<smex ...> element (Platform
Messaging)
smex, short for Simple Messaging EXtension, is a
SALT element that communicates with the external component of the SALT platform.
It can be used to implement any application control of platform functionality
such as logging and telephony control. As such, smex represents a useful mechanism
for extensibility in SALT, since it allows any new functionality to be added
through this messaging layer.
On its instantiation, the object is directed to establish an asynchronous message
exchange channel with a platform component through its configuration parameters
(specified in param elements) or attributes. The smex
object can send or receive messages through this channel. The content of a message
to be sent is defined in the sent property. Whenever the value
of this property is updated (either on page load or by dynamic assignment through
script or binding), the message is sent to the platform. The smex
element can also receive XML messages from the platform component in its received
property. The onReceive event is fired whenever
a platform message is received. Since the smex object's
basic operations are asynchronous, it also maintains a built-in timer for the
manipulation of timeout settings. onTimeout
and onError events may also be thrown.
The smex object makes no requirement on the means
of communication with platform components. It should also be noted that the
smex object has the same life span as other XML elements,
that is, it will be destroyed when its hosting document is unloaded. While in
many cases, the smex object can perform automatic clean-up and release communication
resources when it is unloaded, there might be use cases (e.g. call control)
in which a persistent communication link is desirable across pages. For those
cases, SALT places the responsibility of relinquishing the allocated resources
(e.g. closing the socket) on the application.
The smex object also is neutral on the format (schema)
of messages. In order to encourage interoperability, however, the conformance
criteria in Part 4 recommend that implementations support a known schema for
common functionality, with a strong preference for existing standard message
formats. Such a schema for telephony call control is suggested in section 2.4.4,
and 4.3 of the SALT 1.0 Specs. In essence, SALT allows both platform and application
developers to take the full advantage of the standardized extensibility of XML
to introduce innovative and perhaps proprietary features without necessarily
losing interoperability.
Attributes
| Name |
Data type |
Default |
| id
|
ID |
implied |
|
script.statement |
implied |
|
script.statement |
implied |
|
script.statement |
implied |
|
CDATA |
implied |
|
milliseconds |
implied |
Children
Parents
Properties
- received - Read only. XML DOM Node data indicating
the received message. The message is held as the value of this property until
the next onreceive event is ready to fire.
- status - Read-only. Integer indicating the recent
status of the object. The possible values are 0, -1, and -2, which indicate,
respectively, normal, timeout expired, and communication with the platform
cannot be established or has been interrupted. Platform-specific error messages
are conveyed through the received property. For the cases that the error message
is successfully delivered, the status code is 0.
Methods
none
Examples
<html xmlns:salt="http://www.saltforum.org/2002/SALT">
<body>
<!-- the data section
-->
<form id="get_team">
<input
name="team" />
<input
name="uid" type="hidden"/>
</form>
<!-- The speech section
-->
<salt:prompt id="welcome">
Welcome,
caller!
</salt:prompt>
<salt:prompt id="ask">
Which
team would you like the latest results for:
Arsenal,
Chelsea, Spurs or West Ham?
</salt:prompt>
<salt:prompt id="confirm">
I
heard <value targetelement="team" />.
Is
this correct?
</salt:prompt>
<salt:prompt id="thanks">
Thank
you. Please wait while I get the latest results.
</salt:prompt>
<salt:prompt id="retry">
Okay,
let's do this again
</salt:prompt>
<salt:prompt id="reprompt">
Sorry,
I missed that.
</salt:prompt>
<salt:listen id ="listen_team">
<salt:grammar
src="./teamtypes.grxml" />
<salt:bind
test="/[@confidence $gt$ 10]"
targetelement="team"
value="//team" />
<salt:bind
test="/[@confidence $gt$ 10]"
targetelement="confirm"
targetmethod="start" />
<salt:bind
test="/[@confidence $gt$ 10]"
targetelement="listen_yesno"
targetmethod="start" />
<salt:bind
test="/[@confidence $le$ 10]"
targetelement="reprompt"
targetmethod="start" />
<salt:bind
test="/[@confidence $le$ 10]"
targetelement="ask"
targetmethod="start" />
<salt:bind
test="/[@confidence $le$ 10]"
targetelement="listen_team"
targetmethod="start" />
</salt:listen>
<salt:listen id="listen_yesno">
<salt:grammar
src="./yesno.grxml" />
<salt:bind
test="/yes[@confidence $gt$ 10]"
targetelement="thanks"
targetmethod="start" />
<salt:bind
test="/yes[@confidence $gt$ 10]"
targetelement="get_team"
targetmethod="submit" />
<salt:bind
test="/no or ./[@confidence $le$ 10]" />
targetelement="retry"
targetmethod="start"
<salt:bind
test="/no or ./[@confidence $le$ 10]"
targetelement="ask"
targetmethod="start" />
<salt:bind
test="/no or ./[@confidence $le$ 10]"
targetelement="listen_team"
targetmethod="start" />
</salt:listen>
<!-- call control
section -->
<salt:smex
id="telephone"
sent="start_listening">
<salt:param
name="server" value="ccxmlproc" />
<salt:bind
targetelement="uid" value="/@uid" />
<salt:bind
test="/Call_connected"
targetelement="welcome"
targetmethod="queue" />
<salt:bind
test="/Call_connected"
targetelement="ask"
targetmethod="start" />
<salt:bind
test="/Call_connected"
targetelement="listen_team"
targetmethod="start" />
</salt:smex>
</body>
</html>
|
<!-- logging mechanism that uses a COM object with its class id
and interface id -->
<!-- See SALT 1.0 Specs (2.6.6) for more detailed info -->
<salt:smex id="logServer">
<salt:param name="d:server"
xmlns:d="urn:Microsoft.com/COM">
<d:protocol>DCOM</d:protocol>
<d:clsid>2093093029302029320942098432098</d:clsid>
<d:iid>0903859304903498530985309094803</d:iid>
</salt:param>
</salt:smex>
<salt:listen>
// other directives binding listen results to
input fields
<salt:bind targetelement="logServer"
targetattribute="sent"
value="*[@log
$ge$ 3]"/>
</salt:listen> |
Extra info
For details on usage of this element, see the SALT Specification, Version
1.0.