Many NetAlive applications give meaningful results when applied
to diverse sources. However, NetAlive requires a source agent
for accessing each source. This document describes how to find
a suitable agent if one exists and describes how to make one if
Finding an Existing Agent
NetAlive's agents are external to the program itself. The advantage
of this is that anybody can create agents and share them through
Web self-publishing. The disadvantage is that it can be tricky
to find a specific agent. Here are different places where agents
may be stored:
- As part of the NetAlive system NetAlive includes agents
that can monitor common sites.
- Hard disk. Any user can create agents and store them
on their hard disk.
- On a content-provider's site A site operator can create
a NetAlive agent for their site. The operator can put a hyperlink
to these agents on their Website or can index them in Web search
- On a third party's site A third party can create an
agent for any site and post the agent on their own Web site. The
third party can put hyperlinks to these agents on pages on their
site or can index them in Web search engines.
Creating a New Agent
NetAlive uses source agents to access and pre-process each source.
The job of a source agent is to analyze a Web page, separate the
information from the formatting, and divide the information into
concepts. Since computers lack the judgment required for this
task, a human imparts their judgment to the agent during creation.
This can be done in several ways:
- Creating an agent by configuring a general-purpose agent.
NetAlive has some general purpose agents which can be applied
to any Web site. In this method, the user selects a general-purpose
agent and then fills out a form with certain parameters. The resulting
agent can be used directly or self-published to a Web site for
others to use.
- Creating a new agent using programming. If there is no suitable
general purpose agent, a new agent will have to be programmed.
Using a General-Purpose Agent
figure illustrates the procedure for creating an agent.
- NetAlive has a page with instructions on how a human can analyze
a Web page. After selecting an agent using human judgment, a hyperlink
causes the agent to be displayed in a separate window on the computer's
- Drag the selected agent with the mouse. It can be dropped
directly into an application or into a palette.
- Most general-purpose agents need to be configured. This may
be as easy as typing a URL or there may be other parameters.
- The computer's memory now contains an edited application or
agent. The user can run it or save it for later use. To self-publish
to the Internet, save the application to a Web server.
Click here for instructions on how to
add a new source to a palette.
Programming An Agent
Refer to the "programmers only" section of this Web
site for full instructions on programming an agent.
Source agents are generally Perl programs. The program's input
is HTML data and its output is a series of application-dependent
records. A record includes:
- headline (text)
- call to action (URL) -- URL to load in a Web browser when
the user clicks on the headline
- name of the source (e. g. "NetAlive home page")
- graphic (URL) -- a picture in lieu or in addition to a textual
- advertisement (URL) -- a picture representing an advertisement
by the content supplier
- price (number) A numeric field for sorting.
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