KR100924088B1 - Method for Controlling flow of Communication between URC Server and Client - Google Patents

Abstract

The present invention relates to a partial flow control method of communication between a URC server and a client. According to the present invention, a communication connection between a URC server and a URC client is composed of a plurality of channels, at least one channel is allocated to each component constituting the URC client, and a receiving buffer is provided at a receiving side of each channel. In the situation where the receiving side of the channel causes a change in the available space of the receiving buffer, the available space is checked, and when the available space is below a certain level or above a certain level, it is notified to the transmitting side of the channel, independently for each channel. Perform flow control. Therefore, it is possible to prevent the problem of stabilization in other components caused by one component constituting the URC client.

Network Robot, URC Server, URC Client, Channel, Partial Flow Control

Description

Method for controlling flow of communication between URC server and client

The present invention relates to a partial flow control method of communication between a URC server and a client. According to the present invention, a communication connection between a URC server and a URC client is composed of a plurality of channels, at least one channel is allocated to each component constituting the URC client, and a receiving buffer is provided at a receiving side of each channel. In the situation where the receiving side of the channel causes a change in the available space of the receiving buffer, the available space is checked, and when the available space is below a certain level or above a certain level, it is notified to the transmitting side of the channel, independently for each channel. Perform flow control. Therefore, it is possible to prevent the problem of stabilization in other components caused by one component constituting the URC client.

As robot technology develops, research on a network robot combining a conventional robot technology and a network technology has been actively conducted. The URC (Ubiquitous Robotic Companion) robot, which is such a network robot, is not configured and released from the beginning, but is configured to download and use functions necessary for the robot from the URC server through the network. The URC robot is also called a URC client, and such a URC robot can provide various services according to a user's request.

The communication between the URC server and the client is based on the RPC (Remote Procedure Call) model. The RPC model is a function call format of the local programming model applied to a network system, and the client can use the services provided by the server simply by calling the function without considering the server-client communication. That is, in the conventional method using the RPC model, the RPC model uniformly handles communication between the URC server and the client. However, as the scale and range of URC robots are expanded, one URC server communicates with various types of URC clients. Accordingly, the types and sizes of data transmitted and received have also increased. As a result, a communication latency problem occurs due to the accumulation of communication lines. In particular, when the URC client communicating with the URC server is composed of a plurality of components, a starvation problem occurs in another component communicating with the server due to the accumulation of communication with one component.

The present invention has been made to solve the above-described problems, in the present invention, the communication connection between the URC server and the URC client to configure a plurality of channels, one or more channels to each component constituting the URC client The receiving side of each channel is provided with a receiving buffer. In the situation where the receiving side of the channel causes a change in the available space of the receiving buffer, the available space is checked, and when the available space is below a certain level or above a certain level, it is notified to the transmitting side of the channel, independently for each channel. It is intended to provide a partial flow control method of communication between a URC server and a client that performs flow control.

The present invention relates to a partial flow control method of communication between a URC server and a client. The method includes a URC server in which a communication connection between a URC server and a URC client consists of a plurality of channels, one or more channels are allocated to each component constituting the URC client, and a receive buffer is provided in each of the plurality of channels; CLAIMS 1. A flow control method in communication between URC clients, the method comprising: measuring an available space of the receive buffer in a situation of causing a change in the available space of the receive buffer at a receiving side of each of the plurality of channels; (B) checking whether the measured available space is equal to or greater than a predetermined level specified by the user; If the available space is less than or equal to the predetermined level, transferring information related to a reception buffer of the channel from a receiving side of a channel to a transmitting side; And (d) restricting transmission of data over the channel at the transmitting side of the channel.

According to the present invention, when the URC client communicating with the URC server is composed of a plurality of components, it is possible to prevent the problem of stabilization in other components caused by one component to improve the quality of service.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited by the following examples.

1 is a diagram illustrating a three-layer communication protocol according to the present invention. In the present invention, a communication protocol divided into three layers is introduced into a communication between a URC server and a URC client.

The communication protocol according to the present invention is composed of a remote procedure call (RPC) layer, a transport layer and one or more mapping layers as shown in FIG. 1. That is, the matters related to data transmission uniformly processed in the conventional RPC layer are separated into separate transport layers.

