JPH05346898A - Client/server system by tcp/ip - Google Patents

Abstract

PURPOSE:To automatically release the connection, in the case a communication error is generated on the connection between a server and a client by a TCP/IP. CONSTITUTION:In a TCP layer of a client 1, in the case a communication error is generated at the time of data communication by a connection, a data transmission/reception processing part 11 detects its error, a connection control part 13 closes the connection, and a connection establishment request part 12 outputs a connection establishment request until the connection is established. On a server 2 side, a connection establishment passive part 22 receives its establishment request and establishes the connection, and by the normal connection concerned, data is subjected to communication by the data transmission/reception processing parts 11, 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a client / server system based on TCP / IP for establishing a connection between a client and a server and performing data communication by the connection.

[0002]

2. Description of the Related Art In a client / server system based on TCP / IP, a socket interface based on UNIX is used to perform TCP between a client and a server.
Establish a connection through a port (communication port),
There is a method of performing data communication by the connection.

In such a system, when a data transmission / reception error occurs while establishing a connection at a TCP port, connection closing processing is performed by the operator at each of the client and server, and then software by the operator at both the client and server. Is restarted.

[0004]

However, in such conventional error processing, connection closing processing and software startup operation by the operator are required in both the client and server, and moreover, synchronization between the client and server is required. Therefore, there is a problem that the recovery work is very troublesome because it is necessary to take measures.

Therefore, the present invention has been made by paying attention to such a problem, and when an error occurs during data transmission / reception,
It is an object of the present invention to provide a TCP / IP client / server system capable of automatically restoring a connection between a client and a server.

[0006]

In order to achieve the above object, according to the present invention, a TCP / IP client / server system which establishes a connection between a client and a server and performs data communication by the connection is used at the time of data communication. Error detection means for detecting a communication error on the connection, a detection output of the error detection means, a connection erasing means for closing the connection during data communication, and a detection output of the error detection means for requesting connection establishment Is provided, and a connection establishing means for receiving a connection establishing request from the connection establishing requesting means and newly establishing a connection.

[0007]

In the above configuration, when a communication error occurs on the connection during data communication, the error is detected,
It automatically closes the connection when an error occurs, outputs a connection establishment request, and establishes a new connection.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a TCP / IP client / server system according to the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of the TCP layers (corresponding to the four transport layers in the OSI reference model) of the client 1 and the server 2 which constitute this system.

In this system, the client 1 and the server 2 use UNIX as an operating system, and TCP / IP is used as the three-layer, four-layer protocol of the OSI reference model, and Ethernet is used as the one-layer and two-layer protocol. And are connected via the transmission line 3.

The client 1 transmits / receives data via the connection, detects an error during transmission / reception, a connection closing process on the server 2 side when connecting a cable or the like, and outputs a connection closing instruction and a connection establishment request output. Data transmission / reception processing unit 11 for giving an instruction
And a connection establishment request unit 12 that continues to send a connection establishment request to the server 2 until a connection is established by an instruction from the data transmission / reception processing unit 11, and a connection control that closes the connection according to an instruction from the data transmission / reception processing unit 11. And a part 13 in the TCP layer.

The server 2 transmits / receives data via a connection similarly to the data transmission / reception processing unit 11, and
A data transmission / reception processing unit 21 that detects an error during transmission / reception or a connection closing process on the client 1 side when a cable or the like is connected, and issues a connection close instruction and a connection establishment request output instruction, and a connection establishment request unit of the client 1. A connection establishment passive unit 22 that performs connection establishment processing in response to a request from 12;
The connection established by the connection passive unit 22 is made normal, and the process control unit 23 that closes the old connection (process) and the connection control unit 24 that closes the connection according to the instruction from the data transmission / reception processing unit 23 are transmitted by TCP. Have on layer.

As a result, between the client 1 and the server 2, the connection communication type transmission mode, that is, each TCP at both ends of the connection established by the socket interface is used.
Data communication is performed via a port (communication port).

Next, the connection restoration process when an error occurs during data communication between the client 1 and the server 2 in this system will be described with reference to the flowchart of FIG.

