The present invention relates generally to data transmission on computer networks, and more particularly to a networking device including a Hypertext Transfer Protocol (HTTP) Multiplexor/Demultiplexor.
The Internet has experienced explosive growth in recent years. The emergence of the World Wide Web has enabled millions of users around the world to easily download web resources containing text, graphics, video, and sound data while at home, work, or from remote locations via wireless devices. These web resources often are large in size and therefore require a long time to download, causing the user delay and frustration. Delay often causes users to abandon the requested web page and move on to another web page, resulting in lost revenue and exposure for many commercial web sites.
One cause of delay is accumulation of Hypertext Transfer Protocol (HTTP) requests within a Transfer Control Protocol (TCP) buffer of a server socket. When a user requests a web page, a web browser sends HTTP requests to a server socket via an established TCP connection. When the server does not process requests to a socket quickly enough, HTTP requests build up in the TCP buffer for that socket, resulting in processing delay in that socket.
An additional cause of delay is socket-related overhead processing. Conventional networking systems open up a server socket for each client that connects to the server, so that server overhead tends to increase in proportion to the number of connected clients. A given server can efficiently handle only so much overhead at once. Accordingly, the one-socket-per-client approach fundamentally limits the number clients that can simultaneously access a server. This limitation is worse still in secure environments, which, due to key exchanges and other security-related considerations, involve even more overhead per socket.
A system, method and device for multiplexing and demultiplexing HTTP requests and responses are provided. The method may include receiving HTTP requests from a plurality of clients and routing those requests to a single socket on a server system. The HTTP requests may be routed to a particular server socket based on socket response time, the type or size of data being requested, and/or on other parameters related to the HTTP requests. The method may also include receiving HTTP responses from the server system, and selectively routing those responses to corresponding clients.
According to another aspect of the invention, the method typically includes at an intermediate networking device, receiving HTTP requests from multiple originating clients, multiplexing the HTTP requests, and sending the multiplexed HTTP requests to an optimal server socket. The method may further include receiving the HTTP responses from the server system, demultiplexing the HTTP responses, and sending the demultiplexed HTTP responses to corresponding originating clients.
The system typically includes a server system, plural clients configured to connect to the server system via a computer network, and a computer networking device positioned intermediate the server system and the clients on the computer network. The computer networking device typically has an HTTP multiplexor/demultiplexor configured to receive HTTP requests from more than one of the clients and to distribute those requests as a multiplexed transmission to a socket on the server system via a TCP connection.
The device typically includes an HTTP multiplexor/demultiplexor configured to receive HTTP requests from a plurality of clients and to distribute those requests in multiplexed form to a server system via a TCP connection. The device typically is further configured to receive HTTP responses from the server system, demultiplex the responses, and route the demultiplexed responses to corresponding clients.
Referring initially to
In addition, each server socket 16b opened requires a certain amount of overhead processing by the server. This overhead processing tends to increase in proportion to the number of sockets that are opened, and thus in proportion to the number of clients connecting to the system. To maintain acceptable response times, the server system must limit the number of client computers that may be connected at any given time, typically by periodically timing out established client connections.
In
Multiplexing and demultiplexing reduces the amount of server sockets necessary to service a given number of connected clients. The resulting reduction in socket-related overhead processing improves system performance and/or frees resources to allow more clients to connect to the system. In addition, where multiple server sockets are available, the system may be configured to further optimize performance through performance-based selection of server sockets. For example, HTTP requests may be selectively routed to a particular server socket based on optimal response time, in order to ensure efficient processing of the requests. It should be appreciated that the term socket, as used in connection with the present invention, refers to a port, buffer, logical node, or object configured to receive data in HTTP and other formats from a remote device via a network connection, and is not limited to a “socket” as defined in the Unix operating system environment.
