5/24/99 Gateway Workshop T. Haupt1 The Gateway System This project is a collaborative effort between Northeast Parallel Architectures Center (NPAC) Ohio Supercomputer Center (OSC) Aeronautical Systems Center (ASC) MSRC

5/24/99 Gateway Workshop T. Haupt2 Overview

5/24/99 Gateway Workshop T. Haupt3 Goals To provide a problem-oriented interface to more effectively utilize HPC resources from the desktop via the Web browser. This “point & click” view hides the underlying complexities and details of the HPC resources and creates a seamless interface between the user’s problem description on his/her desktop system and the heterogeneous computing resources These HPC resources include supercomputers, mass storage systems, databases, workstation clusters, collaborative tools, and visualization servers.

5/24/99 Gateway Workshop T. Haupt4 Seamless Access Create an illusion that all resources needed to complete the user tasks are available locally. In particular, an authorized user can allocate the resources she needs without explicit login to the host controlling the resources. An analogy: NSF mounted disk or a network printer.

5/24/99 Gateway Workshop T. Haupt5 Services User Modules Back-End Resources Front-End Back-End services comprise Tier 3. Distributed, object-based, scalable, and reusable Web server, Object broker and Resource Manager Middleware forms Tier 2 Three-Tier Architecture Tier 1 is a high-level, browser-based Front End for visual programming (including selection of applications, generation of input data sets, specification of resources, post-processing and visualizations)

Towards a complete solution... Problem description : I need to model the surface damage due to the impact of laser to harden the material bulk. I need access to models including material bulk properties and interaction with intense electromagnetic fields. Task description: I need 64 nodes of SP-2 at Argonne to run my MPI-based executable “a.out” you can find in “/tmp/users/haupt” on marylin.npac.syr.edu. In addition, I need any idle workstation with jdk1.1 installed. Make sure that the output of my a.out is transferred to that workstation Middle-Tier: map the user’s task description onto the resource specification; this may include resource discovery, and other services Resource Specification Resource Allocation: run, transfer data, run

7 PSE Example: CCM Ken Flurchick, 1. Enter the Gateway system 2. Define your problem 3. Identify resources (software and hardware) 4. Create input file 5. Run your application 6. Analyze results

Target Architecture Middle-Tier Resource Specification Abstract Task Specification CTA specific knowledge databases Visual Authoring Tools User and Group Profiles Resource Identification and Access Visualizations Collaboration WebFlow Back-End Resources Problem Solving Environment

5/24/99 Gateway Workshop T. Haupt9 Design Issues Support for a seamless access (security) Support for distributed, heterogeneous Back-End services (HPCC, DBMS, Internet,...) managed independently from Gateway Variable pool of resources: support for discovery and dynamical incorporation into the system Scalable, extensible, low-maintenance Middle Tier Web-based, extensible, customizable, self-adjusting to varying capacities and capabilities of clients (humans, software and hardware) front end

5/24/99 Gateway Workshop T. Haupt10 Gateway Implementation Distributed, object-oriented middle tier –CORBA objects (Gateway Containers, Gateway Modules and Gateway Services) implemented in Java. [ Scalable, extensible, low-maintenance middle tier] –Containers define the user environment. –Modules and Services serve as proxies: they accept the user requests (Front End) and delegate them to the Back End. [ Support for distributed, heterogeneous back-end services managed independently from Gateway] Note: modules can be implemented in C++; also can be DCOM components

5/24/99 Gateway Workshop T. Haupt11 Gateway Implementation (2) Gateway operates in a keberized environment [Support for a seamless access] –tickets are generated on the client side –Keberos-based CORBA security service is used to manage the user sessions –Globus GSSAPI implemented over Keberos is used for resource allocation

5/24/99 Gateway Workshop T. Haupt12 Gateway Implementation (3) Task Specification is expressed in XML –CTA independent –Decouples implementation of the Front End and the Middle Tier –Allows for an abstract (platform independent) task specification, and thus the Middle Tier may act as a resource broker Resource Specification is expressed in XML –Simplifies match-making and resource discovery –Simplifies generating Globus RSL in-the-fly [Support for distributed, heterogeneous Back-End services; Variable pool of resources; Scalable, extensible, low-maintenance Middle Tier]

5/24/99 Gateway Workshop T. Haupt13 Gateway Implementation (4) Component-based Front-End [extensible] Front-End Components (“toolbox interfaces”) are –applets (interfaces for common services) –XML pages or frames [Web-based, extensible, customizable, self-adjusting] All components (Front End, Middle-Tier) are defined in XML and contain metadata (used for component mining)

5/24/99 Gateway Workshop T. Haupt14 Front End

5/24/99 Gateway Workshop T. Haupt15 CTA specific knowledge database Subject of Ken’s talk –requires server side support (both the middle tier and the back-end) through well defined interfaces –should be constructed from reusable or cloneable components –allows for identification of software components best suited to solve the problem at hand

