Part I

Web Portalsfor Scientific and Engineering communities

Portals for scientific and engineering communities

• Seamless access to HPC resources• Seamless access to instruments• Data storage• Application specific data base• Visualization Tools• Collaboratory• Scientific notepads

Remote Resources

Front-End

FRONT-END:high-level user friendly - visual programming and authoring tools - application GUI

RESOURCES:all hardware and software components needed to complete the user task, including, but not limited to, compute engines from workstations to supercomputers, storage, databases, instruments, codes, libraries, and licenses.

Desktop/Laptop

Seamless Access

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.

Example: Globus

Advantages:- platform independent mini-language (RSL) for specification of resources- can be layered on top of different schedulers- enables interoperability between resources (can allocate many resources at a time, file transfer, monitoring, etc.)

Disadvantage: - a bag of low level tools

GRAMClient

Gatekeeper Gatekeeper Gatekeeper

Contact addressResource Language Specification

MDSDirectoryService

GSS-API

Towards a complete solution ...PSE: problem description (physics, chemistry, ...)

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 workstationwith 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

Remote Resources

Front-End Front-End

Middle-Tier

Resource Specification

Abstract Task Specification

We need a third tier!

Target Architecture

Middle-Tier

Resource Specification

Abstract Task Specification

CTA specificknowledgedatabases

VisualAuthoring

Tools

User andGroup

Profiles

ResourceIdentificationand Access

VisualizationsCollaboration

WebFlow

Back-End Resources

Problem Solving Environment

Example of a portalNavigate and choose an existing application

to solve the problem at hand.Import all necessary data.

Retrieve data

Pre/post-processing

Run simulations

Select host

Select model

Set parameters

Run

PSE Example: CCM IPSE

Ken Flurchick, http://www.osc.edu/~kenf/Gateway

1 .Define your problem2. Identify resources (software and hardware)3. Create input file4. Run your application5. Analyze results

QS Front End

Compose interactivelyyour applicationfrom pre-existing

modules

Data-Flow Front-End

Part II

WebFlow

WebFlow design

• Object Oriented, follows JavaBeans model– everything is an object

– objects interact through events

Object A(event source)

Object B(event target)

Fire event EMethod M(){…}

Firing event E by object A causes invocation of method M of object B.The association of event E and method M is achieved by an eventregistration mechanism. An event is also an object and it carries data.

A few words about CORBA

(a digression)

more information on Java, Corba, Distributed Object:

http://www.npac.syr.edu/projects/cps616spring96/index.html

Distributed objects

• Typically WebFlow objects live in different address spaces. We use CORBA to invoke methods of the remote objects.

Object A(event source)

Object B(event target)

Fire event EMethod M(){…}

ORB

How is this possible?

ORB2

Object A(event source)

Object B(event target)

Fire event EMethod M(){…}

ORB1IIOP

- Objects A and B are CORBA objects (thus not Java objects)- Objects are defined in IDL (Interface Definition Language)- IDL definitions are compiled using (Java)IDL compiler- The IDL compiler generates new classes to be used by the Java compiler (javac) instead of the original ones, on both the client and server side- The IDL compiler generates either classes to be extended, or interfaces to be implemented

Object Adapterserves also as a daemon

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 packageWebFlow.lms

We need more flexibility...

• WebFlow objects are developed independently of each other(reusable modules): we cannot assume that the event source knows anything about the event target and vice versa

Event binding

addEventListenerrmEventListenerfireEvent(E,M)

method M

Event Source Event TargetAdapter

Event

ORB

binding table

DII DSI

Controlling a moduleApplet

ModuleControls

Proxy Module

ModuleActionButton1ActionButton2

….

IIOP

Another complication:Java sandbox!

Adding a remote moduleLocal Host

Add module

Module Factory

Proxy Module

Remote Host

FE

requestAdd module

Module Factory

Module

Back to WebFlow design

CORBA Based Middle-Tier

Mesh of WebFlow Serversimplemented as CORBA objects

that manage and coordinate

distributed computation.

