XML to Videotex Translation

Carapace offers two methods for translation between XML and Videotex:

• XML Server which receives XML commands and returns results from the commands -- this is useful for thin client applications which talk to a remote Carapace XML Videotex Server to manage the Videotex sessions.
• A Carapace.TourOpSession object -- accessible using COM -- which provides a function interface to manage the underlying Videotex session. This interface offers methods which handle identical XML command strings as the XML server.

The method of mapping a Videotex service is described here.

XML Videotex Server

The XML Videotex Server reads an XML command from a communications channel, processes the command and returns an XML response. An example of such a command/response pair is as follows:

Command:	<invoke command='status'/>

Response:	<status session='disconnected'/>

The complete set of XML commands is described here.

The XML Videotex Server runs as an agent within the multi-threaded Carapace Hub. It offers the XML-Videotex translation service by using the Carapace.TourOpSession object. The Server reads its configuration on startup and so requires less configuration than the Carapace.TourOpSession session object. For example, the communications parameters to connect to the Videotex host as well as the maps for the individual Videotex services are all configured within the Server -- clients of the Server therefore do not need to supply these.

The Server can also be configured to check the incoming calls are sufficiently authorised. In thhe default configuration no authorisation checking is performed.

The XML Server uses the Carapace.TourOpSession object to perform the translation.

Carapace.TourOpSession Object

The Carapace object TourOpSession can be accessed using COM to give control over the Videotex session -- this is done via the COM interface with progId Carapace.TourOpSession. The COM client can then use the xml method to invoke any of the XML commands defined for the XML Videotex translation.

In addition, the TourOpSession object supports background XML requests -- for these, the COM client is notified of the result via the outbound (events) interface having progId Carapace.TourOpSessionEvents.

The important methods are summarised below:

interface progId	method name	description
Carapace.TourOpSession	xml	submit an XML command -- the method does not complete until the XML result is available
Carapace.TourOpSession	xmlBackground	submit an XML command along with an identifier for this command -- the method queues the command for execution an returns immediately
Carapace.TourOpSessionEvents	xmlResponse	return the command identifier along with the result to the COM client

Click here for an extended description of the TourOpSession object.

Contents

Current topic: videotex

Related topics: Carapace Hub