Before you start
In this tutorial you learn about Web Services Policy, or WS-Policy. This standard is for developers who want to expose their own services in an environment and use policies that define how these web services are allowed to interact with other clients and services. The term WS-Policy refers to a framework that defines governance, such as the method of transport, and security, such as the level of encryption.
In order to follow along with this tutorial, you should have a basic understanding of SOAP, which you can achieve by reading Part 1 of this series (by extension, you also need a basic understanding of XML). SOAP is programming-language agnostic. However, the samples in this tutorial use Java™ and the Apache Axis2 project, even though the concepts apply to any programming language and environment.
This tutorial series teaches the basic concepts of web services by following the exploits of the fictional newspaper, Daily Moon, as the staff uses web services to create a workflow system to increase productivity in this competitive environment.
Part 1 starts simply, explaining the basic concepts behind web services and showing you how to use SOAP, the specification that underlies most of what is to come, connecting the classifieds department with the Content Management System.
Part 2 takes things a step further, explaining how to use Web Services Description Language (WSDL) to define the messages that web services produce, enabling the team to more easily create services and the clients that connect to them.
Part 3 finds the team with a number of services in place and a desire to locate them easily. In response, Universal Description, Discovery, and Integration (UDDI) provides a searchable registry of available services as a way to publicize its own services to others.
In Part 4, Rudy, publisher of the Daily Moon, decides that the paper needs to institute better security procedures for web services that access their internal systems.
In this Part 5, WS-Policy, you see the changes the teams need to make in order to access those newly secured services.
Part 6 focuses on interoperability, as services from several different implementations must be accessed from a single system. Part 6 covers the requirements and tests involved in WS-I certification.
Finally, Part 7 shows how to use Business Process Execution Language (WS-BPEL) to create complex applications from individual services.
In this tutorial, follow along as the Daily Moon newspaper team uses the WS-Policy specification to specify the policies that web services must adhere to in order to use the company's web services.
In the course of this tutorial, you will:
- Learn the syntax of creating policy documents, as well as how to create your own policies, and how to use other, already existing assertions.
- See how you can manipulate Policy documents using mathematical properties of the underlying XML constructs.
- Use Apache Neethi, the incomplete WS-Policy implementation from Axis2 that allows Axis2 users to manipulate and combine policy documents.
- Learn how to use WS-Policy and WSDL together, and learn how to write WSDL that requires ports to adhere to a defined policy.
You will need a few tools to begin.
Much of this tutorial is conceptual, but in order to follow along with the code that uses Apache Neethi to work with WS-Policy documents, you need the following software installed:
Java 2 Standard Edition version 1.4.2 or higher -- All of these tools are Java-based, as are the services and clients you build in this tutorial.
Apache Neethi -- Apache Neethi is what Axis2 uses to create a run-time representation of policy documents, and to perform normalization, merging, and intersection operations on policy documents.