Chapter 49 Robot Application Functions - Sources and Destinations

Most of the Robot Application Functions (RAFs) require sources of information and generate data that goes to destinations. The sources are defined within the robot itself and are not necessarily related to the fields in the resource description it ultimately generates. Destinations, on the other hand, are generally the names of fields in the resource description, as defined by the resource description server’s schema.

For details on using the administration console to determine the database schema, see Sun Java System Portal Server Administration Guide.

The following sections describe the different stages of the filtering process, and the sources available at those stages.

Setup Stage

At the Setup stage, the filter is set up and cannot yet get information about the resource’s URL or content.

MetaData Filtering Stage

At the MetaData stage, the robot encounters a URL for a resource, but it has not downloaded the resource’s content, thus information is available about the URL as well as data that is derived from other sources such as the filter.conf file. At this stage, however, information is not available about the content of the resource.

Table 49-1 lists the sources available to the RAFs at the MetaData phase. The table contains three columns. The first column lists the source, the second column provides a description, and the third column provides an example.

Table 49-1 Sources Available to the RAFs at the MetaData Phase
Source	Description	Example
csid	Catalog Server ID	x-catalog//budgie.siroe.com:8086/alexandria
depth	Number of links traversed from starting point	10
enumeration filter	Name of Enumeration filter	enumeration1
generation filter	Name of Generation filter	generation1
host	Host portion of URL	home.siroe.com
IP	Numeric version of host	198.95.249.6
protocol	Access portion of the URL	http, https, ftp, file
path	Path portion of the URL	/, /index.html, /documents/listing.html
URL	Complete URL	http://developer.siroe.com/docs/manuals/

Data Stage

At the Data stage, the robot has downloaded the content of the resource at the URL, and can access data about the content, such as the description, the author, and so on.

If the resource is an HTML file, the Robot parses the <META> tags in the HTML headers. Consequently, any data contained in <META> tags is available at the Data stage.

During the data phase, the following sources (shown in Table 49-2) are available to RAFs, in addition to those available during the MetaData phase. The table contains three columns. The first column lists the source, the second column provides a description, and the third column provides an example.

Table 49-2 Sources Available to the RAFs at the Data Phase
Source	Description	Example
content-charset	Character set used by the resource
content-encoding	Any form of encoding
content-length	Size of the resource in bytes
content-type	MIME type of the resource	text/html, image/jpeg
expires	Date the resource itself expires
last-modified	Date the resource was last modified
data in <META> tags	Any data that is provided in <META> tags in the header of HTML resources	Author Description Keywords

Enumeration, Generation, and Shutdown Stages

At the Enumeration and Generation stages, the same data sources are available as the Data stage.

At the Shutdown stage, the filter completes its filtering and is shuts down. Although functions written for this stage can use the same data sources as those available at the Data stage, the shutdown functions typically restrict their operations to shutdown and cleanup activities.

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Sun Java System Portal Server 6 2005Q4 Technical Reference Guide