Patent Document

This application is a continuation of allowed U.S. application Ser. No. 11/535,056 filed Sep. 25, 2006, (U.S. Pat. No. 7,895,446), which is a continuation of U.S. application Ser. No. 09/323,415 filed Jun. 1, 1999, (U.S. Pat. No. 7,146,505). Both are titled “Secure Data Exchange Between Data Processing Systems” and are incorporated by reference in their entirety. 
    
    
     BACKGROUND 
       FIG. 1  shows a computer network  100  that includes both client computers  111 - 113  and server computers  131 - 133 . The network  100  also includes data connections that allow the client computers to communicate with the servers. Those data connections include access connections  114 - 116 , a service provider&#39;s point of presence (POP)  110 , network  120 , proxy server  117 , and network  130 . POP  110  includes data communications equipment that allows a client computer  111 - 113  to connect to the network  120 . For example, POP  110  may include dial-up modem banks, cable modem banks, a T1 interface, wireless communications equipment, or other data transmission equipment. 
     After a client computer  111 - 113  has been connected to the network  120  (through POP  110 ) it may exchange data with other computers on the network  120 . Computers on different networks  120  and  130  also can exchange data with each other by sending their data request to proxy server  117  which, in turn, can forward their request to the destination computer, obtain a response from the destination, and return the response to the requesting computer. 
     The servers  131 - 133  and clients  111 - 113  may communicate with each other using the hypertext transfer protocol (HTTP). HTTP is a data communications protocol that is used by web browser programs (such as Microsoft Internet Explorer and Netscape Navigator) to communicate with web server applications (such as Microsoft Internet Information Server and Netscape Server). Thus, by executing a web browser, a client computer  111 - 113  can exchange data with a server  131 - 133  that is executing a web server application. 
     When a web server receives a HTTP data request from a browser, a web server application, such as a Common Gateway Interface (CGI) script, may be used to query databases, customize responses, and/or perform other processing used to generate a response. The web server application may need data about the client computer, the browser, its user, and/or other data in order to complete its processing of the data request. For example, a web server application may provide customized weather information based on a user&#39;s home address. The web application may obtain the user&#39;s address information by sending a data input form to the browser and receiving a user&#39;s response that contains the needed information. A web server application also may obtain needed data from web server environmental variables that are populated by data in HTTP header fields, by a web server, and/or by a web server sub-component. For example, a CGI script&#39;s response to a data request may depend on the type of browser originating the request. The CGI script may access a HTTP environment variable (“HTTP_USER_AGENT”) populated by the web server using data from a “User-Agent” field in a HTTP header. The value of the HTTP_USER_AGENT variable identifies the type of browser originating a request so that the CGI script can customize its response to that browser. 
     A web server and a browser also may exchange web cookies that contain data. A web cookie is data file that can be automatically exchanged between browsers and servers along with the request and responses exchanged between the browsers and servers. When a web cookie is received by a browser, it can be stored at the client computer. During future transactions with the web server, the web cookie (and any data that it contains) can be sent back to the web server. By using data stored in web cookies, a web server&#39;s need to request data from a user may be reduced. However, since web cookies are typically stored on a client computer, they may be deleted and their data lost. Furthermore, if a user moves to another computer, web cookie information stored on the user&#39;s original computer will be unavailable to that user. These factors may reduce the utility of web cookies. 
     The present inventors recognize that information service systems, such as web servers, should provide convenient, secure, reliable, and simple means of interacting with users. The present inventors further recognize when a server must query a user for data or use web cookies for data storage and input, convenience, security, reliability, and simplicity may suffer. Consequently, the invention disclosed herein provides additional means of providing information to a web server application that may provide additional flexibility in implementing information systems. 
     SUMMARY 