Front End

GatekeeperAuthenticationAuthorization

WebFlow Server

• The WebFlow server is a container object, a.k.a. context - in fact it implements JavaBeanContext class (Java1.2)

• The BeanContext acts as a logical container for JavaBeans (“WebFlow modules and services”) and BeanContexts.

User 1 User 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 maintainsa number of applications

composed of custom modules

and common services

WebFlow Services

WebFlow Context HierarchyMaster Server (Gatekeeper)

Slave Server

Slave Server

User Context

Application Context

Module

Slave Server Proxy

Gatekeeper

Services User Modules

Browserbased

Front-End

Middle-Tier modulesserve as proxies ofBack-End Services

Browserbased

Front-End

User Space Definition and Task Specification

Metacomputing Services

Back-End Resources

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)

Services

• Services are modules provided by the system and offers a generic functionality– job services (submit,monitor,kill,... a job)

– file services (edit,copy,move,… a file)

– XML parser

– database access

– mass storage access

– ...

Example of a proxy module

&(rsl_substitution = (MYDIR “/tmp/haupt”))(DATADIR $(MYDIR)/data)(EXECDIR) $MYDIR)/bin))(executable = $(EXECDIR)/a.out)(arguments=$(DATADIR)/file1)(stdout=(MYDIR)/result.dat))(count=1)

GRAM resource descriptionGenerate Data

Run Job

Analyze

The Run Job module is a proxy module. It generates the RSL on-the-fly and submits the job for execution using globusrun function.

The module knows only exec name, location and its arguments/parameters.

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

Secure Access: terminology• Access Control (or Authorization)

– Assurance that the person or computer at the other end of the session is permitted to do what he asks for.

• Authentication– Assurance that the resource (human or machine) at the other end of the session is

what it claims to be

• Integrity– Assurance that the information that arrives is the same as when it was sent

• Accountability (or non-repudiation)– Assurance that any transaction that takes place can subsequently proved to have

taken place

• Privacy– Assurance that sensitive information is not visible to an eavesdropper (usually

achieved using encryption)

Secure Access

• Mutual authentication of servers and users– Certificates, Keberos/SecurID

• Access control– Full autonomy of the resources owner(s)

– Akenti

• Privacy• Integrity

SECIOP

Security Model

Front End Applet

https

authentication& authorization

Gatekeeper

delegation

Stakeholders

HPCC resources

GSSAPIGSSAPI

Layer 1: secure Web

Layer 2: secure CORBA

Layer 3: Secure access to resources

Policies defined by resource owners

https (SSL)AKENTI

CORBA security service

GSSAPI (Globus)

Distributed Objects are less secure

• can play both client and server– in client/server you trust the server, but not the clients

• evolve continually– objects delegate parts of their implementation to the other objects (also dynamically composed at runtime).

Because of subclassing, the implementation of an object may change over time

• interactions are not well defined– because of encapsulation, you cannot understand all the interactions between objects

• are polymorphic (ideal for Trojan horses!)

• can scale without limit – how do you manage the access right to millions of servers?

• are very dynamic

CORBA security is built into ORB

Secure Communications

Authentication

ClientUser

Encryption Audit Authorization

Server

Encryption

Credentials

ObjectAdapterORB

Authentication

• A principal is authenticated once by ORB and given a set of credentials, including one or more roles, privileges, and an authenticated ID.

• An authenticated ID is automatically propagated by a secure ORB; it is part of the caller context

Principal Credentials

Current

Client Server

set_credentials get_attributes

authenticate

Privilege Delegation

• No delegation– The intermediary uses its own credentials

• Simple delegation– The intermediary impersonates the client

• Composite delegation– The intermediary uses both

ClientT

arge

t

Clie

nt

Tar

get

Clie

nt

Tar

get

Clie

nt TargetObject

IIOP

CORBA access model

• Based on a trusted ORB model:you must trust that your ORB will enforce the access policy on the server resource

• The ORB determines:if this client on behalf of this principal can do this operation on this object