The RPC layer is a protocol used by a client mounted program to request a service from a program on a server. The RPC layer does not need to know detailed information about the underlying network. Perform all communication using

The transport layer is a protocol located between the RPC layer and the mapping layer that is responsible for the transmission of messages. The commands provided by the transport layer to the RPC layer include Bind, Unbind, Open, Close, Disconnect, Listen, Accept, Send, Send. There are Error, Receive, Status, and Connected.

1> Bind

Bind creates a local end-point of the connection, receives an argument to use the identity and SASL mechanism used to authenticate outgoing connections made through the end, and access handle to the local end. Provide a local port name that acts. At this time, the identity is a kind of address assigned to each server or client to uniquely identify the URC server or client.

Bind (local identity, SASL mechanism list)-> local port name

2> Unbind

Unbind returns all resources associated with the local port name provided by the Bind command.

Unbind (local port name)

3> Open

Open is for establishing a foreign identity and channel, and takes a list of profiles to be used for the channel. If the external identity does not already have a connection via the local port name, create a new connection and complete the authentication using the identity and SASL mechanism provided by the Bind command. Open provides a local channel name that acts as an access handle to the channel.

Open (local port name, foreign identity, profile list)-> local channel name

4> Close

Close returns all resources associated with the local channel name opened by the Open command.

Close (local channel name)

5> Disconnect

Disconnect terminates all connections and channels through the local port name. At this time, if the upper identity is provided, only the connection and channel with the corresponding external identity are terminated.

Disconnect (local port name [, foreign identity])

6> Listen

Listen allows incoming connections to the local port name, providing as arguments a list of SASL mechanisms and profiles to be used for authenticating incoming connections.

Listen (local port name, SASL mechanism list, profile list)

7> Accept

Accept accepts the receive channel to the local port name. The Accept command can accept the receive channel even if the Listen command is not performed.

Accept (local port name)-> local channel name

8> Send

Send is a command to send a chunk through a channel, and receives a request / response separating factor and a completion indicating whether the message is at the end.In some cases, the chunk data may be omitted. .

Send (local channel name, request / response, complete [, chunk data])

9> Send - Error

Send-Error is a command for sending an error chunk through a channel, and receives a request / response and error code as arguments. In some cases, error data may be omitted.

Send-Error (local channel name, request / response, error code [, Error data])

10> Receive

Receive is a command to receive a chunk from a channel. It provides a request / response classification, whether it is the last chunk and whether it is an error, and sends the chunk data when it is included.

Receive (local channel name)-> request / response, complete, error [, chunk data])

11> Status

Status provides status information, including at least a local port name, a local identity, an external identity, a SASL mechanism, and a profile.

Status (local channel name)-> status data

12> Connected

Connected is a command that checks if the port maintains a connection with an external identity.

Connected (local port name, foreign identity)-> true / false

The mapping layer is related to network input / output. As shown in FIG. 1, heterogeneous networks are supported by allowing various types of mapping layers to be used as necessary, such as a UDP mapping layer and a TCP mapping layer.

By separating the communication protocols into three layers in this way, the platform independence can be improved to improve the portability of the platform. In addition, due to protocol layering, performance can be measured for each layer, thereby easily identifying the cause of a problem in communication and effectively solving the problem.

The partial flow control method of communication between the URC server and the client according to the present invention relates to a transport layer that is responsible for transmitting a message among the above-described three-layer communication protocols.

The basic unit of message transmission in the transport layer is a frame. That is, the chunk requested by the upper layer RPC layer to the transport layer is divided into several frames in the transport layer and transmitted. 2 is a diagram illustrating a format of a frame that is a basic unit of message transmission according to the present invention.

In the communication between the URC server and the client according to the present invention, one connection is composed of a plurality of channels. In the frame format shown in FIG. 2, the channel number indicates the channel to which the frame belongs. When the channel number is represented by 16 bits according to an embodiment of the present invention, each connection may include up to 65535 independent channels.

In addition, SEQ is used for partial flow control according to the present invention. If SEQ is 1, it indicates that an arc number and a window size field exist. Each channel has a receive buffer for partial flow control. Part of the reception buffer is filled with data that has been received based on a specific time point but has not yet been processed, and the remaining area of the reception buffer becomes available space for data to be arrived later. In order to inform the sender of the available space of the receiving buffer, SEQ is set to 1, and the size of the available space at a specific time is 2 in the window size field, and the total number of bytes of payload received in the corresponding channel until the specific time is 2 ^The remainder divided by ³² is included in the arc number field.

