Abstract:
A method of adjusting a timer is disclosed. The method includes adjusting a timer activation period based on a characteristic of a network and setting the timer using the timer activation period. The timer is used in communicating information over the network.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to timers in digital systems that have adjustable granularity, granularity which dynamically adjusts to communication conditions. 
     2. Description of the Related Art 
     In many digital systems, such as communication systems and computer systems, streams of information (data) between parties do not travel in a continuous fashion. Typical to many digital systems, the information is provided in the form of small and manageable pieces. To properly manage packets and streams of information, digital systems make use of protocols such as the transmission control protocol (TCP). 
     Information in a digital system can be broken down into a basic piece of data called a frame. A flow is a series of frames exchanged between two connection endpoints defined by a network address and a port number pair for each end of the connection. Typically a flow is initiated by a request at one of the endpoints for content which is accessible through the other connection endpoint. The flow that is created in response to the request consist of packets containing the requested content and control messages exchanged between the two endpoints. 
     Examples of exchanges of information include requests and transmission of data to and from client entities (client) and server entities (server). Typically, a client is the requesting endpoint; however, the server at times also requests information from a client. Applications of digital systems include transactions on the Internet, where the client is an individual connecting to a host&#39;s site and the host&#39;s site is considered the server. The individual requests information from the host site. Information is then transmitted along the Internet from the host site to the individual. In the case of electronic commerce on the Internet, the individual and the host site exchange various information packets with one another. The individual browses the host&#39;s site for specific products and/or services. The host site responds with availability and price of the goods and services. The individual responds with an order, which can include credit card information and shipping information. 
     The use of protocols allows efficient management of information and exchange over communication networks such as the Internet. Protocols are able to decide how to break up the transmission of information. As an example, using TCP, when a receiver (e.g., server) receives a request packet, the receiver sends an acknowledge packet back to the sender (e.g., client). If the sender does not receive an acknowledge packet after an allotted amount of time, TCP requires that the sender retransmit the packet. Other features of TCP allow for flow control; a receiver allows the sender to send only as much information at a time that the receiver&#39;s data buffers can store. 
     TCP and other communication protocols implement the use of timers. Timers are used to acknowledge control, and initiate and request (or re-initiate) transmission of information and information packets. Timers can also be implemented to control and monitor events. TCP includes, among other timers, an acknowledge timer, a round trip timer, a persist timer, and a keep alive timer. In TCP, timers can have a range of 200 milliseconds (ms) to several seconds. 
     Associated with each timer is the concept of granularity. Granularity relates to the number of interrupts over a defined time period. An interrupt is when a timer activates. The fewer number of interrupts over the defined time period, the lesser the granularity. In other words, if a timer activates (interrupts) 10 times over the defined time period, the granularity is lesser than if the timer activates (interrupts) 20 times over the same defined time period. 
     Under ideal conditions, communications between a client and a server are immediate and continuous. In other words, a client would not have to wait to be connected to a server, and information exchange is not interrupted. Practical conditions, however, include instances when connections between clients and servers are less than ideal. Using the example of the Internet, during certain times numerous clients (individuals) are accessing, or trying to access, the server (host site). The server in turn is trying to handle the requests from each of the clients. As more and more clients try to access the server, resources, in particular memory bandwidth, become constrained. An increased number of clients leads to increased congestion along the communication path (memory bandwidth). Processors handling the data flows are forced to handle numerous information flows. Processors responsible for computing received information are inundated with retransmitted packets. The retransmitted packets are packets containing information that has yet to be processed. Situations in which packets can be retransmitted are when an entity does not receive an acknowledge packet, the timer is started and after the set time the packet is retransmitted. Received packets that are yet to be processed, can be stored in memory buffers of devices; however, memory buffers are a limited resource that can be quickly filled during periods of peak network traffic. If memory buffers fill up, a retransmit can be requested, or transmission can be ceased. 
     Traffic related to information flows over networks, such as the Internet, varies depending on various factors. A simplistic example of congestion takes place when numerous clients are attempting to access a particular server. Factors that affect information (data) flows include the current data stream bandwidth, the number of data flows (TCP flows), the number of requests for memory access, the current network traffic, network congestion, the time of day, the season of the year, or a combination of any of the factors. 
