Information Technology Reference
In-Depth Information
5.2.1 The Concept of the Application of Agents
in the Service-Oriented Systems (SOA)
The modern service-oriented systems consist of a relatively large number of mutu-
ally cooperating servers which realize complex tasks. Complex services are decom-
posed into a certain number of simple services which, when performed according to
the plans, realize complex functions using the cooperation of many systems. These
servers may constitute the environment for agents operating in the system, which
cooperating with servers, allow for the significant extension of functionality of the
whole scattered system which realizes the complex services based on of the concept
of SOA [5].
Particularly, it may be observed that cooperation of servers in the realization of
services according to the rules “client-server” comes down to the special use of these
servers. In this particular conformation the server realizing a given service notices the
fact that it is being performed, memorizing it as the state of performing a given service.
However, after completing the task the server should not remember this fact (apart
from the changes in appropriate data bases predicted by the algorithm of service etc.)
and should be ready to perform another new service it will be given. Schema of a typi-
cal service CRUD, (Create, Read, Update, Delete) performed by a group of servers is
shown in Fig.
5.10
, and the appropriate realization scenario is as follows (Fig.
5.11
):
The beginning of performance of the service is called by the client which asks the
servers (in a given example—three severs) to realize a certain service (Fig.
5.10
a).
The servers performing a service need the realization of certain component services
and turn to (playing the role of other clients) further servers (Fig.
5.10
b, c).
Individual servers finish performing their partial services and send results to the
appropriate clients (Fig.
5.10
d).
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
Fig. 5.10
Schema illustrating stages of performing services by a group of servers,
a
a client asks
a sever to realize a certain service,
b, c
more servers are used to realize the service,
d, e
results of
the partial services are returned to the client
