Full HTML for

Basic foilset Gateway Overview and Middle Tier

Given by Tom Haupt at Gateway Workshop Aberdeen Maryland on 24-25 May 99. Foils prepared May 26 99
Outside Index Summary of Material

One of four Gateway talks: Bill Asbury, Geoffrey Foox, Tom Haupt and Ken Flurchick
This has overview of system/requirements, Middle Tier and what it means to add a component to Gateway

Table of Contents for full HTML of Gateway Overview and Middle Tier

 Denote Foils where Image Critical
Denote Foils where HTML is sufficient
1 The Gateway System
2 Overview
3 Goals
4 Seamless Access
5 Three-Tier Architecture
6 Towards a complete solution ...
7 PSE Example: CCM
8 Target Architecture
9 Design Issues
10 Gateway Implementation
11 Gateway Implementation (2)
12 Gateway Implementation (3)
13 Gateway Implementation (4)
14 Front End
15 CTA specific knowledge database
16 Visual Authoring Tools
17 Example: Data Flow
18 Example: DARP
19 User and Group Profile
20 Resource Identification and Access
21 Visualizations, Collaboration, ...
22 Front-End infrastructure
23 Front-End Support
24 Portal Page
25 User Context
26 Gateway Initial Page
27 Control Applet
28 Screen Dump of the Control Applet
29 Navigator
30 CCM PSE Invoked from Gateway
31 Problem description toolboxes
32 Code toolboxes
33 Resource Request Toolbox
34 Other toolboxes
35 Middle-Tier
36 WebFlow Server
37 CORBA Based Middle-Tier
38 WebFlow Context Hierarchy
39 Middle-Tier modules serve as proxies of Back-End Services
40 Back End
41 Back End Services
42 WebFlow over Globus
43 How to add new Back-End hardware resources
44 Gateway Security
45 Security Model (Keberos)
46 Building Gateway Components
47 Middle-Tier is given by a mesh of WebFlow Servers that manage and coordinate distributed computation
48 How to develop a Gateway component (or a toolbox)
49 What does it take to convert a legacy (high performance) application into a Gateway Back-End service?
50 How the Back-End interacts with the rest of the system?
51 Implementing Back-End Services
52 What does it take to develop a Gateway module (a proxy)?
53 Example of IDL definition
54 Module functionality
55 Event binding
56 Front-End controls
57 Controlling a module
58 Selecting a Predefined Task
59 Visual Authoring Tools

Outside Index Summary of Material

HTML version of Basic Foils prepared May 26 99

Foil 1 The Gateway System

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
This project is a collaborative effort between
  • Northeast Parallel Architectures Center (NPAC)
  • Ohio Supercomputer Center (OSC)
  • Aeronautical Systems Center (ASC) MSRC
Tom Haupt
NPAC Syracuse University
111 College Place
Syracuse
NY 13244-4100
HTML version of Basic Foils prepared May 26 99

Foil 2 Overview

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 3 Goals

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 4 Seamless Access

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 5 Three-Tier Architecture

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Back-End services
comprise Tier 3.
Distributed, object-based,
scalable, and reusable
Web server, Object broker
and Resource Manager
Middleware forms Tier 2
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)
HTML version of Basic Foils prepared May 26 99

Foil 6 Towards a complete solution ...

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 7 PSE Example: CCM

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Ken Flurchick, http://www.osc.edu/~kenf/theGateway
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
HTML version of Basic Foils prepared May 26 99

Foil 8 Target Architecture

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
CTA specific knowledge databases
Visual
Authoring
Tools
User and
Group
Profiles
Resource Identification and Access
Visualizations
Collaboration
WebFlow
Back-End Resources
Problem Solving Environment
HTML version of Basic Foils prepared May 26 99

Foil 9 Design Issues

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 10 Gateway Implementation

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 11 Gateway Implementation (2)

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 12 Gateway Implementation (3)

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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]
HTML version of Basic Foils prepared May 26 99

Foil 13 Gateway Implementation (4)

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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)
HTML version of Basic Foils prepared May 26 99

Foil 14 Front End

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 15 CTA specific knowledge database

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 16 Visual Authoring Tools

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 17 Example: Data Flow

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 18 Example: DARP

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 19 User and Group Profile

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Controls the user/group environment
  • file access
  • job monitoring
  • ...
Allows for customization
  • preferences
  • users with disabilities
  • ...
History of actions
Scientific notebook
HTML version of Basic Foils prepared May 26 99

Foil 20 Resource Identification and Access

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Computational resources
  • hardware, software, licenses
  • desktop applications
Data
  • file systems, mass storage, distributed databases
  • Internet data repositories
Networks
HTML version of Basic Foils prepared May 26 99

Foil 21 Visualizations, Collaboration, ...