     As networks become congested (i.e., experience more traffic), and resources become constrained, in particular as processors are asked to handle increased data streams (flows), connections are terminated and lost by the inability to properly service all client and server demands. Overall communication transactions are slowed with the increased congestion on the networks. Customers that are trying to purchase goods and/or services from server host sites are dropped. Dropped connections lead to frustrated customers who may decide not to continue transaction with the host site and seek business elsewhere. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a method of adjusting a timer is disclosed. The method includes adjusting a timer activation period based on a characteristic of a network and setting the timer using the timer activation period. The timer is used in communicating information over the network. 
     In another embodiment, a timing unit for a network is disclosed. The timing unit includes a timer and a timing control unit. The timing control unit is coupled to the timer, and is configured to adjust a timer activation period based on a characteristic of the network. The timing control unit is also configured to provide the timer activation period to the timer. 
     The foregoing is a summary and thus contains, by necessity, simplifications, generalizations and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the present invention, as defined solely by the claims, will become apparent in the non-limiting detailed description set forth below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the figures designates a like or similar element. 
         FIG. 1  illustrates a transmission flow between a client and server. 
         FIG. 2  illustrates a transmission flow between a client and server with a router intermediary. 
         FIG. 3  is a flow chart illustrating detecting congestion and modifying timer granularity. 
         FIG. 4  is a flow chart illustrating detecting various flows and modifying timer granularity. 
         FIG. 5  is a block diagram illustrating a router. 
         FIG. 6  is a block diagram illustrating a router with timer memories. 
         FIG. 7  is a block diagram illustrating a network environment in which a system according to the present invention may be practiced. 
         FIG. 8  depicts a block diagram of a computer system suitable for implementing the present invention, and example of one or more of client computers. 
         FIG. 9  is a block diagram depicting a network in which a computer system is coupled to an internetwork, which is coupled, in turn, to client systems, as well as a server. 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail, it should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular aim disclosed but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIG. 1  is a block diagram illustrating transmission between a client  100  and a server  110 . Client  100  transmits a synchronize (SYN) packet  102  to server  110 . Server  110  acknowledges packet  102  by transmitting a SYN-ACK packet  104  to client  100 . Client  100  responds to server  110  by transmitting an acknowledge (ACK) packet  106 . Information is transmitted in the form of packets DATA 1   108  and DATA 2   112  from client  100  to server  110 . Server  110  acknowledges receipt of this information by transmitting an ACK packet  114 . Along with ACK packet  114 , information such as DATA 3   116  can be transmitted to client  100 . Client  100  acknowledges receipt of DATA 3   116  by transmitting an ACK packet  118 . Client  100  terminates transmission flow made by client  100  by transmitting a FIN packet  120  to server  110 . A FIN-ACK packet  122  is sent to client  100  to acknowledge that server  110  recognizes that transmission is ended. Client  100  in turn transmits an ACK packet  124  to complete transmission. 
     In this direct communication from client to server, timers can be used to control when retransmission of packets is performed, if retransmission is required. There is a connection establishment timer for SYN packets, a retransmission timer for ACK packet, a 2MSL timer (timer to measure time that a connection has been in the TIME_WAIT state) to avoid reusing current socket pairs, a persist timer to verify window size, and a keep alive timer to verify that a connection is still active. Additional timers may exist depending on TCP implementation. Client  100  and server  110  can incorporate memory buffers to store packet information. 
       FIG. 2  is a block diagram illustrating transmission between client  100  and server  110 , with the use of an intermediary device. In this particular example a router  205  is illustrated as the intermediary device. Router  205  intercepts the flows from client  100  and generates a new flow between itself and server  110 . Therefore, two flows exist, with one flow between client  100  and router  205 , and a second flow between router  205  and server  110 . In a digital system that employs an intermediate device such as router  205 , router  205  controls information that passes between client  100  and server  110 . Communication paths are established from router  205 , namely between client  100  and server  110 . In certain cases, congestion and constrained resources are greater at server  110 , at other times at client  100 , and at certain times resources are equally congested and constrained for both server  110  and client  100 . Client  100 , server  110 , and router  205  can make use of memory buffers to store packet information with the memory buffer storing excess data. 
