CN105051713A - System and method of web-based keyboard, video and mouse (kvm) redirection and application of the same - Google Patents

Abstract

Certain aspects of the present disclosure are directed to a method of performing web-based keyboard, video and mouse (KVM) redirection implemented by a baseboard management controller (BMC). The method includes: (a) receiving, at a BMC, first and second video frames redirected from a host computer, the BMC performing a management function of the host computer, (b) generating a webpage at a web server of the BMC and sending the webpage to a browser program running on a computing device in a network, the webpage being programmed to instruct the browser program to initiate a drawable area and to establish a Web Socket connection with the web server, (c) generating a processed image representing the second video frame, (d) establishing a Web Socket connection between the web server and the browser program, and (e) sending the processed image to the browser program through the Web Socket connection.

Description

System and method of network-based keyboard, video and mouse (KVM) redirection and application thereof

Cross References to Related Applications

This PCT application requires a filing date of March 15, 2013, application serial number No. 13/839,151, entitled "System and method for network-based keyboard, video, and mouse (KVM) redirection and its application", and Inventors Sanjoy Maity, Baskar Parthiban, Samvinesh Christopher and Varadachari Sudan Ayanam U.S. Priority and benefit to a patent application, which is hereby incorporated by reference in its entirety.

technical field

The present invention relates to the field of computer systems, and more particularly to a system and method for network-based keyboard, video, and mouse (KVM) redirection between a host computer and a computing device.

Background technique

The background art described here is intended to summarize the content of the application. The work of the presently mentioned inventors described in this Background section, and aspects of the specification that are not admitted to be prior art as at the filing date of this application, are neither expressly nor implicitly admitted to be present in this application. have technology.

Generally, the term "computer system" refers to a stand-alone system or a plurality of interconnected systems, such as a client-server network. Regardless of their implementation, the various components that make up a computer system typically operate within a set of parameters defined by performance protocols or standards. For example, the temperature of a computer case is often monitored to detect periods in time when the system may exceed a certain preset temperature reading. Other forms of information that are monitored within a computer system include, but are not limited to, voltages associated with semiconductor devices located on the system's base board, the speed (e.g., in rpm) of cooling fans located on the base board or within the system chassis, and The speed of the spindle motor in a hard disk drive or in an optical drive.

Different types of sensors are used to detect operating and performance-related parameters related to computer systems and their component parts. See the examples provided above, these sensors include thermostats, voltmeters, and speedometers, among others. A computer system typically employs one or more management modules to assist in the collection and analysis of information sensed by various sensors for measuring operational and performance-related parameters within the system. These management modules can be software or hardware components, but typically include both software and hardware components. One such management module is called a "baseboard management controller" (BMC). The BMC is a microprocessor of a computer system, and has a specified number of contact pins through which information sensed by various sensors can be received for analysis by the BMC. In order to perform this analysis, the BMC is programmed by firmware to execute programs related to monitoring and recovery of the system. Program the BMC through this firmware to monitor various operating and performance-related parameters sensed in the computer system, and analyze the information to determine whether any sensed parameters currently exceed the expected or recommended operating range. The occurrence of these situations is commonly known as "ACCIDENT".

The BMC can perform keyboard, video, and mouse (KVM) redirection. However, there are still unresolved needs in the execution of this KVM redirection.

Contents of the invention

Certain aspects of the present application relate to a method of performing keyboard, video, and mouse (KVM) redirection. The method is implemented by a Baseboard Management Controller (BMC). The method comprises: (a) receiving the first video frame and the second video frame redirected from the host on the BMC; wherein the BMC executes the management function of the host; (b) on the network server of the BMC generating a webpage, and sending the webpage to a browser program running in a computing device through a network; wherein, the webpage is programmed to instruct the browser program to initiate (initiate) a drawable area, and communicate with the web server establishing a web socket connection; (c) generating a processed image representing said second video frame; (d) establishing a web socket connection between said web server and said browser program; and (e ) sending the processed image to the browser program through the network socket connection. In some embodiments, the method includes: (a) comparing, at the BMC, the second video frame to the first video frame to determine a first pixel of the second video frame ; wherein the first pixel has a pixel value different from that of a corresponding pixel of the first video frame; (b) generating a first tile image and related tile parameters, the first tile image represents a portion of the second video frame that includes the first pixel. In some embodiments, the method includes: sending the first tile image and tile parameters to the browser program through the network socket connection. In some embodiments, the web page is programmed to instruct the browser program to patch the first patch image on the drawable area at the position specified by the patch parameter.

In some embodiments, the method includes: (a) generating a redirected image representing the first video frame; and (b) sending the redirected image to the A browser program; wherein, the webpage is programmed to display the redirected image in the drawable area. Wherein, the drawable area is a canvas defined by HTML5. The webpage is programmed to instruct the browser program to display the redirection image on the canvas, and patch the first patch image on the displayed redirection image.

In some embodiments, the method further includes: (a) dividing the second video frame into a plurality of tiles; (b) combining the pixel value of each pixel of the second video frame with the first (c) determining a plurality of changed pixels in the second video frame; wherein the pixel value of each of the changed pixels is the same as each of the changed pixels The pixel value of the corresponding pixel of the pixel in the first video frame is different; (d) determining a plurality of changed tiles; wherein each of the changed tiles includes at least one changed pixel; (e ) generating a plurality of changed tile images; wherein each of the changed tile images represents one of the changed tiles; and (f) passing the plurality of changed tile images through the network A socket connection is sent to the browser program; wherein the web page is programmed to instruct the browser program to patch the changed patch image on the drawing area.

In some embodiments, the method further includes: (a) determining the position of each changed tile on the second video frame; and (b) according to the position represented by each of the changed tile images The position of each changed tile is generated, and the tile parameters of each changed tile image are generated. The webpage is programmed to instruct the browser program to patch each of the changed tile images on the drawing area at a position specified by the tile parameters. The tile parameters include coordinates indicating the position of the drawable area, the width of each of the changed tile images, and the height of each of the changed tile images. The webpage is programmed to instruct the browser program to capture the first event occurring on the drawable area, and send the event data of the first event to the web server; the first event is a mouse event or keyboard event. The method includes: (a) receiving event data from the browser program over the web socket connection; (b) generating input data compatible with the host and representing the event data; and (c ) sending the input data to an input controller of the host computer. In some embodiments, the first event is a mouse event, and the event data indicates an event location where the event occurs on the drawable area. The method includes: (a) determining location coordinates of the host based on the event location; and (b) generating input data representing the mouse event and location coordinates. In some embodiments, the first event is a keyboard event; wherein the event data indicates a key press. The method includes generating input data representative of the key press.

In some embodiments, the method includes: (a) based on pixel values of a plurality of surrounding pixels surrounding a given pixel and pixels on the first video frame corresponding to the given pixel and surrounding pixels A pixel value for generating a predicted value of a given pixel of the second image on the BMC; and (b) selectively replacing the pixel value of the given pixel with the predicted value according to lossy or lossless requirements , to generate an encoded image. In some embodiments, the method further comprises compressing the encoded image on the web server to generate a processed image. The web page is programmed to instruct the browser program to invoke a JavaScript routine to decompress and decode the processed image to display the decompressed and decoded image in the drawable area.

