MAs should be able to perform the following operations in order to build a robust system: Creation, Cloning, Dispatching or Migration, Retraction, Activation, Deactivation and finally Disposal [22, 23].
Creation is the first period in the mobile agent life cycle. For example, when a system requests a service to be done by the mobile agent, the system must create a mobile agent instance in the first place before any work can be done. During this creation stage, the mobile agent will be equipped with the desired parameters in order to achieve its goal.
Cloning basically creates a copy of the original mobile agent object. This operation is used when the need for another agent (with the same features and properties to do the same or other job in conjunction with the original one ) arises.
Dispatching or migrating is another main function in the mobile agent life cycle. This function is responsible for moving the agent from one node to another within the network environment by specifying the destination address (e.g. URL) to the agent. By the way, there are two types of migration; Strong migration is which mobile agent can carry itself, its data and its state. While weak migration is which mobile agent can carry only itself and its data.
The retraction function is done where the agent’s source node requires its agent to be returned to the original host or node.
Activation and deactivation are operations done when the mobile agent is required to start or to stop only within certain time of its lifetime. Finally, the dispose operation is done where the agent life comes to the end. Figure 2.5 explains the above mobile agent operations as suggested by an Aglet system:
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