     When client  100  desires to transmit information, client  100  transmits a SYN 1  packet  202  to router  205 . Router  205  acknowledges receipt of SYN 1  packet  202 , by transmitting a SYN-ACK 1  packet  204  to client  100 . Client  100  sends an ACK 1  packet  206  to router  205 . Information from client  100  is transmitted to router  205  in the form of packets DATA 1   210  and DATA 2   216 . 
     Router  205  establishes communication with server  110  by transmitting a SYN 1 ′ packet  208 . Server  110  replies to router  205  with a SYN-ACK 1 ′ packet  212 . Router  205  transmits an ACK 2  packet  214  to server  110  recognizing SYN-ACK 1 ′ packet  212 . Router  205  is then authorized to transmit packets DATA 1 ′  218  and DATA 2 ′  222  to server  110 . 
     Server  110  has the ability to transmit information back to client  100 . This process is illustrated by server  110  sending a DATA 3  packet  226  to router  205 . Router  205  passes DATA 3 ′ packet  228  along to client  100 . Router  205  also sends an ACK 5  packet  230  back to server  110 , acknowledging receipt of DATA 3  packet  226  from server  110 . The client  100  transmits an ACK 6   232  packet to router  205  acknowledging receipt of DATA 3 ′ packet  228  from router  205 . ACK 3  packet  220  is sent from router  205  to recognize receipt of DATA 1   210  and DATA 2   216  packets. ACK 4  packet  224  is sent from server  110  to recognize receipt of DATA 1 ′  218  and DATA 2 ′  222  packets. 
     In this particular example, client  100  wishes to terminate communication, and sends a FIN packet  234  to router  205 . Router  205  advises server  110  that client  100  desires to end communication by sending a FIN′ packet  236  to server  110 . Server  110  acknowledges FIN′ packet  236  by transmitting a FIN-ACK packet  240  to router  205 . Router  205  acknowledges FIN-ACK packet  240  by transmitting an ACK 7  packet  242  to server  110 . Router  205  sends a FIN-ACK′ packet  238  to client  100 . Client  100 , in turn, acknowledges FIN-ACK′ packet  238  by transmitting an ACK 8  packet  244  back to router  205 . 
     Variations of the configurations with client(s) and server(s) are possible. There can be multiple clients and servers, and multiple intermediary devices (e.g., routers). Regardless of the configuration that is used in transmitting and receiving packets; a timer is associated with the each of the packets. 
     Associated with each timer is a specific granularity. Historically, granularity is a predetermined and set value for each timer. To account for experienced or anticipated congestion (e.g., increased traffic flows), timer granularity can be altered (e.g., decreased or increased). In other words, the time between timer interrupts or timer activation can be decreased or increased. A decrease in granularity allows processors, specifically processors in transmitting and receiving devices, to limit the computing that the processors are requested to perform. When less network congestion is experienced, and/or when resources are less constrained, granularity can be increased. In other words, a shorter period is seen for timer activation (i.e., interrupts). An increase in granularity allows transmission between devices to occur more rapidly. 
     With a decrease in granularity, as packets are transmitted to and from devices, processors responsible for receiving and transmitting packets (e.g., information) are able to keep up with processing during situations in which congestion exists or is anticipated. An example of events or situations in which congestion exists includes peak shopping seasons where a multitude of individuals are attempting to access shopping sites. Another situation is a busy time of day in which individuals are checking their stock portfolios at their respective Internet brokerage sites. An example of an expected event that can cause congestion is when equipment is being repaired or maintained, limiting the capabilities of the network. Decrease or increase changes in granularity can be based on several metrics, metrics that are actually seen in the communication network or are anticipated in the communication network. 
     During peak congestion, granularity is decreased in order to alleviate the tasks imposed on processors that are handling the communication transfers of transmitted and received information. During less congested periods, granularity is increased to allow for quicker transmission of packets. 
