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OGSA/GT3 evaluation at CERN

This report covers the evaluation of OGSA/GT3 at CERN, exploring the promise of web services framework, GT3 offerings, and hosting environments for grid services development. It discusses the motivations, objectives, and outcomes of the evaluation, highlighting the GT3 toolkit, performance studies, and integration of existing codes/services. The document also delves into designing grid services, understanding service data, subscriptions, and notifications, and provides insights into test beds for hands-on experiences with Globus Toolkit 3.

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OGSA/GT3 evaluation at CERN

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  1. OGSA/GT3 evaluation at CERN Activity Report M. Lamanna (CERN), R. Brito Da Rocha (European Data Grid), Tao-Sheng Chen (Academia Sinica Taipei), A. Demichev (Moscow State Univ. MSU), D. Foster (CERN), V. Kalyaev (MSU), A. Kryukov (MSU), V. Pose (JINR Dubna), C. Wang (Academica Sinica Taipei) OGSA/GT3 evaluation

  2. Table of Content • Introduction • Activity highlights • GT3 ToolKit Experience • GT3 Performance studies • Integration of Existing Codes/Services • Conclusions OGSA/GT3 evaluation

  3. Motivation • The promise of the web services framework • Standard environment for Grid applications • New projects are looking to OGSA as the solution to all problems… • Here and now • Globus a release of the new toolkit in May 2003. • OGSI framework and some grid services • GT3 out July the 1st (new major release -3.2- 1H04) • To provide input to the EGEE middleware activity • OGSA/GT3 project • Primary objectives of the OGSA/GT3 evaluation: • Understand the GT3 offering and its “quality” • Learn how to create new services in this framework • Study how to leverage existing developments in an OGSA context • Create local know-how on promising technologies • Most people at CERN only for short periods • Variable geometry approach • 75% of the people are not always at CERN • Open to new collaborators OGSA/GT3 evaluation

  4. What does GT3 offer? (NOW) • The first OGSI implementation (July 2003: 3.0.x) • The toolkit itself • Build new services and extend existing ones • Security Infrastructure • GSI (Globus Security Infrastructure) • Services • GRAM (GT2 implementation wrapped up as a Grid service) • IS ( Index Service; new GT3 implementation) • RFT (Reliable File Transfer; it uses Globus FTP) • Explore these three lines OGSA/GT3 evaluation

  5. HOSTING ENVIRONMENT GRID CONTAINER GRID SERVICES OGSI IMPL. COMPLEMENTARY WEB SERVICES ENGINE Grid Service Development • Grid Services • Extended Web Services complying to the OGSI specification • Converge on a standard system OGSA/GT3 evaluation

  6. Grid Service Development • What we get: • From Web Services • Interoperability • standard for message creation and definition - XML • standard for protocol-independent message passing – SOAP • standard for service definition – WSDL • choice on hosting environment is left to the service provider • Service Oriented Design approach • From OGSI • Stateful Services (Service Data) • Other common features on independent services • Different from GT2 where nothing is common between services apart from GSI • Straightforward development: common framework for service usage and management OGSA/GT3 evaluation

  7. Grid Service Development • Current options: • Hosting Environments: • J2EE Application Server – Jakarta Tomcat, GT3 StandaloneContainer, Websphere, … • Microsoft .NET Platform • OGSI implementations: • J2EE Servers: Globus Toolkit 3 • Microsoft .NET: OGSI.NET (Virginia Univ.); MS.NETGrid (EPCC) • Others are appearing • Any environment with an existing implementation of a Web Services engine is one single step away from providing Grid Services • Ex: OGSI::Lite (Perl), pyGridWare (Python) OGSA/GT3 evaluation

  8. Designing Grid Services • Important concepts when designing Grid Services: • Factories and Instances 1 FACTORY CLIENT INSTANCE 2 • Factories create instances and respond to instance creation requests by clients • Instances respond to client’s service specific interaction requests • Advantages: • Workload balancing between pools of instances • User dependent instances • Disadvantages: • Instance creation overhead OGSA/GT3 evaluation