Certain aspects of the present application relate to another method of performing keyboard, video, and mouse (KVM) redirection. The method is implemented by a Baseboard Management Controller (BMC). The method comprises: (a) receiving the first video frame and the second video frame redirected from the host on the BMC; wherein the BMC executes the management function of the host; (b) on the network server of the BMC generating a web page, and sending the web page over a network to a browser program running on a computing device; (c) generating a processed image representing the second video frame; (d) storing a Java object on the network In the server; wherein, the webpage is programmed to instruct the browser program to download the Java object, wherein the Java object defines a Java display; (e) between the BMC and the downloaded Java object establishing a network connection; wherein said Java object executes on a Java virtual machine of said computing device; and (f) sending said processed image to said executed Java object.

In some embodiments, the method further includes: (a) based on pixel values of a plurality of surrounding pixels surrounding a given pixel and pixels on the first video frame corresponding to the given pixel and surrounding pixels Generate a predicted value of a given pixel of the second image on the BMC; and (b) selectively replace the pixel value of the given pixel with the predicted value according to lossy or lossless requirements value to generate an encoded image. In some embodiments, the method further includes: (a) compressing the encoded image on the web server to generate a processed image; (b) compressing the encoded image on the executed Java object decompressing and decoding the processed image; and (c) displaying the decompressed and decoded image on the Java display.

Certain aspects of the present application relate to a non-transitory computer storage medium. The non-transitory computer storage medium stores computer-executable instructions. The computer-executable instructions, when executed by a processor of a baseboard management controller (BMC) computer, cause the host to: (a) receive a first video frame and a second video frame redirected from the host ; Wherein said BMC executes the management function of mainframe; (b) generates webpage on the network server of said BMC, and said webpage is sent to the browser program running in computing equipment through network; Wherein, said webpage is programming to instruct the browser program to start a drawable area and establish a network socket connection with the network server; (c) generate a processed image representing the second video frame; establishing a network socket connection between the server and the browser program; and (e) sending the processed image to the browser program through the network socket connection.

From the detailed description provided below, the application prospects of the present application become quite clear. It should be understood that the specific description and specific examples are only used to illustrate the present application and are not intended to limit the protection scope of the present application.

Description of drawings

A more complete understanding of the present application can be obtained from the detailed specification and drawings in which:

Fig. 1 schematically describes the network-based KVM redirection system provided by one embodiment of the present invention;

Fig. 2 has described schematically the network socket connection (websocket) that an embodiment of the present invention provides;

Fig. 3 A has described the HTTP request and HTTP response of using GET instruction by example;

Fig. 3B exemplifies the network socket handshake request and response provided by one embodiment of the present invention;

Fig. 4 has schematically described network-based KVM redirection provided by an embodiment of the present invention;

Fig. 5 has schematically described network-based video redirection provided by an embodiment of the present invention;

Fig. 6 schematically describes a video frame and a patch (tile) provided by an embodiment of the present invention;

Figure 7A schematically describes the flow of video redirection provided by one embodiment of the present invention;

Fig. 7B schematically describes the flow of video redirection provided by another embodiment of the present invention;

Fig. 8 schematically describes network-based video redirection provided by another embodiment of the present invention; and

Fig. 9 schematically describes the flow of video redirection provided by another embodiment of the present invention.

Detailed ways

The following examples describe the present application in more detail and are provided by way of illustration only as various modifications and variations of these examples will become apparent to those skilled in the art. Various embodiments of the invention will now be described in detail. With respect to the drawings, like numerals, if any, indicate like structures throughout the drawings. In the specification herein and throughout the claims that follow, the meanings of "a" and "the" include plural reference unless the context clearly dictates otherwise. Likewise, in the description herein and throughout the claims that follow, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise. Moreover, the headings and subheadings used in the specification are for the convenience of the reader and have no impact on the scope of the application. In addition, some terms used in the specification will be more specifically defined below.

In the text of the application and the specific content of terms used, the terms used in this specification generally have their usual meanings in the technical field. Certain terms used in this application are discussed below or elsewhere in the specification to provide guidance to the preactitioner describing the invention. For convenience, certain terms will be emphasized, for example using italics and/or quotation marks. The use of emphasis does not affect the scope and meaning of a term; the scope and meaning of a term are the same in the same context whether or not it is emphasized. It should be understood that the same thing can be expressed in many different ways. Accordingly, there may be alternative language and synonyms for any one or more terms discussed herein, without any material effect on whether a term is mentioned or discussed herein. Synonyms for certain terms are provided. The listing of one or more synonyms does not exclude that other synonyms may also be used. Examples used anywhere in this specification, including examples of any terms discussed herein, are for illustration only and are not intended to limit the scope and meaning of the application or of any listed term. Likewise, the present application should not be limited to the various examples given in the specification.

Unless defined otherwise, all technical and scientific terms used herein have the usual meaning as understood by one of ordinary skill in the art to which this application belongs. In case of conflict, the present specification, including definitions, will control.

Generally, "about", "approximately" or "approximately" used in this application means within 20%, preferably within 10%, more preferably within 5% of a given value or range. Numerical quantities given herein are approximate, meaning that terms such as "about," "approximately," or "approximately" are inferred if not expressly stated.

As used herein, "plurality" means two and more.

The terms "comprising", "including", "having", "containing" and the like used herein are open-ended, meaning including but not limited to.

As used herein, the phrase at least one of A, B, and C should be understood as a logical (A or B or C) using a non-exclusive OR logic. It should be understood that one or more steps included in a method may be executed in a different order (or simultaneously) without changing the principles of the present application.

The term module as used herein may refer to a portion of or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a combinational logic circuit, a Field Programmable Gate Array (FPGA), a processor (shared, dedicated, or clustered) that executes code, Other suitable hardware combinations, or combinations of some or all of the above, providing the described functionality, such as a system on a chip. A module may include memory (shared, dedicated, or clustered) that stores code executed by a processor.

The above term code may include software, firmware and/or microcode and may refer to programs, threads, functions, classes and/or objects. The term shared above means that some or all code from multiple modules can be executed using a single (shared) processor. Additionally, some or all code from multiple modules may be stored in a single (shared) memory. The term clustered above means that some or all code from a single module can be executed by a group of processors. Additionally, some or all code from a single module may be stored in a cluster of memories.

The apparatus and methods described herein may be implemented by one or more computer programs executed by one or more processors. A computer program includes processor-executable instructions stored in a non-transitory tangible computer readable medium. Computer instructions may also include stored data. Non-limiting examples of non-transitory tangible computer readable media include nonvolatile memory, magnetic storage, and optical storage.

The application will be described more fully below with reference to the accompanying drawings, in which embodiments of the application are shown. However, the present application can be implemented in various forms and is not limited to the examples given herein; rather, these examples are provided so that the present application can be fully and thoroughly understood and the present Those skilled in the art will fully appreciate the scope of the present application. Like reference numerals refer to like parts.

This application relates to computer systems. As depicted in the figures, computer components may include physical hardware components represented by solid lined boxes and software components represented by dashed lined boxes. It should be understood by those skilled in the art that unless explicitly indicated, these computer components may be implemented in, but not limited to, software, firmware or hardware, or a combination thereof.

Fig. 1 schematically describes a network-based KVM redirection system provided by an embodiment of the present invention. As shown in FIG. 1 , the system 100 includes a host 110 and a computing device 140 connected to the host 110 through a network 130 . System 100 may be incorporated into more than one interconnected system, such as a client-server network. Network 130 may be a wired or wireless network and may take various forms such as a local area network (LAN) or a wide area network (WAN) including the Internet.