     In general, in one aspect, the invention features a data transfer method performed at a proxy server. The method includes intercepting a data request from a client computer that is so directed to a target server, encrypting profile information, augmenting the data request by adding the encrypted profile information to the data request, and sending the augmented data request to the target server. In another aspect, the invention features a data transfer method performed at an information server. The method includes receiving a data request from a proxy server, extracting profile information added to the data request by the proxy server, using the extracted profile information to generate a response, and sending the response to the proxy server. 
     In general, in another aspect, the invention features a computer program residing on a computer-readable medium. The program includes instructions for causing a computer to intercept a data request from a client computer that is directed to a target server, encrypt profile information, augment the data request by adding the encrypted profile information to the data request, and send the augmented data request to the target server. In another aspect, the invention features a computer program residing on a computer-readable medium that includes instructions for causing a computer to receive a data request comprising encrypted profile information that was added to the data request by a proxy server, extract the profile information added by the proxy server, use the extracted profile information to generate a response, and send the response to the proxy server. 
     In general, in another aspect, the invention features a proxy server that includes a database, a network interface, a processor, and a memory. The database includes records storing user profile information. The network interface operatively couples the proxy server to a network to exchange data with a client computer and with a target server. The processor is operatively coupled to the network interface, the database, and a memory. The memory includes executable instructions for causing the processor to intercept a data request that is directed to a target server, retrieve a record from the database, encrypt profile information in the record, augment the data request by adding the encrypted profile information, and send the augmented data request to the target server 
     In general, in another aspect, the invention features an information server that includes a network interface, a processor, and a memory. The network interface operatively couples the information server to a proxy server. The processor is operatively coupled to the network interface and to the memory. The memory includes executable instructions for causing the processor to receive a data request from the proxy server, decrypt user profile information added to the data request by the target server; and use the decrypted user profile information to generate a response to the data request. 
     Implementations may include one or more of the following features. A reference token may be exchanged between servers and used to refer to previously exchanged profile information. The reference token may be placed in subsequent data request sent by the proxy server to the target in place of full profile information. The profile information that is encrypted by the proxy server can be stored in proxy server database records. The particular user profile information encrypted and included in a data request can be selected based on an identity of a client computer user or a browser user. The identity may be determined using the Internet Engineering Task Force IDENT protocol or by using another method. 
     Implementations also may include one or more of the following features. Profile information may be encrypted at the proxy server using a session key as an encryption key, and may be decrypted at the target server using the same session key. The session key may be determined by the proxy server and sent to the target server using a public key cryptography algorithm and a public key associated with the target server. 
     A data request may use the hypertext transfer protocol. Profile information extracted from the data request at the target/information server can be provided to a web application, such as a CGI script, that is used to generate a response. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Implementations may provide advantages including reduction of redundant data entry, reduction of user data entry errors, secure storage of user data, and automated user profile determination and dissemination. Different encryption keys can be used for different information servers, and each information server may establish characteristics associated with its encryption key. A web site may dynamically generate, maintain, and change its unique encryption key. This may help to minimize risk of replay attacks, message forgery, and message tampering. In addition, implementations may support multiple levels of security. 
     Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a computer network diagram. 
         FIG. 2  is a computer network diagram. 
         FIGS. 3A and 3B  show exemplary HTTP headers. 
         FIGS. 4A and 4B  are flowcharts. 
         FIG. 5  is a message flow diagram. 
     
