Abstract:
A method of updating a content detection module includes obtaining content detection data, and transmitting the content detection data to a content detection module, wherein the transmitting is performed not in response to a request from the content detection module. A method of sending content detection data includes obtaining content detection data, selecting an update station from a plurality of update stations, and sending the, content detection data to the selected update station. A method of building a content detection system includes establishing a first communication link between a central station and an update station, the central station configured to transmit content detection data to the update station, and establishing a second communication link between the update station and a content detection module.

Description:
RELATED APPLICATION DATA 
     This application claims priority to U.S. patent application Ser. No. 11/000,703 filed on Nov. 30, 2004 entitled SYSTEMS AND METHODS FOR UPDATING CONTENT DETECTION DEVICES AND SYSTEM which claims priority to U.S. Provisional Patent Application No. 60/552,457, filed on Mar. 12, 2004, the entire disclosures of which are expressly incorporated herein by reference. 
     This application is also related to U.S. patent application Ser. No. 12/639,800 filed on Dec. 16, 2009 entitled SYSTEMS AND METHODS FOR UPDATING CONTENT DETECTION DEVICES AND SYSTEM which claims priority to U.S. patent application Ser. No. 11/000,703 filed on Nov. 30, 2004 entitled SYSTEMS AND METHODS FOR UPDATING CONTENT DETECTION DEVICES AND SYSTEM which claims priority to U.S. Provisional Patent Application No. 60/552,457, filed on Mar. 12, 2004, the entire disclosures of which are expressly incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The field of the invention relates to computer network and computer systems, and more particularly, to systems and methods for updating content detection modules. 
     2. Background 
     The generation and spreading of computer viruses are major problems in computer systems and computer networks. A computer virus is a program that is capable of attaching to other programs or sets of computer instructions, replicating itself, and/or performing unsolicited or malicious actions on a computer system. Viruses may be embedded in email attachments, files downloaded from Internet, and macros in MS Office files. The damage that can be done by a computer virus may range from mild interference with a program, such as a display of unsolicited messages or graphics, to complete destruction of data on a user&#39;s hard drive or server. 
     To provide protection from viruses, most organizations have installed virus scanning software on computers in their network. However, these organizations may still be vulnerable to a virus attack until every host in their network has received updated anti-virus software. With new attacks reported almost weekly, organizations are constantly exposed to virus attacks, and spend significant resources ensuring that all hosts are constantly updated with new antivirus information. For example, with existing content detection software, a user may have to request for a download of a new virus signature in order to enable the content detection software to detect new virus that has been created since the last update. If a user delays in downloading the new virus signature, the content detection software would be unable to detect the new virus. Also, with existing content detection systems, new virus signatures are generally not made available shortly after they are discovered. As such, a computer mat be subjected to attack by the new virus until the new virus signature is available and is downloaded by a user. 
     Besides virus attacks, many organizations also face the challenge of dealing with inappropriate content, such as email spam, misuse of networks in the form of browsing or downloading inappropriate content, and use of the network for non-productive tasks. Many organizations are struggling to control access to appropriate content without unduly restricting access to legitimate material and services. Currently, the most popular solution for blocking unwanted web activity is to block access to a list of banned or blacklisted web sites and pages based on their URLs. However, as with virus scanning, the list of blocked URL requires constant updating. If a user delays in downloading the list of URL, or if the list of URL is not made available soon enough, the content detection software would be unable to detect undesirable content, such as web pages. 
     Many email spam elimination systems also use blacklists (spammer lists) to eliminate unwanted email messages. These systems match incoming email messages against a list of mail servers that have been pre-identified to be spam hosts, and prevent user access of messages from these servers. However, as with virus scanning, the spammer list also requires constant updating. If a user delays in downloading the spammer list, or if the spammer list is not made available soon enough, the content detection software would be unable to detect undesirable content. 
     SUMMARY 
     In accordance with some embodiments, a method of updating a content detection module includes obtaining content detection data, and transmitting the content detection data to a content detection module, wherein the transmitting is performed not in response to a request from the content detection module. 
