JSONStore concurrency

Learn about JSONStore concurrency.

JavaScript

Most of the operations that can be performed on a collection, such as add and find, are asynchronous. These operations return a jQuery promise that is resolved when the operation completes successfully and rejected when a failure occurs. These promises are similar to success and failure callbacks.

A jQuery Deferred is a promise that can be resolved or rejected. The following examples are not specific to JSONStore, but are intended to help understand their usage in general.

The Options Object with onSuccess and onFailure callbacks that were used in JSONStore for IBM Worklight V5.0.5 are deprecated in favor of promises.

Instead of promises and callbacks, we can also listen to JSONStore success ('WL/JSONSTORE/SUCCESS') and failure ('WL/JSONSTORE/FAILURE' events. Perform actions that are based on the arguments that are passed to the event listener.

Example promise definition

var asyncOperation = function () {
  // Assumes we have jQuery defined via $ in the environment   var deferred = $.Deferred();
  setTimeout(function() {
    deferred.resolve('Hello');
  }, 1000);
  return deferred.promise();
};

Example promise usage

// The function that is passed to .then is executed after 1000 ms.
asyncOperation.then(function (response) {
  // response = 'Hello'
});

Example callback definition

var asyncOperation = function (callback) {
  setTimeout(function() {
    callback('Hello');
  }, 1000);
};

Example callback usage

// The function that is passed to asyncOperation is executed after 1000 ms.
asyncOperation(function (response) {
  // response = 'Hello'
});

Example events

$(document.body).on('WL/JSONSTORE/SUCCESS', function (evt, data, src, collectionName) {
  // evt - Contains information about the event
  // data - Data that is sent ater the operation (add, find, etc.) finished
  // src - Name of the operation (add, find, push, etc.)
  // collectionName - Name of the collection
});

Objective-C

When we use the Native iOS API for JSONStore, all operations are added to a synchronous dispatch queue. This behavior ensures that operations that touch the store are executed in order on a thread that is not the main thread. See Apple documentation at Grand Central Dispatch (GCD).

Java

When we use the Native Android API for JSONStore, all operations are executed on the main thread. Create threads or use thread pools to have asynchronous behavior. All store operations are thread-safe.

Parent topic: JSONStore advanced topics