ISysInfo.GetNotification()

Description:

The GetNotification method notifies the client +when the value of a system +attribute is changed.

This is an asynchronous method.

Syntax:

+ +

result = so.ISysInfo.GetNotification(criteria, callback);

Arguments:

criteria:
+ +
This is an object that specifies the system attribute to monitor for +changes. For more information about the object properties and how to define +them, see section Criteria for change notifications.
+ +
callback:
+ +
The callback argument is the name of the method +that is executed when a GetNotification call has results +or status information to return. You must define this method separately. Follow +the instructions in section Defining the callback handler for an asynchronous method to +define the callback method.
+ +

Return value:

The GetNotification method returns an object that +contains the initial return value for the asynchronous call it started (see +the following table). The actual notification information is returned by the callback method +in the ReturnValue property of its result object.

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**Table:** Return value +properties for GetNotification
+ Property +	+ Description +	+ Value +
+ `result.TransactionID` +	+ This is a number used as an identification to match transactions started +with the asynchronous `GetNotification` call to one or +more calls it generates to `callback`. +
+ `result.ErrorCode` +	+ This is a number that specifies a predefined error code. +	+ See Service API error codes. +
+ `result.ErrorMessage` +	+ This is a text string that describes the error. +	+ See SystemInfo Service API error messages. +

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**Table:** Return +value properties for GetNotification callback
+ Property +	+ Description +	+ Value +
+ `result.ReturnValue` +	+ This is an object (a system attribute object) that contains the information +for the changed system attribute. + This object contains the properties `Entity` and `Key` as +well as one or more additional properties representing the system attribute +value. The name and type of these properties depend on the specific +system attribute and its system +data type. + For example, if you request notification for the `Connectivity +- ConnectionStatus` system attribute, whose system data type is `ConnectionInfo`, +callback returns the following properties: + + `ReturnValue.Entity` + `ReturnValue.Key` + `ReturnValue.ConnectionStatus` + + `ReturnValue.IAPID` + `ReturnValue.ConnectionType` + `ReturnValue.IAPName` + `ReturnValue.NetworkName` + `ReturnValue.IAPConnectionName` + + +	+ See System attributes. +
+ `result.ErrorCode` +	+ This is a number that specifies a predefined error code. +	+ See Service API error codes. +
+ `result.ErrorMessage` +	+ This is a text string that describes the error. +	+ See SystemInfo Service API error messages. +

Remarks:

GetNotification returns notifications +until cancelled with Cancel.
Only some system attributes can be monitored for changes. +To find out which system attributes support GetNotification, +see section Supported system attributes (entities and keys).
+

Example code:

For the complete source of a sample widget +that demonstrates how to use this Service API, see the +full example.

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