     In accordance with other embodiments, a system for updating a content detection module includes means for obtaining content detection data, and means for transmitting the content detection data to a content detection module, wherein the means for transmitting is configured to perform the transmitting not in response to a request from the content detection module. 
     In accordance with other embodiments, a computer-program product having a medium, the medium having a set of instructions readable by a processor, an execution of the instructions by the processor causes a process to be performed, the process includes obtaining content detection data, and transmitting the content detection data to a content detection module, wherein the transmitting is performed not in response to a request from the content detection module. 
     In accordance with other embodiments, a content detection system includes a station having a computer-readable medium for storing content detection data, the content detection data usable by a content detection module to detect content, wherein the station is configured to transmit the content detection data not in response to a request by the content detection module. 
     In accordance with other embodiments, a method of sending content detection data includes determining whether a first update station received the content detection data, and sending the content detection data to the first update station if the first update station did not receive the content detection data. 
     In accordance with other embodiments, a system for sending content detection data includes means for determining whether a first update station received the content detection data, and means for sending the content detection data to the first update station if the first update station did not receive the content detection data. 
     In accordance with other embodiments, a computer-program product having a medium, the medium having a set of instructions readable by a processor, an execution of the instructions by the processor causes a process to be performed, the process includes determining whether a first update station received the content detection data, and sending the content detection data to the first update station if the first update station did not receive the content detection data. 
     In accordance with other embodiments, a method of sending content detection data includes obtaining content detection data, selecting an update station from a plurality of update stations, and sending the content detection data to the selected update station. 
     In accordance with other embodiments, a system for sending content detection data includes means for obtaining content detection data, means for selecting an update station from a plurality of update stations, and means for sending the content detection data to the selected update station. 
     In accordance with other embodiments, a computer-program product having a medium, the medium having a set of instructions readable by a processor, an execution of the instructions by the processor causes a process to be performed, the process includes obtaining content detection data, selecting an update station from a plurality of update stations, and sending the content detection data to the selected update station. 
     In accordance with other embodiments, a method of building a content detection system includes establishing a first communication link between a central station and an update station, the central station configured to transmit content detection data to the update station, and establishing a second communication link between the update station and a content detection module. 
     In accordance with other embodiments, a system for building a content detection system includes means for establishing a first communication link between a central station and an update station, the central station configured to transmit content detection data to the update station, and means for establishing a second communication link between the update station and a content detection module. 
     In accordance with other embodiments, a computer-program product having a medium, the medium having a set of instructions readable by a processor, an execution of the instructions by the processor causes a process to be performed, the process includes establishing a first communication link between a central station and an update station, the central station configured to transmit content detection data to the update station, and establishing a second communication link between the update station and a content detection module. 
     Other aspects and features of the invention will be evident from reading the following detailed description of the preferred embodiments, which are intended to illustrate, not limit, the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate the design and utility of preferred embodiments of the application, in which similar elements are referred to by common reference numerals. In order to better appreciate how advantages and objects of various embodiments are obtained, a more particular description of the embodiments are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the application and are not therefore to be considered limiting its scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings. 
         FIG. 1  illustrates a block diagram of a content detection system in accordance with some embodiments; and 
         FIG. 2  is a diagram of a computer hardware system. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments are described hereinafter with reference to the figures. It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of specific embodiments. They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment may not show all aspects or advantages. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments, even if not so illustrated or described. 
       FIG. 1  illustrates a block diagram of a content detection system  100  in accordance with some embodiments. The content detection system  100  includes a central station  102 , a processing station  104  for providing content detection data to the central station  102 , a plurality of base stations  106  in communication with the central station  102 , and a plurality of content detection modules  108  in communication with the base stations  106 . 
