Websight Visualizing the Execution of Web Services

1. WebsightVisualizing the Execution of Web Services Wim De Pauw, Bob Hoch, Sophia Krasikov, Michelle Lei, John Morar, Raju Pavuluri, Amit Phalgune, Ed Pring, Senthil Velayudham Contact: wim@us.ibm.com

2. Outline • Motivation • Debugging Web Services • Profiling and understanding Web Services • Dealing with complexity • Technology • Conclusions Agenda slide

3. What are Web Services? "A WSDL described interface that defines a collection of network accessible operations" • Modular • Composed • Described • Published • Found • Bound • Invoked

4. Evolution of Web Services • Internal Enterprise Application Integration • External Integration • Dynamic adaptation in e-business => Lingua Franca for (loosely coupled) distributed systems

5. Web Services: the Challenge • Do you know how your Web Services are interacting ? • Ever tried to read their trace logs? • Ever tried to collate ten trace logs? • Where are the bottlenecks? • Is your workflow correct?

6. Websight: Problem Determination for Web Services • Debugging and understanding • Analysis at application level • Understand message flow of Web Services in complex applications • Total processing time vs. business logic time • Experimental research tool

7. -- --- --- --- --- --- -- Sample Target: eServicePac BPEL Engine Compatibility BP Model for SPV Exclusivity Partner World Check warranty period SAP-F Check Model & Serial number Java to Web Services Web Services wrapper Validation Functions

8. Operation Maintenance Problem Determination Lifecycle Implement Deploy Design Business requirements

9. Websight demo

10. Debugging Web Services • Syntax errors • Semantic errors • “Resource unavailable” errors • Business logic errors

11. Syntax Errors • Often relate to representing “unusual values” • Example: ambiguous type conversions XML – Java • In subsequent versions of a SOAP engine: • java.util.GregorianCalendar  xsd:date • java.util.GregorianCalendar  xsd:dateTime • Example: encoding of null String vs. empty String • Example: problem with “out of range” values

12. Find Syntax Errors by Inspecting the Content

13. Semantic Errors: Discordant Meanings • Even if the syntax is correct, service providers and consumers may associate different meanings to certain expressions • Examples: • Empty field means: “wildcard” or “missing information”? • Timestamp (omitting or ignoring time zones) • 2004-07-11T10:49:24.938000-04:00

14. Semantic Errors: Unexpected Modes of Execution • Example: • Client node sends (unexpectedly!) two identical messages for every transaction. • Functional Testing did not reveal this problem

15. Semantic Error: Unexpected Modes of Execution • Unexpected Flow Order: • Architect did not expect “stackingChecker” before “compatibilityChecker” because workflow engine was in parallel instead of serial mode.

16. “Resource Unavailable” Errors • Find out if/where a node is down • Effect / cause may be in different places • Examples: • Database server down, workflow engine continues • Server throws an HTTP error, fed into SOAP parser • We use reactive approach • Proactive approach: synthetic heartbeat

17. Business logic error • Example: • For this operation we didn’t need to call StackingChecker service • Unit testing did not expose this problem – since the existing test data generated the correct result

18. Profiling is Understanding • Where is time spent? • Network vs. business logic? • Chatty communication?

19. Profiling: Sorting Statistics • Table view helps find outliers by sorting Network Duration in table view for several transactions • Selecting the outliers in table highlights corresponding messages in other views

20. Understanding Web Services Configurations • Example: Two concurrent Transactions using two workflow engines

21. From Design Document SCM Traced Topology SCM Understanding Web Services Configurations • Supply Chain Management from WS-I

22. Dealing with complexity • High traffic, high number of nodes, complex interactions • Pattern extraction • Selective tracing

23. Dealing with complexity: Pattern Extraction Fifty Concurrent Transactions

24. Selective Tracing for Heavy Loads • Tracing everything during heavy load is undesirable: too much perturbation, too much data • Start with “marked” transaction (carrying correlator) • Tracing will be turned on when this transaction is handled • Reduces amount of data to be traced • Easier to understand 1 typical transaction than 10000

25. Technology: based on Eclipse and Hyades Hyades: Integrated test, trace and monitoring environment Open source basic infrastructure Tool interoperability across testing/profiling process www.eclipse.org/hyades Components Information model (EMF) Communication framework (Remote Agent Controller) Data collection

26. Typical architecture for existing testing/profiling tools

27. Hyades provides a common infrastructure

28. Deployment • Collect runtime • information 2) Present to user

29. SelectiveTracing Websight Runtime (experimental setup) Apache SOAP Parser Axis Parser Websphere Parser Non-SOAP protocols Websight Interface Websight Runtime Websphere Runtime Logging Correlation Remote Agent Controller Visualizer Websight Trace File

30. Correlating Distributed Events • Problem : correlating messages • Goal : trace end-to-end message flow across system ?

31. Correlating Distributed Events • Correlator technology: • ARM correlator technology • Web Services correlator • Websight SOAP header carries correlator • Propagation through business logic handled by middleware Receive Correlator Receive Correlator Attach Correlator Attach Correlator

32. Summary • Debugging Web Services requires new methodologies and tools • Complexity at the application level • Opportunities for work flow

33. Contact:wim@us.ibm.com Closing slide

34. Backup foils

35. New Order Transaction

36. Existing Order Transaction

37. Two Concurrent Transactions using Two Workflow Engines

38. Navigation between Views Selecting an item in one view… …highlights corresponding items in the other views

39. Supply Chain Management: Maximal Transaction(understanding the complex flow)