Note: For HV 2 (VS 2012 help) we have a free API test app with code in CodePlex.
The API Test page allows you to test your HV 1.x help and URLs. Help Library Agent is responsible for interpreting Help URLs and fetching content from the MS Help System data store.
The page allows you to test the various API commands. Commands are embedded into a URL. You can either type the URL directly or select options (and these set the URL).
To test the URL click the Open URL button. If [x] Capture is checked then the output is sent to the edit field (screen bottom) instead of to the browser.
Note: [x] Capture option is only available for the http:/// protocol (not the ms-xhelp:/// protocol).
The Agent application is associated with the ms-xhelp:// protocol. If you ShellExecute() a url starting with ms-xhelp:// Help Library Agent will start up (see the icon in the taskbar notification area), fetch the relevant help info and display it in your default browser.
When Agent starts up you will see a message "Help Library Agent on http://127.0.0.0:47873/help/1-123/".
Agent listens to http traffic, intercepts any URLs starting with http://127.0.0.0:47873/help/1-123/ and returns the help information from the local store.
By default Agent listens on port 47873 (port 80 for the Beta 2). This can be changed if required (see Help Viewer 1.0 release note - readme).
The "/1-123/" is the user session number - Agent process id. Agent makes sure that every users has a unique session ID. If two people are logged into a terminal services box, they would have different session numbers.