Design

OTN developers used Web Services to access data provided by other, completely separate applications. This approach makes the FBS itself smaller and therefore easier to maintain. It also makes the FBS more flexible, because it's relatively easy to swap one Web Service for another.

The FBS uses Web Services to

• Fetch stock quotes.
• Fetch financial news.
• Communicate with other FBS instances

To watch a viewlet that shows how the FBS uses Web Services, browse to:

• /sample_code/tutorials/fbs/files/viewlets/ibfbswebservices_viewlet.html

Fetching Stock Quotes

Rather than build a module to fetch stock quotes, OTN developers used an existing Web Service. The Web Service WSDL URL is http://services.xmethods.net/soap/urn:xmethods-delayed-quotes.wsdl. Oracle9i JDeveloper includes a wizard that takes a WSDL URL and generates the Java stub code required to access the Web Service.

Fetching Financial News

Similarly, the FBS uses another Web Service to fetch financial news. However, instead of using a WSDL URL, the FBS accesses the Web Service via APIs in a library provided by Google. This library is required to build the FBS.

Communicating with Other FBS Instances

Each instance of the FBS represents a unique stock exchange. When an FBS user buys or sells a particular stock, the order is sent to the corresponding stock exchange as a simplified message. If the stock is not traded in the current exchange, the FBS forwards the order to another FBS, and so on until the trade is executed. FBS instances pass orders around via Web Services.