    
    
     DETAILED DESCRIPTION 
     Processing of an information request at a information server, such as a web server, can be facilitated by a data transfer mechanism in which data needed to process the request is stored at a proxy server and automatically transferred to the information servers. Such a data transfer mechanism can be used, for example, by an information service provider (ISP) or on-line service provider (OSP) to automatically transfer information about a user (a “user profile”) to affiliated web sites. Referring to  FIG. 2 , to automatically transfer a user profile to a web server  203 , the user profile information is first stored at a proxy server  202  in a database  220 . When a HTTP data request  211  is received by the proxy server  202  from a web browser  201 , the user profile information from database  220  is encapsulated in a request  212  that is forwarded by the proxy server to web server  203 . The proxy server  202  encapsulates the user profile information in the request  212  by adding HTTP headers containing the user profile information to the headers received in the request  211 . 
       FIGS. 3A and 3B  shows fields in HTTP requests. The fields  300  may be fields in a request  211  from a client computer  201 , and the fields  350  may be fields in a request  212  forwarded by proxy server  202  to a web site  203 . Referring to  FIGS. 3A and 3B , each field  301 - 303  includes a HTTP field name and a value associated with the field. HTTP field names identify the associated field value. For example, the “User-Agent:” field name in field  302  indicates that request  300  originated at a “Mozilla/3.0 compatible” browser; and the “Cookie:” field name in field  303  includes the value “been_here_before” is a web cookie. When a HTTP request  211  having fields  300  is received at proxy  202 , the proxy server  202  can add user profile information to the request  211  by adding additional HTTP fields  304 - 305  containing the profile information, thereby generating a new request  212  with the user profile information encapsulated in fields  304 - 305 . 
     Database  220  may be a local or remote database that can store multiple user profiles. For example, the database  220  may be a database storing user profiles on a hard disk directly connected to the proxy server  202 , or the database may be a SQL database at a remote system and accessed over a TCP/IP connection. Still other database  220  implementations may be used. Each user profile may be associated with a particular user or group of users. A user profile may be selected from the database  220  based on the identifying information associated with a particular computer or user of that computer. To determine the user&#39;s identity, a proxy server may use a table or database that associates user identity information with network connection information. For example, referring to  FIGS. 2 ,  4 A, and  4 B, when a client computer  201  connects to a network  230 , the client computer&#39;s user may submit name and password information to a POP or to a login server. The POP or login server may then send the user name and network connection information unique to that user (such as a unique combination of TCP/IP address and port number) to the proxy server  202  where it is stored in a database  220  (step  400 ). When the proxy server  202  receives a subsequent HTTP request  211  (step  401 ), the proxy server can identify the user associated with the request by querying the database of stored name and network connection associations. A proxy server also may identify a user using the IDENT protocol. The IDENT protocol is an Internet protocol that allows a computer to ask another computer for the name of the user. The IDENT protocol is further described in Internet Engineering Task Force (IETF) document RFC1413. 
     When the proxy server  202  has identified the user (step  402 ), the proxy server can retrieve a user profile associated with that user from its database  220 . The proxy server may then add HTTP fields containing user profile information to fields in the original HTTP request  211  (step  403 ). For example, header fields  304 - 305  may be added to the original header fields  301 - 303  from request  211 . Field  304  may include unencrypted user profile data (“UserName=John_Doe, ZipCode=60609, ParentalControl=YoungTeen), while field  305  may include encrypted user profile data. Encryption of data in the field  305  may use the SecureData protocol (explained later). The proxy server thereby forms the modified HTTP request  212  containing the user profile data. The modified request  212  may then be forwarded by the proxy server for receipt at a web site (steps  404  and  421 ). 
     Particular web servers may or may not be configured to recognize the user profile data fields  304 - 305 . A web server that is not configured to recognize the user profile fields  304 - 305  may ignore the fields. A web server that is configured to recognize the user profile fields  304 - 305  can extract the profile data from the field  304 - 305  (steps  422  and  424 ). Extraction of user profile data in the field  305  may include decryption of the user profile data in encrypted field  305 . The extracted user profile data can be used, for example, to generate or customize data sent in response  213  to the proxy server for forwarding as a response  214  to a user or client computer (step  425 ). For example, a tourist information web server may customize a page based user profile data specifying a browser user&#39;s age, and interest. If a web server looks for a user profile field  304 - 305  in the request  212 , and the user profile field is not present, the server may use “traditional” data input mechanisms (such as forms and web cookies) to obtain needed data from a user (step  422 - 423 ). After the necessary data is obtained, the web server  203  can generate a response (step  425 ). 
