Given a request, the XML server manages the Videotex session and generates a response. Both request and response are XML-formatted strings. The request must be an XML invoke object. The response is a single XML object which at is simplest is just OK. All errors from within the XML server are returned as XML error objects. Any other object returned by the server is treated as a successful execution.
The XML server responds to low-level commands so the client can always determine what the current underlying page looks like. Typically, the server will be configured with page maps so that the raw page data never needs to be seen by the client.
Each command request is contained within an invoke object -- this defines the name of the command and contains the command arguments.
The response to any command may be an error -- since the Videotex session may have been lost etc. Even where not explicitly stated, an error object may be returned by a command.
The commands are grouped into the following categories:
low-level commands
session-control commands
mapped commands
service commands
The following low-level commands allow full control over the raw Videotex session. These can be necessary if the Videotex provider has changed the service and introduced new pages etc.
Return the status of the current session.
Attempt to identify the current Videotex page using the maps loaded into the XML server.
name
attribute of the returned page holds the value unknown.
Send the supplied data through to the Videotex host. This can be
sent through raw or with the addition of an underscore _
character as the field terminator.
Fetch the raw page information -- no mapping of the page data is performed other than to turn it into a page object.
Scrape the raw Videotex page information and return as HTML.
The value returned is valid HTML and XML -- data is returned within a <div> object which shows the cursor position and contains a <table> representing the raw screen.
Capture an HTML representation of the current page -- particularly useful when mapping a new Videotex page since this makes it very easy to mark the locations on screen of the various fields of interest.
Wait for the arrival of the named page or any new page.
The following commands allow control over the actual communications session as well as loading up maps etc. into the XML server.
Setup the supplied information within the server -- the particular setup is defined by the supplied argument.
Connect the XML server to the previously configured Videotex host.
Return configuration information about the current session.
Disconnect the XML server from the connected Videotex host.
The detail of the following commands is driven by the map currently loaded into the XML server.
Upload the supplied data into the named fields on the page -- the input fields are defined by the map for the current Videotex page.
List the options on the current Videotex page -- many Videotex pages are simply a menu asking the user to select the desired option.
Choose the supplied option from the Videotex page.
Skip over all pages which support a continue option.
Submit the supplied data to the form and extract the data from the resultant page.
Apply the page-dependent mapping for the current Videotex page and return the resultant data. If the map does not return an XML object, then an ok is returned by default.
The following commands relate to a Tour Operator service -- rather than being related to control of the underlying Videotex session.
Request the XML server to describe the services offered by the connected Videotex host.
Select the Videotex service from the connected host.
Log on to the connected Videotex service.
Request the XML server to describe the activities available on the currently connected Videotex service.
Select the desired activity from the Videotex service -- the Tour Operator services all provide a list of activities such as searching for late availability holidays, performing a general search and match etc.
Return the HTML which defines the holiday filter for the connected service -- the HTML form field names must correspond to the names of input fields for the identified activity.
Install the supplied filter.
Log off from the connected Videotex service.
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