     In the illustrated embodiments, processing station  104  is a computer. Alternatively, processing station  104  can be a server, a module, a device, a computer program, and the like, e.g., any one of a variety of devices that can receive and transmit information. Processing station  104  is configured to determine content detection data, such as a virus signature, a spammer identification, a URL, and the like, and transmit the content detection data to central station  102 . For example, processing station  104  can be configured (e.g., programmed) to determine the content detection data using any of the techniques known in the art. Alternatively, the content detection data can be input into processing station  104  by a user of processing station  104 . Although one processing station  104  is shown, in other embodiments, content detection system  100  can include more than one processing station  104  in communication with central station  102 . 
     Central station  102  is configured to receive the content detection data from processing station  104 , and send the content detection data to update stations  106  (e.g., through the Internet). In some embodiments, central station  102  also receives subscriber data, such as a user identification of a content detection module  108 , level of protection desired by the user, etc., from processing station  104  or from update station(s)  106  for processing. In the illustrated embodiments, central station  102  is a computer, but alternatively, can be a server, a module, a device, a computer program, and the like, e.g., any one of a variety of devices that can receive and transmit information. Although one processing station  102  is shown, in other embodiments, content detection system  100  can include more than one central station  102 , each of which in communication with at least one update station  106 . In other embodiments, central station  102  and processing station  104  are combined and implemented as a single unit (e.g., a processor, a computer, or the like). 
     Update stations  106  receive the content detection data from central station  102 , and send the content detection data to content detection modules  108  (e.g., through the Internet). Each of the update stations  106  is located at a geographical location that is different from others. For example, update station  106   a  may be located at a different building, a different street, a different city, or a different country, from update station  106   b . In some embodiments, the update stations  106  also receives subscriber data, such as a user identification of a content detection module  108 , level of protection desired by the user, etc., from content detection module(s)  108 , and forward the subscriber data to central station  102  for processing. In other embodiments, update station  106  may be configured to handle requests (such as a subscriber&#39;s contract information, the latest update data, etc.) from content detection module(s)  108 , collect information (such as the version information, IP address, geographical location of the detection module, etc.) from content detection module(s)  108 , and forward collected information to central station  102 . In the illustrated embodiments, each update station  106  is a computer, but alternatively, can be a server, a module, a device, a computer program, and the like, e.g., any one of a variety of devices that can receive and transmit information. In  FIG. 1 , three update stations  106   a - 106   c  and five content detection modules  108   a - 108   e  are shown. However, in alternative embodiments, the system  100  can have different numbers of update station(s)  106  and different numbers of content detection module(s)  108 . 
     In the illustrated embodiments, each content detection module  108  is configured to receive electronic content (content data), and determines whether the electronic content contains undesirable content based on the content detection data it receives from update station  106 . For example, content detection module  108  can be configured to detect virus based on a virus signature received from update station  106 . In the illustrated embodiments, module  10  is implemented as a component of a gateway (or gateway product), which is configured to perform policy enforcement. As used in this specification, the term “policy enforcement” refers to a process or procedure, an execution of which creates a result that can be used to determine whether to pass data to user, and includes (but is not limited to) one or a combination of: source verification, destination verification, user authentication, virus scanning, content scanning (e.g., scanning for undesirable content), and intrusion detection (e.g., detecting undesirable content, such as worms, porno website, etc.). In other embodiments, instead of being a component of gateway, content detection module  108  can be a separate component that is coupled to gateway. In other embodiments, content detection module  108  can be a gateway product by itself. 
     In some embodiments, content detection module  108  can be implemented using software that is loaded onto a computer, a server, or other types of memory, such as a disk or a CD-ROM. Alternatively, content detection module  108  can be implemented as web applications. In alternative embodiments, content detection module  108  can be implemented using hardware. For example, in some embodiments, content detection module  108  includes an application-specific integrated circuit (ASIC), such as a semi-custom ASIC processor or a programmable ASIC processor. ASICs, such as those described in Application-Specific Integrated Circuits by Michael J. S. Smith, Addison-Wesley Pub Co. (1st Edition, June 1997), are well known in the art of circuit design, and therefore will not be described in further detail herein. In still other embodiments, content detection module  108  can be any of a variety of circuits or devices capable of performing the functions described herein. For example, in alternative embodiments, content detection module  108  can include a general purpose processor, such as a Pentium processor. In other embodiments, content detection module  108  can be implemented using a combination of software and hardware. In some embodiments, content detection module  108  may be implemented as a firewall, a component of a firewall, or a component that is configured to be coupled to a firewall. 