5/24/99 Gateway Workshop T. Haupt16 Visual Authoring Tools Allows for composition of the computational task from components (reusable modules) Different tools to support various programming models such as data parallel, task parallel, data flow, object oriented No assumption on granularity Metadata about components and support for archiving and mining the components Support for instrumentation and steering

17 Example: Data Flow

5/24/99 Gateway Workshop T. Haupt18 Example: DARP

5/24/99 Gateway Workshop T. Haupt19 User and Group Profile Controls the user/group environment –file access –job monitoring –... Allows for customization –preferences –users with disabilities –... History of actions Scientific notebook

5/24/99 Gateway Workshop T. Haupt20 Resource Identification and Access Computational resources –hardware, software, licenses –desktop applications Data –file systems, mass storage, distributed databases –Internet data repositories Networks

5/24/99 Gateway Workshop T. Haupt21 Visualizations, Collaboration,... Baker/Clarke’s talk on SciVis Geoffrey’s talk on Collaborative Tools support for “streaming” applications as components support for heterogeneous hardware (capabilities/capacities)

5/24/99 Gateway Workshop T. Haupt22 Front-End infrastructure

5/24/99 Gateway Workshop T. Haupt23 Front-End Support Portal Page User Context Control Applet Navigator (extensible, customizable) PSE specific toolboxes –A placeholder for the Problem Description toolboxes –A placeholder for the code toolbox –Resource request toolbox –Data postprocessing toolbox Other (Collaboration, Visualizations, …)

5/24/99 Gateway Workshop T. Haupt24 Portal Page Provides initial access to the Gateway. After mutual authentication of the user and the Gateway server, creates a user context, and returns a (signed) control applet.

5/24/99 Gateway Workshop T. Haupt25 User Context Represents a Gateway session. The session is associated with a user (or group) profile. WebFlow extends the notion of the UNIX profile via the 'User Data Base' (UDB). This UDB contains information about submitted jobs, history of the users actions, and other user state information. The user context may also contain application/front-end specific information.

5/24/99 Gateway Workshop T. Haupt26

5/24/99 Gateway Workshop T. Haupt27 Control Applet The control applet is responsible for maintaining the session, and direct communication with the middle-tier. Direct communication is the most efficient, but since it is buried into an applet, this mechanism is not readily customizable. The generic services, such as file service (upload, download, edit, copy, move, delete) and job services (show current jobs/show queues/kill jobs) will be supported this way. [combination of the user context and a query] The Gateway will also support a non-direct communication with the middle-tier through servelts.

5/24/99 Gateway Workshop T. Haupt28 Screen Dump of the Control Applet

5/24/99 Gateway Workshop T. Haupt29 Navigator The navigator allows the user to select and customize toolboxes. Embedded in a separate frame, it consists of menus, buttons, links, etc, derived from an XML document. The navigator is a hierarchical, extensible and customizable.

5/24/99 Gateway Workshop T. Haupt30

5/24/99 Gateway Workshop T. Haupt31 Problem description toolboxes The problem description is application specific, and the Gateway only provides a general framework for creating a PSE. The most important part is the specification of what services (middle and back tier) are needed, what is their API, and how to add new services. Example services: access to databases, XML parsing, generating HTML in-the-fly, file services.

5/24/99 Gateway Workshop T. Haupt32 Code toolboxes The end user see it as a mapping between the problem description and software to be used to solve the problem. Actually, it identifies WebFlow modules and their parameters to be used to construct the application (see resource request toolbox below). The module parameters may include input files, and if necessary, the input files are generated at this stage (using this or a separate toolbox). In addition, some parameters will be constructed from information stored in data bases, including UDB, and other sources.

5/24/99 Gateway Workshop T. Haupt33 Resource Request Toolbox The front-end activities result in an abstract task specification. Abstract in the sense that the user may not know nor care what actual resources are used. The task is composed of independently developed modules and services following different programming models.

5/24/99 Gateway Workshop T. Haupt34 Other toolboxes Visualizations Collaboration Scientific notebook...

