for concurrency features
• Play 2.0 is great for:
• high throughput, low memory usage
• many concurrent requests / socket connection
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26. THANK YOU!
@OlaWiberg
olawiberg@gmail.com
Wednesday, 11 July, 12