     Having described the components of the content detection system  100 , methods of using content detection system  100  in accordance with some embodiments will now be described. First, processing station  104  receives an electronic content. By means of non-limiting examples, such electronic content can be a web page, an email, an email attachment, a word file, a program, etc., and the like, e.g., a file that may contain undesirable content. In other examples, electronic content can be a virus, a spam, a worm, or any of other undesirable content. Processing station  104  can receive the electronic content from one or more sources. For example, a content detection module  108  may detect a content that is suspicious (or that requires further processing), in which case, content detection module  108  then sends the electronic content to processing station  104  for processing. Alternatively, processing station  104  can receive electronic content from a person, who sends the content to processing station  104  via email. In other embodiments, electronic content can be input into processing station  104  by a user of processing station  104 . 
     After processing station  104  received the electronic content, processing station  104  then analyzes such information to determine whether the content contains/is a threat (e.g., a virus, a worm, a spam, etc.) that is desired to be detected. If processing station  104  determines that the electronic content contains a threat that is desired to be detected, processing station  104  then generates content detection data for the electronic content. For example, after processing station  104  received a set of content data, processing station  104  then performs an analysis using conventional or known technique(s) to determine whether it is a virus (an example of content that is desired to be detected). In some embodiments, processing station  104  is programmed to perform such analysis. Alternatively, the set of content data can be analyzed by an administrator, a separate device, or a separate software, and the result of the analysis is then input to processing station  104 . If processing station  104  determines that the set of content data includes content that is undesirable (e.g., desired to be detected by content detection modules  108 ), processing station then generates content detection data, which can be used by content detection modules  108  to detect the undesirable content. By means of non-limiting examples, content detection data can be a virus signature, a virus definition, a spammer identification, a URL, a NIDS signature, a time at which content detection data is created, a level of threat, etc., and the like, e.g., any information that can be used in a content detection or screening process. In other embodiments, processing station  104  does not generate the content detection data. In such cases, content detection data can be provided by a separate source, and is input into processing station  104 . 
     As soon as, or shortly after, processing station  104  obtains the content detection data, processing station  104  then transmits the content detection data to central station  102 . If processing station  104  and central station  102  are implemented as a single unit, then the step of transmitting content detection data to central station  102  is omitted. In response to obtaining the content detection data, central station  102  initiates a transmission process for transmitting the content detection data to update stations  106 . In the illustrated embodiments, central station  102  maintains a list of prescribed geographical areas, a list of content detection modules  108  in each prescribed geographical area, and a list of update stations  106  for serving (e.g., sending content detection data to and/or from) each prescribed geographical area. Based on the lists, central station  102  assigns update stations  106  to provide the content detection data to content detection modules  108  within the prescribed geographical areas. In some embodiments, one update station  106  is used to serve content detection modules  108  within a prescribed geographical area. Alternatively, more than one update station  106  can be used to serve content detection modules  108  within a prescribed geographical area. 