5/24/99 Gateway Workshop T. Haupt35 Middle-Tier

User 1User 2 Application 1 Application 2 App 2App 1 WebFlow Server WebFlow server is given by a hierarchy of containers and components WebFlow server hosts users and services Each user maintains a number of applications composed of custom modules and common services WebFlow Services

5/24/99 Gateway Workshop T. Haupt37 CORBA Based Middle-Tier Mesh of WebFlow Servers implemented as CORBA objects that manage and coordinate distributed computation. Front End Gatekeeper Authentication Authorization

T. Haupt38 WebFlow Context Hierarchy Master Server (Gatekeeper) Slave Server User Context Application Context Module Slave Server Proxy

Services User Modules Browser based Front-End Middle-Tier modules serve as proxies of Back-End Services Browser based Front-End User Space Definition and Task Specification Metacomputing Services Back-End Resources

5/24/99 Gateway Workshop T. Haupt40 Back End

5/24/99 Gateway Workshop T. Haupt41 Back End Services Access to HPCC (via Globus) Access to distributed databases (via JDBC) Access to mass storage Access to the Internet resources Access to desktop application and local data Access to code repositories

5/24/99 Gateway Workshop T. Haupt42 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 other jobs 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

5/24/99 Gateway Workshop T. Haupt43 How to add new Back-End hardware resources Computational engines –install Globus –MDS (The Alliance LDAP server) will contain all relevant info, including contact address –we need “private” directory, with entries in XML (learn from MDS, CONDOR’s class-add, NPAC’s … –access control provided by Keberos (cross MSRC) Databases –create a new user: Gateway

5/24/99 Gateway Workshop T. Haupt44 Gateway Security

SECIOP Security Model (Keberos) Front End Applet SECIOP authentication & authorization Gatekeeper delegation HPCC resources GSSAPI Layer 1: secure Web Layer 2: secure CORBA Layer 3: Secure access to resources Policies defined by resource owners

5/24/99 Gateway Workshop T. Haupt46 Building Gateway Components

47 Middle-Tier is given by a mesh of WebFlow Servers that manage and coordinate distributed computation. Gateway applications are composed of independent reusable modules Modules are written by module developers who have only limited knowledge of the system on which the modules will run. The WebFlow system hides module management and coordination functions

5/24/99 Gateway Workshop T. Haupt48 How to develop a Gateway component (or a toolbox) Back-end service Middle-tier proxy Front-end controls

5/24/99 Gateway Workshop T. Haupt49 What does it take to convert a legacy (high performance) application into a Gateway Back-End service? Nothing! –it is the only way we can support commercial codes such as Gaussian A middle-tier proxy will submit your job for you

5/24/99 Gateway Workshop T. Haupt50 How the Back-End interacts with the rest of the system? Often, your job do not need to interact. –Using GRAM and GASS you stage data and executable, submit the job and retrieve output. –Using DUROC you can coallocate resources and run MPI-based parallel/distributed codes. The messages between nodes are sent outside Gateway control or support. –HPF runtime will distribute your job and facilitate interprocess communication.

5/24/99 Gateway Workshop T. Haupt51 Implementing Back-End Services If you need to interact –Using a separate module, you may move files between nodes while your jobs are executing –Your job may be a server (e.g., database, GRAM) [if socket listener - be careful about security!] –Your job my be a CORBA client (Java, C++) –...

5/24/99 Gateway Workshop T. Haupt52 What does it take to develop a Gateway module (a proxy) ? Many come as a standard Gateway modules User’s modules –Are CORBA objects Define IDL (as an XML document) Compile IDL (in the tie mode) Implement the functionality of the module Implement events Develop Front-End controls that invoke methods of the module

Example of IDL definition #include “..\BC.idl” module WebFlow { module lms{ interface runEdys:BeanContextChild { void run(); void receiveData(); void setParameter(in string p); }; interface runCasc2d:BeanContextChild{ void run(); void runAgain(); }; interface DoneEvent{ Object getSource(); }; }; }; We will create 3 CORBA objects * two modules: - runEdys - runCasc2d * one event - DoneEvent They will be added to package WebFlow.lms

5/24/99 Gateway Workshop T. Haupt54 Module functionality May act as a client for a back-end service such as Globus GRAM or a database May invoke other Gateway Middle Tier services such as File Services or Resource Discovery May implement the desired functionality internally (say, in Java) [thus not a proxy] May interact with other modules and the Front End through events

5/24/99 Gateway Workshop T. Haupt55 Event binding addEventListener rmEventListener fireEvent(E,M) method M Event SourceEvent TargetAdapter Event ORB binding table DIIDSI

5/24/99 Gateway Workshop T. Haupt56 Front-End controls Details in Ken’s talk How to control a Middle-Tier module? –Through an applet that serves as a CORBA client, and invokes methods of the module How to build an application from modules? –Generate an XML document - task specification and invoke server-side XML parser which will generate CORBA client code

5/24/99 Gateway Workshop T. Haupt57 Controlling a module Applet Module Controls Proxy Module Module ActionButton1 ActionButton2 …. IIOP Another complication: Java sandbox!

5/24/99 Gateway Workshop T. Haupt58 Selecting a Predefined Task

Visual Authoring Tools XML A visual representation is converted into a XML document XML service Web Server save parse ApplContext Generates Java code to add modules to ApplContext Publishes IOR Front-End Applet Middle-Tier