OGSA-DAI Activities OGSA-DAI for Developers GridWorld 2006, Washington DC 11 September 2006

2 Outline l What are activities? l A new activity framework l How activities are processed l Monitoring

3 Activity Framework l The Activity Framework is a core component of OGSA-DAI l It is reponsible for performing operations (activities) and streaming data

4 Activities l Activities are specific processing tasks l Activities often interact with a data resource l Activities usually consume and produce data l Activities can be chained by connecting outputs and inputs

5 OGSA-DAI Activities l Many activities are shipped with the OGSA- DAI release l Mix and match activities to provide functionality you need l Or implement your own activities that meet specific requirements!

6 Example Activity Pipeline DB Query Delivery block Produces data in blocks Stores and provides access to data blocks Consumes data blocks Pipe

7 Activity Processing (Current Release) l Processing of blocks (and therefore, activities) is controlled by the pipe – from outside the activity u processBlock() is called many times until processing is completed u Usually consumes and produces a single block per call

8 Activity Processing (Future) l Processing of blocks will be controlled by the activity u process() is called exactly once u Consumes and produces blocks as necessary u Each activity in a pipeline processes within its own thread u Pipes receive and may buffer blocks until they are requested

9 Current Release Activity A processBlock() Activity B processBlock() Request Processor processBlock getBlock block processBlock block Called repeatedly Pipe

10 Future Release Activity A process() Activity B process() getBlock process putBlock block Processing Service initialise process Called Once Pipe

11 Activity Interface l All activities must implement the Activity interface l Activities may extend the abstract BaseActivity class which implements common functionality => only need to implement process()

12 Activity Extension Interfaces l New interfaces extend the base activity to provide access to necessary information u Activities that access data resources u Activites that create new requests u Activities that are configurable u …

13 Monitoring l Monitoring Framework: Provides Listener interfaces l Activity Listeners: Receive activity events, for example u Activity initialised u Activity processing u Error occurred u Processing completed u Custom events …

14 More Listeners l Pipe Listeners: Receive pipe events, for example u Block produced u Block consumed l Various listeners may be implemented to support logging, auditing, debugging etc.

15 Summary l The next release of OGSA-DAI will introduce a new Activity Framework l Improved pipeline processing l Simplified interfaces l A monitoring framework

16 The End Questions?