  9. Designing Grid Services • Approach: • Service Data, Subscriptions and Notifications GRID SERVICE A 1 - SUBSCRIPTION GRID SERVICE B SDE A1 SDE A2 SDE B1 2,.. - NOTIFICATIONS • Each Grid Service has it’s own Service Data Set - collection of Service Data Elements (SDEs) • Every SDE has a set of associated values concerning its validity in time – goodFrom, goodUntil, availableUntil • A service or client may declare interest in a SDE by issuing a Subscription • Service Data flows by means of Notifications – normally when a change occurs or the value lifetime has expired OGSA/GT3 evaluation

  10. TestBeds • First hand experience on Globus Toolkit 3 • This can be achieved only by using it! • The main tool are prototypes, with the following common features: • Small • Working (with limited functionality) • No architectural ambition • Engineering approach • Mapping of functionality – prototype functions • GT3 TestBed • 4 CERN machines + 1 in Moscow • Focus on GT3 basic functionality and performances • Performance tests use also some high performance machines and Lxplus (CERN Linux interactive service) • AliEn TestBed • 3 CERN TestBed machines • “Architecture” TestBed • Focus on the complexity of future possible architectures • Deployment use cases OGSA/GT3 evaluation

  11. Example: GT3 Test Bed ToolKit • Resource broker and L&B (Custom service) • Surprisingly fast to set-up • A few computing elements (GT3-GRAM, with modifications) • 2 PC boxes in the CERN Computing Centre • In a second phase, one PC located in Moscow was added • Some problems (solved) in data stage-in/stage-out • See GRAM comments in the performance part • Information service (GT3-IS) • Native GT3 service • In this TestBed talks only with other services Security GT3 Services OGSA/GT3 evaluation

  12. GT3 TestBed coverage… Every service must implement this PortType Modelling activity of this type of service starting OGSA/GT3 evaluation

  13. Prototypes developed within the project • Performance Prototypes • Dummy Service • Dummy Secure Service • Dummy Service with Service Data • Dummy Service with Notifications • Dummy Service + Index Service • Index Listener • Globus 3 “components” tests • GRAM tests • Index Service tests • Reliable File Transfer tests • GSI (Security) tests • Implementation of deployment use cases • Remote installation (via dedicated custom services) • Remote management of different version of a service • Higher Level Prototyping • File Catalog Service • Metadata Catalog Service • Storage Element Service • Workload Management Service • Computing Element • Authentication and Authorization OGSA/GT3 evaluation

  14. Globus Toolkit 3 Overview • The GT 3 is the first complete implementation of the OGSI specification • The development process is much easier when compared with GT2. • Steep learning curve should be taken into account! • New approach to service design and implementation • Deployment Tools (not yet complete) • Backward compatibility: • All GT2 components are shipped with the GT3 full bundle • Others are completely independent implementations (eg. MDS2 and MDS3) • A large user community is being built • Incomplete documentation • But not so bad... • Getting much better now (tutorials, etc...) • Several bugs found in these exercises • Core implementation related - due to framework short lifetime • From tools deployed with the framework – hard to solve (e.g. Axis) • From the outside – easy to solve (e.g. Tomcat) • GT2 GRAM – with an OGSI-compliant but complex architecture behind • Worry to lose past experience (gained within the EDG and LCG projects) • Confirmed by performance tests (see next slides) OGSA/GT3 evaluation

  15. GT3 performance measurements (highlights) • Goal: • explore GT3 under heavy load/concurrency: • maximal throughput/rate of GT3 services • see the limiting factors • Other dimensions to be explored: • Hardware • Hosting environment • Implementations • Security options • Highlights from: • GRAM • DummyService (test custom service) • Security • IndexService • RFT OGSA/GT3 evaluation

  16. GT3 GRAM performance • Results: service node • Saturation throughput for job submission on the service node: 3.8 jobs/minute with an average CPU user+system usage of 62% Comments: • Very slow! • Scalability issues for (heavily used) servers OGSA/GT3 evaluation

