1. Gateway System (new generation WebFlow) NPAC Syracuse University

2. Jan 7, 1999T. Haupt2 Overview What is WebFlow? –Start with examples –Why improve a good product? –Emerging Standards: DATORR Architecture of the new WebFlow Gateway Requirements Deliverables

3. Jan 7, 1999T. Haupt3 WebFlow Mission The visual HPDC framework that offers an intuitive Web browser based interface and a uniform point of interactive control for a variety of computational modules and applications, running at various labs on different platforms. Our technology goal is to build a high-level user friendly commodity software based visual programming and runtime environment for HPDC.

4. Jan 7, 1999T. Haupt4 WebFlow Implementation WebFlow is implemented as a modern three-tier system –Tier 1 is a high-level front-end for visual programming built on top of the Web and OO commodity standards. –Distributed object-based, scalable, and reusable Web server and Object broker Middleware forms Tier 2. – Back-end services comprise Tier 3. In particular, high performance services are implemented using the metacomputing toolkit of Globus.

5. Jan 7, 1999T. Haupt5 Middle-Tier Mesh of Web Servers running servlets that manage and coordinate distributed computation. –Session Manager, –Module Manager, –Connection Manager. Front End

6. Jan 7, 1999T. Haupt6 WebFlow over Globus In order to run WebFlow over Globus there must be at least one WebFlow node capable of executing Globus commands, such as globusrun Jobs that require computational power of massively parallel computers are directed to the Globus domain, while others can be launched on much more modest platforms, such as the user’s desktop or even a laptop running Windows NT. Bridge between WebFlow and Globus

7. Jan 7, 1999T. Haupt7 WebFlow Applications Quantum Simulations –Alliance/NCSA –demonstrated at Alliance ‘98 meeting –technical paper presented at SC’98 Landscape Management System –CEWES: MSRC/PET

8. Jan 7, 1999T. Haupt8 Quantum Simulations

9. Jan 7, 1999T. Haupt9 QS: WebFlow implementation

10. Jan 7, 1999T. Haupt10

11. Jan 7, 1999T. Haupt11 QS: Front-End

12. Jan 7, 1999T. Haupt12 LMS: Changes in Vegetation lA decision maker (the end user of the system) wants to evaluate changes in vegetation in some geographical region over a long time period caused by some short term disturbances such as a fire or human’s activities. lOne of the critical parameters of the vegetation model is soil condition at the time of the disturbance. lThis in turn is dominated by rainfalls that possibly occur at that time

13. Jan 7, 1999T. Haupt13 LMS: Changes in Vegetation lData retrieval lData preprocessing lSimulation: two interacting codes ¶ EDYS · CASC2D lVisualization WMS EDYSCASC2D DEM Land Use Soil Texture Vegetation

14. Jan 7, 1999T. Haupt14 LMS Front-End

15. Jan 7, 1999T. Haupt15 Why do we need to change anything? Middle tier is based on a custom protocol implemented directly on top of sockets –not scalable –difficult to implement security features, fault tolerance, monitoring –impossible to take advantage of new technologies –non-standard

16. Jan 7, 1999T. Haupt16 Remedy New, CORBA based middle tier –robust ORB implementations available now (including JWORB) Event driven system that follows the JavaBeans model –based on industry standards for distributed objects technologies –similar to JINI and EJB

17. Jan 7, 1999T. Haupt17 Java Grande: DATORR Desktop Access to Remote Resources Development of WebFlow coincides with DATORR standardization initiative Could lead to definition of CORBA facilities or Java framework for computing services Defines: – Abstract Task Specification (“user view”) – Metacomputing Services API (“system view”) – Security Standards

18. CORBA based WebFlow (suggested Gateway implementation)

19. Jan 7, 1999T. Haupt19 WebFlow Objectives To provide seamless and secure access to remote (HPCC) resources –single web-based point of access –access policies imposed and monitored by stakeholders –no modifications of the current security model and implementation –integration with the existing authoring tools

20. Jan 7, 1999T. Haupt20 Implementation Strategy Follow industry standards –distributed objects: CORBA, Java, JavaBeans, EJB, … –security: https, PKI, GSSAPI, SSL, Keberos5 –CORBA services: naming (LDAP), lifecycle, security, transactions,… Participate in creation of standards –DATORR, Alliance PKI

21. Jan 7, 1999T. Haupt21 Implementation Strategy Use commodity components (commercial and academic). Examples: –secure WebServer (Jigsaw, Apache, JWORB) –ORB (ORBacus, JWORB) –Java 2 (EJB, JINI) –AKENTI –Globus, Globus-GSSAPI –PBS, Condor

22. Jan 7, 1999T. Haupt22 Multi-tier Architecture of Gateway

23. Jan 7, 1999T. Haupt23 Gateway Components Front End (Java Applets) –many different “plug-ins” implementing WebFlow API Middle Tier (CORBA) Back End modules (anything from JBDC to HPF) –JavaBeans model –Proxy Modules Access to remote HPCC resources

24. Jan 7, 1999T. Haupt24 SECIOP Security Model Front End Applet https authentication & authorization Gatekeeper delegation Stakeholders HPCC resources GSSAPI Layer 1: secure Web Layer 2: secure CORBA Layer 3: Secure access to resources Policies defined by resource owners

25. Jan 7, 1999T. Haupt25 Gatekeeper

26. Jan 7, 1999T. Haupt26 Gateway Portal Page https mutual authentication –X.509 certificates access policies –AKENTI, (LDAP, DB) –controlled by stakeholders returns front-end applet

27. Jan 7, 1999T. Haupt27 Initialization of a session Portal Page Secure Web Server Mutual authentication start AKENTI Credentials Globus Cert. Front End Applet WebFlow Server User Context Netscape’s ORB ORBacus ORB IIOP

28. Jan 7, 1999T. Haupt28 WebFlow API Middle-tier Back-End Services PSEData FlowOO Command Line WebFlow API (Abstract Task Specification)

29. Jan 7, 1999T. Haupt29 Middle Tier

30. Jan 7, 1999T. Haupt30 Building an application Applet Application Context Netscape ORBORBacus ORB IIOP List of servers List of modules List of events List of methods E M Add module Attach Event localremote Adapter LLM

31. Jan 7, 1999T. Haupt31 Adding a remote module Local Host Add module Module Factory Proxy Module Remote Host FE request Add module Module Factory Module

32. Jan 7, 1999T. Haupt32 WebFlow Modules Are CORBA objects conform to JavaBeans specification mimic Java 1.1 (JavaBeans) event model implemented using Dynamic Invocation Interface (DII) and Dynamic Skeleton Interface (DSI) (thus more general than BeanBox, similar to JINI and EJB)

33. Jan 7, 1999T. Haupt33 Event binding addEventListener rmEventListener fireEvent(E,M) method M Event SourceEvent TargetAdapter Event ORB binding table DIIDSI

34. Jan 7, 1999T. Haupt34 Controlling a module Applet Module Controls Proxy Module Module ActionButton1 ActionButton2 …. IIOP

35. Jan 7, 1999T. Haupt35 Modules Similar to JavaBeans –full power of Java (or C++) to implement functionality –can encapsulate legacy applications May serve as Proxies –JDBC –metacomputing services (such as Globus) –schedulers (such as PBS, CONDOR, etc)

36. Jan 7, 1999T. Haupt36 Summary of features Single web-based access via Gateway portal Security based on standards: https, PKI, secure ORB, GSSAPI (SSL/Keberos5) Access policies controlled by stakeholders WebFlow API allows implementation of many different front-ends Modern three-tier architecture (distributed objects) Access to HPCC through metacomputing services