On Using BPEL Extensibility to Implement OGSI and WSRF Grid Workflows Aleksander Slomiski Presented by Onyeka Ezenwoye CIS Advanced Topics in Software Engineering

2 Outline Agenda Background BPEL Overview BPEL/OGSI BPEL/WSRF Other Issues Conclusion Agenda Background BPEL BPEL / OGSI BPEL / WSRF Other Issues Conclusion

3 Outline Grid: A dynamic multi-institutional network of computers that come together to share resources for the purpose of coordinated problem solving. Agenda Background BPEL BPEL / OGSI BPEL / WSRF resource application institutional boundary Achieved through: 1.Open general-purpose protocols 2.Standard interfaces Other Issues Conclusion

4 Outline Agenda BPEL / OGSI BPEL / WSRF Web Services: A Web service is an application that is accessible over the internet. Background BPEL Java RMI App 1App N … Firewall Enterprise A Enterprise B Enterprise C Enterprise D Internet.NET App 1App N … CORBA App 1App N … etc. App 1App N … Core Technologies: XML (eXtensible Markup Language) SOAP (Simple Object Access Protocol) WSDL (Web Service Description Language) Other Issues Conclusion

5 Outline WSDL + defines data elements of operations + components of the message defines the web service interface + operations that can be performed * comms. protocols for operations a list of binding and ports to the bindings Agenda BPEL / OGSI BPEL / WSRF Background BPEL Subscribe Publish Bind Service Consumer Client Service Provider Service Service Broker WSDL Legend request flow reply flow program boundary module boundary Reply Service Description Other Issues Conclusion

6 Outline Open Grid Service Infrastructure (OGSI) –Grid service interface standard Methods allow access to Grid service As well as Grid service state (SDE) –Optional factory interface –Naming and referencing of Grid services –Extends WSDL 1.1 (GWSDL) Agenda BPEL / OGSI BPEL / WSRF Background BPEL Grid Service Handle (GSH) Publish GSR Bind Service Consumer Client Service Provider Grid Service OGSI Registry Grid Service Reference (GSR) Legend request flow reply flow program boundary module boundary Reply Grid Service Reference OGSI Grid service locator: Multiple GHSs + GSRs + interface description Other Issues Conclusion

7 Outline Web Service Resource Framework (WSRF) –Distinguish between service and stateful resource Model stateful resource as a Web service –Modular (users decide which specification to use) Agenda BPEL / OGSI BPEL / WSRF Background BPEL * OGSIWSRF Grid Service ReferenceWS-Addressing Endpoint Reference Grid Service HandleWS-Addressing Endpoint Reference HandleResolver portTypeWS-RenewableReferences Service data defn & accessWS-ResourceProperties GridService lifetime mgmtWS-ResourceLifeCycle Notification portTypesWS-Notification Factory portTypeTreated as a pattern ServiceGroup portTypesWS-ServiceGroup Base fault typeWS-BaseFaults OGSI to WSRF* Other Issues Conclusion

8 Outline Workflow: A description of the sequence of interaction between a set of activities that are performed together to achieve a common goal. Agenda BPEL / OGSI BPEL / WSRF Background BPEL Step 1 Step 3 Step 2 Step 4 Activity Condition / interaction Other Issues Conclusion Rapid composition Automation Management

9 Outline BPEL: An XML based workflow language for composing aggregate Web services. Agenda Background BPEL / OGSI BPEL / WSRF BPEL Amazon Store WS result query Google Spell-checker WS result phrase Other Issues Conclusion

10 Outline Google-Amazon BPEL process BPEL Engine interprets XML-grammar Exposed as a Web service Described by WSDL (version 1.1) Agenda Background BPEL / OGSI BPEL / WSRF BPEL Amazon Store WS result query Google Spell-checker WS result phrase assignment activity Other Issues Conclusion

11 Outline Partners <partnerLink myRole="googleAmazon" … partnerLinkType="lns:googleAmazonLinkType"/> <partnerLink partnerRole =“Google" … partnerLinkType="lns: GoogleLinkType "/> <partnerLink name=“Amazon“ … partnerLinkType="lns:AmazonLinkType"/> Agenda Background BPEL / OGSI BPEL / WSRF BPEL Activities … … … … … receive invoke reply GoogleAmazon Google-Amazon Partners Other Issues Conclusion

12 Outline Google-Amazon BPEL process Agenda Background BPEL / OGSI BPEL / WSRF BPEL Screenshot from ActiveWebflow TM Professional Other Issues Conclusion

13 Outline Fault Handling Two constructs for handling faults; and. Event Handling Timeout Agenda Background BPEL / OGSI BPEL / WSRF BPEL BPEL Engine process n 5 1 Message Correlation Other Issues Conclusion

14 Outline Agenda Background BPEL / OGSI BPEL / WSRF BPEL BPEL And OGSI Integration* Leveraging BPEL abstractions –BPEL Partner is known by interface (PortType) –Very powerful integration mechanism! Understands natively GSH/Locator as service reference –Handle automatically GSH to GSR conversion Supports Explicit and Implicit Lifecycle –GPEL workflow engine is also OGSI Factory * Aleksander Slomiski Other Issues Conclusion

15 Outline Agenda Background BPEL / OGSI BPEL / WSRF BPEL Issues in OGSI Integration * GSH/GSR and WS-Addressing –Endpoint Reference (EPR) is not GSH or GSR … BPEL and OGSI Factory –BPEL Engine acts as factory –BPEL has already implicit creation model BPEL Engine that is NOT OGSI Factory –Will not fit into common OGSI usage pattern –OGSI Factory is optional … * Aleksander Slomiski Other Issues Conclusion

16 Outline Agenda Background BPEL / OGSI BPEL / WSRF BPEL WSRF Support * WS-Addressing (WSA) –Workflow Instance identification WSA is already used by BPEL … –No need to do conversions WS-Resource properties –Similar to OGSI SDEs WS-Notification –Monitoring workflow state * Aleksander Slomiski Other Issues Conclusion

17 Outline Agenda Background BPEL / OGSI BPEL / WSRF BPEL Integration with Today Grid * GridFTP, GSI Security, Condor, … Add set of pseudo partners (services) –No need to extend BPEL syntax! –They represent built-in functionality (handy!) –Can be implemented as real Web Services Will make easy to write workflow that is: –Working on Grid (CoG services) –Manipulating components (XCAT) –Large data transfers (GridFTP, RFT service) Similarly could have OGSI partners –Natively understands GSH/GSR/locator –Maintains soft state etc. * Aleksander Slomiski Other Issues Conclusion

18 Outline Agenda Background BPEL / OGSI BPEL / WSRF BPEL Additional Issues * Workflow Monitoring –How much state exposed as XML is needed? Fault Tolerance –Selection of alternative services –Dealing with “unexpected” exceptions Supporting Large Data and Streaming –Suitable metaphor (in BPEL)? * Aleksander Slomiski Other Issues Conclusion

19 Outline Questions? Agenda Background BPEL / OGSI BPEL / WSRF BPEL Other Issues Conclusion Service Port TypeFactory Port Type OGSI Grid Service WSDL Port Type BPEL Process Smart Proxy