Buzzwords of Web Services

Buzzwords of Web Services

All new technologies are inundated with buzzwords and acronyms that attempt to describe them, but these often produce the opposite effect of making the new technology harder to understand. The Web Services world has its share, as well. To explain the buzzwords, think of a Web Service as a package that will be shipped to a customer.

XML

XML, or eXtensible Markup Language, is used to build Web Service messages that go from one server to another. As you ll see in this chapter, by using JDeveloper, the developer will not need to know much about it to create a Web Service. When it comes to shipping our package to the customer, XML is the alphabet.

SOAP

SOAP, or Simple Object Access Protocol, is what enables the exchange of information over a network. SOAP is an XML-based (text) protocol specification. In other words, SOAP messages are built with XML. The messages are, therefore, platform, protocol, and language independent. The standard doesn t specify a transport mechanism. As a result, messages can travel on HyperText Transfer Protocol/Secure HyperText Transfer Protocol (HTTP/HTTPS); i.e., web site POSTs, Simple Mail Transfer Protocol, or SMTP; i.e., via e-mail, or File Transfer Protocol (FTP); i.e., file transfer. SOAP provides a standard so developers don t have to invent a custom XML message for every service they want to make available. The SOAP message specifies the service name , the method names implemented by the service, the method signature of each method, and address of the service implementation ( expressed as a Uniform Resource Identifier, or URI). Oracle supports the HTTP and HTTPS transports only. The good news about HTTP and HTTPS is that this information is provided through firewall-friendly ports ”messages are transported using existing communications protocols and methods . When it comes to the package that we re sending to our customer, SOAP addresses the envelope or package.

WSDL

WSDL, or Web Services Description Language, is actually a file containing XML that describes the Web Service interfaces and locations; it describes the methods or programs that you can call in the Web Service and input/output parameters for each method. When it comes to the package that we re sending to our customer, WSDL describes the message. Think of WSDL as the metadata about the Web Service. This is the mechanism that provides the self-describing qualities of a Web Service.

UDDI

UDDI, or Universal Description, Discovery, and Integration, specifies a standard business registry by which people can publish/discover information about Web Services. It also specifies a directory naming service (DNS) for business applications. UDDI registry components include:

  • White Pages contact information for a given business

  • Yellow Pages information that categorizes businesses (industry, product, etc.)

  • Green Pages technical descriptions of provided Web Services

There are currently a number of UDDI providers, including Oracle (http://otn.oracle.com/tech/webservices/htdocs/uddi/otnuddi.html), Microsoft (http://uddi.microsoft.com), IBM (http://www-3.ibm.com/software/solutions/ webservices /uddi/), and SAP (http://udditest.sap.com). When it comes to the package we re sending to our customer, UDDI is the directory of services that we can use.



Oracle Application Server 10g Web Development
Oracle Application Server 10g Web Development (Oracle Press)
ISBN: 0072255110
EAN: 2147483647
Year: 2004
Pages: 192

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net