  17. DummyService performance • Setup (1) • each DummyService client executes the following steps: • calls DummyServiceFactory to create a DummyService instance • executes 2 simple methods (echo and getTime) on the DummyService instance • calls DummyService instance to destroy itself • up to 1000 clients talking to the DummyService were run simultaneously on up to 45 client nodes (lxplus) • with and without authentication via GSI message level security used according to guides and tutorials at www.globus.org • grid service node hardware: 2 * Intel Pentium III 600MHz processors, 256MB RAM • Setup (2) • same as Setup (1), but step 2. consists of 100 cycles, each of them calling the 2 simple methods (echo and getTime) on the DummyService instance OGSA/GT3 evaluation

  18. DummyService performance • The security overhead needs further investigation (OGSA/GT3 group and Globus) • The result depend on the type of security. In all tested cases, the penalty is few times a factor of 10 • Some problems have been identified by the Globus team and we will test the new version as soon it becomes available OGSA/GT3 evaluation

  19. IndexService performance • Push setup: IndexService acting as a notification source (pushing data) • multiple notification sinks subscribe to the IndexService "Host" Service Data Element (SDE), and are notified about each update of "Host" SDE, happening at a fixed rate • no security • grid service node hardware: 2 * Intel Pentium III 600MHz processors, 256MB RAM • Pull setup: IndexService responding to findServiceData requests (pulling data) • multiple ogsi-find-service-data clients are run sequentially and in parallel asking for IndexService "Host" Service Data Element • no security • grid service node hardware: 2 * Intel Pentium III 600MHz processors, 256MB RAM OGSA/GT3 evaluation

  20. IndexService performance • Results • No security OGSA/GT3 evaluation

  21. Index Service (Information service building block) in push mode Complex set up (here ~400 client processes distributed on several computers); Modelling activity required as design tool; These tests are being used to validate the first simulation prototypes OGSA/GT3 evaluation

  22. Reliable File Transfer Service • Emphasis on reliability. Solve problems like e.g. • dropped connections, • machine reboots, • temporary network outages, etc • Functionality: OK • Main problem: resource hog • Comprehensive report submit to Globus • Fix found by the GT3 team • Functionality tests on the new version OK (it ships with 3.2 a) • We agreed to test it in detail • Open chapters • gridFTP performances (the RFT “engine”) • WU-FTP and the new globusFTP OGSA/GT3 evaluation

  23. Integration • GRID mainly concerns about the interoperability among heterogeneous grid components • Heterogeneous Grid environments • AliEn (Alice Environment; LHC ALICE experiment) • Should provide first-hand experience within LCG • Heterogeneous Grid technologies (non GT3) • OGSI .NET, MS .NETGrid (.NET environment) • Unicore, others… • Discussion with some teams at GGF9; to be restarted end of November (after SC2003) • Necessary to validate GT3 itself! OGSA/GT3 evaluation

  24. Do not lose the “past” experience • Assessment of OGSA/GT3 • Strategy defined in coordination with embryonic EGEE teams (last August) • EDG • Major issue so far: GRAM and Information Service • LCG deployment • Major issues so far: GRAM, Information Services and configuration issues • VDT • CondorG/GT3 becoming available • Agreement to use it in our test • eScience gap analysis (Geoffry Fox report) • Used to inform the original evaluation plan OGSA/GT3 evaluation

  25. Relationship building:Globus Toolkit 3 • Contact with the GT3 team • Little formalities, working relationship • We acknowledge the good relationship with GT3 team • Status of the interactions: • Access to unreleased software; agreed mechanisms to discuss and give feedback • Job Gatekeeper (GRAM) • Feedback • More priority on performances inside the GT3 team since • Reliable File Transfer (RFT) • Issues (high CPU consumption) confirmed. Fix available • Access to the experimental trunk for verification • Index Server (IS) • Several issues being discussed; 3.2 IS available • Security (GSI) • Issues being discussed; fix available soon OGSA/GT3 evaluation

  26. Conclusions • Much progress has been made in a short time… • Generally impressed with GT3 and the overall concept • Some major issues around the performance of the hosting environments and the factories • Continue closely working with Globus • Continue to validate this approach and prototype interfaces and services in a GT3 context • Be able to hand over a consistent picture to EGEE • Continue to take into account use cases / valuable information from any source • EDG, LCG, • HepCAL, ARDA • … OGSA/GT3 evaluation

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