Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer data transfer regulating
Reexamination Certificate
2000-05-16
2003-09-30
Geckil, Mehmet B. (Department: 2142)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer data transfer regulating
C709S230000, C709S231000, C370S238000
Reexamination Certificate
active
06629146
ABSTRACT:
BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates to a selection intermediary apparatus for selecting and relaying a message, a transmission apparatus for transmitting the message, a selection intermediary program storage medium in which a selection intermediary program is stored to operate a computer system as the selection intermediary apparatus, and a transmission program storage medium in which a transmission program is stored to operate the computer system as the transmission apparatus.
(ii) Description of the Related Art
In the present day when networks such as Internet and Intranet are developed, a large number of servers are present on the network. A user selects a server in accordance with a purpose through a client program, and accesses the server to perform processings such as information retrieval and registration to a database. This access is realized when a message requiring the processing is transmitted on the network.
When a plurality of servers are present in this manner, in a conventional art, a client side needs to know the following two pieces of information beforehand:
(1) the place where the server exists (server address); and
(2) the service presented by the server (server service content).
Here, since the service content of the server is used as a condition in selecting the server, it is hereinafter referred to as the “server condition”. Moreover, a pair of the above information (1) and (2) is referred to as a “rule”, and a group of rules is referred to as “path information” because a message transmission path is determined. Furthermore, the message requiring the processing is hereinafter referred to as the “request” in some cases.
The path information is obtained by the user in a certain method and inputted during operation of a client program, or is directly embedded in the client program. Therefore, when the address or condition of the server changes, the information needs to be notified to the user, or the client program needs to be changed every time. However, when the server address, and the like frequently change, the notification or change is difficult.
Therefore, in order to solve the problem, there has been developed an intermediary system in which a program or a selection intermediary apparatus, referred to as an agent, is placed in a certain address on a network, and the agent selects and relays a message between a client and a server. In a most basic constitution of the intermediary system, only one agent is disposed between the client and the server.
FIG. 1
is a schematic view of an intermediary system by a single agent.
One or more sets of a server condition and an address are registered in Agent
1
. Client C knows the address of Agent
1
, and once sends all requests to Agent
1
. The request sent from the client C is constituted of a client designated condition indicating the server designated by the client C for sending the request, and a request text to be sent to the selected server. The client designated condition is compared with a server condition, and only the request which satisfies the server condition is sent to Server
1
, Server
2
indicated by the address corresponding to the server condition. Specifically, Agent
1
compares the client designated condition with the server condition, selects the appropriate server Server
1
, Server
2
which satisfies the request from the client C, and transfers the request from the client C. Thereafter, a response obtained as a result of a processing by Server
1
, Server
2
is returned to the client C. In this intermediary system, since the user or the client does not have to know the address or service content of the server beforehand, the burden on the client side is light. Moreover, in the intermediary system, since the path information is concentrated on one place, maintenance is easy.
The above-described system by the single agent can easily be constructed, and operates without any problem when the system scale is small. However, when the system intends to be enlarged still with the single agent, various problems arise.
First, a problem occurs that the load during the operation is concentrated on the agent. In the system by the single agent, all communications between the client and the server are concentrated on one agent. Therefore, when the number of clients or servers increases, the agent is easily bottlenecked.
Moreover, when the network is connected to a large number of servers, the server management including the management of the server condition, and the like is allotted to a plurality of managers in many cases. However, in the system by the single agent, since the path information including the server condition to be managed by each manager is concentrated on one agent, it is difficult to limit the range of the server condition to be opened to the public, and a problem on security easily occurs.
Since such problem occurs in the system by the single agent, an intermediary system has to be constructed by a plurality of agents particularly for an enlarged system scale. Moreover, when the intermediary system by the agent is spread, one system is constructed by connecting the systems each operating by the single agent to one another in many cases. In this case, instead of combining a plurality of already operating agents to construct the system by a single huge agent, when the system is constructed by a plurality of agents so that the agents perform communication and cooperate with one another, the system is easily realized without necessarily modifying the existing system.
FIG. 2
is a schematic view of the intermediary system by a plurality of agents.
In the system by the plurality of agents, when the agent transfers the request from the client to the server connected to another agent, the agent needs to know the server condition, and the like owned by the other agent.
The system of teaching the server condition, and the like to the other agent from the certain agent is roughly divided to two types of systems, an advertisement system and a replication system.
FIG. 3
is an explanatory view of the advertisement system.
In the advertisement system, a certain agent generates a rule whose address is rewritten to its own address based on its own rule, and propagates and registers the generated rule to another agent. This registration extends a link for transferring the request to the other agent from the agent. In an example shown in
FIG. 3
, Agent
2
rewrites its rule address “Server
3
”, “Server
4
”, to its own address “Agent
2
”, and transmits the address together with server conditions “Condition
3
”, “Condition
4
” to Agent
1
, and as a result, a conditioned link is extended to Agent
2
from Agent
1
. In the following, the agent to which the server condition, and the like are registered, such as Agent
1
, is referred to as a “client-side agent”, and the agent which sends the server condition, and the like, such as Agent
2
, is referred to as a “server-side agent”. The server condition registered in the client-side agent is explicitly set (conditioned link) in some cases, and the condition is not particularly set (unconditioned link) in other cases. Moreover, as seen from the server-side agent, the client-side agent functions as a message transmission apparatus.
When the above-described conditioned link is extended, the request reaching the client-side Agent
1
from the client C is first compared with the server condition owned by the client-side Agent
1
. When the server condition is satisfied, the request is transferred to the server-side Agent
2
which is designated as a transfer destination. Subsequently, the request is compared with the server condition owned by the server-side Agent
2
, and the next transfer-destination server is determined. When the server condition, and the like are propagated in this manner in the advertisement system, the request from the client C is necessarily passed via the server-side Agent
2
in which the server is already registered. The propagation of the server condition, and the like b
Geckil Mehmet B.
Staas & Halsey , LLP
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