Host 110 may be a general purpose computer system. The host 110 includes a substrate 111, or called "mainboard". The substrate 111 is a printed circuit board to which various components or devices may be connected via a system bus or other electrical communication paths. Although not explicitly shown in FIG. 1 , the components on the substrate 111 are interconnected, and the wiring of the components on the substrate 111 and the interconnection of the components on the substrate 111 are referred to herein as the configuration of the substrate 111 . Those skilled in the art should understand that the structure of the substrate 111 can be adjusted and changed according to design requirements and manufacturing requirements.

Components on base board 111 include, but are not limited to, central processing unit (CPU) 112, memory 113, base board controller (BMC) 120, and other required storage and input/output (I/O) modules (not shown). The CPU 112, the memory 113, and the BMC 120 may be embedded in the substrate 111, or may be connected to the substrate 111 through an interface. In some embodiments, an interface may be a physical hardware interface, such as an electrical connector, bus, port, cable, terminal, or other I/O device.

The CPU 112 is a main processor for controlling the operation of the host computer 110 . The main processor may execute an operating system (OS) or other applications of the host 110 . In some embodiments, host 110 may have more than one CPU acting as the main processor, such as two CPUs, four CPUs, eight CPUs, or any suitable number of CPUs.

The memory 113 may include volatile memory, such as random access memory (RAM), for storing data and information during operation of the host 110 .

BMC120 refers to a dedicated microcontroller that manages the interface between system management software and platform hardware. Various different types of sensors can be built into the system 100 and read by the BMC 120 to obtain parameters such as temperature, cooling fan speed, power status, operating system (OS) status, and the like. The BMC 120 monitors the sensors and if any parameter is not within preset limits the BMC 120 can send an alert over the network to the system administrator, indicating a potential failure of the system 100 . Administrators can also remotely communicate with the BMC120 to take corrective action, such as resetting or rebooting the system to bring a hung operating system back into operation. Further, BMC 120 may include a KVM redirection module 122 for redirecting video and input signals between computing device 140 and host 110 . Thus, a user can initiate a KVM session from computing device 140 to view the video output of host 110 and enter data on host 110 through the input devices of computing device 140 .

In some embodiments, the firmware of BMC 120 complies with the Intelligent Platform Management Interface (IPMI) industry standard for system monitoring and fault recovery. The IPMI protocol is a standardized computer system interface protocol for out-of-band management and operation monitoring of computer systems. The protocol is session-based and requires the establishment of an IPMI between the application module and the target IPMI device before the application module can communicate with the target IPMI device. session. The IPMI specification provides a generic message-based interface for accessing all manageable features of a compatible computer, and includes a large number of predefined commands for reading temperature, pressure, fan speed, chassis disturbance, and other parameters. System fault logs, hardware monitors, and power controls are also available through IPMI. Thus, IPMI defines various parameters for obtaining BMC collected through the operating system or through an external connection, such as through a network or a serial port connection. The BMC can receive IPIM commands or requests from the locally connected management computer through the system interface, or receive external requests from the locally connected management computer through the network interface.

Additionally, in some embodiments, BMC 120 includes a KVM redirection module 122 , a web socket module 124 and a web server module 126 . The KVM module 122 performs KVM redirection functions. The network socket module 124 can establish a full-duplex communication channel through a single transport connection protocol (TCP) connection under the network socket protocol. The web server module 126 may provide web content accessible through the Internet. The details of each module will be described later.

Further, the host 110 includes a memory 114 and at least one I/O device 116 . The memory 114 is a data storage medium for storing an operating system (not shown) of the host 110 and other applications. Examples of memory 114 may include flash memory, memory cards, USB drives, hard drives, floppy disks, optical drives, or other types of data storage. Examples of I/O devices 116 include a keyboard, touch screen, mouse, microphone, display screen, touch screen, or other I/O devices available to host 110 .

Computing device 140 is remotely connected to host 110 through network 130 . Those skilled in the art should understand that the system 100 may include multiple computing devices 140 remotely connected to the host 110 at the same time. Examples of computing device 140 include, for example, portable devices such as smartphones, PDAs, or other removable computing devices.

Computing device 140 includes CPU 171 , memory 173 and storage 142 . Memory 142 is a data storage medium for storing an operating system or other applications of computing device 140 . Examples of memory 142 of computing device 140 may include flash memory, a memory card, a USB drive, a hard drive, a floppy disk, an optical disk, or other types of data storage.

The browser program 143 can be downloaded into the memory 173 and can be executed by the CPU 171 of the computing device 140 . Browser program 143 is a software application for acquiring, presenting, and delivering information resources to users. Further, the browser program 143 can serve as a KVM redirection client for the system 110 to communicate with the BMC 120 . In general, the browser program 143 can obtain information resources provided on an open network, such as the Internet. Information resources may include web pages, pictures, videos, or other types of data content.

Further, the memory 173 can load the operating system 114 and the network socket module 145 . The network socket module 145 is a module corresponding to the network socket module 124 of the BMC 120 on the host 110 , so that a full-duplex communication channel under the network socket protocol can be established between the BMC 120 and the computing device 140 .

Further, computing device 140 includes at least one I/O device 146 . Examples of I/O devices 146 include keyboards, touch screens, mice, microphones, display screens, touch screens, or other I/O devices suitable for computing device 140 . Some I/O devices, such as touch screens, are used to provide bi-directional input/output to computing device 140 .

For displaying information resources such as web pages and other data content using the browser program 143, Hypertext Markup Language (HTML) is a standardized markup language based on the web language format used to display web pages and can be displayed in the browser program 143 additional information for . Data in HTML format is written using HTML elements, or "tags," which are enclosed in angle brackets (eg <html>) within web content. Currently, the HTML format is widely adopted by almost all browser programs on the market, so it is suitable as a web-based communication command between the browser program 143 on the computing device 140 side and the web server 126 of the BMC 120 on the host computer 110 side. language format.

Generally, in addition to the HTML format language, a scripting language such as JavaScript is used to control input and output of a user interface. Further, HTML5, a newly developed version of the HTML language, provides a large number of properties for web storage, which utilizes web application software methods and protocols for storing data through web browsers. Previously commonly used browser programs do not support HTML5 format, but browser programs that support HTML5 format include MOZILLAFIREFOX1.5, GOOGLECHROME4.0, SAFARI3.1, SAFARIMOBILE3.2, OPERA9.0, OPERAMOBILE10.0, ANDROIDBROWSER2.1 and INTERNETEXPLORER9. 0, or any newer versions of these browser programs. Accordingly, the browser program 143 may support HTML5 and may be one of the browser programs listed above.

Browser program 143 may communicate with web server 126 on the BMC using hypertext transfer protocol (HTTP). Specifically, the browser program 143 can send an HTTP request to the web server 126 . Once the HTTP request is received, the server sends an HTTP response to the browser program in response to the HTTP request.

Normally, under HTTP, the web server 126 cannot initiate data transmissions to the browser program 143 . The network socket can provide a full-duplex communication channel on a single TCP connection, so that the server can actively send instructions or information to the client. Web sockets are incorporated into HTML5 so they can be supported by web browsers and servers implementing HTML5.

