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Web Services eXperience LanguageWeb Services eXperience Language

Technical OverviewTechnical Overview

Ravi Konuru (rkonuru@us.ibm.com)e-Business Tools and Frameworks, IBM Research

IBM WSXL Team

OASIS WSCM Technical CommitteeOASIS WSCM Technical Committee

January 2002January 2002

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geThe Innovation Context

ApplicationBack End Services

User Experience Services

Leverage Web services and XML technologies• B2B Integration Experience Integration• Enable simple solutions for syndication, adaptation, delegation and composition of web experience• Ensure migration path for existing applications

Providers Integrator Client

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geExperience Integration: Requirements & Related Work

– Provider• Migrating Interactive Web Applications

– Converting existing web applications to interoperable services– Describing their inputs and outputs.

• Syndication– Separation of Style from Presentation (XML/XSL)– Adaptation description– Explicit MVC decomposition (XFORMS)– Explicit Flow Modeling (WSFL)

– Integrator• Style Composition

– XSL, CSS

• Data binding, sharing and synchronization across components– XFORMS, XML Events, XLINK, XPATH, XML plug-in?

• Event interoperability and synchronization – XML Events, XLINK, XPATH, XML plug-in?

• Flow composition– WSFL

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geRelationship to WSCM Charter

• define a set of "base" web services interfaces that can be used to expose interactive web application function and adaptation.

• define a set of web services interfaces that can be used to partition web applications into model, view and control (MVC).

• define a "wiring mechanism" to declaratively specify web application semantics.

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geWSXL Elements• WSXL Components are built on four kinds of web services:

Base, Data, Presentation and Control.

• The Extensible Control Language (XLink and XML Events) wires WSXL Components.

• A WSXL Container service hosts WSXL components and can provide optional functionalities.

• WSXL Adaptation Description Language enables application providers to specify the adaptability of their service.

• WSXL Applications can be created from one or more WSXL components (Base, Data, Presentation, and Control) and wired using the Extensible Control language.

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geWSXL Base ComponentThe WSXL Base Component specifies the interfaces required by all WSXL Components.

• W3C DOM Events interface is used for describing event listeners, event handlers and WSXL Event types.

• Lifecycle interfaces is the means to identify and manage instances

• getMarkup interface provides its output

All WSXL Entities can additionally export application specific operations

WSXL BaseComponent

W3C DOM Events

getMarkup Interface

Lifecycle Interfaces

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geWSXL Data ComponentThe WSXL Data Component - Interfaces to describe and maintain instances of data - Adopts concepts and ideas from XFORMS - Desired functionality in the data interface

- Access (DOM subset),- Validation, - Update Control, - Re-computation,- Data Availability.

WSXL DataComponent

WSXL Base Interface

Data Interfaces

Application Interfaces

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geWSXL Presentation ComponentThe WSXL Presentation Component - Describes and maintains instances of presentation - Elements from arbitrary namespaces (XHTML, WML, XFORMS, …) - DOM 2 based access interface - Defined events such as focus, select, execute and DOM mutation.

WSXL PresentationComponent

WSXL Base Interface

Presentation Interfaces

Application Interfaces

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geWSXL Control ComponentThe WSXL Control Component implements interfaces used to - Manage the arcs connecting WSXL components - Control the propagation of bi-directional event notification - Parse and interpret the Extensible Control Language.

WSXL ControlComponent

WSXL Base Interface

Control Interfaces (Arc management, Update Model)

Application Interfaces

Common case: Connecting presentation and data components.

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geWSXL Event Wiring

WSXL PresentationComponent

WSXL DataComponent

W3C XML Events

WSXL ControlComponent

W3C XML Events

W3C XML Events

The Extensible Control Language (XLINK and XML Events) wires any WSXL Components together for event synchronization.

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geWSXL ContainersA WSXL Container is responsible for providing an execution and management environment for WSXL Components.

Discovery

Specialized

Lifecycle

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geAdaptation Description Language

• Driven by Integrator Requirements– Robust adaptation

• Reliably observe and/or modify the output of a service

• Reliably change behavior by replacing invocations of one service to invocations of another service.

– Exploit provider capabilities• Use provider’s services/operations to perform adaptations.

• Application Provider specifies– Category of adaptation (XML, CSS, ….)– Points of adaptability– Kinds of adaptability– Assistance for adaptation

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geCreating Applications

A WSXL application can consist of:– A single WSXL component– An adaptation description– Event wiring and synchronization– Flow composition across multiple WSXL

components

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geDistributed Stock Plotting Application

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geMapping WSXL to WSCM-specific elements

WSXL Base Service

WSXL Container

WSFL - Flow modeling

WSFL - Global modeling

WSDL - Operations

Event wiring

WSXL Event Controller

WSXL Data Service WSXL Presentation Service

Existing WS infrastructure

WSXL

Adaptation Description LanguageExtensible Control Language

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