       FIG. 3  illustrates a flow chart of a process that determines congestion in a network. A device that contains a timer receives a flow of transmission packets. Packets can be placed in a memory buffer if processors cannot immediately handle the transmitted packet, and the process may wait a set amount of time, step  310 . A determination is made as to whether an option to receive flows is terminated, step  320 . If the option is terminated, the process ends. If flows continue to be received, a device (e.g., a receiving or a sending device) determines congestion in the network, step  340 . If congestion is seen, granularity is decreased, step  350 . If congestion is not seen, granularity is increased, step  330 . The process pauses for an amount of time, step  310 , and then continues until transmission of the received or transmitted packet is complete, step  320 . 
     A counter can be associated with each timer. The counter is increased whenever congestion flow is experienced. An increase in the counter relates to a decrease in the granularity of the timer. The counter measures delay or lack of transmission (processing) of a packet. The counter sets optimal granularity conditions by experienced flow or congestion. Examples of congestion include network congestion (i.e., congestion with a client network, such as the Internet, and between a client and a router); server network congestion (i.e., between router and server, or both); processor congestion (i.e., processor has more tasks to perform than time to perform the tasks); and memory congestion (i.e., the memory bandwidth is close to fully utilized, and additional requests for data from the memory adversely affects performance). 
     The increased wait, and time out requiring retransmission, increases the counter. Each incremental counter increase decreases the granularity of the timer. For example, an 8 bit binary counter can be used. For the first increase of the counter or the value of 00000001, granularity is decreased and the timer is set to activate every ten seconds. For the next counter increase or value of 00000010, granularity is changed so the timer activates every 20 seconds. The next counter increase or value of 00000011 decreases granularity and sets the timer activation to 30 seconds. The counter progressively increases as the delay of the packet transmission is experienced, the delay relating to network congestion. In this particular example, a maximum timer activation time is set to 160 seconds. With the 8 bit counter, only the first four bits need be used. The maximum value of 160 seconds is reached when the counter has the value of 00001111. Once the set maximum timer value (or minimum granularity) is reached, the granularity stays at the minimum value until congestion flow conditions favorably change. 
     A master counter can be employed, which increments at a continuous rate. Normally, the rate at which the master counter is incremented does not change. When the counter value changes, the processor is interrupted and all of the timer values stored in memory are read. If any of them expire, the corresponding event is scheduled for that TCP flow. If congestion is detected, the interrupts can be generated every other time (i.e., every two times) the counter changes values. Likewise, if congestion continues or increases, the interrupts can be generated every fourth time the counter changes values. This can continue (i.e., every eighth time, every sixteenth time, and so on). This is referred to herein as decreasing granularity. A decrease in granularity goes from many interrupts spaced closely that may cause a small number of events per interrupt to be executed, to few interrupts spaced further apart that usually causes a larger number of events to be executed per interrupt. In this particular example, a change in granularity is based on powers of two. The least significant bit of the counter can be examined for changes. As congestion increases, the second least significant bit is examined for changes; as the congestion further increases, the third significant bit can be examined for changes, and so on. 
       FIG. 4  is a flowchart illustrating a process of detecting various flows and modifying timer granularity. In a TCP network, a particular device can receive up to 128K flows per second. After such number of flows is exceeded, the memory buffers become full, and no more flows can be received. To allow continued transmission, granularity can be adjusted depending on the number of flows. Values that affect data flows include current data stream bandwidth; number of TCP flows; number of arbiter requests for memory access; current network traffic; network congestion; time of day (peak traffic expected or actually experienced); estimated traffic (season of the year); and a combination of the above. A determination can be made on actual or anticipated number of flows or congestion. A factor in estimating congestion is estimating data stream bandwidth. Data stream bandwidth estimates are derived by factors including the number of flows; arbiter device requests; network congestion (historical values); current time of delay (anticipated peak); and estimated traffic (related to event or season). 