FIG. 2 shows a process of establishing a network socket connection between the host 110 and the computing device 140 provided by an embodiment of the present invention. A web socket connection is initiated in a similar manner to an HTTP connection, but provides a continuous bi-directional network-based connection between the host computer 110 and the browser program 124 . When the browser program 143 tries to establish a web socket connection, the browser program 143 instructs the web socket module 145 to send a web socket handshake request to port 80 (the default HTTP port) or the web socket module 124 of the BMC 120 port 443 (HTTPS port). A web socket handshake request is similar to the GET command used in HTTP requests, but it includes more web socket commands and can be considered an "upgraded" request. Once the web socket handshake request is received, the web server 126 can recognize that the request is a web socket handshake request instead of an HTTP request according to the updated information in the web socket handshake request. The web server 126 sends the handshake response message to the browser program 143 . Accordingly, a web socket connection 150 between the browser program 143 and the web server 126 may be established.

Figures 3A and 3B provide a comparison between a web socket handshake request and an HTTP request, where Figure 3A shows an example of an HTTP request using the GET instruction, while Figure 3B shows an example of a web socket handshake request one example. As shown in FIG. 3A , the header of the response information in response to the HTTP request indicates content information in the response information, including the type of the content as text/webpage file, the length of the content file, and the language used in the content. The last line of the header of the response message in response to the HTTP request is used to indicate that the connection between the host 110 and the browser program 124 is closed at the end of the response. In contrast, the first two lines of the web socket handshake request shown in Figure 3B contain the same GET instruction as the HTTP request. Subsequent lines of the web socket handshake request include upgrade information for notifying the web socket module 124 to upgrade or switch from regular HTTP requests to the web socket protocol. Further, unlike the response information in response to the HTTP request, the header of the handshake response information in response to the web socket handshake request does not indicate to close the connection at the end of the response.

Once the web socket connection 150 is established, both the web socket module 124 and the web socket module 145 can send data over the connection to the other end. The data format can be any valid UTF-8 string format, such as JSON or XML, but other data formats can be used if desired.

The network socket modules 124 and 145 can be of various types and designs, such as PHP network socket, Java network socket, Web-Socket-ruby, socket input and output mode (SocketIO-mode), or other types web socket application. In order to set the web socket module 124 as a web socket server on the host 110 side, the domain name or IP address of the host 110 and the port used (such as port 80 or 443) must be provided to indicate the location of the host 110, and a Multiple instructions in response to certain "accidents", such as opening a socket (i.e. a web socket connection), receiving a handshake request or other information in a socket, or closing a socket. When the web socket server is established, the web socket client can use the uniform resource location address (URL) to connect to the web socket server. The uniform resource location address system starts with "ws", which replaces the beginning of the regular HTTP system "http"; or "wss" at the beginning of the Uniform Resource Locator address system, replacing the beginning "https" of the conventional HTTP system.

FIG. 4 shows network-based KVM redirection provided by an embodiment of the present invention. As shown in FIG. 4 , a network socket connection 150 is established between the BMC and computing device 140 . The host 110 may include a video controller 117 for outputting video signals and a redirection controller 118 as an I/O port for video redirection. In this embodiment, the KVM redirection module 122 of the BMC 120 is connected to the redirection controller 118 and the I/O controller 116 respectively. The KVM redirection module can receive redirected video frames from the redirection controller and send keyboard and mouse input signals to the I/O controller 116 .

The computing device 140 includes a display device 147 and input devices such as a keyboard 148, a mouse 149, and a touch screen. Although not shown, the host 110 and computing device 140 may include other elements to perform network-based KVM redirection.

Fig. 5 schematically illustrates network-based KVM redirection in some embodiments of the present invention. As shown, the host 110 has a video controller 117 for outputting video signals. For example, video signals may be output to a display device for display. Video controller 117 is in communication with redirection controller 118 for capturing video signals and generating video frames. The redirection controller then sends the video frames to the KVM redirection module 122 of the BMC 120 .

For example, the KVM redirection module 122 receives the video frames 152 and 154 from the host, processes the video frames, generates a redirection image, and then sends the redirection image to the network server. Upon receiving a request from a browser running on computing device 140, the web server will send a KVM redirect web page to the browser. Under the direction of the web page, the browser will retrieve (retrieve) the redirected image from the web server.

In some embodiments, the web server is configured to generate a KVM redirection web page using an HTML5 supported canvas. The redirected web page includes the canvas tag, which defines the drawable area where the browser displays the page. The canvas tag is one of the elements provided by HTML5 for generating images and video files, and allows dynamic and scriptable rendering of shapes and bitmap images. The Canvas tag defines the height and width properties of the drawable area. JavaScript code can access the drawable area through a set of drawing functions and dynamically display the generated image on the drawable area defined by the canvas tag. The Canvas tag itself does not have the ability to draw, and can be regarded as a container for images. Typically, a Canvas tag has an ID that can be referenced by JavaScript code. FIG. 5 shows that the KVM redirection page rendered by the browser program 143 has a canvas.

Based on configuration information entered by the user, or optionally a default configuration, the web server can set the size of the canvas in the KVM redirection web page. For example, the user may expect it to have the same resolution as the video frame output by the video controller. In other words, each pixel of the video frame output by the video controller has a respective corresponding pixel on the canvas. For example, if the video pixels of a video frame are 1024*768, the canvas defined by the canvas tag can be set to have a width of 1024 and a height of 768 accordingly. As another example, a user may desire to have half the resolution of a video frame. Therefore, if the video resolution of the video frame is 1024*768, the canvas defined by the canvas tag is set to a width of 512 and a height of 384. Generally, in the following description, a one-to-one correspondence between video frame resolution and canvas resolution is used as an example. Those skilled in the art should understand that the techniques discussed below are equally applicable to canvases whose resolutions have other correspondences with video frame resolutions.

KVM redirection module 122 receives first and second video frames 152 and 154 from redirection controller 118 of host 110 . When the first frame 152 was the initial frame received by the KVM redirection module, that is, the KVM redirection module 122 did not receive a video frame before, then the KVM redirection module produced the first frame with all pixel information in the first frame 152. a redirection image 157 and send the first redirection image 157 to the web server 126 . The redirected image is in a format that the browser program 143 can render. The web server 126 then sends the first redirection image 157 to the browser program through the techniques described below.

Upon receiving the second video frame 154, the KVM redirection module 122 compares the second frame 154 with the copy of the first frame 152 retained in the KVM redirection module 122, and detects any discrepancy between the first frame and the second frame. Whether there are different values in the corresponding pixels. When a difference is detected, the KVM redirection module 122 generates a patch (patch) containing the pixel information of the relevant pixel of the second frame 154 that is different from the corresponding pixel of the first frame 152 , and sends the patch to the network server. As described in detail below, web server 126 sends the patch to browser program 143 of computing device 140 , and browser program 143 may patch the canvases in corresponding regions 170 and 172 accordingly.