NUL indicates whether payload is present. If NUL is 1, it indicates that the payload size and payload fields do not exist. The payload size represents the size of the payload in bytes, and the payload contains data to be transmitted. According to an embodiment of the present invention, the payload size is represented by 32 bits, and each frame may include a payload having a length of up to 4294967295 bytes.

If EOM is 1, it indicates that the frame constitutes the last chunk constituting one message. If EOC is 1, it indicates that the frame is the last frame constituting one chunk. If ERR is 1, it indicates that the frame is an error message.

The TOM indicates the type of message formed by the frame, and the TOM value is predefined. For example, the control message (CTL) = 0, the request message (REQ) = 1 and the response message (RES) = 2 can be defined as.

3 is a flowchart illustrating a partial flow control process of communication according to the present invention. As described above, for the flow control according to the present invention, the communication connection between the URC server and the URC client is composed of a plurality of channels, the URC client is composed of one or more components, each of the one or more channels Assume this is allocated. In addition, a receiving buffer is provided at a receiving side of each channel, and the receiving buffer is filled with data received but not yet processed.

First, the receiving side of each channel, e.g., a URC client, makes available the receiving buffer of the channel in a situation that causes a change in the available space of the receiving buffer, i.e. when new data is received or data stored in the receiving buffer is removed. The space is measured (S10). At this time, it is checked whether the measured available space of the channel is above a predetermined level specified by the user (S20), and when the available space is below the predetermined level, information related to the reception buffer is transmitted from the receiving side of the channel to the transmitting side (S30). ). In this case, the information related to the reception buffer includes information on the size of the available space and the remainder obtained by dividing the total number of payloads received on the channel by 2 ³² until the available space measurement time. Thereafter, data transmission to the channel where the available space is lowered below a predetermined level is restricted at the transmitting side of the channel (S40).

Thereafter, the receiving side of the channel continues to measure the available space of the receiving buffer in a situation in which the available space of the receiving buffer is changed as described above (S50). At this time, it is checked whether the measured available space is less than or equal to a predetermined level specified by the user (S60), and when the available space is greater than or equal to the predetermined level, information related to the reception buffer is transferred from the receiving side of the channel to the transmitting side. (S70). Thereafter, at the transmitting side of the channel, the flow of communication is controlled for each channel by releasing the data transmission restriction through the channel in which data transmission is restricted in step S40 (S80).

The embodiment according to the present invention is not limited to the above-described embodiments, and various alternatives, modifications, and changes can be made without departing from the scope of the present invention.

According to the present invention, when the URC client communicating with the URC server is composed of a plurality of components, it is possible to prevent the problem of stabilization in other components caused by one component to improve the quality of service.

1 illustrates a three-layer communication protocol in accordance with the present invention.

2 is a diagram illustrating a format of a frame that is a basic unit of message transmission according to the present invention.

3 is a flow chart illustrating a partial flow control process of communication in accordance with the present invention.

Claims (3)

The communication connection between the URC server and the URC client is composed of a plurality of channels, at least one channel is allocated to each component constituting the URC client, and between the URC server and the URC client provided with a receiving buffer in each of the plurality of channels. As a flow control method in communication, (A) measuring the available space of the receive buffer in a situation that causes a change in the available space of the receive buffer at the receiving side of each of the plurality of channels; (B) checking whether the measured available space is equal to or greater than a predetermined level specified by the user; If the available space is less than or equal to the predetermined level, transferring information related to a reception buffer of the channel from a receiving side of a channel to a transmitting side; And Limiting transmission of data over the channel at the transmitting side of the channel; Information related to the reception buffer, And the remaining information obtained by dividing the total number of bytes of the payload received by the channel by 2 ³² until the available space information of the reception buffer and the available space are measured. The method of claim 1, After step (d), (E) measuring the available space of the receive buffer in a situation in which the receiving side causes a change in the available space of the receive buffer; (F) checking whether the measured available space is equal to or less than the predetermined level; (G) transmitting information related to the reception buffer of the channel from the receiving side of the channel to the transmitting side when the available space is above the predetermined level; And And (h) releasing the restriction of transmission of data through the channel at the transmitting side of the channel. delete

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