KR20020033219A - Method for materializing connection-oriented socket interface - Google Patents

Abstract

PURPOSE: A method for embodying a connection-oriented socket interface is provided to make a transmission control protocol/internet protocol(TCP/IP) application program even if a detailed system call regarding a socket is not known. CONSTITUTION: A connection-oriented socket interface module is initiated, and a port number and a connection identifier wherein a server waits for a connection request from a client are supplied. A user periodically calls an interface function of the server to inspect whether a socket connection request from the client is made. When the socket connection request is made from the client, a connection identifier regarding the socket to communicate with the server is given to a user at the client so that a data communication between the server and the client is made through the connection identifier. The socket is disconnected when the data communication through the connection socket between the server and the client is completed or a socket at either one of the server or client is abnormally finished.

Description

How to implement a connection-oriented socket interface {Method for materializing connection-oriented socket interface}

The present invention relates to a socket interface of a server client system, and in particular, implements a connection-oriented socket interface to facilitate the development or creation of a Transmission Control Protocol / Internet Protocol (TCP / IP) application. It relates to a connection-oriented socket interface implementation method.

In general, when you want to write a TCP / IP application that runs on a server client system, you use sockets provided by almost any platform (such as Platform or Windows or UNIX).

In particular, stream sockets are used for applications that require connection-oriented applications. Stream socket related system calls vary, and an application program may make a combination of several system calls using the stream socket.

1 is a block diagram of a server client system.

As shown in FIG. 1, the server client system sets a path for data exchange between each other through a network. The path of the data exchange differs depending on a protocol used by the network.

In the case of a network using the TCP / IP protocol, each system call must be used in order according to the state of the socket.

In the above, the socket is to provide an environment in which the user of the processor can process the interprocess communication as if the input and output of the file, without being aware of the environment of the system or the network. This technique corresponds to the session layer of the OSI reference model and is applied as an application program interface of TCP / IP.

The initiation of a socket consists of the two communicating processes making the socket declaration by the socket () system call to create a socket that becomes the input / output path of the communication. It then executes the bind () system call to give the socket a name that each process can recognize. Socket names are defined by three types: in the same domain, in the Internet, and in a Xerox XNS network.

The socket connection performs the preparation of receiving the process of the server through the listen () system call, the socket connection request from the process of the client through the connect () system call, and the server through the accept () system call. Receipt of request is made.

When the socket connection is established between the server and the client through the above operation, data is transmitted and received through a read () / write () system call like the input / output of a normal file. Termination of data communication is done by the close () system call.

However, if you do not make timely use of complex system calls on socket connections, you will not only be able to provide the desired services, but also the performance of your program.

The present invention is intended to improve the socket interface of the server client system, the prior art will be described as follows.

First, Figure 2 is a block diagram of a socket interface of a server client system according to the prior art.

As shown in FIG. 2, the conventional interface basically conforms to the TCP / IP protocol, and the application program for the protocol operates in a client server structure.

Conventionally, in the socket connection establishment process, the server side processes the system call sequentially to wait for the connection request. Examples of system call routines used here include socket (), bind (), listen (), and accept (). The accept () system call operates in a blocking mode, and continuously waits for a socket connection to be normally made for a client's connection request.

The client side creates a socket and then requests the server side for a socket connection. That is, after a client creates a socket (socket ()), it requests a connection (connect ()) according to the socket.

Thus, when a socket connection is made between the server and the client, data exchange between the subjects of the connection is possible.

The connection management process is performed in the blocking mode, waiting for the client side in the blocking mode, and waiting for a response to the connection request to the server. The synchronization process between the server side and the client side may be different for each developer when developing an application program.

Once the connection is established by the above operation, data transmission and reception between each subject is possible. When the data exchange between the connecting entities is completed and no further data exchange is necessary, the established connection is further released.

This series of operations will be described in more detail.

Functions such as socket (), bind (), listen (), and accept () are called on the server side, and a series of steps are performed to open the socket and wait for a connection with the client side to be established. At this time, the client side calls socket () and connect () functions in order to open a socket and request a socket connection from the server side through the socket.

When a connection is established between the server side socket and the client side socket by the client side connection request, the client side calls a write () or send () routine to request data to be transmitted to the server side. request)).

In response to the data request, the server side calls a read () or recv () routine to receive a request from the client, performs a process of the requested data, and then performs a data transmission process through a connected socket.

The response to the client side request is made by the server side sending the result of processing the request data to the client side by calling a write () or send () routine (data (reply)). At this time, the response data transmitted from the server side is received by the read () or recv () routine of the client side.

Data exchange through the connected socket is repeatedly performed according to the above scheme, and when the data transmission is completed, the connection state of the socket is released. The server client system requires limited management of system resources because a large number of clients are connected to a small number of servers through sockets, and connection and disconnection of the sockets is performed during resource management.

