z2-Environment

h1. Offline Mode

The purpose of the offline mode is twofold:

* You may use the offline mode to avoid long synchronisation times when developing in a situation poor network connectivity without turning off network connectivity as a whole.

* You may use the offline mode to prohibit download of latest changes from a central repository ahead of time. So you may use it as a "development in isolation" feature.

h2. How the offline mode is used.

The offline mode can be turned on and off via a system property and interactively on the GUI.

h2. Design

* Component Repository use @AbstractRepository.checkOffline()@ whenever a connection is normally required.

The method looks essentially like this:

<pre><code class="java">

	protected void checkOfflineMode() {

		if (Foundation.isOffline()) {

			throw new OfflineModeException("Running in offline mode");

		}

	}

</code></pre>

where @Foundation.isOffline()* checks for the boolean String value of the system property *com.zfabrik.offline*.

* Changing the system property can happen any time

* Initially the property is assumed as @false@ and should only be specified otherwise in @runtime.properties@.

* The system property status is backed in a JMX MBean attribute of the newly created Foundation MBean. 

* We use the internal JMX implementation to broadcast attribute changes to all worker processes.

* There is a toggle checkbox in the GUI.