web service standards relevant to soa

1. Web Service Standards Relevant to SOA By Mark Zalar

2. Seminar Outline

SOA basics

Web Services

Web Service Protocol Stack

Overview

Closer look at each level

Protocols and how theyre used

Tools

Alternative SOA web service tool and protocol

3. What is SOA?

Service-Oriented Architecture

An architecture that relies on loosely-coupled software agents to perform specified tasks

Software agents can be independent of one another

Interaction requires no knowledge of a software agents underlying details

4. What is SOA?

Loose-coupling

An approach/design goal where interaction between services is developed with minimal assumptions between the services

A change in one service should not force a change in another service that interacts with it

Interface is independent of implementation

5. What is SOA?

Service

A unit of work performed by a service provider for a service consumer

Service providers and service consumers are both software agents

6. What is SOA?

Web Services

A software system designed to support interoperable machine to machine interaction over a network (W3C definition)

A web service is SOA if:

Interfaces are based on Internet protocols

Messages are XML

7. SOA and Web Service Standards

SOA web services are typically built on web service standards (a.k.a. web service specifications)

More interoperability

Freedom from proprietary vendor software

Many of these standards, like SOAP, already have widespread industry acceptance

8. SOA and Web Service Standards

The base level web service standards relevant to SOA are common standards that most of us have used or at least heard of.

XML, HTTP, SOAP, etc.

These standards can be usefully categorized using the web services protocol stack

9. Web Services Protocol Stack

The web service protocol stack is a collection of computer networking protocols that are used to:

Define web services

Locate web services

Implement web services

Make web services interact with each other


Four major parts

Service Transport

HTTP, SMTP, FTP

XML Messaging

XML, SOAP

Service Description

WSDL

Service Discovery

UDDI


What is each part responsible for?

Service transport

Transporting messages between network applications

XML messaging

Message encoding in a common XML format so messages can be understood at both ends of a connection

Service description

Standardized Description of how to interface with the web service

Service discovery

Centralized registry where web services can publish their location and description

12. Web Services: The Big Picture Image from Wikipedia link

13. Service Transport

HTTP

Hypertext Transfer Protocol

Request/response protocol between clients & servers

HTML

SMTP

Simple Mail Transfer Protocol

e-mail

FTP

File Transfer Protocol

Exchanging files over a network

14. XML Messaging

XML

Extensible Markup Language

General-purpose

Open, free standard

Used to share data between systems

Human readable

Can represent general data structures

Trees, lists, etc.

Hierarchical structure

15. XML Messaging

XML Example

Basic bread

Flour

Yeast

Water

Salt

Mix all ingredients together, and knead thoroughly.

Cover with a cloth, and leave for one hour in warm room.

Knead again, place in a tin, and then bake in the oven.

Example from Wikipedia

16. XML Messaging

Genshi

A Python library for parsing and generating XML

Image from Genshi website

17. XML Messaging

SOAP

Simple Object Access Protocol

Used to exchange XML messages over a network (using HTTP or other service transport protocol)

Most common messaging pattern is RPC

Client sends request, server immediately responds

Allows easy interaction between very different systems

18. XML Messaging

SOAP Example

Client request

827635


19. XML Messaging

SOAP Example

Server response

Toptimate 3-Piece Set827635

3-Piece luggage set. Black Polyester.

96.50true


20. Service Description

WSDL

Web Service Definition Language

An XML format for describing web services

Describes the public interface to a particular web service

Data Types

Messages

Operations

Communication Protocols

Often used with SOAP and XML

WSDL tells a client what functions are available

The client uses SOAP to actually call functions

21. Service Description

WSDL Example

Example from W3Schools

22. Service Discovery

UDDI

Universal Description Discovery and Integration

XML-based, platform independent, standardized worldwide business registry

Businesses can publish service listings and describe how services interact over the Internet

Focuses on the discovery aspect of SOA

Three types of information can be registered into a UDDI registry

White Pages - business identification information (address, name, contact information)

Yellow Pages - characterization/description of service

Green Pages - technical information about service

Used with SOAP messages to access WSDL documents describing services in the directory

23. Service Discovery Table from uddi.org UDDI Business Registry (UBR) From an end-users perspective, a public registry appears to be a service in a cloud. Although administrative functions may be secured, access to the registry data itself is essentially open and public. Data may be shared or transferred among other registries, and content may or may not be moderated. Public Trading Partner Network A registry deployed within a controlled environment, but with limited access by authorized clients. Administrative features may be delegated to trusted parties. Data may be shared with other registries in a controlled manner. Affiliated Enterprise Web Service Registry An internal registry, behind a firewall, that is isolated from the public network. Access to both administrative features and registry data is restricted. Data is not shared with other registries. Corporate/Private EXAMPLE APPLICATION DESCRIPTION REGISTRY TYPE

24. Service Discovery

UDDI Example

http:// soapclient.com/uddisearch.html

25. Other SOA Web Services Options

Although the standards discussed offer much flexibility for service-oriented development, they are not the only means to implement SOA web services.

Almost any service-based technology will work

Service oriented systems have been implemented using

Jini

CORBA

26. Jini

Originally developed by Sun, now Apache (Apache River)

Jini is used to create distributed services

Java Based

Seven suite used to develop and deploy services

Both a specification and an implementation

Has discovery features

27. Jini

Jini service browser example

Image from Warren Strange

28. CORBA

Distributed programming protocol

Jini uses CORBA

Standard defined by Object Management Group

Allows interoperation between software components written in different languages running on different computers

Wraps code with a description that contains information about what the code can do and how to use it

Uses an interface definition language to specify how code interacts

Mappings exist between the interface definition language and implementation programming languages

Ada, C, C++, Lisp, Smalltalk, Java, COBOL, PL/I, and Python

29. CORBA Image from Wikipedia

30. Summary

SOA

Web Service Protocol Stack

Service Transport

HTTP, SMTP, FTP

XML Messaging

XML, SOAP

Service Description

WSDL

Service Discovery

UDDI

Alternatives

Jini, CORBA

web service standards relevant to soa

Documents

interface

xml messaging

web service

web services

administrative

registry data

standards

service