     Exchange of user profile data between a proxy server  202  and a web server  203  may implemented using custom filtering software (“proxy data exchange filter” software) that can be added to commercially available proxy and web site server software. For example, Microsoft Internet Information Server (IIS) provides an application programming interface known as the information server application programming interface (ISAPI) that allows custom filtering software to be added to an IIS web site. A Netscape web site server provides an application programming interface known as the Netscape server application programming interface (NSAPI) that may also be used to develop custom filtering software. When a request  212  from the proxy server  203  is received at an IIS or Netscape server web site, the request  212  is passed to the proxy data exchange filter by the IIS or Netscape server software and the user profile data is extracted from the headers  304 - 305 . The extracted profile data may then be made available as HTTP environment variables, database entries, or other data exchange structures that can be used by web applications. The remaining header information in request  212  (e.g., the original information from request  211 ), may then be processed by the web server to obtain response  213  information. 
     A proxy server  202  and web server  203  may implement the SecureData protocol so (described below) to encrypt user profile data. Encrypted user profile data may be indicated by a special HTTP header. For example, the field name “User-Profile-SecureData” in field  305  indicates that the field value segment of field  305  contains encrypted profile data. 
     The SecureData protocol uses multiple cryptography algorithms to provide secure user profile data transfers between a proxy server  202  and a web server  203 . For example, the SecureData protocol may use the Rivest, Shamir, Adelman (RSA) public key encryption algorithm or the pretty-good-privacy (PGP) public key cryptography algorithm along with the RSA RC4 symmetric encryption algorithm. Additional information on the RC4 algorithm can be found, for example, in  Applied Cryptography,  2nd edition, By Bruce Schneier, John Wiley &amp; Sons, 1996. 
     User profile information may be encrypted at proxy server  202  using a symmetric encryption algorithm. A symmetric encryption algorithm, such as the RSA RC4 algorithm, uses the same encryption key (referred to herein as a “session” key) to encrypt and decrypt data. The proxy server  202  may encrypt user profile data and place it in a HTTP field in request message  212 . The proxy server  202  can also separately encrypt the session key using a public key cryptography algorithm and the public key of the web server  203 . The public key encrypted session key may also be placed in the request message  212 , or may be sent separately to the web server  203 . When the web server  203  has received the encrypted session key and user profile data, the web server  203  can decrypt its session key by using the public key cryptography algorithm and the web server&#39;s private key. The web server  203  may then decrypt the user profile information using the decrypted session key.  FIG. 5  shows further details of an implementation in which a request message may include both the encrypted session key and the encrypted user profile data. 
     Referring to  FIG. 5 , when a request  511  is received at the proxy server  502 , the proxy server determines whether it should add encrypted user profile data to the request. To do so, the proxy server may extract a destination web site address from URL information in the request  511 , and query a database to determine whether the destination web site is to receive user profile information and whether the information is to be encrypted. If the destination web site is to receive encrypted user profile information, the proxy server  502  may then query its database to determine whether it has a valid public key for the web server  503 . If the proxy server  502  has a valid public key, the proxy server can use the public key to encrypt session key information that can be provided to a symmetric encryption algorithm to encrypt user profile data. The encrypted session key and user profile data may then be forwarded in requests  514  to the web server  503 . 
     If the proxy server  502  does not have a valid public key for web server  503 , the proxy server will obtain the public key from the web server  503  using a HTTP request  512 . The request  512  includes a URL that identifies a public key file (“pub_key_file”) stored on the server  503 . The public key file may include additional information used by the proxy server  502 . For example, the public key file may include the length of the public key, a SecureData protocol version number, a list of supported encryption algorithms, and shortcut configuration information (“shortcut” information is further explained, below). 
     An exemplary public key may have the format shown below (chevrons ‘&lt;’ and ‘&gt;’ delineate fields in the public key file and brackets ‘[’ and ‘]’ delineate optional information): 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 Exemplary Public Key File 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 &lt;public key = length-of-key  key&gt; 
               
