callWithoutWaiting

Calls a function asynchronously in a Cordova plugin, without waiting for a result.

Syntax

ui.Interface.frontCall("cordova", "callWithoutWaiting",
  [plugin-name, function-name [, param1, param2, ... ] ],
  [callback-id])
  1. plugin-name - This is the name of the Cordova plugin.
  2. function-name - This is the name of plugin function to be called.
  3. param1, param2, ... - Optional parameters to be passed to the Cordova function.
  4. callback-id - Holds the callback identifier for this Cordova asynchroneous front call.

Usage

The callWithoutWaiting front call executes asynchronously the Cordova plugin function identified by the plugin-name and the function-name.

The other arguments (param1, param2, …) are arguments for the Cordova plugin function. Each argument may have a different type like FLOAT, INTEGER, STRING, RECORD or DYNAMIC ARRAY (for RECORD and DYNAMIC ARRAY, the runtime system will do the BDL to JSON conversion automatically).

The callWithoutWaiting front call behaves the same as the call front call, but does not wait for a result from the plugin. Instead it returns directly a unique callback ID, to be able to identify the call later on. The program execution can continue, while the plugin processes the result asynchronously.

When the plugin produces the result, it is stored internally by GMI/GMA in a result queue. Then result data can be retrieved with getCallbackData/getAllCallbackData front calls in conjunction with the "cordovacallback" action.

When the current dialog contains an ON ACTION handler for the cordovacallback predefined action, this action is triggered by the front-end to notify the Genero program that there is plugin data to fetch.

The cordovacallback action is triggered:
  1. If the result queue is empty, and a result is added to the queue.
  2. If a new dialog that contains this action is entered or re-entered, and the result queue is non empty.
Important: Some plugin functions may return results repeatedly in a short time intervals with one and the same callback-id, examples are for delivering motion/audio/bluetooth data.
In case of an error, the front call raises a runtime error -6333 that can be caught with TRY/CATCH or WHENEVER ERROR.
Note: Use the err_get() function, to identify the reason of the error. For more details about front call error handling, see ui.Interface.frontCall().

Example

DEFINE id, song STRING
CALL ui.interface.frontcall( "cordova", "callWithoutWaiting",
     ["Media", "play", song], [id] )
...
   ON ACTION cordovacallback ATTRIBUTE(DEFAULTVIEW=NO)
      -- Process results
   ...