Referring now to
Remote client 12 typically is configured to run an operating system (OS) 48 to manage programs or applications. Operating system 48 is stored in mass storage device 34. Examples of suitable operating systems include UNIX, WINDOWS, MACOS, VMS, and OS/2, although virtually any suitable operating system may be used. Remote client 12 includes a browser program 50 stored in mass storage device 34 configured to display requested web resoures to a user of remote client 12. Exemplary browser programs 50 include the NETSCAPE browser commercially available from Netscape Communications Corporation of Santa Clara, Calif. and the INTERNET EXPLORER browser commercially available from Microsoft Corporation of Redmond, Wash.
Server 14 also typically is a computer similar to that shown in
Networking device 26 may be connected to server system 22 and remote clients 12 in various ways. On the client side, device 26 typically is connected to remote clients 12 via a public-type network, such as wide area network (WAN) 24, as seen in
Web site 25 typically includes a collection of web resources typically located at a web address called a URL (Uniform Resource Locator), or at another form of URI (Uniform Resource Identifier). The term “web resource” refers generally to a data resource that may be downloaded or accessed by a web browser. Web resources may include web pages, executable code, scripts, graphics, video, sounds, text, and/or other data. Web resources may be static (e.g. stored file) or dynamic (e.g. dynamically generated output). Web resources may be stored on and served by a single server 14 or a number of servers 14. For example, images may be stored on one server while code may be stored in another server, and alternatively, copies of images and code may be stored on multiple redundant servers.
As shown in
In
As indicated above, networking device 26 typically is connected to server system 22 via LAN 84. Because the server-side connection is a private-type connection, while the client connections are public-type connections (e.g., WAN 24), networking device 26 may be considered a server-side proxy server. A proxy server is a program or device that acts as an intermediary between a browser and a server. Networking device 26 acts as an intermediary by receiving HTTP requests from remote clients 12 and sending those requests to a socket on server system 22, and by receiving server-generated HTTP responses and sending those responses to the remote client that originated the requests.
The networking devices of the present invention typically are provided with a software or firmware multiplexor/demultiplexor configured to route network traffic between remote clients and a server system. Typically, this is done by multiplexing HTTP requests received at network device 26 via multiple client TCP connections 120, so that those requests may be forwarded from device 26 as a multiplexed transmission to server system 22. This multiplexed transmission normally occurs via a single server TCP connection 124, so that only one socket is opened on the server side. Server system 22 in turn generates HTTP responses corresponding to the various requests of the remote clients 12. These responses are provided along a single server TCP connection 124 to device 26, where they are demultiplexed so that they may be selectively routed and delivered to the appropriate originating client 12.
The above description contemplates routing of all traffic from multiple client TCP connections onto a single server-side TCP connection. Alternatively, as will be seen with reference to
Referring now to
Server system 22 is coupled with networking device 26 via various server TCP connections 124. Similar to the client side, each server connection 124 includes a server-side device socket 124b (or, simply server-side socket 124b) associated with networking device 26 and a server socket 124a associated with server system 22. As indicated, server system 22 may include a plurality of servers 14 configured to perform various functions. Server connections 124 and their associated sockets may be in a one-to-one relationship with servers 14, or multiple connections 124 may be associated with a given individual server.
The previously described multiplexing, demultiplexing and routing capabilities are more clearly seen with reference to
As indicated, networking device 26 is configured to selectively route HTTP requests and responses between client and server sockets. For example, as indicated by HTTP request/response streams R1, R2 and R3, networking device 26 is configured to receive HTTP requests from one or more of client computers 12, and selectively route those requests via one of server connections 124 to an individual server socket 124a. Networking device is also configured to receive HTTP responses from server system 22, and route those responses back to the appropriate originating client 12.