     In an embodiment of the invention, granularity change can correspond directly to a preset value for the number of flows encountered. In this particular example, the receiving device controls the granularity change and measures the flow; however, a sending device can address the task of detecting flow and modifying granularity. A wait is performed for a predetermined amount of time, step  410 . A determination is made as to whether the transmission is complete or if a memory buffer has accepted the transmission, step  420 . If transmission is complete, the process ends. If continued transmission is seen, the number of flows is compared to the value A, step  430 . If flows are not greater than A, the granularity remains the same, step  440 . A wait is performed for the predetermined set of time, step  410 , and a determination is made as to whether transmission is completed  420 . If flows are greater than A, a determination is made to see if the flows are greater than B, step  450 . If the flows are greater than A, but less than B, granularity is decreased by two, step  460 . A wait is performed for the predetermined set of time, step  410 , and a determination is made as to whether transmission is completed  420 . A determination is made as to whether the flows are greater than B, but less than C, step  470 . If flows are less than C, then granularity is decreased by four, step  480 . In this particular example, the value of C is an upper limit value; if flows are greater than C, then granularity is decreased by eight, step  490 . A wait is performed for the predetermined set of time, step  410 , and a determination is made as to whether transmission is completed  420 . 
     Flow control can also be measured by high and low watermarks. The status of the watermark determines flow, is used to determine flow control, and in turn determines the granularity of the timer. Flows can be assigned a high watermark and a low watermark. The high watermark value indicates the upper limit related to the number of frames contained in the flow. When the flow reaches the high watermark, granularity can be increased. When the flow reaches the low watermark, granularity can be decreased. Memory buffers can also make use of the high and low watermark concept, and adjust the granularity of the respective timers accordingly. 
       FIG. 5  is a block diagram illustrating a router. A router can include a memory  500  that is directly interfaced to a processor  505 . Processor  505  communicates to an internal bus  510 . Router bus communicates to a packet memory  515 . Packet memory can be used to store flows prior to processing by the processor  505 . An interface or interfaces  520  provides connection to an external network from the router. Interfaces  520  communicates to the other devices in the router by way of bus  510 . 
       FIG. 6  is a block diagram illustrating a router with timer memories. Three timer memories are added to the router of  FIG. 5 . Timer memories can have timers based on timer length, priority, content, and/or a combination of the three. The memories include a timer memory A  600 , a timer memory B  605 , and a timer memory C  610 . In this embodiment, each of the memories are independently connected to bus  510 . Timers (e.g., TCP timers) can be stored on a per flow basis in timer memories  600 ,  605 , and  610 . Because storage is based on a per flow basis, and the router can handle up to 128K flows at a single time, 128 or more timers can be stored in one memory at one time. Timer memory A  600 , timer memory B  605 , and/or timer memory C  610  can be accessed at a predetermined time interval (e.g., N ms, where N is a predetermined number) to verify each timer. If the timer has expired, the process related to the timer is executed by the digital system (e.g., communication network) and the associated timer event is removed from memory. If the timer has not expired, the timer remains in memory until a future verification is made to determine if the timer has expired. As the system, processor  505 , timer memory A  600 , timer memory B  605 , or timer memory C  610  become congested, the memory containing the timer is verified (i.e., inspected) at twice the predetermined time interval (i.e., two times N ms). The increase in time interval slows down the protocol process (e.g., TCP) while allowing a congested router added time to operate on flows that the router currently is processing. Further additional processing times can be provided to allow the router to handle added flows. 
     In certain cases, such as transmission contents that include voice or real-time video, delays are not desirable. Timer memory A  600 , timer memory B  605 , and timer memory C  610  can be sorted to provide for different priorities. In particular, as congestion increases, reading of the timer memories  600 ,  605 , or  610 , memory (or memories) containing voice and/or video packets is not affected (i.e., the time interval remains at N ms). However, during the same time, memory that contains other content (e.g., email content) is accessed at twice the predetermined time interval (i.e., two times X ms). With additional congestion, the time intervals can be increased accordingly. For example, voice content stored in a particular memory would continue to be accessed at the predetermined time interval (i.e., N ms); video content in a particular memory would be accessed at two times the predetermined time interval (i.e., two times N ms); and other content would be accessed at four times the predetermined time interval (i.e., four times N ms). 
     Determining content in a particular memory and setting priority can be based on any of the following: contents of the packet, Media Access Control (MAC) address, Internet Protocol (IP) address, the type of service, the class of service type, quality of service metric, service level agreement, or virtual local area network (VLAN) information. Any or all of the preceding data provides information on content type. Determining content based on the preceding data avoids the need to inspect the actual content of the flows or packets stored in memory. 
