Adaptation tactics are specified in an adaptation policy language. The language is interpreted and executed by a run time support system - the decision engine. Adaptation tactics are usually mixed with other codes without Awareware, making check and verification a difficult job. Awareware treats adaptation and configuration behaviors explicitly  in a XML file, and the adaptation tactic is separated from the application.

Through adaptation policy language, the developer decides what awareness to use, the condition of the configuration, and when reconfiguration should be invoked. An example of the tactic is shown as below:

if (Awareness.Network.Bandwidth < 100K ) then

if (Awareness.User.Preference == Interactive ) then ...

The decision module is a virtual machine that interprets the adaptation tactic at run time. Reconfiguration command scripts are a set of reconfiguration primitives defined in system configurator.

The UML diagram of the decision engine is shown below:

A composite event is a combination of multiple simple events. A simple event is specified as triple: an awareness value collected from the measurement tool, a comparison operator, and condition value. A composite event is organized in a tree structure, as shown in the figures below.

The hierarchical implementation organizes one Composite Event as a binary tree. The root of the tree is a Boolean operator or an Event if the tree has a single node. The leaf of this tree is a Simple Event. The Boolean operator has a left hand side and a right hand side, where each side would be a Simple Event or a Composite Event. The awareness measurement tools notify their values to the Awareness class.

To specify the adaptation policies, AwareWare utilizes XML to describe the adaptation policies. There are four major sections: a section for the directory server, a section for awareness source, a section for contextual conditions, and a section for actions to be performed under this contextual condition.

The XML file and XML Scheme file can be downloaded by clicking the link.