Information Technology Reference
In-Depth Information
544 Advanced Artificial Intelligence
which build the correct and security environment for mobile agents to run. It also
provides basic services (including create, transmit and execute),constraint
mechanism, fault tolerance policy, security control and communication
mechanism. MA's mobility and problem solution ability is decided by the
MAE's services. Generally speaking, MAE includes the following services:
(1) Transaction service: realizing the creation, mobility, persistence and
environment allocation for mobile agents.
(2) Event service: including agent transfer and communication protocol, realizing
events move in mobile agents.
(3) Directory service: providing locating and routing services
(4) Security service: providing secure run-environment
(5) Application service: providing service interface for special task
In general, a MAE can only locate at one machine. However, a MAE can run
in multi machines if the hosts are connected by fast network. MAE uses agent
transfer protocol to realize the mobility and allocate the run-time environment
and service interface. MA runs in MAE which communicates with each other by
Agent Communication Language (ACL) and access the services provided by
MAE.
In architecture of mobile agent, MA can be divided into two types: user
agent(UA) and server agent(SA).UA can move from a MAE to anther MAE. It
runs in MAE and communicates with other MA through ACL. It can access the
services provided by MAE. SA can not move whose main function is to provide
services for local and visit MA. A MAE holds several SAs which provide
different services. Because SA can not move and can only be controlled by local
MAE administrator, it ensures that SA can not be vicious. A can not directly
access the system resource. It can only through the SA's interfaces to access the
restrictive resources which can avoid the hostile agents to attack the hosts. This is
the common security policy in mobile agent system.
Mobile agent is a novel concept which has not unified definition. However,
almost all mobile agent has the following characteristics:
(1) Unique Identification Mobile agents must hole the specifically identification
which can delegate the willing of users.
(2) Autonomic mobility Mobile agents can automatically move from one node to
anther. This is the basic characteristics of mobile agent which distinguishes it
with other kinds of agents.