FIG. 6 shows a first video frame 152 and a second video frame 154 . In this example, the KVM redirection module 122 divides each video frame into 30 tiles, wherein the 30 tiles form a matrix form with 5 rows and 6 columns. The number of tiles is configurable. For example, the default patch configuration can be a 16*16 matrix. The KVM redirection module 122 compares the pixel values of the first video frame and the second video frame on a pixel-by-pixel basis. In other words, the KVM redirection module 122 determines whether the value of any pixel of the second video frame is different from the value of the corresponding pixel of the first video frame. If any pixel within the tile of the second video frame 154 has changed compared to the corresponding pixel of the first image frame 152, the KVM redirection module 122 determines that the tile has changed. For example, as shown in FIG. 6 , compared to the first frame 152, the tiles 615′, 625′, 622′, 623′, 632′, 633′, 642′, and 643′ of the second frame have changed. The KVM redirection module 122 therefore sends only the pixel values of the tiles 622', 623', 632', 633', 642', 643', 615' and 625' as tile images and the tile parameters to the web server 126 . The tile position is indicated by the coordinates of the video frame; wherein, the tile location is included in the tile parameter. The location of a tile is typically defined as the location (eg, coordinates) of the upper left corner of the tile.

The web server 126 receives the patch coordinates as a part of the patch parameters, and determines whether to convert the video frame coordinates of the patch image into browser coordinates, so that the browser program can correct the currently rendered redirected image. For example, the tile parameter (x, y, W, H) received by the web server may indicate that the location of the tile is at the coordinate (x, y) of the video frame, and the tile has a width of W and a height of H. The width and height parameters are optional.

When the resolution of the canvas is configured to have a one-to-one correspondence with the resolution of the video frame, that is, each pixel of the video frame has a corresponding pixel on the canvas, then the network server 126 can determine the tile parameter (x , y, W, H) can also be used directly by the canvas without transformations to patch patches on the canvas. The web server can convert the tile image received from the KVM redirection module 122 into a different format that the browser program 143 can render. The patch image can be in different image or picture file formats, such as commonly used JPEG, PNG or BMP formats, or other image file formats that can be displayed by the browser program 143 . The web server 126 then sends the tile image with tile parameters to the browser program 143 as described below. The browser program 143 accordingly uses the tile image to patch the canvas within the area specified by the tile parameter. For example, a redirect webpage generated by a web server may have JavaScript code for instructing the browser to patch a tile image on the canvas, eg context.drawlmage(tile, x, y, W, H). When the resolution of the canvas is configured to have other ratios (such as 1:2) relative to the resolution of the video frame, then the web server 126 can convert the video frame coordinates into browser coordinates (such as x/2, y/ 2, W/2, H/2). FIG. 5 shows browser program 143 initially displaying first redirection image 157 on canvas 160 . After the BMC 120 sends the patch including one or more patches 170 and 172 to the browser program 143 , the browser program 143 then patches the first redirected image 157 to generate the second redirected image 159 .

The web server 126 can send the sticker image to the browser program 143 in various ways. For example, the network server 126 may store the patch image and its patch parameters at a predetermined location of the network server. The redirection web page generated by web server 126 may instruct browser program 143 to periodically check a predetermined location to determine if a new patch is available. Optionally, the redirected webpage may instruct the browser program 143 to establish a network socket connection with the web server, and the network server may then send the patch image with patch parameters to the browser program 143 through the network socket connection.

In some embodiments, the tile image can be in various formats, such as PNG, BMP, JPEG, and so on. The web server 126 may identify each tile of the video frame by an identifier, such as a numerical value or a letter. Web server 126 may send the tile image and its identifier to browser program 143 via web socket connection 150 . For example, the web server 126 may send the sticker image #5 to the browser program 143 . The canvas 160 on the browser program 143 may be divided into tiles corresponding to tiles of video frames. In other words, each tile identifier may also identify a single tile on canvas 160 . The redirected web page rendered by the browser program 143 correspondingly has a JavaScript path that can draw the received tile image in the tile area on the canvas 160 identified by the identifier. After receiving the tile image #5, the redirection webpage correspondingly instructs the browser program to draw the tile image (for example, PNG, JPEG or BMP format) in the area marked as #5 on the canvas.

Fig. 7A shows the flow of video redirection using web socket connection and HTML5 canvas according to some embodiments of the present invention. In operation 710 , the browser program 143 sends a request for the KVM redirection web page to the BMC 120 through the network 130 . The request may be in HTTP format. Once the request for the KVM redirection webpage is received, the web server 126 of the BMC 120 sends the KVM redirection webpage to the browser program 143 in operation 720 . Accordingly, the browser program 143 may display a KVM redirection webpage to the user, enabling the user of the computing device 140 to input or select configuration information of the KVM redirection module 122 of the BMC 120 in operation 722 . The configuration information for the KVM redirection module may include redirection image resolution information, redirection image refresh rate information, machine and network settings, authentication settings, and other information for KVM redirection. Then, in operation 724 , the browser program 143 sends the configuration information to the web server 126 of the BMC 120 , for example, using the HTTP protocol. Once receiving the configuration information, the web server 126 correspondingly sends the configuration information to the KVM redirection module. In operation 730, the BMC 120 sets up the KVM redirection module 122 accordingly. The KVM redirection module can establish a connection with the redirection controller 118 of the host computer 110 .

In operation 760, the browser program 143 sends a web socket handshake request to the web server 126 to establish a full-duplex communication connection under the web socket protocol. Upon receiving the web socket handshake request, in operation 762 the web server 126 instructs the web socket module 124 to open the web socket. Similarly, in operation 764, the browser program 143 instructs the web socket module 145 to open the web socket. Accordingly, in operation 766 a web socket connection is established between the web socket module 124 and the web socket module 145 .

Once the network socket connection is established, the BMC 120 can start redirecting the video output from the host 110 to the browser program 143 through the network socket connection. Specifically, in operation 770 , the KVM redirection module receives the first video frame of the host 110 . The KVM redirection module then processes the first video frame to generate a first redirection image, and sends the first redirection image to the network server 126 . In operation 772 , the web server 126 sends the first redirected image to the web socket module 124 . In operation 774, the web socket module 124 sends the first redirected image to the web socket module 145 of the computing device through the web socket connection. In operation 776 , the web socket module 145 sends the first redirection image to the browser program 143 . In operation 778, the browser program 143 may then display the first redirected image on the canvas 160 as indicated by the redirected web page.

Subsequently, the KVM redirection module 122 receives the second video frame from the host 110 in operation 780 . The KVM redirection module 122 then compares the second video frame with the first video frame to determine whether each pixel of the second video frame has a different pixel value than the corresponding pixel of the first video frame. If any pixel in the second video frame changes, the KVM redirection module 122 correspondingly generates one or more tile images and related tile parameters. The KVM redirection module 122 sends the patch image and patch parameters to the network server 126 . The web server then converts the tile image to a format supported by the browser program 143, if necessary. In operation 782 , the web server 126 of the BMC 120 sends the tile image and parameters to the web socket module 124 . In operation 784, the web socket module 124 sends the tile image and parameters to the web socket module 145 through the web socket connection. In operation 786 , the web socket module 145 transmits the tile image and parameters to the browser program 143 . In operation 788, the browser program 143 may patch the first redirected image on the canvas with the received tiled image within the area specified by the tiled parameter as indicated by the KVM redirected webpage.

