Building Web Services

Web services are applications stored on web servers that you can access remotely through standard web protocols (HTTP, SOAP) and data formats (HTML, XML...), whatever the systems and programming languages.

In SOAP requests, queries are encapsulated into services, whereas in HTTP requests, operations are invoked directly. In PowerDesigner, you can design web services for both protocols.

PowerDesigner supports web services for the following databases:

Web services can be used to simplify access to databases. If you use web services to query databases, you no longer need drivers to communicate with those databases.

In the following example, you can see the result of an HTTP request for a database web service:

Web services are made of a set of operations. Each operation contains a SQL query for retrieving data from a database.

• Web Services (PDM)
  In PowerDesigner, web services are made of web operations which themselves contain web parameters and result columns:
• Web Operations (PDM)
  A web operation is a child object of a web service. It allows you to define the SQL statement of a web service and to display its parameters and result columns.
• Web Parameters (PDM)
  Web parameters are child objects of web operations. They are part of the SQL statement defined in the Implementation tab of a web operation property sheet. They are listed in the Parameters tab of a web operation property sheet.
• Testing Web Services
  PowerDesigner provides a method for testing web services within the model environment. You must be connected to the appropriate database.
• Generating Web Services
  You generate web services in order to implement them on target databases.
• Reverse Engineering Web Services
  You reverse engineer web services from a database to a PDM, when you want to reuse these web services in the PDM. Once reverse engineered, you can modify and generate them in the database.