DataHub

Introduction

DataHub provides [a]synchronous data sharing between objects without requiring either to have direct access to or knowledge of the other. Objects using DataHub to watch data need only know the property used to share that data then implement a setter for that property i.e.:

All of DataHub's functionality can be added to any object by using its enhance method as follows:

DataHub.enhance (myObject); ).
myObject.share ({ something: { data:This is fun!" }});

Using DataHub

Observing

Note: Namespace collisions with ECMAScript additions/browser experiments have required supporting observe() instead, but watch() still works too if your browser supports it.

DataHub.observe    ({ something: myObject, something: myFunctionCallback }, { option: value });

OPTIONS:

• newOnly: boolean Ignores any "kept" data.
• async: boolean Data will be shared to the observer asynchronously if true
• queue: boolean Multiple asynchronous shares will be queued instead of sharing only the latest value
• name: string Name of watcher
• debug: boolean Show debug output for activity relating to observer

Sharing

DataHub.share    ({ something: dataToShare}, { option: value }, [optionalObserverArray]);

OPTIONS:

• keep: boolean Data will be "kept" for late observers
• multiple: boolean Data represents multiple arguments
• sharer: string Name of sharer
• debug: boolean Show debug output for activity relating to share

Arrays of observations / shares

An array of share or watch options can be passed i.e.:

DataHub.share   ([
    [{something: thingToShare, ...}, {keep: true}],
    [{someother: otherToShare, ...}]
]);

Freeing

DataHub.free    ({ something: 1 });

Ignoring

DataHub.ignore    ({ something: myObject });

Clearing

DataHub.clearHub();

Chaining

All DataHub actions can be chained i.e.:

DataHub.share ({things:some}).observe ({things:this}).ignore ({things:this}).clearHub();

TODOS

• Go into further detail for queue + keep with late observers.

Copyright and License Information

This source code was extracted from the WebOS Calendar application, available publicly at the location below:

https://github.com/openwebos/core-apps

All content, including all source code files and documentation files in this repository unless otherwise noted are:

Copyright (c) 2010-2012 Hewlett-Packard Development Company, L.P.

All content, including all source code files and documentation files in this repository unless otherwise noted are: Licensed under the Apache License, Version 2.0 (the "License"); you may not use this content except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.