FIG. 7B shows a flow of video redirection using a network socket connection 150 and specific image processing techniques according to some embodiments of the present invention. In this example, KVM redirection module 122 initially forwads to browser program 143 a first redirection image representing the first frame. Correspondingly, the browser program 143 can display the first redirection image in the display area 161 of the browser program 143 . KVM redirection module 122 may then process a second redirected image representing second frame 154 using a different encoding and compression technique. The processed (ie encoded and compressed) second redirected image is then transmitted to the browser program 143 via the web socket connection 150 . The redirected web page received by the browser program 143 includes a JavaScript path that can be used to instruct the browser program 143 to decompress and decode the processed second redirected image. After the browser program 143 decompresses and decodes the processed second redirection image to obtain a display image, the browser program 143 can display the image in the display area of the browser program 143 .

One such processing technique (ie, encoding/decoding and compression/decompression) is disclosed in US Patent Nos. 7,567,717 and 7,970,218, which are expressly incorporated herein by reference. Briefly, as disclosed in these patents, based on the values of the pixels surrounding a given pixel in the second redirected image and the values of the corresponding pixels in the first redirected image, the KVM redirection module 122 can generate The predicted value for a given pixel of the redirected image. Further, according to lossy or lossless requirements, the KVM redirection module 122 selectively replaces the actual value of a given pixel in the second redirected image with a predicted value, and then encodes the second redirected image accordingly. Subsequently, the KVM redirection module 122 compresses the encoded second redirected image using a predetermined algorithm, such as a reduced run-length encoding ("RLE") algorithm, and thereby obtains a processed second redirected image. Additionally or alternatively, the KVM redirection module 122 may process the second redirected image using conventional image compression techniques. Wherein, the conventional image compression technology includes lossless image compression method and lossy image compression method. Wherein, the lossless image compression method is such as DPCM, entropy coding, deflation or chain coding compression; and the lossy image compression method is such as color space reduction, sub-sampling or transform coding.

In particular, operations 710 through 776 shown in FIG. 7B are similar to corresponding operations in FIG. 7A . In operation 779 , the browser program 143 displays the first redirection image in the browser display area 161 of the browser program 143 . In operation 781, the KVM redirection module 122 receives a second video frame of the host 110, and generates a second redirection image. The KVM redirection module 122 then processes the second redirected image using the techniques discussed above to generate a processed (ie, encoded and compressed) image. In operation 783 , the web server 126 of the BMC 120 sends the processed image to the web socket module 124 . In operation 784 , the web socket module 124 sends the processed image to the web socket module 145 over the web socket connection 150 . In operation 787 , the web socket module 145 sends the processed image to the browser program 143 . In operation 78, the browser program 143 may decompress and decode the processed image to obtain an image for display, e.g. Display the image.

Fig. 8 schematically shows network-based KVM redirection according to another embodiment of the present invention. In the present embodiment, computing device 140 includes a Java Virtual Machine (JVM) 166 . Alternatively, the JVM can be downloaded from the web server 126 of the BMC 120 through the browser program 143 .

Initially, the browser program 143 connects with the web server 126 of the BMC 120 to receive a redirected web page. The user can input verification information, and send the verification information to the web server through the redirection webpage. The web server 126 authenticates the user and then sends the session token to the browser program 143 . Web server 126 stores precompiled Java objects 164 that are executable by a JVM on computing device 140 . The browser program 143 downloads the Java object 164 with the permission of the user operating the browser program. Java object 164 is then executed in the JVM of computing device 140 . The Java object launches a Java display module 163 that can be used to display redirected images and patches. The Java display module 163 renders images on the display device 147 . The browser program 143 passes the session token received from the web server 126 to the Java object 164 . Java object 164 may establish connection 151 with redirection server 122 . Typically, connection 151 is established between TCP/IP socket 195 of computing device 140 and TCP/IP socket 125 of BMC 120 . Through JVM 166 , the Java object 164 can instruct the operating system 144 to open a TCP/IP socket 195 for the Java object 164 . Using the session token, the Java object 164 can establish a communication channel for the session with the KVM redirection module 122 .

After the communication channel is established, the KVM redirection module 122 can send the redirection image and patch to the Java object through the communication channel. The Java object 164 calls the Java display module 163 to display redirected images and patches. Based on the user's configuration of the desired resolution of the redirected image, the Java object 164 sets the Java display module 163 to the desired resolution. The Java object 164 can define a function, such as drawImage(), which can display a complete redirected image on the Java display module 163 when this function is called, and patch the Java display module 163 with a patch image in a specified area. Similar to the canvas 160 , the Java object 164 can take coordinate parameters to draw tile images on the Java display module 163 .

Alternatively, with respect to FIG. 7B, KVM redirection module 122 may process redirected images as described above. Subsequently, the KVM redirection module 122 sends the processed image to the Java object 164 through the communication channel. The Java object 164 can decompress and decode the processed image to obtain an image for display. Subsequently, the Java object 164 can display an image on the Java display module 163 .

FIG. 9 shows the flow of video redirection using Java objects according to some embodiments of the present invention. In operation 910, the browser program 143 sends a KVM redirect web page request to the BMC 120 through the network. The request may be in HTTP format. Once the request for the KVM redirection webpage is received, in operation 920 , the web server 126 of the BMC 120 sends the KVM redirection webpage to the browser program 143 . Therefore, in operation 922 , the browser program 143 may display the KVM redirection webpage to the user, and allow the user of the computing device 140 to input or select configuration information of the KVM redirection module 122 . The configuration item information of the KVM redirection module may include redirection image resolution information, redirection image refresh rate information, machine and network settings, authentication settings, and other information for KVM redirection. Then, in operation 924 , the browser program 143 sends the configuration information to the web server 126 of the BMC 120 , for example, using the HTTP protocol. The web server 126 correspondingly sends the configuration information to the KVM redirection module 122 . Browser program 143 also requests Java objects from web server 126 . Once the configuration information is received, in operation 926 the web server 126 configures the Java object 164 if necessary and then sends the Java object 164 and the session token to the browser program 143 . Once the Java object 164 is received, the browser program 143 starts the Java object 164 on the JVM 166 and passes the session token to the Java object 164 in operation 928 .

Meanwhile, in operation 930, the BMC sets the KVM redirection module 122 accordingly. The KVM redirection module 122 can establish a connection with the redirection controller 118 of the host 110 .

In operation 960, the Java object 164 initiates a communication connection with the KVM redirection module 122 by employing the session token. In operation 966 , a TCP/IP connection is established between the TCP/IP socket module 195 of the computing device 140 and the TCP/IP socket module 125 of the BMC 120 .

Once the TCP/IP connection is established, the BMC 120 can start redirecting the video output from the host 110 to the Java object 164 through the TCP/IP connection. Specifically, in operation 970 , the KVM redirection module receives a first video frame, or frame 1 , from the host 110 . The KVM redirection module may process (ie, encode and compress) the first video frame to generate a processed first redirected image. In operation 972 , the KVM redirection module 122 sends the processed first redirection image to the TCP/IP socket module 125 . In operation 974 , the TCP/IP socket module 125 sends the processed first redirected image to the TCP/IP socket module 195 of the computing device 140 over the TCP/IP connection. In operation 976 , the TCP/IP socket module 195 sends the first compressed image to the Java object 164 . In operation 978, the Java object 164 decompresses the compressed image. In operation 979 , the Java object displays the decompressed image in the Java display module 163 .