     In some cases, an update station  106  can be configured to check another update station  106  to determine whether it has received content detection data. For example, if update station  106   a  determines that update station  106   b  did not receive content detection data, update station  106   a  then sends content detection data to update station  106   b . Various techniques can be used to determine whether update station  106   b  received content detection data. For example, in some embodiments, update station  106   a  is configured to send an inquiry to update station  106   b . If update station  106   b  did not receive content detection data, update station  106   b  then transmits a signal or a reply to update station  106   a , indicating that update station  106   b  did not receive content detection data. Alternatively, update station  106   a  is configured to initiate a timer after it has received content detection data. The timer continues to run until update station  106   a  receives a signal from update station  106   b  indicating that update station  106   b  received content detection data. If update station  106   a  does not receive such signal from update station  106   b  within a prescribed time period, update station  106   a  then determines that update station  106   b  did not receive the content detection data. Other techniques known in the art can also be used to check whether update station  106   b  received content detection data. If it is determined that update station  106   b  did not receive content detection data, update station  106   a  then sends content detection data to update station  106   b . It should be noted that in other embodiments, instead of having one update station check another update station, one update station can check a plurality of other update stations. Also, in other embodiments, more than one update station  106  can check another update station  106 . 
     In the illustrated embodiments, each of the update stations  106  are configured (e.g., pre-assigned) to serve one or more content detection module  108 . For example, update station  106   a  can be configured to serve content detection modules  108   a ,  108   b , update station  106   b  can be configured to serve content detection module  108   c , and update station  106   c  can be configured to serve content detection modules  108   d ,  108   e.    
     In other embodiments, instead of pre-assigning update stations  106  to serve certain content detection modules  108 , central station  102  determines which update station  106  to use for sending content detection data based on a condition during use, e.g., based on load demands and/or capacities of update stations  106 . As used in this specification, “capacity” refers to a variable that represents or associates with a level of ability for an update station  104  to handle content transmitted thereto. For example, capacity of an update station  104  can be an amount of memory space available, etc. Using the example of  FIG. 1 , central station  102  receives information regarding capacities of update stations  106   a - 106   c , and selects one or more update stations  106  for transmitting content detection data based on their load and/or capacities. For example, if update station  106   a  has a high load demand (e.g., above a prescribed load demand) and/or if its remaining capacity to handle additional traffic is low (e.g., below a prescribed capacity threshold), central station  102  then uses update stations  106   b  and  106   c  to transmit content detection data to content detection modules  108   a - 108   e . Load on the update stations  106   b  and  106   c  can be approximately shared in equal portion. For example, if central station  102  determines that update stations  106   b  and  106   c  are available, central station  102  can assign update station  106   b  to transmit content detection data to modules  108   a  and  108   b , and update station  106   c  to transmit content detection data to modules  108   a - 108   c . Alternatively, load among the available update stations  106  can be distributed based on the respective load demand and/or capacities of the available update stations  106 . For example, if update stations  106   b ,  106   c  have capacities to serve twenty (20) and eighty (80) content detection modules  108 , respectively, central station  102  then assign update stations  106   b ,  106   c  to transmit content detection data such that the ratio of the assigned loads approximately corresponds with the ratio of the capacities of the available update stations  106   b ,  106   c . Following the above example, central station  102  will assign update station  106   b  to serve content detection module  108   a , and update station  106   c  to serve content detection modules  108   b - 108   e.    
     In other embodiments, central station  102  maintains an order list of update station  106 , which prescribes an order (e.g., in a round-robin configuration) in which load is to be assigned to update stations  106 . For example, the order list may have update stations  106   a - 106   c  as primary, secondary, and tertiary stations, respectively, for serving content detection modules  108   a - 108   e . In such cases, central station  102  will initially attempt to use update station  106   a  (the primary station) for transmitting content detection data to content detection modules  108   a - 108   e . However, if update station  106   a  is unavailable (e.g., due to heavy load demand), central station  102  will then attempt to use update station  106   b  (the secondary station) for transmitting content detection data to content detection modules  108   a - 108   e . If update station  106   b  is unavailable (e.g., due to heavy load demand), central station  102  will then attempt to use update station  106   c  (the third station on the order list) for transmitting content detection data to content detection modules  108   a - 108   e.    