Networking device 26 may be configured to multiplex requests from multiple clients, for example by taking HTTP requests from multiple clients and routing those requests to server system 22 via a single server connection 124. For example,
Various methods may be used to combine the requests for transmission via a single server-side connection 124. Typically, a multiplexing state agent, shown at M1-M6, is assigned to each client-side socket 120b on the networking device. Each multiplexing state agent is configured to, for each request received from the client, route the request to an optimal server-side socket 124b on the networking device, for transmission to a server 14 of server system 22. When a response to the request is received from the server on the server-side socket 124b, the multiplexing state agent is configured to route the request back to the client-side socket 120b for the requesting client. The multiplexing state agent is free to route subsequent requests from the same client to an optimal server-side socket 124b, whether that be a different server socket, or the same server socket as used for previous requests. While typically each multiplexing state agent is configured to route requests from only one client-side socket 120b to an optimal one of a plurality of server-side sockets 124b, it will be appreciated that alternatively a single multiplexing state agent may be configured to route requests from more than one client-side socket 120b to (1) an optimal one of a plurality of server-side sockets 124b and/or (2) a single server-side socket 124b.
Networking device 26 may be further configured to demultiplex the response stream received from server-side sockets 124b in response to the client requests. Specifically, a series of responses received from a particular server socket is processed by the multiplexing state agents managing transactions with that socket, to unbundle the response stream into discrete responses or streams corresponding to an individual one of clients 12. Each multiplexing agent is configured to detect those responses on the server-side socket 124b that correspond to requests from the client with which the agent is associated, and route the responses back to the originating client, via the client-side socket 120b for the originating client. This process is referred to as demultiplexing because a series of responses from a single server-side connection 124 is broken up and routed over a plurality of client connections 120 to a plurality of clients 12.
As indicated, client-side connections 120 may correspond with server-side connections 124 in various ways. For example, the system may be operated so that all client connections are multiplexed to an individual server connection. Where multiplexing is employed, networking device 26 is configured to multiplex HTTP requests provided from two or more client connections (e.g., the connections corresponding to R1, R2 and R3) into a single server connection, such that only one server socket need be opened. Alternatively, multiple server connections may be employed, where each server connection corresponds either to an individual client connection, or is multiplexed so as to correspond to multiple client connections. In any event, it will normally be desirable that the server connections be fewer in number than the client connections, in order to achieve an optimal reduction of socket-related overhead processing on the server side of the system. Regardless of the particular multiplexing configuration, networking device 26 is further configured to demultiplex the responses generated by server system 22, and cause those responses to be selectively routed to the appropriate originating client 12.
Where multiple server connections are available, various optimization schemes may be employed to reduce delay and otherwise improve performance. In particular, networking device 26 may be configured to route HTTP requests to an optimal server socket, which typically is a least busy server socket. To determine the optimal server socket, multiplexor/demultiplexor 80 (
In addition to or instead of the above-described optimization techniques, networking device 26 may be configured to determine the type of request being made and/or the type of data being requested and use that information to effect optimal routing. For example, all image requests may be handled by a predetermined set of sockets on server system 22, while all HTML requests may be handled by a different predetermined set of sockets. In addition, certain sockets may be designated to handle specified protocols or protocol versions. For example, one set of sockets could be designated for all HTTP 1.0 requests, with another set being designated to handle HTTP 1.1 requests.
Regardless of the particular implementation, these optimization techniques increase the overall efficiency and response time of server system 22 by adjusting the flow of requests away from slow, congested server sockets and toward fast congestion-free server sockets. These optimization techniques may be employed in the described networking devices of the present invention, in addition to or instead of the routing, multiplexing and demultiplexing features discussed above.
Typically, the connections between networking device 26, server system 22 and clients 12 (e.g., connections 120 and 124) are persistent TCP connections. Persistent TCP connections are connections that remain open until explicitly commanded to close or until the server times-out the connection. Alternatively, a connection other than a persistent TCP connection may be used. Effective use of persistent connections is a significant advantage of the present invention over prior systems. Often the persistence feature is not used in conventional networking systems, or is only partially used, because of the significant amount of per-connection overhead placed on the system. As discussed above, this overhead fundamentally limits the number of clients that can be connected at any one time. Thus, to provide access to a large number of potential connected clients, many existing systems periodically terminate client connections, to allow others access to the system. This effectively is a disabling of the persistence feature available in newer networking protocols. The failure to leverage persistence is particularly a drawback in secure environments, such as SSL, where setting up and tearing down TCP connections involves key exchanges and other overhead intensive tasks relating to security. By reducing the excessive overhead that necessitates periodic terminating of client connections, networking device is able to establish and maintain persistent connections with clients and servers.
