KR20060068517A - Method of supporting rtp in node where rtp module is realized in kernel area - Google Patents

Abstract

A method of supporting RTP in a node in which an RTP module is implemented in a kernel region is disclosed. According to the present invention, a method of supporting RTP in a node in which an RTP module is implemented in a kernel region may include: generating a RTP socket and an RTCP socket by calling a socket system call function, and generating an RTP file descriptor and an RTCP file descriptor; Calling a bind system call function to set an RTP receiving address and port and an RTCP receiving address and port; And calling a connect system call function to set an RTP send address and port and an RTCP send address and port to perform the RTP session and the RTCP session connection. According to the present invention, since the common RTP processing routines exist in the kernel region by implementing the RTP module in the kernel region, no extra effort for RTP implementation is required, and the RTP module implemented in the kernel region is integrated into the standard network API. This provides the effect of providing a single network interface to application developers.

Real-Time Protocol (RTP), Kernel, Network API

Description

Method of supporting RTP in node where RTP module is realized in kernel area}

1 is a diagram illustrating an example of an application program incorporating an RTP module;

2 is a diagram illustrating an example of supporting an RTP module in a library;

3 is a diagram illustrating an RTP module implemented in a kernel region according to an embodiment of the present invention;

4 is a view showing an example of a socket system call internal procedure according to an embodiment of the present invention;

5 illustrates an example of a bind system call internal procedure according to an embodiment of the present invention;

6 is a view showing an example of a connect system call internal procedure according to an embodiment of the present invention;

7 is a view showing an example of a write system call internal procedure according to an embodiment of the present invention;

8 is a view showing an example of a lead system call internal procedure according to an embodiment of the present invention;

9 is a diagram illustrating an example of a closed system call internal procedure according to an embodiment of the present invention.

The present invention relates to a method of supporting RTP in a node in which a real time protocol (RTP) module is implemented in a kernel area, and more particularly, to implement a streaming service between server clients on a network. When using Real-Time Protocol, put the RTP module used by two nodes at the kernel level, not the application level, and set the Network Standard API for them. It is about a method to provide.

In the future, it is expected that more people will access the Internet through non-PC devices or embedded devices such as PDAs, mobile phones, e-books, home servers, web TVs, etc. than those who use the Internet. In addition, the demand for multimedia services on such devices is increasing. Multimedia services in such embedded systems can be broadly classified into on-demand multimedia services such as video on demand (VOD) and audio on demand (AOD), and internet telephony services such as video conferencing systems and voice over IP (VoIP). RTP was developed to provide end-to-end transmission of real-time data, such as audio, video and simulation data, over a multicast or unicast network. Real Time Control Protocol (RTCP) provides data in RTP packets. By providing feedback on the quality of transmission, the application provides information to guarantee the quality of service (QoS). In a narrow sense, RTP refers only to a communication protocol for actual multimedia data transmission, but broadly includes a control protocol such as RTCP.

Recently, research on RTP has been actively conducted to support QoS, which is a weak point of RTP, in order to utilize RTP more efficiently, and many companies develop RTP libraries for their own products. RADVISION sells the RTP / RTCP protocol stack toolkit as one of its VoIP development solutions. The toolkit is a library that meets the RTP protocol stack standard, and is a general-purpose library that can be applied to any domain such as multimedia server, home gateway, and media player. Bell Labs, Columbia University, and the University of Massachusetts have co-developed the RTP library. The library is based on Unix and supports IP multicast and unicast. The main concern of such companies, universities or research institutes is the development of libraries to ensure better QoS of RTP. In other words, all these studies are based on the premise that RTP is implemented in a library, user space.

Consider the application compatibility and overall system performance depending on where you implement RTP. First, as shown in FIG. 1, when the application program is developed, the RTP module is embedded. If this application is implemented based on POSIX (Portable Operating System Interface) compatible network API, it can be operated on any system that supports the API, so application compatibility can be expected. However, in terms of system performance, this is not a desirable direction. If we assume that several applications using RTP are running in the same system at the same time, each RTP module must be implemented separately without a common RTP module. This is a huge waste of space in the system. Such implementation is very difficult in non-PC or embedded systems, which have more limited performance and system resources than conventional PCs.

Secondly, as shown in FIG. 2, the case of implementing RTP in a library of an application layer may be considered. In this case, if the provided RTP API is integrated with the existing POSIX based network API and the library is developed (if ① and ② are the same), the compatibility of the application program can be guaranteed to some extent. Currently, however, most RTP-related libraries provide their own RTP APIs (does not support POSIX standard network APIs; they are different from ① and ②), and most of them are developed internally by calling existing network APIs. to be. This approach is only for the convenience of implementing a new network protocol, and there is a problem in that compatibility of applications using this API cannot be guaranteed.

On the other hand, if a developer who develops a network application program develops with different APIs for each network protocol, it is necessary to first understand each API before thinking about the design and algorithm of the application program. This task seems seemingly simple, but when you actually get into the development phase and get to prototypes and maintenance, you end up with confusion and this burden is passed on to the developer.

Therefore, providing a standard network interface is a very important factor in implementing network protocols, but this attempt has never occurred in the field of RTP. With the proliferation of portable embedded devices and the increasing demand for multimedia content, the number of RTP-related applications is increasing. In this situation, there is an increasing demand for RTP supporting standard network interfaces.

An object of the present invention is to provide a method for supporting RTP in a node in which a Real Time Protocol (RTP) module is implemented in a kernel region.

According to an aspect of the present invention for achieving the above object, a method of supporting RTP in a node in which a Real Time Protocol (RTP) module is implemented in a kernel region is provided.

Calling a socket system call function to create an RTP socket and a Real Time Control Protocol (RTCP) socket, and to generate an RTP file descriptor and an RTCP file descriptor; Calling a bind system call function to set an RTP receiving address and port and an RTCP receiving address and port; And setting a RTP transmission address and port and an RTCP transmission address and port by calling a connect system call function to perform the RTP session and the RTCP session connection.

According to another aspect of the present invention, calling the write system call function for transmitting the RTP data, generating an RTP packet in the RTP module implemented in the kernel region, and transmitting the RTP packet; do.

According to another aspect of the present invention, the method further includes calling a read system call function for receiving RTP data to reconstruct an RTP packet received by an RTP module implemented in a kernel region.

According to still another aspect of the present invention, there is provided a method, comprising: calling a close system call function to transmit a message indicating release of an RTP session and an RTCP session connection; Removing the RTP socket and freeing the memory allocated for the RTP session; And removing the RTCP socket and releasing memory allocated for the RTCP session.

According to another aspect of the invention, the RTP module is characterized in that it supports POSIX compatible network API.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, the same components are denoted by the same reference numerals even if they are shown on different drawings. In addition, in the following description there are shown a number of specific details, such as components of the specific circuit, which are provided to aid a more general understanding of the invention, it is to be understood that the present invention may be practiced without these specific details. It will be self-evident to those of ordinary knowledge. In describing the present invention, when it is determined that detailed descriptions of related known functions or configurations may obscure the gist of the present invention, the detailed description thereof will be omitted.

3 is a diagram illustrating an RTP module implemented in a kernel region according to an embodiment of the present invention. As shown in FIG. 3, if the RTP module supporting the POSIX-based standard network API is implemented at the kernel level, since the common RTP processing routines exist in the kernel area, extra effort must be taken to implement the RTP. There is no. In addition, RTP supporting POSIX-based standard network APIs can provide a single network interface to application developers, and can compensate for the shortcomings of the two models.

POSIX, on the other hand, is a set of standard operating system interfaces based on the Unix operating system. And, the kernel is the most important core of the computer operating system, providing several basic services to all other parts of the operating system. In general, the kernel has an interrupt handler that handles all requests that competitively require kernel services, such as terminated I / O operations, and a scheduler that determines which programs will share the kernel's processing time and in what order. It includes a supervisor that gives each process a license to the computer. The kernel also has a memory manager that manages the operating system's address space in memory or storage and distributes it to all peripherals and other users of the kernel's services. Kernel services are requested through different parts of the operating system or through a set of program interfaces known as system calls. Because the code to maintain the kernel is used continuously, the kernel is usually loaded in a protected memory area so that it is not overwritten by the rest of the less frequently used operating system.

In the method of supporting RTP at the kernel level proposed in the present invention, when the RTP module is implemented in the kernel region, it is necessary to change a system call internal procedure and add a system call parameter accordingly. A system call is a function called by an application program or a user program to use an operating system function.

In one embodiment of the present invention, there are three system calls associated with the connection of a session: socket, bind, and connect. 4 is a diagram illustrating an example of a socket system call internal procedure according to an embodiment of the present invention. The socket system call is internally connected to the sys_socket function. The sys_socket function creates a socket structure and maps a file descriptor to the generated structure. Since RTP / RTCP must create each session separately when connecting sessions, two sessions must be opened. Soon, when calling the socket system call, the option to open an RTP related session (SOCK_RTP) must be passed as a socket type parameter, and the procedure to open two sessions internally must be performed.

5 is a diagram illustrating an example of a bind system call internal procedure according to an embodiment of the present invention. The bind system call is a system call that assigns a listening address and a listening port number to a created socket. Since two sockets were created for RTP / RTCP in the previous socket system call, the bind operation must also be performed twice.

6 is a diagram illustrating an example of a connect system call internal procedure according to an embodiment of the present invention. The connect system call internally performs a connection to a given socket. As with the bind system call, the connect operation must be performed twice because two sockets were created for RTP in the socket system call. It is also necessary to set the RTP / RTCP sending address and sending port in the session related data structure.

The system calls to send and receive data through the session are read / write, send / sendto and recv / recvfrom. 7 is a diagram illustrating an example of a write system call internal procedure according to an embodiment of the present invention. The write system call is responsible for sending data received as arguments through the socket data structures created inside the kernel. The write system call has a structure that calls sock_sendmsg, inet_sendmsg, and udp_sendmsg in order. The sys_write (send, sendto) function retrieves the file descriptor. If it is an RTP socket, it calls the rtp_send function and creates an RTP packet by attaching an RTP header to the data received from the application. Next, the kudp_send function is called to form an RTP packet in the form of an msghdr structure, which is then passed to the udp_sendmsg function, which is a UDP layer send function.

8 is a diagram illustrating an example of a lead system call internal procedure according to an embodiment of the present invention. The read system call is a system call that receives data. The read system call is connected to the sock_read function. The sock_read function has a structure that calls the sock_recvmsg, inet_recvmsg, and udp_recvmsg functions in the lower layer in order. In addition, rtp_get_packet function, which is a function to receive RTP packet as a function to support RTP, is not a structure to receive data by calling data receiving function of lower layer, but to read data from RTP packet buffer of a corresponding session. When the RTP packet is received, the packet is delivered to the rtp_demux function through the udp_recvmsg function. This packet calls rtp_insert_packet to store the RTP packet in the RTP packet buffer of the corresponding process session, and the rtp_get_packet function wakes up the process waiting for data that is sleeping.

9 is a diagram illustrating an example of a closed system call internal procedure according to an embodiment of the present invention. The closed system call is a system call for releasing an RTP / RTCP session. The closed system call sends a BYE RTCP message before removing the RTP / RTCP socket, indicating that the session is disconnected between the two sides. It then removes the RTP / RTCP session sockets and returns the memory allocated for each.

As described above, the RTP supporting method in a node in which the RTP module implemented in the kernel region is implemented may be implemented as computer readable code on a computer readable recording medium. Computer-readable recording media include any type of recording device that stores data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). It includes being. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

According to the present invention, since the common RTP processing routines exist in the kernel region by implementing the RTP module in the kernel region, no extra effort for RTP implementation is required. In addition, by integrating the RTP module implemented in the kernel domain into the standard network API, it provides the effect of providing a single network interface to application developers.

Claims (5)

In a method of supporting RTP in a node in which a real time protocol (RTP) module is implemented in a kernel region, Calling a socket system call function to create an RTP socket and a Real Time Control Protocol (RTCP) socket, and to generate an RTP file descriptor and an RTCP file descriptor; Calling a bind system call function to set an RTP receiving address and port and an RTCP receiving address and port; And Invoking a connect system call function to set an RTP send address and port and an RTCP send address and port to perform the RTP session and the RTCP session connection. According to claim 1, Calling a write system call function for transmitting RTP data, generating an RTP packet in an RTP module implemented in a kernel region, and transmitting the RTP packet. According to claim 1, Calling a read system call function for receiving RTP data to reconstruct an RTP packet received by an RTP module implemented in a kernel region. According to claim 1, Calling a close system call function to transmit a message informing of the release of the RTP session and the RTCP session; Removing the RTP socket and freeing the memory allocated for the RTP session; And Removing the RTCP socket and releasing memory allocated for the RTCP session. According to claim 1, And the RTP module supports a POSIX compliant network API.

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