Disconnecting a socket causes the client side to close the socket by invoking the close () routine when there is no more data to send, and the close () routine notifies the server side of the disconnection. Then, the server side receives the disconnect notification and calls the close () routine to disconnect the socket and restore the socket resource to the available state.

However, the prior art described above has the inconvenience of managing information on each connection when multiple connections are required.

In addition, there is a problem that the connection management structure is very complicated because it uses a socket-related system call.

Accordingly, the present invention has been proposed to solve the above conventional problems, and an object of the present invention is to implement a connection-oriented socket interface (TCP / IP) in a server client system. Protocol / Internet Protocol) A method for implementing a connection-oriented socket interface that facilitates the development or writing of an application program.

In order to achieve the above object, a connection-oriented socket interface implementation method according to the present invention includes: initializing a connection-oriented socket interface module and providing a port number and a connection identifier for a server side waiting for a client side connection request; A user periodically calling a server-side interface function to check whether a socket connection request from a client side occurs; When a socket connection request on the client side occurs, granting a client side user a connection identifier for a socket to communicate with the server to perform data communication between the server side and the client side through the connection identifier; When the data communication through the connection socket between the server side and the client side is completed or one socket is abnormally terminated, the step of releasing the socket connection is characterized in that the technical configuration.

1 is a block diagram of a server client system,

2 is a block diagram illustrating a socket interface of a server client system according to the related art.

3 is a block diagram of a protocol stack to which the present invention is applied;

4 is a detailed block diagram of a connection-oriented socket interface according to an embodiment of the present invention in FIG.

5 is a flowchart illustrating a method of operating a connection-oriented socket interface according to an embodiment of the present invention.

Hereinafter, the configuration and operation of the present invention will be described based on the embodiment of the present invention.

First, Figure 3 is a block diagram of a protocol stack to which the present invention is applied, Figure 4 is a detailed block diagram of a connection-oriented socket interface according to an embodiment of the present invention in Figure 3, Figure 5 is a view of the present invention 1 is a flowchart illustrating a method of operating a connection-oriented socket interface according to an embodiment.

As shown in FIG. 5, a preferred embodiment of the present invention includes the steps of: initializing an interface module and providing a port number and a connection identifier for a server side waiting for a client side connection request (ST21 to ST22); An operator periodically calling a server-side interface function to check whether a socket connection request from a client side occurs (ST23 to ST24); When a socket connection request on the client side is generated, granting a connection identifier for the socket to communicate with the server to the client side user to perform data communication between the server side and the client side through the connection identifier (ST25 ~ ST26) and When the data communication through the connection socket between the server side and the client side is completed or the socket on one side is abnormally terminated, the step of releasing the socket connection (ST27 ~ ST28) is configured.

Operation according to the method configured as described above is as follows.

The present invention simplifies the actual socket use by providing an interface function of sending and receiving data using a stream socket through TCP / IP.

The stream socket corresponds to a connection-oriented socket. Connection-oriented or stream-oriented is a type of transport layer data communication service, in which one host sends continuous stream data to another host. At this point, the connection-oriented service guarantees that all data transmitted is reached at the receiving end without the same order and duplication. This connection-oriented service is performed in three stages: connection establishment, data transfer and disconnection.

The typical case of connection-oriented services is the TCP protocol.

The structure of the protocol stack for the connection-oriented socket interface proposed in the present invention is as shown in FIG.

When using the protocol of Figure 3, regardless of the server / client side, the user can send and receive data using the connection identifier for the connection. Here, the Connect-Oriented Socket Interface is denoted by COSI.

The Connection Oriented Interface (COSI) function for the protocol is as follows.

The initialization function allocates a table for internal use and receives user parameters.

The connection request function calls subfunctions for performing server socket opening, client socket opening, and server connection management. The server socket open subfunction allows the server side to create a socket and wait for a connection request, and the client socket open subfunction causes the client side to create a socket to perform a connection request, and the server connection management subfunction allows the server side to It examines the connection request of and performs the response to the connection request.

The disconnect function allows you to release the socket connection between the server and the client.

The data transmission / reception function performs data transmission, reception 1, reception 2 and acknowledgment functions. The transmission function is to transmit data on an already created connection, and reception 1 is to designate and receive a maximum size of data from an already created connection. Receive 2 is to receive the desired amount of data from the connection already created, and the acknowledgment function is to check whether there is data received.

Other functions include functions for processing status information.

Functional associations between the respective functions and the overall operation flow will be described in more detail with reference to the accompanying drawings.

Figure 4 shows an application example of the connection-oriented socket interface proposed in the present invention.

As shown in FIG. 5, in order to use the connection-oriented socket interface, each module must be initialized (ST21).