It will be appreciated that the described networking devices and systems are extremely flexible, and may be configured in a nearly limitless number of ways to enhance the performance of client-server networking systems. Other network device implementations are described in co-pending U.S. patent applications Ser. Nos. 09/680,675, 09/680,997, and 09/680,998, filed Oct. 6, 2000, Nos. 60/239,552 and 60/239,071, filed Oct. 10, 2000, No. 60/287,188, filed Apr. 27, 2001, and No. 60/308,234 filed Jul. 26, 2001, and No. 60/313,006 filed Aug. 16, 2001, the disclosures of each of which are herein incorporated by reference, in their entirety and for all purposes. The features of these devices may variously be implemented in connection with the networking devices and systems of the present invention.
Turning to
When HTTP requests are detected at networking device 26, method 140 continues, at 148, with receiving HTTP requests at one or more client-side sockets 120b. Method 100 further includes, at 150, multiplexing HTTP requests so that the multiplexed requests may be transmitted to the server system via a single TCP connection. At 152, the method further includes routing the requests to the server system, typically by sending the multiplexed requests to an optimal server socket.
Prior to step 152, method 140 may also include monitoring server sockets to determine an optimal server socket. The optimal server socket may be determined by identifying a server socket with a least-lengthy response time. Alternatively, the optimal server socket may be determined by determining a last-accessed server socket, determining a server socket with the fewest number of unfulfilled requests, determining the type or size of data being requested or other parameters related to the HTTP requests, or by weighing all or some of these conditions. By determining an optimal server socket, the multiplexor/demultiplexor is able to improve performance by facilitating more efficient use of server resources.
When HTTP responses are detected at the multiplexor/demultiplexor at step 146, method 140 proceeds to 154, and includes receiving HTTP responses from the server system. The multiplexor/demultiplexor typically is configured to determine the destination of the HTTP responses. At 156, the method includes demultiplexing HTTP responses received from server system, in order to permit selective routing and delivery of certain of those responses to the appropriate originating client. At 158, method 140 includes sending the demultiplexed responses to the originating remote client.
When there is a new remote client or server detected at 160, the method includes returning to step 144 to establish a persistent TCP connection with the new remote client, or returning to step 142 to establish a persistent TCP connection with the new server, respectively. It will also be appreciated that networking device 26 may be configured to establish a plurality of TCP connections with a plurality of servers and a plurality of remote clients, and therefore may be configured to handle HTTP requests and HTTP responses from multiple servers and remote clients at once.
Similar to the devices and systems described above, the described method enhances the performance of client-server networking systems. This is accomplished through multiplexing and demultiplexing of HTTP requests/responses, in order to reduce overhead processing that results in conventional systems from opening a server socket for each client computer connecting to the server. This also allows for fuller utilization of the persistent connection features that are now available in connection with HTTP and other protocols. Additionally, or alternatively, the method may include selection of optimal server sockets, in order to further enhance server sufficiency.
While the present invention has been particularly shown and described with reference to the foregoing preferred embodiments, those skilled in the art will understand that many variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims. The description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. Where the claims recite “a” or “a first” element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.
This application is a continuation-in-part of U.S. patent application, Ser. No. 09/882,375, entitled “HTTP Multiplexor/Demultiplexor,” filed on Jun. 15, 2001, now abandoned, which in turn claims priority from U.S. Provisional Patent Application, Ser. No. 60/239,552, entitled “HTTP Multiplexor/Demultiplexor,” filed on Oct. 10, 2000. The disclosures of both these applications are incorporated herein by this reference, in their entirety and for all purposes.
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Child | 09975522 | US |