               
                   
                 [&lt;Version = SecureData protocol version number&gt;] 
               
               
                   
                 [&lt;crypto = &lt;encryption method&gt;] 
               
               
                   
                 [&lt;shortcut =[none|low|med|high|max]&gt;] 
               
               
                   
                   
               
             
          
         
       
     
     The web server&#39;s public key file is returned to the proxy server  503  in a HTTP response  513 . The web server  503  may provide additional SecureData protocol information in HTTP fields of response  513  and/or in the public key file returned by the response message  513 . For example, HTTP fields in response  513  may specify a time to live (TTL) for the key. The TTL value can be used to indicate the period during which the public key is valid. 
     A proxy server  502  or web server  503  may check a SecureData protocol version number returned in the public key file, in request  512  and/or in response  513  to ensure that the protocol is functioning properly and to recover from or to avoid errors. For example, if a proxy server  502  detects that protocol versions numbers in a retrieved public key file and those in a header of a response  513  do not match, the proxy server may re-submit the request  512  to the server  503 . When the request  512  is re-submitted, the proxy server  502  can include the HTTP “no-cache” pragma to instruct caching systems between the proxy  502  and the web server  503  not to use cached data. This may help avoid errors introduced by using stale cached data. When the proxy server  502  has received the web server&#39;s public key, it may cache the public key subject to a time-to-live (TTL) value specified by the web server  503  and/or the proxy server&#39;s own TTL policies. 
     If the proxy server  502  is unable to retrieve a web server&#39;s public key information or the public key information is otherwise unusable, the proxy server can add a problem report information to fields in a HTTP request  514  to indicate why the public key information is unusable. For example, the proxy server may indicate that the key information has been corrupted or a protocol version number or encryption level specified in the public key file is not supported. If the a web server&#39;s public key information is unusable and, consequently, the SecureData encryption protocol cannot be used, a proxy server may continue to forward the HTTP requests from browser clients to the web server without adding additional SecureData proxy headers. Alternatively the proxy server may block or otherwise filter request to the web server. The specific behavior may be defined on a per-web server basis using configuration information stored at the proxy server  502 . 
     Once the proxy server  502  has the public key of web server  503 , the proxy server can use the public key to encrypt session key data. The encrypted session key data may then be added to HTTP fields in the request from a browser or client computer  511  to form a modified request  514  that includes the public-key-encrypted session key information. The proxy server also can encrypt the user profile data using the session key information and a symmetric encryption algorithm and place the encrypted user profile data in HTTP fields in the modified request  514 . For example, referring to  FIG. 3B , the field  305  includes session key data “session=a3f792b210dafad” that may be public-key encrypted, and user profile data “Profile=A389C2ZA845MRAS02VMA39v1Z93AYC39AC3ABCEG78BB” that may be encrypted using a symmetric algorithm. 
     Different web server&#39;s or groups of web servers can have different session keys. A web server&#39;s session key may be formed by combining a “master” session key that is the same for a group of web servers with a key mask that can be used to create a unique session key for a web server or a group of web servers. For example, a 64-bit master session key may be combined with a 64-bit key mask using an exclusive-or (‘XOR’) operation, to yield a unique 64-bit session key. In some implementations, the master session key may be the proxy server&#39;s public key. Other methods of generating unique keys can be used. The session key data can in field  305  (e.g., “session=a3f792b210dafad”) can include numerous sub-fields. For example, the session key data can include a master key, a key mask, a timestamp, a URL hash, a Proxy IP field, and an encoding scheme field. These fields can contain the following data:
     Master key: The master key is a value that is generated by the SecureData proxy server that can be combined with a key mask to generate a unique session key. The proxy server may periodically generate a new master session key. For example, a new master session key may be generated every n minutes. The Master key may be the proxy server&#39;s public key.   Key mask: The key mask is a value generated by a SecureData proxy server that is unique to a particular web site and which can be combined with a master key to generate a unique session key for that web site. A master key and a key mask can be combined using an exclusive-or (‘XOR’) operation, by appending the keys together, or by another key combination algorithm. A new key mask may be periodically generated. For example, a new key mask may be generated every n minutes.   Timestamp: A timestamp value may be added to the public-key encrypted data to make replay attacks more difficult. The timestamp value can be checked by the receiving web server and compared to the current time. If the difference between the timestamp value and current time exceeds a threshold value, the request may be denied or other error recovery or security procedures may be employed.   URL hash: A hash value derived from a requested URL may be added to the public-key encrypted data to make forging or tampering more difficult.   Proxy IP: The IP address of the proxy server be inserted in the session key data. When a request  514  is received at a web server  503 , the web server may compare the IP address in the proxy IP field to help confirm that the request came from a particular proxy server  502 . If the addresses differ, the request  514  may be rejected or other error recovery or security procedures may be employed.   Encoding scheme: Encoding scheme data may be sent from the SecureData proxy server to a SecureData web server to identify how user profile data is encoded. For example, the encoding scheme value may indicate that profile data is in a binary (bin) form, or in name-value pair (nvp) form (which may be expressed using the Abstract Syntax Notation 1 (ASN.1) or other name-value coding scheme), or in another form.   