     It should be noted that the technique for transmitting content detection data from central station  102  and/or update station(s)  106  to content detection module(s)  108  should not be limited to the examples discussed previously, and that other techniques can also be used in other embodiments. For example, one or more of the techniques described previously can be combined with another technique. Also, in other embodiments, central station  102  does not maintain the list of content detection modules  108  and the list of geographical areas. In such cases, after central station  102  receives content detection data, it transmits the content detection data to all update stations  106 . The update stations  106  are configured to coordinate among themselves to ensure that all content detection modules  108  are provided with the content detection data. For example, in the example of  FIG. 1 , update station  106   a  can be configured (e.g., programmed) to communicate with update station  106   b  for various purposes, such as, to check a load demand on update station  106   b , to check a capacity of update station  106   b , to check an availability of update station  106   b , and/or to verify that update station  106   b  has received content detection data. In some embodiments, based on the load demand and/or the capacities on the update stations  106 , update stations  106  share the load among themselves (e.g., by dividing the load in equal parts, or by distributing the load based on respective ratios of the demand and/or capacities on the update stations  106 ) to pass the content detection data to content detection modules  108 . In some embodiments, one update station  106  can be configured to communicate with one or more other update station  106 . In such cases, the update station  106  can check one or more other update station  106  to make sure that content detection data have been received, and/or to serve as backup for the one or more other update station  106 . In other embodiments, more than one update stations  106  can check an update station  106 , and serve as backup for the update station  106 . 
     After content detection modules  108  received the content detection data (e.g., a virus signature), content detection modules  108  can then utilize the content detection data to detect content. In some embodiments, the content detection data is a virus signature, in which case, content detection modules  108  utilizes the virus signature to detect the virus that corresponds with the virus signature. Alternatively, the content detection data is a spammer identification, in which case, content detection modules  108  utilizes the spammer identification to detect and screen undesirable spam that corresponds with the spammer identification. In other embodiments; the content detection data can be other information, such as, a time at which content detection data is created, that content detection modules  108  can use in a content detection or screening process. 
     Using the above method, content detection data can be provided to content detection modules  108  within a short period, such as, several minutes, and in some cases, within seconds, after the content detection data has been obtained (determined) by processing station  104  and/or central station  102 . This allows content detection modules  108  to be updated in substantially real time. This is advantageous because some content detection data such as virus definitions are very time-sensitive, and should be distributed to all content detection modules  108  as soon as the content detection data are available. Also, with system  100 , the responsibility to keep up with the latest security update (e.g., content detection data) is shifted from users of content detection modules  108  to processing station  104  and/or central station  102 . In addition, unlike typical update method, which requires a content detection module to regularly “poll” an update station to check if there is a new update, central station  102  and/or update stations  106  “push” the latest security update data within minutes (or even seconds) after they are available to all content detection modules  108 . This method has the advantage of faster response time during an outbreak and less resource consumption on content detection modules  108 . 
     Further, using a network of update stations  106  for transmitting content detection data is reliable because if update station(s)  106  is not available or fail to work properly, a nearby update station  106  in the same prescribed geographical area or update station(s)  106  located in other prescribed geographical area can provide the content detection data to content detection modules  108 . Also, with content detection system  100 , an update station  106  can be added, removed from the content detection system  100  at run-time without causing service interruption. If the update stations  106  for a certain geographical areas cannot keep up with the ever-increasing load, more update station(s) can be added to the content detection system  100 . As such, content detection system  100  provides high scalability. 
     In some embodiments, an update station can be customized to serve the need of certain organization(s). Some organizations have some special policies that restrict their network device&#39;s access to the Internet. For example, their network connection from Intranet to Internet is only limited to certain host(s). Therefore, it may not be possible for their content detection modules  108  inside the Intranet to access update station(s)  106 . In such cases, a customized update station can be provided outside the Intranet of the organization (customer). For example, the customer can configure [ ] an update station to serve its own content detection module(s)  108 . In some embodiments, a user interface can be provided for allowing a user to select which content detection module(s)  108  within the organization to use a customized update station and which content detection module(s)  108  to use a regular update station. As with update stations  106 , more than one customized update station can be provided, and these customized update stations can back up each other and distribute their load. 