First, during normal data communication, a connection is established between the client 1 and the server 2, and data is transmitted / received by both the data transmission / reception processing units 11 and 21 through the connection (step 100,
200 "OK").

Here, for example, when a data transmission / reception error occurs in the TCP port of the client 1 (step 100 “NG”), the data transmission / reception processing unit 11 on the client 1 side detects the error and the connection control unit 13 is detected. To close the connection (step 110), and then cause the connection establishment request unit 12 to output a connection establishment request until a new connection is established (step 120 "OK").

On the server 2 side, the data transmission / reception control unit 11 detects the connection closing process on the client 1 side, sends an instruction to the connection establishment passive unit 22 and the connection control unit 24, and the connection control unit 24 closes the connection. (Step 21
0), the connection establishment passive unit 22 is always set to the connection establishment request waiting state.

Then, the connection establishment passive unit 22 receives the connection establishment request from the client 1 side to establish a new connection, and processes the connection as a regular TCP port (step 220).
"OK"), and then the old connection is closed in steps 110 and 210, but the process controller 23 closes the old connection (step 230). When a connection establishment request is sent from the client 1 side during the establishment of the connection, a new connection is established (step 220 “OK”), and the old connection, that is, the connection that was being established is closed. (Step 230),
Make the most recently requested connection a regular TCP port.

After a new connection is established between the client 1 and the server 2, data transmission / reception is performed by the new connection (steps 100, 200 "O").
K ”).

The same thing can be said when an error occurs on the server 2 side. In this case, the connection is closed from the server 2 side (steps 210 and 11).
0), the server side establishes a connection by receiving a connection establishment request from the client 1 side (step 220), and data is transmitted and received by the new connection (steps 100 "OK", 200 "OK").

Further, the connection error may include disconnection (disconnection) of the communication cable which is the transmission line 3 between the client 1 or the server 2. In this case, the client 1 side outputs a connection establishment request. Also,
On the server 2 side, the connection is not established (step 120 “NG”, step 220 “NG”), and the connection disconnection state continues. However, when the communication cable is reconnected, the connection establishment request unit 12 outputs a connection establishment request, and the connection establishment passive unit 22 on the server 2 side receives the connection establishment request and establishes a new connection. (Step 120 "O
K ”, step 220“ OK ”), then the old connection is automatically closed (step 230) by the processing of the process control unit 22 after the connection is established, and the client 1 and the server are automatically connected via the new connection. Two-way communication begins (step 100 “OK”, 200
"OK").

Therefore, according to the present system, even if a data transmission / reception error occurs on the connection between the client and the server, the connection establishment request is automatically output and the connection is established. The time and effort required to restore the connection are greatly reduced.

Even when the communication cable is disconnected, a connection establishment request is automatically output when the communication cable is reconnected, a new connection is established, and the old connection is closed. No time and effort is required, and the time to restore the connection is shortened.

[0024]

As described above, according to the present invention, when an error occurs during data transmission / reception between a client and a server, the error is detected, a connection establishment request is automatically output, and a new connection is established. Since it is established, the connection can be automatically restored without human intervention, and the time to restore the connection can be greatly shortened.

[Brief description of drawings]

FIG. 1 is a block diagram showing a client and a server that form the present system.

FIG. 2 is a block diagram showing a connection restoration process when an error occurs in this system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 client 2 server 3 transmission line 11 data transmission / reception processing unit (error detection unit) 12 connection establishment request unit (connection establishment request unit) 13 connection control unit (connection erasing unit) 21 connection establishment passive unit (connection establishment unit) 22 process control Part 23 Data transmission / reception processing part (error detecting means) 24 Connection control part (connection erasing means)

Claims (1)

[Claims] 1. A T that establishes a connection between a client and a server and performs data communication by the connection.
In a client / server system based on CP / IP, an error detecting means for detecting a communication error on a connection during data communication, and a connection erasing means for receiving a detection output of the error detecting means and closing a connection during data communication, A connection establishment request means for receiving a detection output of the error detection means and outputting a connection establishment request; and a connection establishment means for receiving a connection establishment request from the connection establishment request means and newly establishing a connection. A client / server system based on TCP / IP characterized by: