KR20030060713A - Method for caching font data in thin client/server system - Google Patents

Abstract

According to the present invention, a thin client configured to map and transmit only data on a changed font to a thin client and display the same on the thin client without compressing or transmitting a font image transmitted to the thin client to display an application program executed on a server. It relates to the font cache control method of the server system.

The font cache control method of the thin client-server system of the present invention is executed by interacting with both thin clients / servers, and the server operation load is reduced by drastically reducing the load on image compression to be processed by the server itself. In addition, since the data transmission amount is significantly reduced compared to the data transmission amount transmitted by conventional image compression, it is possible to reduce the traffic of the network and also increase the utilization of limited resources of the thin client.

Description

Method for caching font data in thin client / server system

The present invention does not compress and transmit the font image transmitted to the thin client to display the result of the application executed on the server, and transmits only the data and the virtual indexes for the changed font to the thin client, and transmits the font itself in the thin client. The present invention relates to a font cache control method of a thin client-server system that can reduce the operation load of the server system and the traffic of the network and increase the utilization of limited resources by configuring the display.

In order to solve the problems caused by the increasing size and cost of personal computers (PCs), in particular, the increase in total cost (TCO) and the deprivation of time for non-business activities such as Internet surfing and securities access, etc. The thin client / server system is in the spotlight. Thin clinet refers to a lightweight, thin terminal with minimal requirements for user operation, and is being developed to replace a large, heavy PC that has taken up a corner of a desk.

1 is a diagram illustrating a connection state of a conventional thin client / server system. As shown, the high performance server 101 and a plurality of thin clients 130 are connected through a network, and the server 101 requests a specific application installed in the server by a request from the thin client 130. The image of the region changed according to the result of the execution is compressed and transmitted to be output on the monitor screen of the thin client 130.

This thin client (terminal) 130 operates not only in appearance, but also fundamentally different from the conventional PC. This can be seen from another name of the thin client system, 'server-based computing', where the thin client 130 is installed every time an application is needed with the server 101 installed. It connects to the server 101 to operate the corresponding application, and the server 101 is driven by transmitting only the result of the application (the changed image) to the thin client and displaying it on the monitor screen.

2 shows a simplified block configuration of the server 101 and the thin client 130 as described above. Referring to this, the process of the conventional thin client / server system is briefly described as follows.

When the user requests the control unit 134 to operate a specific application by using a keyboard or a mouse (not shown) from the thin client 130, a corresponding request signal is transmitted from the control unit 134 to the data transmission / reception unit 131. It is input to the control part 105 of the server 101 via 106, and the control part 105 makes the said application program run from the application program loading part 102. FIG. After executing the application, the server 101 records the changed image generated from the operation result of the application in the frame buffer 103 allocated to the thin client 130 and compresses the image of the changed area. The data transmission / reception unit 106 or 131 transmits the data. The frame buffer 103 is allocated to the corresponding thin client and separated / protected from other thin clients.

The compressed image data transmitted to the thin client 130 is stored in the video memory 133 to be visually displayed after being decoded by the decoder 132. When the thin client 130 sees the monitor screen on which the font is displayed, inputs a necessary command or data, and then transmits the same to the server 101, the thin client 130 executes the application program using the input data in the corresponding application program of the server 101. The image data of the newly changed area is stored in the frame buffer 103 again, and then compressed and transmitted.

By such a driving method, the capacity of the memory or hard disk mounted in the thin client 130 does not need to be large. Also, if the thin client and the server are connected to a network, a CD-ROM drive or a floppy disk drive connected to the server may be used. It can be used to reduce the cost of hardware purchase, and also has the advantage that the cost of purchasing the application is also reduced because the application does not need to be installed on all thin client systems.

In fact, in one embodiment of the thin client / server system, the thin client has a keyboard, a mouse, and a monitor screen. In the server, an application that creates a framebuffer separated / protected according to the thin client's request, and uses it for each user The execution results of the program are recorded in the frame buffer, and the contents of the frame buffer are compressed and transmitted to the thin client when the thin client requests or updates the contents of the frame buffer. The transmitted data is displayed on the monitor after decompression on the thin client.

