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Experiences with WS-Transfer and WS-Eventing for Grids. Marty Humphrey Glenn Wasson Computer Science Department University of Virginia GGF14 OGSA-MWS BOF June 28, 2005. Some Goals of OGSA. Leverage Web services tooling and run-time infrastructure
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Experiences with WS-Transfer and WS-Eventing for Grids Marty Humphrey Glenn Wasson Computer Science Department University of Virginia GGF14 OGSA-MWS BOF June 28, 2005
Some Goals of OGSA • Leverage Web services tooling and run-time infrastructure • Minimize the amount of “stuff” that our community has to provide and/or maintain • Promote interoperability and composability
WSRF.NET • M. Humphrey, G. Wasson, K. Jackson, J. Boverhof, M. Rodriguez, J. Gawor, S. Lang, I. Foster, S. Meder, S. Pickles, and M. McKeown. State and Events for Web Services: A Comparison of Five WS-Resource Framework and WS-Notification Implementations. 14th IEEE International Symposium on High Performance Distributed Computing (HPDC-14), Research Triangle Park, NC, 24-27 July 2005. • http://www.ws-rf.net
Comparing WSRF to WS-Transfer et. al. • Goal: Objective, scientific exploration and comparison of WSRF to WS-Transfer, WS-Eventing, et. al. • M. Humphrey, G. Wasson, Y. Kiryakov, S-M. Park, D. Del Vecchio, N. Beekwilder, and J. Gray. Alternative Software Stacks for OGSA-based Grids.Proceedings of Supercomputing 2005, Seattle, WA, Nov 12-18, 2005.
Methodology • Implement both stacks on .NET • Comparing the specs • Comparing the implementation of the specs • Comparing the performance of the implementation of the specs
Results: Comparing the Specs • Lack of “create” in WSRF is problematic • Lack of input/output schema in WS-Transfer is problematic • WS-Transfer is less complex (implications?) • WSRF: single “type” of resource; WS-Transfer is agnostic • WS-Notification is more complex than WS-Eventing • But much of WS-Notification is optional
Results: Implementing the Specifications • Both are resource-oriented, so not surprising that both are back-ended with an XML database (Xindice) • WS-Transfer was easier to implement than WSRF • Neither define a Programming model • Not many implementations of WS-Notification are going to implement all of it
Account Service Exec Service Data Service Resource Allocation Service Proc Spawn Win Service Reservation Service Client WSRF.NET Grid-in-a-Box WS-Resources are processes Claim reservation by lengthening resource’s lifetime WS-Resources are reservations 10b Does this user have an account in this VO? 9 Launch job WS-Resources are accounts 2 8 Create new reservation under client’s DN Start application 11 5 Async. notification when done 10a Data input/output 1 What resources are available for my application? 6 WS-Resources are allocatable resources Create new data resource 3 Available Exec/Data Services 7 Stage-in data WS-Resources are directories 4 Authorization based on DN, all messages X509 signed Reserve resources
Summary of Results • Is one spec/implementation faster? • No. • Is one spec/implementation easier to program clients/services? • No – both are complicated by resource vs. representation issue. Programming model is (arguably) orthogonal. • Can WS-Transfer imply mapping too much to CRUD? • Yes.
Summary of Results • If one is "more full-featured" than another, are the extra features useful? • Jury is still out on the additional functionality of WSRF (brokered notification, service groups, lifetime management, resource property queries) • How easy is it to switch from one stack to the other? • Switching from WS-Transfer/WS-Eventing to WSRF/WS-Notification is likely easier.
WSRF Translator Filter Web Service WS-T WSRF Client (any platform) WS-T Web Service (.Net based) WSRF WST Translationvia Server-Side Translation Filter WSRF request WSRF response Works similarly for a WS-T client and a WSRF service.
1. translate() WSRF request message 2. WS-T equivalent WSRF WS-T WSRF Client (any platform) WS-T Web Service (any platform) WSRF WST Translationvia Translation Service 5. translate() WS-T response message 6. WSRF equivalent TranslationService (.Net based) 3. WS-T request 4. WS-T response
Summary • We have concrete experience that Grid services can be built via WS-Transfer et. al. • Services comparable to WSRF-based services, in behavior and performance • Microsoft et. al. has enumerated plans to build on WS-Transfer et. al. • “these specs should be in a standards body within 1 year” • OGSA needs the plumbing to be “just there” • Is it time for an OGSA Profile based on WS-Transfer et. al.?