Oracle® Fusion Middleware

What Are Web Services?

A Web service is a program that can be accessed remotely using different XML-based languages. What this program can do (that is, the functionality it implements) is described in a standard XML vocabulary called Web Services Description Language (WSDL). For example, a banking Web service may implement functions to check an account, print a statement, and deposit and withdraw funds. These functions are described in a WSDL file that any consumer can invoke to access the banking Web service. As a result, a consumer does not have to know anything more about a Web service than the WSDL file that describes what it can do.

A Web service consumer (such as, a desktop application or a Java Platform, Enterprise Edition client such as a portlet) invokes a Web service by submitting a request in the form of an XML document to a Web service provider. The Web service provider processes the request and returns the result to the Web service consumer in an XML document as shown in the example below.

In this example, the Web service consumer sends a request in the form of a Simple Object Access Protocol (SOAP) message (SOAP is an XML messaging framework designed to allow heterogeneous applications to exchange structured information in a distributed environment). The Web service provider (www.xmethods.com) processes the request and returns the response, in this case the stock quote for Oracle. In the example above, the Web service provider may have asked for credentials to access the service, for example a username and a password. Also, the Web service provider may have encrypted the response (the value of the stock).

You can also develop Representational State Transfer (REST) Web services, or "RESTful" Web services. REST describes any simple interface that transmits data over a standardized interface (such as HTTP) without an additional messaging layer, such as SOAP. REST provides a set of design rules for creating stateless services that are viewed as resources, or sources of specific information, and can be identified by their unique URIs. A client accesses the resource using the URI, a standardized fixed set of methods, and a representation of the resource is returned. The client is said to transfer state with each new resource representation.

In summary, Web services are loosely coupled, distributed environments that allow companies to integrate heterogeneous applications within the enterprise or expose business functions to their customers and partners over the Internet.

Web services are characterized by three factors:

• What they do (the business functionality they expose),

• Where they are (the web site which exposes that functionality),

• How they can be accessed (the set of published interfaces necessary to use the exposed functionality).

Web services rely on XML-based industry standards:

• Extensible Markup Language (XML)—A data format that allows uniform communication between Web services consumers and Web services providers.

• XML Schema—A framework that describes XML vocabularies used in business transactions.

• SOAP—A protocol for exchanging structured information in the implementation of Web services.

• WSDL—An XML-based language providing a model for describing Web services.

• WS-Policy—The WS-Policy framework provides a flexible and extensible grammar for describing the capabilities, requirements, and general characteristics of Web services using policies.

• Universal Description, Discovery, and Integration (UDDI)—A framework to publish and look up Web services on the Internet.

Overview of Web Services in Oracle Fusion Middleware 11g

The following illustration shows common interactions between Oracle Fusion Middleware Web services and clients, and identifies Web service policy support at each interaction point.

The Oracle Web Services Manager (WSM) Policy Manager is the security and management policy lynchpin for Oracle Fusion Middleware 11g Web services. For more information about how the Oracle WSM Policy Manager provides the policy framework for managing policies, see "Understanding Oracle WSM Policy Framework" in Security and Administrator's Guide for Web Services.

Figure 1 Web Services in Oracle Fusion Middleware 11g

Description of "Figure 1 Web Services in Oracle Fusion Middleware 11g"

The following sections provide more detail about the Oracle Fusion Middleware 11g Web services architecture and each of the Web service components shown in the previous figure:

• Web Services Architecture

• Types of Web Services and Clients

• Types of Web Service Policies

• Tools for Web Service Development, Security, and Administration

For a complete roadmap of all Web service development, security, and administration tasks, see "Roadmap for Implementing Oracle Fusion Middleware Web Services".

Web Services Architecture

In Oracle Fusion Middleware 11g, there are two categories of Web services:

• Oracle Infrastructure Web services—SOA, ADF, and WebCenter services

• WebLogic Web services (Java EE Web services)

The following figure illustrates the two Web services categories.

Figure 2 Web Services in Oracle Fusion Middleware 11g

Description of "Figure 2 Web Services in Oracle Fusion Middleware 11g"

Roadmap for Implementing Oracle Fusion Middleware Web Services

The following sections provide roadmaps of common tasks for developing, securing, and administering Oracle Fusion Middleware Web services. Roadmaps are presented for each Web service category shown in Figure 2:

• Roadmap for Implementing Oracle Infrastructure Web Services

• Roadmap for Implementing WebLogic (Java EE) Web Services

Related Documentation

The following table summarizes the documentation that is related to Web services development, security, and administration.

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