However, in spite of the above advantages, since one server 101 must process all requests from a plurality of thin clients, a problem occurs that the server 101 is overloaded when concurrent processing occurs.

To explain this in detail, a key technique in thin client / server systems is to synchronize the image created in the framebuffer in real time between the client and server. The server compresses only the changed image area in the frame buffer and transmits it to the thin client. The received thin client decompresses the received data and uses the data.

At this time, the server consumes most of the system resources for preparing the data to transmit the changed area, for example, a font image, for synchronization of the frame buffer with the thin client. Therefore, when multiple thin clients are connected to the server at the same time, the load is temporarily higher than the server system can handle, and the frame buffer synchronization between the thin client and the server is not well performed and data processing is slow. Losing problems occur. In addition, it is possible to increase the performance of the server to solve this problem, but it is not preferable in terms of cost increase.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to compress the font image transmitted to the thin client so as to display the result of the application program executed on the server, and to transmit data on the font changed to the thin client. By mapping only the virtual indexes and configuring the thin client to display the fonts on its own, the font cache control method of the thin client-server system can reduce the server system's operating load and network traffic and increase the utilization of limited resources. To provide.

1 is a schematic connection state diagram of a conventional thin client / server system;

2 is a schematic block diagram of the thin client / server system of FIG. 1;

3 is a block diagram of a thin client / server system according to the present invention;

4 is a flowchart showing a font caching process executed in a server;

5 is a flowchart illustrating a font caching process executed in a thin client.

※ Explanation of symbols about main part of drawing ※

101: server (system) 102: loading application

103: frame buffer 104: encoder

105: control unit 106: data transmission and reception unit

130: thin client 131: data transmission and reception unit

132: decoder 133: video memory

134: control unit 201: server

202: Loading application part 203: Frame buffer

204: font mapping table 205: encoder

206: control unit 207: data transmission and reception unit

230: thin client 231: data transmission and reception unit

232: decoder 233: font cache table

234: video memory 235: control unit

Font cache control method in the thin client-server system of the present invention for achieving the above object, and stores a plurality of applications, and by executing a specific application in the server alone or at the same time by the request from the thin client results A client / server system for transmitting data to a client and displaying the data, the server comprising: a first step of outputting corresponding font data to an allocated frame buffer when the server is requested to input fonts to be displayed according to an execution result of an application program; After outputting the font data, it is determined whether the font to be output to the font mapping table is cached, and if it is cached, the virtual index of the font mapping table of the corresponding font is obtained, and the virtual index is output to the thin client side. Transmitting a virtual index group; If the font to be printed in the font mapping table is not cached, it searches whether there is an empty cache area. If there is an empty cache area, it registers the font in the font mapping table of the server and transmits the font data to the client cache side. Transmitting a virtual index group and a command for outputting the corresponding virtual index to the thin client side; If there is no empty cache area, delete the oldest (font) index in the font mapping table, send a command to remove the corresponding font index from the thin client, register the font in the server's font mapping table, and print the font data. A fourth step of transmitting a virtual index group and a command for outputting the virtual index to the thin client side, and transmitting the data to be stored at the client cache side, wherein the thin client receives data transmitted from the server. A fifth step of reading a command; If the read command is a font cache command, the cache area is searched for, and if there is an empty cache area, the font is cached. If there is no empty cache area, the sixth cache is deleted after deleting the oldest virtual index and font data in the font cache table. step; A seventh step of notifying the server that the virtual index of the cached font is cached after the font cache in the sixth step; An eighth step of reading whether it is a command for removing a font if it is not a font cache command, and if not, removing the corresponding font in the font cache (table) area and notifying the server that the corresponding virtual index is deleted; If it is not the font removal command, it is determined whether it is a command for outputting a font, and if it is a font output command, the font for the corresponding virtual index is output, and if it is not a font output command, the ninth step of performing the command is performed.