Parameters entered during the initialization phase include the maximum number of connections the user will use, the size of the maximum message the user will send, and the size of the message that can be received. In this case, the parameters used when the interface module is initialized are for convenience in managing the interface module and do not have a direct relationship with the function of the interface function.

If the module is successfully initialized using the parameter, the connection request can be performed.

Connection requests are different for the server and client side.

When a connection request is made, the server side provides as an input the port number waiting for the connection request. When the corresponding port is connected to the input, the connection identifier for the corresponding connection is provided to the user (ST22).

In this case, a series of steps of processing the connection request in the server to perform a socket connection are performed using a constant system call function as in the prior art.

In order to confirm the connection request from the client, the user is periodically called by the interface function (ST23). That is, it is performed by the user because no process (or task) exists inside the interface function.

Thus, the connection request on the client side provides a port number as an input, and when the requested connection is made, a connection identifier capable of communicating with the server side is given to the user (ST24 to ST25).

If all of the above procedures are successfully performed, the user can perform data transmission and reception through the generated connection using each connection identifier (ST26).

First, in data transmission, when a message is sent by using a connection identifier assigned by a user, a message is transmitted to the other party by using a socket.

In data reception, two methods are provided for the user.

The first is a case where a desired size of data is received and is called a reception 1 method. The reception 1 method is a method used by the user to know the size of the next data to be received.

The second method is to designate and receive the size of data that a user can receive. The reception 2 method provides a user with the maximum size when there is data exceeding the maximum size requested by the user. At this time, the user should receive the data again after exceeding the maximum size.

The reception 1 and reception 2 methods are based on the operation characteristics of the stream socket. In the stream socket, since the start and end of the message sent from the other party cannot be distinguished, they are provided in the reception method as described above. Therefore, the start and end of the message must be determined by the user.

When the data transmission / reception is no longer required by performing the series of data transmission / reception operations described above, the socket connection is released according to a user's request.

The socket disconnection is not only performed when data transmission and reception is completed, but also when the other end is abnormally terminated. It is up to the user to decide whether to disconnect the socket due to abnormal termination of the other party (ST27 ~ ST28).

As such, the present invention provides a connection-oriented socket interface so that all the matters related to the execution of a socket management command or a processing step performed by an operator in an application program layer are collectively performed by the interface, thereby connecting a TCP / IP socket. The operator does not have to participate in the request / approval / release of the server and the client, and the server side does not have to operate in the blocking mode for the socket connection request.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments.

In other words, the current status information is managed in the equipment, and it can be applied to the network configuration which is operated by a PC interconnected via TCP / IP. In such a configuration, it can be applied to requesting and responding to information in communication with each other.

Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, the connection-oriented socket interface implementation method according to the present invention has an effect of easily writing a TCP / IP application even if a detailed socket-related system call is not known.

And even in an environment where one process (or task) runs, the server can connect to multiple clients on one port.

In addition, since the interface according to the present invention is basically processed as non-blocking, multiple connection management is possible and the user can obtain information on the multiple connections, thereby enabling application to an application program operating on multiple processors. Has an effect.

Claims (5)

Initializing a connection-oriented socket interface module and providing a port number and a connection identifier for the server side to wait for a client side connection request; A user periodically calling a server-side interface function to check whether a socket connection request from a client side occurs; When a socket connection request on the client side is generated, granting a client side user a connection identifier for a socket to communicate with the server to perform data communication between the server side and the client side through the connection identifier; And releasing the socket connection when data communication through the connection socket between the server side and the client side is completed or the socket on one side is abnormally terminated. The method of claim 1, wherein the connection-oriented socket interface module, Implemented to interface between stream sockets and applications in the TCP / IP protocol. Command processing at the application layer is divided into open server socket, open client socket, and send / receive data. Related functions for processing each command of the application program layer are called by an interface function, and data or processing result generated by performing the command processing related function is passed to the corresponding routine of the application program requesting the corresponding command through the interface function. A method of implementing a connection-oriented socket interface, comprising returning a message. The method of claim 1, wherein the initialization of the connection-oriented socket interface module, The maximum number of socket connections to be used by the user, the maximum size of the message sent by the user, and the maximum size of the receivable message are transmitted to the connection-oriented socket interface module as parameters so that the corresponding interface module is initialized according to the parameter. How to implement a connection-oriented socket interface. The method of claim 1, wherein the transmitting and receiving data through the connected socket comprises: Connection-oriented socket interface implementation method characterized in that the data receiving side to specify the size of the data to receive. The method of claim 1, wherein the transmitting and receiving data through the connected socket comprises: And specifying a maximum size of data that can be received at a receiving side of the data in the initialization step of the interface module, and receiving data by the specified maximum size.