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Baker/Clarke's talk on SciVis
Geoffrey's talk on Collaborative Tools
support for "streaming" applications as components
support for heterogeneous hardware (capabilities/capacities)
HTML version of Basic Foils prepared May 26 99

Foil 22 Front-End infrastructure

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 23 Front-End Support

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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, ...)
HTML version of Basic Foils prepared May 26 99

Foil 24 Portal Page

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 25 User Context

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 26 Gateway Initial Page

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 27 Control Applet

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 28 Screen Dump of the Control Applet

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 29 Navigator

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 30 CCM PSE Invoked from Gateway

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 31 Problem description toolboxes

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 32 Code toolboxes

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 33 Resource Request Toolbox

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 34 Other toolboxes

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Visualizations
Collaboration
Scientific notebook
...
HTML version of Basic Foils prepared May 26 99

Foil 35 Middle-Tier

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 36 WebFlow Server

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
User 1
User 2
Application 1
Application 2
App 2
App 1
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
HTML version of Basic Foils prepared May 26 99

Foil 37 CORBA Based Middle-Tier

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Mesh of WebFlow Servers
implemented as CORBA objects
that manage and coordinate
distributed computation.
Gatekeeper
Authentication
Authorization
HTML version of Basic Foils prepared May 26 99

Foil 38 WebFlow Context Hierarchy

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Master Server (Gatekeeper)
Slave Server
Slave Server
User Context
Application Context
Module
Slave Server Proxy
HTML version of Basic Foils prepared May 26 99

Foil 39 Middle-Tier modules serve as proxies of Back-End Services

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Services
User Modules
Browser based Front-End
Browser
based
Front-End
User Space Definition and Task Specification
Metacomputing Services
Back-End Resources
HTML version of Basic Foils prepared May 26 99

Foil 40 Back End

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 41 Back End Services

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 42 WebFlow over Globus

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 43 How to add new Back-End hardware resources

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 44 Gateway Security

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 45 Security Model (Keberos)

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
SECIOP
Front End Applet
SECIOP
authentication
& authorization
Gatekeeper
delegation
HPCC resources
GSSAPI
GSSAPI
Layer 1: secure Web
Layer 2: secure CORBA
Layer 3: Secure access to resources
Policies defined by resource owners
HTML version of Basic Foils prepared May 26 99

Foil 46 Building Gateway Components

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 47 Middle-Tier is given by a mesh of WebFlow Servers that manage and coordinate distributed computation

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
.
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
HTML version of Basic Foils prepared May 26 99

Foil 48 How to develop a Gateway component (or a toolbox)

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Back-end service
Middle-tier proxy
Front-end controls
HTML version of Basic Foils prepared May 26 99

Foil 49 What does it take to convert a legacy (high performance) application into a Gateway Back-End service?

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Nothing!
  • it is the only way we can support commercial codes such as Gaussian
A middle-tier proxy will submit your job for you
HTML version of Basic Foils prepared May 26 99

Foil 50 How the Back-End interacts with the rest of the system?

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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.
HTML version of Basic Foils prepared May 26 99

Foil 51 Implementing Back-End Services

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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++)
  • ...
HTML version of Basic Foils prepared May 26 99

Foil 52 What does it take to develop a Gateway module (a proxy)?

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 53 Example of IDL definition

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
#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
HTML version of Basic Foils prepared May 26 99

Foil 54 Module functionality

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 55 Event binding

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
addEventListener
rmEventListener
fireEvent(E,M)
method M
Event Source
Event Target
Adapter
Event
ORB
binding
table
DII
DSI
HTML version of Basic Foils prepared May 26 99

Foil 56 Front-End controls

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
HTML version of Basic Foils prepared May 26 99

Foil 57 Controlling a module

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
Proxy Module
Module
ActionButton1
ActionButton2
....
IIOP
Another complication:
Java sandbox!
HTML version of Basic Foils prepared May 26 99

Foil 58 Selecting a Predefined Task

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
HTML version of Basic Foils prepared May 26 99

Foil 59 Visual Authoring Tools

From Gateway Overview and Middle Tier Gateway Workshop Aberdeen Maryland -- 24-25 May 99. *
Full HTML Index
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
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