Hereinafter, a font cache control method in the thin client-server system of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating a configuration of a server 201 and a thin client 230 further including a font mapping table 204 and a font cache table 233 according to the present invention. Comparing this with FIG. 2, it can be seen that the font mapping table 204 and the font cache table 233 are further added. First, each component is briefly described.

The server 201 includes an application program loading unit 202, a frame buffer 203, an encoder 205, a font mapping table 204, a control unit 206, and a data transmission / reception unit 207, and a thin client. 230 includes a data transmitter / receiver 231, a decoder 232, a controller 235, a font cache table 233, and a video memory 234.

The application program loading unit 202 includes all applications supported on the OS, and is typically a storage medium such as a hard disk drive (HDD), and runs on a computer OS (Linux, Windows 2000 server, Unix, etc.). Any application that can be installed can be installed. In the present invention, "fonts" (glyphs) refer to characters input by a user and characters output by an application program. The loaded application programs are executed by the controller 206. Cached is used in the sense commonly used in computers and related fields.

The frame buffer 203 is a space in which data (especially font data) to be displayed is temporarily stored, and may be configured by using a memory device that is commonly used.

The encoder 205 encodes data of the frame buffer 203 and various commands for transmission to the thin client 230, and in particular, compresses data.

In addition, the data transmission and reception unit 207 is composed of a socket (socket), and exchanges data with the data transmission and reception unit 231 of the thin client 230.

The font mapping table 204 maps an actual index and a virtual index of a glyph to be output from the application program and the controller 206 to n: 1, which will be described later.

The data transmission / reception unit 231 of the thin client 230 receives data transmitted from the data transmission / reception unit 207 of the server 201, and transmits a request of the thin client to the data transmission / reception unit 207 of the server 201. It performs the function.

The thin client decoder 232 receives, decompresses and outputs the data compressed by the encoder 205 of the server 201.

The thin client controller 235 separates a command and data from the data restored by the decoder 232, and outputs font data corresponding to a virtual index transmitted from the server 201 according to the command. Perform commands such as output to

In addition, the thin client font cache table 233 retrieves the virtual index value transmitted from the control unit 235 of the thin client 230, and in accordance with the instruction of the control unit 235, font data corresponding to the virtual index is stored in the video memory 234. Output to

The method of the present invention executed using the above thin client / server system is described. 4 shows a process executed in the server 201 of the method of the present invention, and a process executed in the thin client 230 is shown separately in FIG. 5.

First, a font cache process and a font data transfer process in the server 201 will be described with reference to FIG. 4. When a command for executing a specific application is input by a user and the command is transmitted from the thin client 230 to the server 201, the application is executed by the controller 206. If there is a request for font input to be output to the frame buffer 203 in order to be displayed by the thin client 230 while executing the corresponding application program (S301), the requested font data are output to the frame buffer 203 (S302). ). The font caching operation is performed to synchronize the font data stored in the video memory 234 of the thin client 230 and the data stored in the frame buffer 203.

First, it is determined whether the font data to be output to the thin client 230 is cached in the font mapping table 204 by the font caching operation (S303). If font characters to be output to the font mapping table are cached, a virtual index of the corresponding font is obtained according to the above (S305). The virtual index is already stored by the controller 206.

The control unit 206 retrieves the virtual (cache) index of the font mapping table for the font to be output, and then generates a command and a virtual index group for outputting the font to the thin client 230 through the data transmission / reception unit 207. Transfer and end (S308). The transmitted data is processed by the thin client 230 and described in detail later.

If it is found that the font data to be output is not registered in the font mapping table (S303), it is determined whether an empty cache area remains in the font mapping table 204 (S304). If it is determined that the empty cache area remains, the font is registered in the font mapping table of the server 201 and the data including the virtual index is transmitted to store the font in the cache side of the thin client 230 (S309). ). After that, the command and virtual index group for outputting the virtual cache index and the thin client 230 are terminated (S308).