     Computer Architecture 
     As described previously, any of central station  102 , processing station  104 , update station  106 , and content detection module  108  can be implemented using a computer. For example, one or more instructions can be imported into a computer to enable the computer to perform any of the functions described herein. 
       FIG. 2  is a block diagram that illustrates an embodiment of a computer system  200  upon which embodiments of the invention may be implemented. Computer system  200  includes a bus  202  or other communication mechanism for communicating information, and a processor  204  coupled with bus  202  for processing information. Computer system  200  also includes a main memory  206 , such as a random access memory (RAM) or other dynamic storage device, coupled to bus  202  for storing information and instructions to be executed by processor  204 . Main memory  206  also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor  204 . Computer system  200  may further include a read only memory (ROM)  208  or other static storage device(s) coupled to bus  202  for storing static information and instructions for processor  204 . A data storage device  210 , such as a magnetic disk or optical disk, is provided and coupled to bus  202  for storing information and instructions. 
     Computer system  200  may be coupled via bus  202  to a display  212 , such as a cathode ray tube (CRT), for displaying information to a user. An input device  214 , including alphanumeric and other keys, is coupled to bus  202  for communicating information and command selections to processor  204 . Another type of user input device is cursor control  216 , such as a mouse, a trackball, cursor direction keys, or the like, for communicating direction information and command selections to processor  204  and for controlling cursor movement on display  212 . This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane. 
     Embodiments of the invention are related to the use of computer system  200  for transmitting content data. According to some embodiments of the invention, such use may be provided by computer system  200  in response to processor  204  executing one or more sequences of one or more instructions contained in the main memory  206 . Such instructions may be read into main memory  206  from another computer-readable medium, such as storage device  210 . Execution of the sequences of instructions contained in main memory  206  causes processor  204  to perform the process steps described herein. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in main memory  206 . In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the invention. Thus, embodiments of the invention are not limited to any specific combination of hardware circuitry and software. 
     The term “computer-readable medium” as used herein refers to any medium that participates in providing instructions to processor  204  for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks, such as storage device  210 . Volatile media includes dynamic memory, such as main memory  206 . Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise bus  202 . Transmission media can also take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications. 
     Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read. 
     Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to processor  204  for execution. For example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system  200  can receive the data on the telephone line and use an infrared transmitter to convert the data to an infrared signal. An infrared detector coupled to bus  202  can receive the data carried in the infrared signal and place the data on bus  202 . Bus  202  carries the data to main memory  206 , from which processor  204  retrieves and executes the instructions. The instructions received by main memory  206  may optionally be stored on storage device  210  either before or after execution by processor  204 . 
     Computer system  200  also includes a communication interface  218  coupled to bus  202 . Communication interface  218  provides a two-way data communication coupling to a network link  220  that is connected to a local network  222 . For example, communication interface  218  may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, communication interface  218  may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, communication interface  218  sends and receives electrical, electromagnetic or optical signals that carry data streams representing various types of information. 
     Network link  220  typically provides data communication through one or more networks to other devices. For example, network link  220  may provide a connection through local network  222  to a host computer  224 . Network link  220  may also transmits data between an equipment  226  and communication interface  218 . The data streams transported over the network link  220  can comprise electrical, electromagnetic or optical signals. The signals through the various networks and the signals on network link  220  and through communication interface  218 , which carry data to and from computer system  200 , are exemplary forms of carrier waves transporting the information. Computer system  200  can send messages and receive data, including program code, through the network(s), network link  220 , and communication interface  218 . Although one network link  220  is shown, in alternative embodiments, communication interface  218  can provide coupling to a plurality of network links, each of which connected to one or more local networks. In some embodiments, computer system  200  may receive data from one network, and transmit the data to another network. Computer system  200  may process and/or modify the data before transmitting it to another network. 
     Although particular embodiments have been shown and described, it will be understood that it is not intended to limit the present inventions to the preferred embodiments, and it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present inventions. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The present inventions are intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the present inventions as defined by the claims.