|Oracle8i Application Developer's Guide - XML
Release 3 (8.1.7)
Part Number A86030-01
Personalizing Data Display With XML: Portal-to-Go , 7 of 16
A Portal-to-Go service encapsulates a unit of information requested by, and delivered to, a Portal-to-Go client. Examples of services include:
You can build services from an existing Web site, a query to any database, or any XML source.
A Master Service is a Portal-to-Go object that implements a service and invokes a specific adapter. The end-user typically sees a service as a menu item on a handset or a link on a Web page. End-users invoke Master Services by choosing menu items in their device interface. The Master Service returns the following kinds of data:
By mapping an Adapter to device Transformers, master services link Portal-to-Go content sources to the delivery platforms. Each Master Service is based on one Adapter. A Master Service creates its own instance of the Adapter it uses. Therefore, several services can use the same type of Adapter, and each can pass the Adapter its service-specific argument values.
A Portal-to-Go Adapter is a Java application that retrieves data from an external source and renders it in Portal-to-Go XML. When invoked by a Master Service, an Adapter returns an XML document that contains the service content. Adapters provide the interface between the Portal-to-Go server and the content source.
An Adapter does the following:
Portal-to-Go provides pre-built Adapters for popular content sources, including Web pages and JDBC-enabled data sources, and adapters you can modify to work with other content sources.
All adapters must generate Portal-to-Go XML. This is a well-formed, valid XML document that complies with the Portal-to-Go DTD.
Portal-to-Go Transformers are Java programs or XSL-T stylesheets that convert an XML document into the target or another Portal-to-Go format. They can also rearrange, filter, and add text. The Transformers enable you to present content in a format best suited to your target device. Portal-to-Go supplies transformers for the following markup languages:
Figure 7-3 illustrates these markup languages and their derivation.
Use Transformers to optimize content presentation for any device, and support new device platforms. In most cases, you can simply modify or re-use an existing Transformer.