Subsequently, in operation 980 , the KVM redirection module 122 receives the second video frame from the host 110 . The KVM redirection module 122 then processes (ie, encodes and compresses) the second video frame and thereby generates a processed second redirected image. In operation 982 , the KVM redirection module sends the processed second redirection image to the TCP/IOP socket module 125 . In operation 984 , the socket module 125 sends the processed second redirected image to the TCP/IP socket module 195 of the computing device 140 over the TCP/IP connection. In operation 986 , the TCP/IP socket module 195 sends the second compressed image to the Java object 164 . In operation 988, the Java object 164 decompresses and decodes the processed second redirected image and generates a second image for display. In operation 989 , the Java object displays the second image in the Java display module 163 .

Referring back to FIG. 4, in some embodiments, input redirection, including keyboard and mouse redirection, is performed concurrently with video redirection. The browser program 143 can receive input signals from input devices such as a keyboard 148, a mouse 149, and a touch screen. Browser program 143 may send input data to web socket 124 of BMC 120 via web socket connection 150 . When the network socket 124 of the BMC 120 receives input data, the network socket 124 passes the input data to the network server 126, and the network server 126 can process the input data to retrieve keyboard and mouse input. The web server 126 sends keyboard and mouse input to the KVM redirection module 122 . If desired, KVM redirection module 122 may convert keyboard and mouse input to the format used by host 110 and send the input to I/O controller 116 . In this way, the host 110 can treat the input from the browser program 143 as input from the local input device.

Using operating system 144 , browser program 143 may generate input events representing input from keyboard 148 and mouse 149 pointing at browser program 143 . For example, on keyboard 148, when a key is pressed, a keyboard action will occur. Some keyboard actions may involve combinations of multiple keys being pressed simultaneously. Such keyboard actions are typically associated with specific function keys of the keyboard 148, such as the Ctrl key, Atl key, or Shift key, which are expected to work in combination with other keys. In such actions, this combination will produce a different key entry than each individual key entry. Each keyboard action will generate corresponding input data, which may include character codes, or other representative values corresponding to keyboard events.

The mouse can perform many different actions, such as placing the mouse cursor over a specific area, moving the mouse cursor, scrolling the mouse wheel, and clicking (single-clicking or double-clicking) a mouse button. In some embodiments, the above actions can be combined, for example, clicking a mouse button while placing the mouse cursor in a specific area, or "dragging" the mouse, ie clicking a mouse button and moving the mouse cursor without releasing the button. Generally, mouse events can be divided into several categories, such as click events, drag events, and move events.

JavaScript provides functions and event objects corresponding to these mouse and keyboard actions. For example, a click action may include a mouse down event and a mouse up event, which respectively refer to an action in which a mouse button is pressed and an action in which the pressed mouse button is released. Movement actions may include mouse movement events, which refer to moving the mouse cursor from one location to another. A drag action refers to a combination of a mouse down event, a mouse move event, and a mouse up event. Examples of other JavaScript functions and test drives related to mouse events may include a mouseover event, which involves moving the mouse cursor to a predetermined area on the screen; and a mouseenter event, which involves moving the mouse The cursor moves to a predetermined area on the screen. JavaScript also provides the getMousePos() function for use in combination with mouse movement events. Each mouse event can include multiple parameters. For example, when a mouse down event occurs, the event will generate a code representing the mouse down event and a coordinate parameter representing the position of the mouse cursor where the mouse down event occurs.

In some embodiments, when an event occurs on the canvas 160 or the Java display module 163, the KVM redirects the web page to capture the location of the mouse event. For example, a redirection image displayed on canvas 160 of browser program 143 may show a user interface output by host 110 . The user may use the mouse of the computing device 140 to click the mouse of the user interface displayed on the canvas. The redirect webpage may have a JavaScript path that detects the location of the mouse event and the coordinates that detect the generation of the mouse event relative to the canvas 160 or Java display module 163 . At locations where the canvas 160 or Java display module 163 has a one-to-one relationship with the resolution of the video frame output by the video controller 117 of the host 110, these browser coordinates also indicate the desired location on the host 110 for redirected mouse events . In other cases, the web server 126 may convert the browser coordinates obtained from the browser program 143 into video frame coordinates on the host 110 to correctly display the desired coordinate position of the redirected mouse event on the host 110 .

For example, referring back to FIG. 5 , while canvas 160 of browser program 140 displays redirection image 159 , a user of computing device 140 may use a mouse to click on location 180 on the canvas. Therefore, the browser program 143 can use JavaScript (including the mouse down event and the getMousePos() function) to obtain the coordinate parameters of the mouse click position 180 , and send the mouse click event data to the BMC 120 . The BMC 120 then converts the mouse click data into a format used by the host 110 and sends the event data to the input controller 116 of the host 110, if necessary.

The foregoing description of the above exemplary embodiments of the present application has been presented for purposes of illustration and description, and is not intended to be exhaustive or to limit the application to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.

The embodiments were chosen and described in order to explain the principles of the application and its practical application to enable others skilled in the art to practice the application and various embodiments with various modifications to various intended uses. Alternative embodiments will be apparent to those skilled in the art to which this application pertains without departing from the spirit and scope of the application. For example, various detectors may be used simultaneously to practice the invention. Accordingly, the scope of the application is to be determined by its claims rather than the foregoing specification and the exemplary embodiments described therein.

Claims (25)