     An Example Computing and Network Environment 
       FIG. 7  is a block diagram illustrating a network environment in which a system according to the present invention may be practiced. As is illustrated in  FIG. 7 , network  700 , such as a private wide area network (WAN) or the Internet, includes a number of networked servers  710 ( 1 )-(N) that are accessible by client computers  720 ( 1 )-(N). Communication between client computers  720 ( 1 )-(N) and servers  710 ( 1 )-(N) typically occurs over a publicly accessible network, such as a public switched telephone network (PSTN), a DSL connection, a cable modem connection or large bandwidth trunks (e.g., communications channels providing T 1  or  0 C 3  service). Client computers  720 ( 1 )-(N) access servers  710 ( 1 )-(N) through, for example, a service provider. This might be, for example, an Internet Service Provider (ISP) such as America On-Line™, Prodigy™, CompuServe™ or the like. Access is typically had by executing application specific software (e.g., network connection software and a browser) on the given one of client computers  720 ( 1 )-(N). 
     One or more of client computers  720 ( 1 )-(N) and/or one or more of servers  710 ( 1 )-(N) may be, for example, a computer system of any appropriate design, in general, including a mainframe, a mini-computer or a personal computer system. Such a computer system typically includes a system unit having a system processor and associated volatile and non-volatile memory, one or more display monitors and keyboards, one or more diskette drives, one or more fixed disk storage devices and one or more printers. These computer systems are typically information handling systems which are designed to provide computing power to one or more users, either locally or remotely. Such a computer system may also include one or a plurality of I/O devices (i.e., peripheral devices) which are coupled to the system processor and which perforin specialized functions. Examples of I/O devices include modems, sound and video devices and specialized communication devices. Mass storage devices such as hard disks, CD-ROM drives and magneto-optical drives may also be provided, either as an integrated or peripheral device. One such example computer system, discussed in terms of client computers  720 ( 1 )-(N) is shown in detail in  FIG. 8 . 
       FIG. 8  depicts a block diagram of a computer system  810  suitable for implementing the present invention, and example of one or more of client computers  720 ( 1 )-(N). Computer system  810  includes a bus  812  which interconnects major subsystems of computer system  810  such as a central processor  814 , a system memory  816  (typically RAM, but which may also include ROM, flash RAM, or the like), an input/output controller  818 , an external audio device such as a speaker system  820  via an audio output interface  822 , an external device such as a display screen  824  via display adapter  826 , serial ports  828  and  830 , a keyboard  832  (interfaced with a keyboard controller  833 ), a storage interface  834 , a floppy disk drive  836  operative to receive a floppy disk  838 , and a CD-ROM drive  840  operative to receive a CD-ROM  842 . Also included are a mouse  846  (or other point-and-click device, coupled to bus  812  via serial port  828 ), a modem  847  (coupled to bus  812  via serial port  830 ) and a network interface  848  (coupled directly to bus  812 ). 
     Bus  812  allows data communication between central processor  814  and system memory  816 , which may include both read only memory (ROM) or flash memory (neither shown), and random access memory (RAM) (not shown), as previously noted. The RAM is generally the main memory into which the operating system and application programs are loaded and typically affords at least 64 megabytes of memory space. The ROM or flash memory may contain, among other code, the Basic Input-Output system (BIOS) which controls basic hardware operation such as the interaction with peripheral components. Applications resident with computer system  810  are generally stored on and accessed via a computer readable medium, such as a hard disk drive (e.g., fixed disk  844 ), an optical drive (e.g., CD-ROM drive  840 ), floppy disk unit  836  or other storage medium. Additionally, applications may be in the form of electronic packets modulated in accordance with the application and data communication technology when accessed via network modem  847  or interface  848 . 
     Storage interface  834 , as with the other storage interfaces of computer system  810 , may connect to a standard computer readable medium for storage and/or retrieval of information, such as a fixed disk drive  844 . Fixed disk drive  844  may be a part of computer system  810  or may be separate and accessed through other interface systems. Many other devices can be connected such as a mouse  846  connected to bus  812  via serial port  828 , a modem  847  connected to bus  812  via serial port  830  and a network interface  848  connected directly to bus  812 . Modem  847  may provide a direct connection to a remote server via a telephone link or to the Internet via an internet service provider (ISP). Network interface  848  may provide a direct connection to a remote server via a direct network link to the Internet via a POP (point of presence). Network interface  848  may provide such connection using wireless techniques, including digital cellular telephone connection, Cellular Digital Packet Data (CDPD) connection, digital satellite data connection or the like. 
