Using Web Services Technologies to Build Internet-scale Applications

1. Using Web Services Technologies to Build Internet-scale Applications Savas Parastatidis School of Computing Science University of Newcastle upon Tyne savas@parastatidis.name http://savas.parastatidis.name

2. Outline • NEReSC • Grid Computing • Service-orientation and Web Services • WS-GAF • Applications • Conclusions

3. NEReSC • Active participation • Global Grid Forum • UK e-Science task forces and various committees • Regular regional meetings • Local grid-group meetings • Established in July 2001 • First-point of contact in the region for companies and research groups • Part of the national e-Science Grid network • Great number of research projects • Many in collaboration with industry • $16M

4. Information management for Internet-scale applications Data-intensive Scalability, loose-coupling Computation-intensive Dynamic formation and management of virtual organizations Trust Security Structure Service-oriented computing and Web Services technologies Some projects... BASIS OGSA-DAI OGSA-DQP GridMIST eXSys Microbase e-Demand myGrid GridSHED GOLD Polar* CoreGRID Web Services Grid Application Framework (WS-GAF) NEReSC Research Themes

5. The Grid

6. “What is the Grid?” • “Neo, the Grid is everything you would like it to be” • IBM: “on-demand computing” • HP: “utility computing” • Microsoft: “seamless computing” • ORACLE: “10g” • Sun: “Sun Grid Engine” • Intel: “Seti@home or whatever makes money” • HPC community: Interconnected (super)computers • … • More… • Virtual organisations • Integration of distributed resources • Universal computer • Interconnection technologies for supercomputers

7. Or… if you are a technologist • An application domain for the Web Services ideas and technologies • Or… if you are a researcher/academic • A new set of interesting problems in distributed computing applied at a large scale • Service-orientation • Computational resources • Data resources • Integration • Protocol • Policies • Contracts • Service-level agreements • QoS • etc. etc. etc. • The Newcastle team: “Internet-scale distributed computing (using Web Services as the infrastructure)”

8. Grid Build applications that span organisations Create virtual organisations Seamless integration Hide (virtualise) or share use of resources, network, infrastructure Web Services Glue for heterogeneous platforms/applications/systems Cross- and intra-organisation integration Standards-based distributed computing Interoperability Composability …Based on the concepts of Service Orientation The promises

9. Service-Orientation and Web Services

10. Service Orientation • Built around the concepts of service and message • A service is the logical manifestation of some physical or logical resources (like databases, programs, devices, humans, etc.) and/or some application logic that is exposed to the networkand • A message is a unit of communication for exchanging information. All communication between services is facilitated by the sending and receiving of messages • A service adheres to a contract • Describes the format of the messages exchanged • Defines the message exchange patterns in which a service is prepared to participate • Services are governed by policy • Declaratively describe service interaction requirements, quality of service, security, etc • Focus on messages (message-orientation)

11. Services exchange messages • Service-orientation (and Web Services) helps architects achieve the following properties (but do not guarantee them) • Scalability, encapsulation, maintenance, re-use, composability, loose coupling, etc.

12. Service-orientation vs Resource-orientation Service-orientation Resource-orientation Object-orientation

13. A Service

14. Service-oriented Application

15. A Cluster-based Service-oriented Application

16. An Intranet Service-oriented Application

17. An Internet-scale Service-oriented Application

18. Service-orientation Web Services ≠

19. A Web Service • Specifications for • Security • Orchestration • Reliability • Policies • Federation • Management • etc.

20. The WS Stack

21. Demo

22. Implementation Issues • Focus on message exchanges • Asynchrony • Request-response may cause problems • Latency • Bad bad bad • INTERFACES!!! CLASSES!!! METHODS!!! • The message is the abstraction, not the method • Message Transfer (MEST) • Behaviour is moved from interfaces to protocols, contracts, policies, etc. • Standards are important • No assumptions about programming models, classes/types (object-orientation), implementations

23. Web Services Grid Application Framework(WS-GAF)

24. Motivation • Milestones • OGSI release • WS-GAF paper • WS-RF release • Community concerns over WS specification instability • We now focus on creating applications and demonstrating ideas • Internet-scale applications • Distinction between production and experimental deployments • Ideas and approach are now part of the UK e-Science Strategy whitepaper for a Web Services-based National Grid infrastructure • Protocol-based integration

25. WS-GAF • Simplicity and Minimalism • Composability • No changes in the semantics/characteristics of Web Services • Synergy with existing WS specifications and practices • Avoid effort involved in influencing WS community • Avoid risk associated with not being able to influence WS community • Focus from the low-level “networking” to the more important high-level services (application-domain specific) • Supporting tools • Do not need anything other than existing industry and open-source provided WS tools and platforms (e.g., ASP.NET, Axis, etc.) • Education materials • Industry investment • Performance and scalability • Encourages large granularity, loose coupling (richer, fewer message exchanges)

26. WS-GAF Applications • Needed to build Grid applications using Web Services in order to demonstrate claims • Aims • Define the characteristics of a “typical” Grid application • Demonstrate the applicability of the WS-GAF approach in building Grid applications • Learn from the challenges of constructing a truly global, distributed, scalable, loosely-coupled application • Tools • .NET 2.0 Beta 1 & .NET 1.1 • VS.NET 2005 Beta 1 & VS.NET 2003 • Web Services Enhancements 2.0 SP1

27. Logistics in Chemical Engineering VOs • GOLD UK e-Science pilot project • Use RFIDs to identify bottles with chemicals • Bottles may reside in larger containers • Containers move between organisations • Security/trust • Databases – continuous queries – large amount of information

28. Logistics in Chemical Engineering VOs

29. Logistics in Chemical Engineering VOs

30. Jim Gray’s SkyServer and Edinburgh’s SuperCOSMOS archive Utilise computational resources Visualise Searching for “White Dwarfs”

31. Searching for “White Dwarfs”

32. Demo

33. A Year of WS-GAF • 3 journal publications (with more being prepared) • 1 conference paper • 1 accepted tutorial on Web Services for the W3C's WWW2005 conference • 1 invited MIT Press book chapter (currently under review) • Co-authorship of the white paper-strategy for the UK e-Science community • 1 industrial journal paper • Workshop presentations • >20 invited talks throughout the world • >500 blog entries

34. What’s Next? • Contracts, service description • Capture behaviour through models and make it available as part of the service description • Create tools • Apply ideas throughout NEReSC projects • Build interesting applications • P2P for Internet-scale, service-oriented applications • SOAP Service Description Language (SSDL) - An announcement and initial release end of January 2005 (will be submitted as input to W3C’s WSDL WG)

35. Summary • Service-orientation a good paradigm for Internet-scale computing when used appropriately • Web Services as the implementation technology • Web Services technologies do not implicitly mean scalability and loose-coupling • Good architecture design • Focus on messages • Protocol-based integration

36. People and Links • Paul Watson (Paul.Watson@newcastle.ac.uk) • Savas Parastatidis (Savas.Parastatidis@newcastle.ac.uk) • Jim Webber (Jim.Webber@newcastle.ac.uk) Web Services Grid Application Framework (WS-GAF)http://www.neresc.ac.uk/ws-gaf Mailing list (>90 people from all over the world) ws-gaf@newcastle.ac.uk Join by sending a message to mailbase@newcastle.ac.uk including the following line in the body join ws-gaf YourFirstName YourLastName

37. Thanks • DTI • JISC • UK e-Science Core programme