• Server uses Access Control Lists (ACL) to control user access

Principal Role Rights Operation

Part III

WebFlow Applications

• Applications vary by the functionality of their Front-Ends– Front-End Applications

• must be pre-installed

• run fast, no restrictions

– Front-End Applets• no installation, but may take time to download

• sandbox restrictions apply, unless signed

• Applications vary by how they are composed from modules– statically

• can by prepared in the Middle-Tier

– dynamically• the user composes them from reusable components

• The modules can interact with each other in different ways:– through events (object oriented approach)

– through ports (data flow model)

– through message passing

• Applications vary on how the Front-End interacts with the Middle-Tier– A complete task description is sent to the middle-tier

• composed of reusable modules

• predefined

– Objects are added to the user context one at a time, and Front-End keeps their references

Landscape Management System

(CEWES)

LMS Objectives To develop a web based system that implements a

“navigate-and-choose” paradigm and allows the end user to: – Select (a set of) computational modules that provide answers to

the problem at hand

– Retrieve input data sets from remote sources

– Use adequate (remote) computational resources

– Visualize and analyze output data on the local host

Anytime, anywhere, using any platform

(e.g., a connected to the Internet laptop PC)

LMS: Changes in Vegetation A decision maker (the end user of the system) wants to evaluate

changes in vegetation in a geographical region over a long time period caused by short term disturbances such as a fire or human activity.

One of the critical parameters of the vegetation model (EDYS) is soil condition at the time of the disturbance.

This in turn is dominated by rainfall that possibly occurs at that time (CASC2D simulation)

Input data for the simulations are available from the Internet, such as Data Elevation Models (DEM) from USGS web site or from custom databases (spices characteristics)

LMS: Changes in Vegetation

Data retrieval Data preprocessing Simulation: two

interacting codes EDYS CASC2D

Visualization

WMS

EDYS CASC2D

DEM Land UseSoil

TextureVegetation

EDYS: vegetation model CASC2D: watershed modelWMS: Watershed Modeling System

LMS Front End

Data retrieval Data pre- and post-processing Simulations

Data RetrievalThe data wizard allows the user to

interactivelyselect the data anddownload them tothe local machine.The raw data arethen fed to the WMS system

launched from the browser to

generate input filesfor simulations.

Launching coupled simulations on different Back-End computational resources

Select host

Select model

Set parameters

Run

WMS based Visualizations

The results of the simulations are send

back to the Front-End, and can be visualized using tools included

in WMS package

Implementation of LMS

• Front-End (client) is a Java application– Data wizard, EDYS and WMS are run locally

• “navigate and choose” - no interactive composition of applications– EDYS, CASC2D, EDYS and CASC2D

• modules exchange data through message passing mediated by WebFlow

• client keeps the module references

slave

Running LMS

runCasc2d

master

UNIXWinNT

slave

runEdys

lms.class

Data wizardWMS

exeCasc2d

WebServer

WebServer

WebFlow ServersClient

- WebFlow modules

Client code

try { //add modules p1 = slaveNT.addNewModule("runEdys"); //as defined in conf.file runEdys re = runEdysHelper.narrow(p1); p2 = slaveUNIX.addNewModule("runCasc2d"); //as defined in conf.file runCasc2d rc = runCasc2dHelper.narrow(p2); //bind events master.attachEvent(p2,"Casc2dDone","Casc2dDone",p1,"run"); master.attachEvent(p1,"EdysStarted","EdysStarted",p2,"run"); master.attachEvent(p1,"EdysDone","EdysDone",p2,"runAgain"); //invoke methods of runCasc2dImp rc.run(); } catch(COMM_FAILURE ex) {System.err.println(ex.getMessage()); System.exit(1);}

