Emulator Communications Agent

The Carapace Emulator is simply a display device for displaying Videotex (and, eventually, for displaying other protocols as well!). The Emulator delegates all communications to a 'communications agent' object.

This page describes the methods which such a communications agent must offer in order to be used by the Emulator.

A simple communications agent is supplied with Carapace: when registered with COM, it has the following progID:


    Carapace.SimpleEmuCommsAgent

Agent Requirements

For a COM object to be usable as an Emulator communications agent, it must have the following methods and properties on its dispatch interface:

name	method or property	description
`protocol`	property	String which is set to hold the particular protocol being used
`setEmulator`	method	make the Emulator known to the Agent -- so the Agent can display text etc. on the Emulator
`setContainer`	method	make the Container known to the Agent -- so the Agent can update the Container (eg. modify the appearance of the Web page if embedded in InternetExplorer)
`connect`	method	connect to the service
`connectionState`	method	return the state of the current connection
`disconnect`	method	disconnect from the service
`write`	method	write data to the service
`execScript`	method	execute the supplied Carapace script
`uiComponent`	method	give the comms agent acccess to UI component -- eg. a button on the web page

`setEmulator`

Make the Emulator known to the Agent -- so the Agent can display text etc. on the Emulator.

Arguments:

emu Unknown

Return type: the empty List ()

`setContainer`

Make the Container known to the Agent -- so the Agent can update the Container (eg. modify the appearance of the Web page if embedded in InternetExplorer).

The Agent can then use the container method on the Unknown object to get the Dispatch interface for the container. This dispatch interface can then be used to control the container.

If Microsoft's web browser InternetExplorer is used as the OLE container, then this dispatch interface is used to modify the appearance of the web page on which this object is embedded -- click here for details.

Arguments:

container Unknown

Return type: the empty List ()

`connect`

Connect to the service. The supplied string is the address for the service. The default comms agent supplied with Carapace requires the address to be in one of the following formats:

name - a simple string (containing no colons) which is taken to be the name of a configured service
modules:attribValues - where modules is a comma-separated list of comms modules and attribValues is a comma separated list of attribute=value pairs. The type of the value is determined as follows:
1. a String is surrounded by single quotation marks eg. 'this is a string'
2. an Integer is a contiguous sequence of digits
3. a Real is a sequence of digits and a single decimal point
4. a Binary starts with 0x and is followed by an even number of hex digits.

Arguments:

address String

Return type: the empty List ()

`connectionState`

Return the state of the current connection. Possible return values are:

Disconnected
Connecting
Connected
Disconnecting

Arguments: none

Return type: String

`disconnect`

Disonnect from the service.

Arguments: none

Return type: the empty List ()

`write`

Write data to the service.

Arguments:

data String

Return type: the empty List ()

`execScript`

Execute the supplied Carapace script.

Arguments:

script String

Return type: Object

`uiComponent`

Store a reference to a UI component -- eg. a button on the web page.

Arguments:

name	`String`
uiObject	`Dispatch`

Return type: the empty List ()

Contents

Index

Current topic: communications

Related topics: communications classes, objects