1. A method of performing network-based keyboard, video and mouse (KVM) redirection implemented by a baseboard management controller (BMC), comprising: Receiving the first video frame and the second video frame redirected from the host on the BMC; wherein the BMC performs a management function of the host; Generate a webpage on the network server of the BMC, and send the webpage to the browser program running in the computing device through the network; wherein, the webpage is programmed to instruct the browser program to start the drawable area, and establishing a network socket connection with the network server; generating a processed image representing the second video frame; establishing a web socket connection between the web server and the browser program; and sending the processed image to the browser program through the network socket connection. 2. The method according to claim 1, wherein generating the processed image comprises: On the BMC, comparing the second video frame with the first video frame to determine a first pixel of the second video frame; wherein the first pixel has the same A pixel value with a different pixel value from the corresponding pixel of the frame; generating a first tile image representing a portion of the second video frame including the first pixel and associated tile parameters; Wherein, sending the processed image includes: sending the first patch image and patch parameters to the browser program through the network socket connection; wherein, programming the web page to indicate the The browser program patches the first patch image on the drawable area at the position specified by the patch parameter. 3. The method of claim 2, comprising: generating a redirected image representative of said first video frame; and sending the redirected image to the browser program through the network socket connection; wherein the webpage is programmed to display the redirected image in the drawable area. 4. The method according to claim 3, wherein the drawable area is a canvas defined by HTML5; wherein, the webpage is programmed to instruct the browser program to display the reprint on the canvas. orienting an image, and patching the first patch image on the displayed redirected image. 5. The method of claim 3, comprising: dividing the second video frame into a plurality of tiles; comparing the pixel value of each pixel of the second video frame with the pixel value of a corresponding pixel of the first video frame; determining a plurality of changed pixels in the second video frame; wherein the pixel value of each of the changed pixels is the same as that of a corresponding pixel of each of the changed pixels in the first video frame different values; determining a plurality of changed tiles; wherein each of the changed tiles includes at least one changed pixel; generating a plurality of changed tile images; wherein each of said changed tile images represents one of said changed tiles; and sending the plurality of changed patch images to the browser program through the network socket connection; wherein the web page is programmed to instruct the browser program to patch the changed patch images in on the drawing area. 6. The method of claim 5, comprising: determining the position of each changed tile on the second video frame; and According to the positions of the respective changed tiles represented by each of the changed tile images, tile parameters of each of the changed tile images are generated; wherein, the webpage is programmed to instruct the browser The program patches each changed patch image on the drawing area at the position specified by the patch parameter. 7. The method according to claim 6, wherein the tile parameters include coordinates indicating the position of the drawable area, the width of each of the changed tile images, and the width of each of the changed The height of the tile image. 8. The method according to claim 1, wherein the web page is programmed to instruct the browser program to capture a first event that occurs on the drawable area, and convert the event of the first event to The data is sent to the network server; the first event is a mouse event or a keyboard event; the method includes: receiving event data from the browser program over the web socket connection; generating input data compatible with the host and representative of the event data; and The input data is sent to an input controller of the host computer. 9. The method according to claim 8, wherein the first event is a mouse event, and the event data indicates an event location where an event occurs on the drawable area; the method comprises: determining location coordinates of the host based on the event location; and Input data representing the mouse event and position coordinates are generated. 10. The method according to claim 8, wherein the first event is a keyboard event; wherein the event data indicates a key; the method comprises: Input data representing the key press is generated. 11. The method of claim 1, comprising: generating the second image on the BMC based on pixel values of a plurality of surrounding pixels surrounding a given pixel and pixel values of pixels on the first video frame corresponding to the given pixel and surrounding pixels the predicted value for a given pixel; and selectively replacing the pixel value of the given pixel with the predicted value according to lossy or lossless requirements, so as to generate a coded image. 12. The method of claim 11, comprising: compressing the encoded image on the web server to generate a processed image; wherein the web page is programmed to indicate the The browser program invokes a JavaScript path to decompress and decode the processed image, so as to display the decompressed and decoded image in the drawable area. 13. A method of performing network-based keyboard, video, and mouse (KVM) redirection implemented by a baseboard management controller (BMC), comprising: Receiving the first video frame and the second video frame redirected from the host on the BMC; wherein the BMC performs a management function of the host; Generate a webpage on the network server of the BMC, and send the webpage to a browser program running in the computing device through the network; generating a processed image representing the second video frame; storing a Java object in said web server; wherein said web page is programmed to instruct said browser program to download said Java object, wherein said Java object defines a Java display; Establishing a network connection between the BMC and the downloaded Java object; wherein the Java object is executed on a Java virtual machine of the computing device; and Sending the processed image to the executed Java object. 14. The method of claim 13, comprising: generating the second image on the BMC based on pixel values of a plurality of surrounding pixels surrounding a given pixel and pixel values of pixels on the first video frame corresponding to the given pixel and surrounding pixels the predicted value for a given pixel; and selectively replacing the pixel value of the given pixel with the predicted value according to lossy or lossless requirements, so as to generate a coded image. 15. The method of claim 14, comprising: compressing the encoded image on the web server to generate a processed image; decompressing and decoding said processed image on said executed Java object; and The decompressed and decoded image is displayed on the Java Display. 16. A non-transitory computer storage medium having computer-executable instructions stored in said storage medium, when said computer-executable instructions are executed by a processor of a baseboard management controller (BMC) computer , causing the processor to: receiving the first video frame and the second video frame redirected from the host; wherein the BMC performs a management function of the host; Generate a webpage on the network server of the BMC, and send the webpage to the browser program running in the computing device through the network; wherein, the webpage is programmed to instruct the browser program to start the drawable area, and establishing a network socket connection with the network server; generating a processed image representing the second video frame; establishing a web socket connection between the web server and the browser program; and sending the processed image to the browser program through the network socket connection. 17. The non-transitory computer storage medium of claim 16 , wherein the instructions, when executed, cause the processor to: comparing the second video frame with the first video frame to determine a first pixel of the second video frame; wherein the first pixel has a pixel corresponding to a pixel of the first video frame Pixel values with different values; generating a first tile image representing a portion of the second video frame including the first pixel and associated tile parameters; sending the first patch image and patch parameters to the browser program through the network socket connection; Wherein, the webpage is programmed to instruct the browser program to patch the first patch image on the drawable area at the position specified by the patch parameter. 18. The non-transitory computer storage medium of claim 17 , wherein the instructions, when executed, cause the processor to: generating a redirected image representative of said first video frame; and sending the redirected image to the browser program through the network socket connection; Wherein, the webpage is programmed to display the redirection image in the drawable area; The drawable area is a canvas defined by HTML5; wherein, the webpage is programmed to instruct the browser program to display the redirected image on the canvas, and patch the first patch image on the above the displayed redirected image. 19. The non-transitory computer storage medium of claim 18 , wherein the instructions, when executed, cause the processor to: dividing the second video frame into a plurality of tiles; comparing the pixel value of each pixel of the second video frame with the pixel value of a corresponding pixel of the first video frame; determining a plurality of changed pixels in the second video frame; wherein the pixel value of each of the changed pixels is the same as that of a corresponding pixel of each of the changed pixels in the first video frame different values; determining a plurality of changed tiles; wherein each of the changed tiles includes at least one changed pixel; generating a plurality of changed tile images; wherein each of the changed tile images represents one of the changed tiles; sending the plurality of changed patch images to the browser program through the network socket connection; wherein the web page is programmed to instruct the browser program to patch the changed patch images in on the drawing area. 20. The non-transitory computer storage medium of claim 17 , wherein the instructions, when executed, cause the processor to: determining the position of each changed tile on the second video frame; and According to the positions of the respective changed tiles represented by each of the changed tile images, tile parameters of each of the changed tile images are generated; wherein, the webpage is programmed to instruct the browser The program patches each changed patch image on the drawing area at a position specified by the patch parameter; The tile parameters include coordinates indicating the position of the drawable area, the width of each of the changed tile images, and the height of each of the changed tile images. 21. The non-transitory computer storage medium of claim 20, wherein the web page is programmed to instruct the browser program to capture the first event that occurs on the drawable area and The event data of the first event is sent to the network server; the first event is a mouse event or a keyboard event; when the instruction is executed, the processor is caused to: receiving event data from the browser program over the web socket connection; generating input data compatible with the host and representative of the event data; and The input data is sent to an input controller of the host computer. 22. The non-transitory computer storage medium according to claim 21, wherein the first event is a mouse event, and the event data indicates an event location where an event occurs on the drawable area; when the instruction When executed, causes the processor to: determining location coordinates of the host based on the event location; and Input data representing the mouse event and position coordinates are generated. 23. The non-transitory computer storage medium according to claim 21, wherein the first event is a keyboard event; wherein the event data specifies a key; when the instruction is executed, the processor is caused to Input data representing the key press is generated. 24. The non-transitory computer storage medium of claim 16 , wherein the instructions, when executed, cause the processor to: generating the second image on the BMC based on pixel values of a plurality of surrounding pixels surrounding a given pixel and pixel values of pixels on the first video frame corresponding to the given pixel and surrounding pixels the predicted value for a given pixel; and selectively replacing the pixel value of the given pixel with the predicted value according to lossy or lossless requirements, so as to generate a coded image. 25. The non-transitory computer storage medium according to claim 24, wherein when the instructions are executed, the processor is caused to compress the encoded image on the network server to generate a processed image; wherein the web page is programmed to instruct the browser program to call a JavaScript path to decompress and decode the processed image to display the decompressed and decoded image.