     Many other devices or subsystems (not shown) may be connected in a similar manner (e.g., bar code readers, document scanners, digital cameras and so on). Conversely, it is not necessary for all of the devices shown in  FIG. 8  to be present to practice the present invention. The devices and subsystems may be interconnected in different ways from that shown in  FIG. 8 . The operation of a computer system such as that shown in  FIG. 8  is readily known in the art and is not discussed in detail in this application. Code to implement the present invention may be stored in computer-readable storage media such as one or more of system memory  816 , fixed disk  844 , CD-ROM  842 , or floppy disk  838 . Additionally, computer system  810  may be any kind of computing device, and so includes personal data assistants (PDAs), network appliance, X-window terminal or other such computing device. The operating system provided on computer system  810  may be MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, Linux®, Cisco IOS®, CATOS® or other known operating system. Computer system  810  also supports a number of Internet access tools, including, for example, an HTTP-compliant web browser having a JavaScript interpreter, such as Netscape Navigator® 8.0, Microsoft Explorer® 8.0 and the like. 
     Moreover, regarding the packets described herein, those skilled in the art will recognize that a packet may be directly transmitted from a first block to a second block, or a packet may be modified (e.g., amplified, attenuated, delayed, latched, buffered, inverted, filtered, encoded or otherwise modified) between the blocks. Although the packets of the above described embodiment are characterized as transmitted from one block to the next, other embodiments of the present invention may include modified packets in place of such directly transmitted packets as long as the informational and/or functional aspect of the packet is transmitted between blocks. To some extent, a packet input at a second block may be conceptualized as a second packet derived from a first packet output from a first block due to physical limitations of the circuitry involved (e.g., there will inevitably be some attenuation and delay). Therefore, as used herein, a second packet derived from a first packet includes the first packet or any modifications to the first packet, whether due to circuit limitations or due to passage through other circuit elements which do not change the informational and/or final functional aspect of the first packet. 
     The foregoing described embodiment wherein the different components are contained within different other components (e.g., the various elements shown as components of computer system  810 ). It is to be understood that such depicted architectures are merely examples, and that in fact many other architectures can be implemented which achieve the same functionality. In an abstract, but still definite sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermediate components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled”, to each other to achieve the desired functionality. 
       FIG. 9  is a block diagram depicting a network  900  in which computer system  810  is coupled to an internetwork  910 , which is coupled, in turn, to client systems  920  and  930 , as well as a server  940 . Internetwork  910  (e.g., the Internet) is also capable of coupling client systems  920  and  930 , and server  940  to one another. With reference to computer system  810 , modem  847 , network interface  848  or some other method can be used to provide connectivity from computer system  810  to internetwork  910 . Computer system  810 , client system  920  and client system  930  are able to access information on server  940  using, for example, a web browser (not shown). Such a web browser allows computer system  810 , as well as client systems  920  and  930 , to access data on server  940  representing the pages of a website hosted on server  940 . Protocols for exchanging data via the Internet are well known to those skilled in the art. Although  FIG. 9  depicts the use of the Internet for exchanging data, the present invention is not limited to the Internet or any particular network-based environment. 
     Referring to  FIGS. 7 ,  8  and  9 , a browser running on computer system  810  employs a TCP/IP connection to pass a request to server  940 , which can run an HTTP “service” (e.g., under the WINDOWS® operating system) or a “daemon” (e.g., under the UNIX® operating system), for example. Such a request can be processed, for example, by contacting an HTTP server employing a protocol that can be used to communicate between the HTTP server and the client computer. The HTTP server then responds to the protocol, typically by sending a “web page” formatted as an HTML file. The browser interprets the HTML file and may form a visual representation of the same using local resources (e.g., fonts and colors). 
     Although the present invention has been described in connection with several embodiments, the invention is not intended to be limited to the specific forms set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as can be reasonably included within the scope of the invention as defined by the appended claims.