The New Nation - Internet Edition

Azizur Rahman

Now in the world you have not do anything without a web address. If you want to communicate to the people you must need a web address. You have not find any organization its Government or non government, news, media, game, movie, cultural, or any thing that's need an individual wed address. So its huge emergency for us to communicate to vast people or communicate world wide.

The ability for a program on one computer to exchange information with a program on a remote computer is a typical requirement for today's businesses. The most common means of accessing remote resources is to use HTTP to transfer HTML files from a server to a client; in other words, a Web site. This way of transferring information works because it is uses simple, commonly available technology and standards. The primary limitation of web sites is that they are only understandable to humans and not machines.

Web Services are one way of accessing remote resources on a machine-to-machine basis. Let's take a look at some basic Web Service standards such as SOAP, as well as more advanced extensions known as the WS-* series of standards. Web Services differ from other methods in that they use simple XML messages to transfer information, can use HTTP as a transport, and do not require two-way (synchronous) communications. Because Web Services use simple, commonly available technology and standards, they are rapidly becoming the tool of choice for machine-to-machine interactions. The exact definition of a Web Service, according to the World Wide Web Consortium's Web Services Architecture, is a software system designed to support interoperable machine-to-machine interaction over a network. It has an interface described in a machine-processable format (specifically WSDL). Other systems interact with the Web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards.

This definition highlights the core technologies of Web Services. SOAP is a standardized way of passing messages between machines, Web Services Interface Language (WSDL) defines how to interface with a Web Service and Extensible Markup Language (XML) is the basis for both of these technologies. Every Web Service standard builds upon these basic building blocks in some form. In addition to SOAP and WSDL, Universal Description Discovery and Integration (UDDI) is often considered one of the core Web Service standards. UDDI is a registry that contains information regarding Web Services.

XML

XML is the foundation of all Web Services standards. It is a flexible language for describing any type of data. It uses simple text tags to describe each element of data. The use of text tags, as opposed to a binary encoding, allows humans to read XML. The extensible aspect of XML allows developers to add new data elements as necessary without adversely affecting existing data definitions.

Because of the flexibility inherent in XML and a variety of tools to process it, XML has become the popular choice for defining new data formats. As a testament to the utility of XML, there exist XML schemas to describe geographic features (Geographic Markup Language), mathematics (Math Markup Language), graphics (Scalable Vector Graphics) and numerous other types of data. Additionally, Microsoft Office 2007 and OpenOffice office suites both use XML formats to store their data. For all of its advantages, XML is not without its flaws. In contrast to binary formats, XML is very verbose. In general, this means XML requires more processing power, storage space and bandwidth as compared to the same information encoded in a binary format. Efficient representations of XML are in development to address many of these concerns.

SOAP

SOAP is the XML-based language that defines the format of Web Services messages. SOAP, formerly known as the Simple Object Access Protocol, is now not an acronym. SOAP can use both asynchronous and synchronous messaging patterns. This means that SOAP can use either a one-way messaging pattern or a request-response pattern. This allows SOAP a great deal of flexibility in its implementation.

A SOAP message contains three basic elements, a header, body and fault. These elements can include any type of XML data and is therefore very flexible. The SOAP header generally incorporates information regarding the handling of the SOAP message. Many of the WS-* specifications (WS-Security, WS-Addressing, WS-ReliableMessaging …) implement additional features as SOAP headers. The body contains application data, parameters of functions and the return values from completed functions. The fault element conveys error conditions in processing SOAP messages.

SOAP's major shortcomings are performance and bandwidth. Because SOAP uses XML, there is significant overhead associated in the representation of data as compared to binary protocols. According to a paper comparing SOAP and CORBA, SOAP can take 30-60 times longer to process and consume 50 to 100 times the bandwidth as compared to binary protocols. It is for this reason that Common Object Request Broker Architecture (CORBA), a binary-based remote procedure protocol, is very popular for connecting components within embedded systems.

(To be continued)