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Class: WorkerClient
[ AMD Module Require | Legacy Module Require ]
require(["esri/workers/WorkerClient"], function(WorkerClient) { /* code goes here */ });
Description
(Added at v3.9)
The WorkerClient is the primary entry point for interfacing with background Workers. You can use any valid and accessible worker script file. See importScripts for limitations on what can be used and assumed in a worker script.
Additionally, the worker script should expect messages to contain a
msgId property and responses from that worker should contain the msgId of the message that they are responding to.
If you want the the addWorkerCallback or importScripts functions to work, then workers used here should use "esri/workers/mutableWorker" as the worker and build it up via this class's methods.
Samples
Search for samples that use this class.Constructors
| Name | Summary |
|---|---|
| new WorkerClient(path, deferreds?) | Creates a WorkerClient. |
Properties
| Name | Type | Summary |
|---|---|---|
| returnDeferreds | Boolean | Return Deferreds rather than Promises from postMessage. |
| worker | Worker | Reference to the actual HTML5 Worker instance. |
Methods
| Name | Return type | Summary |
|---|---|---|
| addWorkerCallback(module, name?) | Promise | Adds a function to the worker that takes the worker's internal calls to postMessage and calls this function before sending the original message back to the main thread. |
| importScripts(paths) | Promise | Import any script or function into the worker. |
| postMessage(msg, transfers?) | Promise | Posts a message to the worker. |
| setWorker(paths) | None | Sets the worker that is used in the Worker Client. |
| terminate() | None | Terminates the worker and cancels all unresolved messages. |
Constructor Details
Creates a WorkerClient.
Property Details
<Boolean
BooleanReturn Deferreds rather than Promises from postMessage.
Known values:
true | falseDefault value:
falseMethod Details
Adds a function to the worker that takes the worker's internal calls to
The script file whose path is passed in will be imported into the worker directly. It will not pass through the main thread and can not expect to have access to any objects in the main thread. This script is not required to have a
Note. If a callback or any callback in a series of chained callbacks returns
postMessage and calls this function before sending the original message back to the main thread. The function takes the same inputs as postMessage. The function should act on these inputs. This obviously assumes some familiarity with the type of messages that a worker is passing. The function should be able to correctly interogate
the message to determine if it is an appropiate message to act on. Additional calls to addWorkerCallback can be used
to chain functions together in a "last in, first executed" fashion.
The script file whose path is passed in will be imported into the worker directly. It will not pass through the main thread and can not expect to have access to any objects in the main thread. This script is not required to have a
message event handler or even postMessage calls back to the main thread. However, it must conform to the same limitations listed for importScripts. By default, the script should provide a function
named main. If not then you must indicate the function via the name parameter. This function will be executed each time that the worker attempts to postMessage back to the main thread.
Note. If a callback or any callback in a series of chained callbacks returns
false then postMessage is never executed, thus preventing the main UI thread from recieving the message.Return type:
PromiseImport any script or function into the worker. Please note the following conditions:
- Script(s) / function(s) can ONLY include objects, classes, or methods available to Workers, plus whatever else has already been imported.
- The imported items will be executed immediately and in the same order they are specified
- The imported script won't be able to share or directly access any objects in the main thread or other workers
- The worker can't access the DOM and thus can't use libraries which assume a browser environment
Return type:
PromisePosts a message to the worker.
Return type:
PromiseSets the worker that is used in the Worker Client. Please note the following conditions:
- Script(s) / function(s) can ONLY include objects, classes, or methods available to Workers, plus whatever else has already been imported.
- The imported items will be executed immediately and in the same order they are specified
- The imported script won't be able to share or directly access any objects in the main thread or other workers
- The worker can't access the DOM and thus can't use libraries which assume a browser environment
importScript to bring in other worker scripts and functions.