Write

slave

Interactions between components

runCasc2d

master

UNIXWinNT

slave

runEdys

lms.class

Data wizardWMS

exeCasc2d

WebServer

WebServer

casc2dIIOP

http

Write

http

Quantum Simulations

Quantum Simulations

QS: WebFlow implementation

Implementation of QS

• Front-End (client) is a Java applet• applications are created dynamically from pre-

existing modules• modules exchange data through ports

(data flow model)• server keeps the module references;

the references are published on a web site

QS: Front-End

Building an application

XMLA visual representation

is converted into a XMLdocument

XMLservice

WebServer

save

parse

ApplContext

Generates Java code to add modules to ApplContextPublishes IOR

Front-End Applet

Middle-Tier

Document Type Definition <!DOCTYPE taskspec [ <!ELEMENT taskspec (task)+> <!ATTLIST taskspec UserContextRef CDATA #REQUIRED AppName CDATA #REQUIRED><!ELEMENT task ((task | module)*,connection*) > <!ELEMENT module (#PCDATA) > <!ATTLIST module modulename CDATA #REQUIRED host CDATA #REQUIRED > <!ELEMENT connection (out,in)> <!ELEMENT in EMPTY> <!ELEMENT out EMPTY> <!ATTLIST out modulename CDATA #REQUIRED eventname CDATA #REQUIRED<!ATTLIST in modulename CDATA #REQUIRED method CDATA #REQUIRED > ]>

Example XML document

<taskspec UserContextRef="123as321" AppName="TestApplication"><task> <module modulename="FileBrowser" host="localhost"> </module> <module modulename="FileEditor" host="localhost"> </module> <module modulename="Gaussian" host="localhost"> </module> <connection> <out modulename="FileBrowser" eventname="FileEvent" event="File"/> <in modulename="FileEditor" method="run"/> </connection> <connection> <out modulename="FileEditor" eventname="FileEvent" event="File"/> <in modulename="Gaussian" method="run"/> </connection></task></taskspec>

Object Oriented Applications

Mobility System’s Applications

Coordinatestransformations

databases

Remote HPCC resources

- object oriented approach - implementation:- CORBA based Middle-Tier - bean-box type API - JDBC proxy modules

- Web interface to store data in DB in variable format- Data transfer from DB to a visualization engine- Coordinates transformations on a remote server- Launching simulations on remote hosts with interactive input

Part IV

Gateway:Portal for Computing

Target Architecture

Middle-Tier

Resource Specification

Abstract Task Specification

CTA specificknowledgedatabases

VisualAuthoring

Tools

User andGroup

Profiles

ResourceIdentificationand Access

VisualizationsCollaboration

WebFlow

Back-End Resources

Problem Solving Environment

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

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

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

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]

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)

Front End

CTA specific knowledge database

– 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

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

Example: Data Flow

Example: DARP

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

Resource Identification and Access

• Computational resources– hardware, software, licenses

– desktop applications

• Data– file systems, mass storage, distributed databases

– Internet data repositories

• Networks

Front-End infrastructure

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, …)

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.

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.

Screen Dump of the Control Applet

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.

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.

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.

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.

Other toolboxes

• Visualizations• Collaboration• Scientific notebook• ...

Middle-Tier

User 1 User 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 maintainsa number of applications

composed of custom modules

and common services

WebFlow Services

CORBA Based Middle-Tier

Mesh of WebFlow Serversimplemented as CORBA objects

that manage and coordinate

distributed computation.

Front End

GatekeeperAuthenticationAuthorization

Back End

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

Gateway Security

SECIOP

Security Model (Keberos)

Front End Applet

SECIOP

authentication& authorization

Gatekeeper

delegation

HPCC resources

GSSAPIGSSAPI

Layer 1: secure Web

Layer 2: secure CORBA

Layer 3: Secure access to resources

Policies defined by resource owners

Building Gateway Components

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

How to develop a Gateway component (or a toolbox)

• Back-end service• Middle-tier proxy• Front-end controls

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.

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++)

– ...

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

Selecting a Predefined Task

Gateway/WebFlow Mission

• seamless access to remote resources– through a Web based user interface

– customized application GUI

• high-level user friendly visual programming and runtime environment for HPDC

• portable system based on industry standards and commodity software components

Updates

• Contact person: Tomasz Haupt

• haupt@npac.syr.edu

• voice (315) 443-2087

• http://www.npac.syr.edu/users/haupt/WebFlow/