Web Services Architecture Overview

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Web Services Architecture Overview
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Web Services Poll

• Will Web Services be the next BIG thing?
• Yes
• No

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Web Services Model
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Web Services Definition

• What is a Web Service?

1. Loosely coupled, reusable software component

1. A self-contained "applet" that performs a single
   task

1. An interface that describes a collection of
   operations that are network-accessible through
   standardized XML messaging

1. Web-native building blocks that can be combined
   to form the "next generation of Internet
   applications

1. Protocol that will transform the Internet into a
   way to program and specify the way you exchange
   information

1. Any service offered over the Web

1. Programmable application logic accessible using
   standard Internet protocols

1. .NET

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Web Services (Interoperability) Stack

• Needed for publish, find, bind operations
• Upper layers build on lower ones
• Lower 3 layers required for a Web Service
• QOS, Management, and Security needed for
  e-business

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Network

• Foundation of the Web Services Stack
• HTTP is the de facto standard network protocol
• Other Internet protocols can be supported
• SMTP, FTP,
• Intranet domains can use reliable messaging
• CORBA, MOM, RMI,
• Transparent to the Web Services developer

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XML-messaging based Distributed Computing

• Fundamental underpinning of Web Services is XML
• SOAP is the current XML messaging protocol
• Will most likely be replaced by XMLP (W3C)
• SOAP consists of 3 parts
• Envelope defines framework for describing what
  is in a message
• Encoding rules expressing instances of
  application-defined data types
• Request/Response model for RPCs
• May be asynchronous or synchronous

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Basic SOAP Architecture
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Service Description

• Communicate the specifications for invoking the
  Web service to the service requestor
• Neither requestor/provider are aware of
• OS
• Programming language
• Distributed Object Model
• Key to loose coupling

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Web Services Description Language

• XML-based language used to define Web services
  and to describe how to access them.
• Similar to Java Interfaces, IDL, abstract classes

A set of related ports
An address for a binding (URL)
Message format and protocol details
Set of operations (input, output)
Abstract definition of data being sent
Data type definitions describing the messages
(XSD)
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Completing the Web Service Description

• Business Info (Name, Type, Products, Category,)
• Universal Description, Discovery Integration
  (UDDI)
• Data structure standard for representing
  description information in XML
• 4 fundamental data structures

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Publication of Service Descriptions

• Making a WSDL document available to a service
  requestor
• Production of Service Descriptions
• Most tools generate the service description
• Publishing
• Varies based on the dynamic nature of the
  application
• Direct publish (email, FTP, snailmail,)
• Retrieved via a URL (DISCO, ADS)
• HTTP GET

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Publication of Service Descriptions

• Universal Description, Discovery and Integration
• Private Nodes (Control, security, reliability,)
• Internal Enterprise Application
• Portal
• Partner Catalog
• E-Marketplace
• Public Node
• Operator Node
• Supported, replicated, and hosted by IBM,
  Microsoft, and HP (Ariba has become a registrar)

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Service Discovery

• Mechanism for providing runtime access to the
  service description
• Dependency on service publication
• Cant be discovered if it aint published
• Service Registry/UDDI Node
• Query mechanism
• Private Nodes
• Price, Quality of Service, Brand, etc
• Public Nodes
• ???, exercise caution

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e-Business

• Extensions needed to fully support e-business
• Security Authorization, Digital signatures,
  SSL,
• Reliable Messaging Guaranteed delivery (HTTPR)
• Quality of Service Expected execution time,
  timeout values,
• Systems Application Management Control
  configure infrastructure and components
• Service Context Type of wireless device, User
  profile,
• Conversations Activities Transactions,
  collaboration,
• Portals Portlets Provide support for Web
  services

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Business Processes Workflows

• Choreography for interactions between component
  Web Services
• Aggregation of Web services (business transaction)

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Business Processes Workflows

• Long way to go
• Web Services Flow Language IBM
• XLang Microsoft
• ebXML
• Business Process Modeling Language OASIS
• RosettaNet

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Web Services Benefits

• Interoperability
• Any web service can interact with any other web
  service.
• Ubiquity
• Web services communicate using HTTP and XML.
• Low barrier to entry
• The concepts behind Web services are easy to
  understand, many toolkits are free and allow
  developers to quickly create and deploy Web
  services.
• Industry Support
• All of the major vendors are supporting SOAP and
  the surrounding Web services technologies.
• Web services are relatively low risk technology
  that can be used to implement high risk business
  strategies.

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• Questions???