Web Services

What is web services?

Web services describes a standardized way of integrating Web-based applications, self-contained and self-describing using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol backbone. Primarily used for businesses to communicate with each other and with clients.

  • HTTP and XML is the basis for Web services
  • XML is used to tag the data
  • SOAP is used to transfer the data
  • WSDL is used for describing the services available
  • UDDI is used for listing what services are available.
Web services are not tied to any one operating system or programming language. For example, Java or .NET can talk with Perl, Windows applications can talk with UNIX applications. Unlike traditional client/server models, such as a Web server/Web page system, Web services do not provide the user with a GUI. Web services instead share business logic, data and processes through a programmatic interface across a network.

SOAP

  • SOAP - defines Simple Object Access Protocol
  • It is simple, lightweight XML-based protocol for exchanging structured and type information on the Web.
  • It is to keep it as simple as possible, and to provide a minimum of functionality.
  • It defines a messaging framework that contains no application or transport semantics.
  • It is modular and very extensible.

The SOAP protocol specification consists of four main parts.

1. Defines a mandatory extensible envelope for encapsulating data. The SOAP envelope defines a SOAP message and is the basic unit of exchange between SOAP message processors. This is the only mandatory part of the specification. 2. It's specification defines optional data-encoding rules for representing application-defined data types and directed graphs, and a uniform model for serializing non-syntactic data models. 3. It's defines an RPC-style (request/response) message exchange pattern. Each SOAP message is a one-way transmission. Although SOAP's roots are in RPC, it is not limited to being a request/response mechanism. XML Web services often combine SOAP messages to implement such patterns, but SOAP does not mandate a message exchange pattern and this part of the specification is also optional. 4. It defines a binding between SOAP and HTTP. However, this part is also optional. You can use SOAP in combination with any transport protocol or mechanism that is able to transport the SOAP envelope, including SMTP, FTP, or even a floppy disk. For the SOAP specification, see the W3C Web site (http://www.w3.org/TR/soap).

What is WSE?

Web Services Enhancements (WSE) is an obsolete add-on to the Microsoft .NET Framework which includes a set of classes that implement additional WS-* web service specifications chiefly in areas such as security, reliable messaging, and sending attachments.[1] Web services are business logic components which provide functionality via the Internet using standard protocols such as HTTP. Web services communicate via either SOAP or REST messages. WSE provides extensions to the SOAP protocol and allows the definition of custom security, reliable messaging, policy, etc. Developers can add these capabilities at design time using code or at deployment time through the use of a policy file. There is no update for WSE to work with VS2008 or later versions. WSE is now obsolete. WCF provides the equivalent functionality.