If no empty cache area remains, the oldest font index in the font mapping table 204 is deleted (S306). Thereafter, a command for removing the corresponding font index in the thin client 230 is transmitted to the thin client 230. The control unit 235 of the thin client 230 removes the corresponding virtual font index and font data according to the input command and transmits the result to the control unit 206 of the server 201.

Since the controller 206 of the server 201 secures the empty cache space as described above, the virtual index includes the virtual index to store the font cache index in the thin client 230 after registering the font in the server 201 side font mapping table. Data is transmitted (S309). Thereafter, a command and a virtual cache index group for outputting the corresponding virtual cache index to the thin client 230 are transmitted (S308).

When the command and the virtual cache index group are transmitted as described above, the thin client 230 receives the data through the data transmitter / receiver 231. The method of the present invention executed in the thin client 230 is described with reference to FIG.

When data is received from the server 201 to the data transceiver 231 of the thin client 230 (C401), a process of reading the input command is performed (C402). If the read command is a command to cache the font, it is read whether a cache area remains (C403). If the empty cache area remains, the font is cached (C405), the server 201 is notified that the corresponding virtual index of the cached font is cached, and ends (C408).

If the empty cache area remains, the cache is transmitted after deleting the oldest virtual index and font data in the font cache table 233 (C406). After the cache is cached, the server 201 notifies that the corresponding virtual index of the cached font is cached and terminates (C408).

If it is not a command to cache the font (C402), it is determined whether the command is to remove (delete) the cache (C404). If the cache removal command, the server 201 is notified that the virtual index has been removed after removing the font of the cache area. However, if the command is not to delete the font cache (C404), it is determined whether the command to output the font (C409).

If the command to output the font, the font for the index is output and ends (C410). The printed font data is used for font display on the monitor screen. If the command is not to print the font (C409), the command is executed and the result is returned.

According to the present invention, by caching font data transmitted to the thin client to be displayed in the thin client according to the execution result of the application program in the server system by caching the thin client can reduce the operating load of the server system and improve the resource utilization It has an effect.

Claims (1)

In a client / server system that stores a plurality of applications and executes a specific application alone or simultaneously at the server by a request from a thin client, and transmits and displays the result data to the client. A first step of outputting corresponding font data to the allocated frame buffer when the server is requested to input fonts to be displayed according to an execution result of an application program; After outputting the font data, it is determined whether the font to be output to the font mapping table is cached, and if it is cached, the virtual index of the font mapping table of the corresponding font is obtained, and the virtual index is output to the thin client side. Transmitting a virtual index group; If the font to be printed in the font mapping table is not cached, it searches whether there is an empty cache area. If there is an empty cache area, it registers the font in the font mapping table of the server and transmits the font data to the client cache side. Transmitting a virtual index group and a command for outputting the corresponding virtual index to the thin client side; If there is no empty cache area, delete the oldest (font) index in the font mapping table, send a command to remove the corresponding font index from the thin client, register the font in the server's font mapping table, and print the font data. A fourth step of transmitting a virtual index group and a command for outputting the virtual index to the thin client side for transmission to the client cache side; A fifth step of the thin client receiving data transmitted from the server and reading a command; If the read command is a font cache command, the cache area is searched for, and if there is an empty cache area, the font is cached. If there is no empty cache area, the sixth cache is deleted after deleting the oldest virtual index and font data in the font cache table. step; A seventh step of notifying the server that the virtual index of the cached font is cached after the font cache in the sixth step; An eighth step of reading whether it is a command for removing a font if it is not a font cache command, and if not, removing the corresponding font in the font cache (table) area and notifying the server that the corresponding virtual index is deleted; Determining whether the command is a font output command if the font removal command is not a font output command, and outputting a font for the corresponding virtual index if the font output command is included, and performing a corresponding command if the font output command is not a font output command. -Font cache control method of server system.