     The proxy server  502  can use a web server&#39;s unique session key to encrypt user profile data that is add it to the field  305 . In some implementations, the user profile data may be placed in one or more additional fields. The request  514 , now containing the public-key encrypted session data and the symmetric encrypted user profile data, is then sent to web server  503 . 
     When request  514  is received by the web server  503 , the request can be passed to proxy data exchange filter software that can extract the added fields  304 - 205  from the request  514 , decrypt the session key and the user profile information contained in the fields  304 - 205 , and make the user profile information available to web server applications. The user profile information may be made available to web server applications by setting HTTP environment variables, by storing it in a database, by placing it in shared memory, and/or using other data exchange techniques. The proxy data exchange filter software may then pass the request  514  back to the web server for further processing and for generation of a response  515 . 
     The web server  503  can store received profile data in a local database for future request processing purposes. The web server  503  may return a shortcut token to the proxy server  502 . The proxy server  502  may add the shortcut token to a subsequent request  518  in place of the ‘full’ user profile data sent in the request  514 . This can be used to reduce the amount of data that needs be transferred in subsequent request  518 . A shortcut token can be an index value, database query information, file name, other pointer data, or an arbitrary value generated by the web site  503  and used to reference the stored user profile data. 
     A web server&#39;s public key file may be sent to the proxy server  502  using a security level specified by the site  503 . For example, a web site&#39;s public key file include data indicating that the web site will use a specified one of the following shortcut key security levels:
         none: If “none” is specified, the shortcut token is sent to the proxy server as a clear (e.g., unencrypted value).   low: If “low” is specified, the shortcut token is sent to the proxy server as a clear value and is accompanied by a hash of a previously requested URL.   medium: If “medium” is specified, the “low” security level information is further accompanied by a timestamp value.   high: If “high” is specified, the “medium” security information is further accompanied by the proxy server&#39;s IP address.   max: If “max” is specified, the “high” security information is further accompanied by a sequence counter value. The sequence counter value may be based on a initial URL hash, the key mask, or other value, and is incremented in subsequent transactions.       

     At low, medium, high, and max security levels, the shortcut token and related security data can be sent in encrypted form using, for example, the proxy server&#39;s public key (which may be the master key value). Shortcut token security levels may also be indicated using HTTP fields in a response  513  or  515 , or may be specified using data stored in a configuration database at the proxy server  513  using a data entry terminal. 
     A proxy server  502  or web server  503  may include other HTTP fields in a request  512 ,  514 ,  518  or in a response  513 ,  515 ,  519  to control user profile data transfers and/or the operation of the SecureData protocol. For example, HTTP fields in requests and/or responses may specify the following directives:
     Flush=&lt;shortcut value|ALL&gt;: The ‘Flush’ directive can be sent to the proxy server  502  to discard a specified shortcut token or to discard all shortcut tokens from a particular web server. The ‘Flush’ directive may also be sent to a web server to cause the web server to discard stored user profile data associated with a particular shortcut token or to discard all stored user profile data associated with the sending proxy server. This directive may be used by a web server  503  or proxy server  502  that is performing a reset operation.   WrongKey: The WrongKey directive indicate that improper security protocol information was received. A proxy server that receives the WrongKey directive may re-send a request using a HTTP “no-cache” pragma. The “no-cache” pragma indicates that cached data should not be used to satisfy the request.   SendFull: A web server can issue a SendFull directive to indicate that a proxy server should send “full” user profile data (rather than a shortcut token) in a subsequent HTTP request.   TTL=&lt;n&gt;: The TTL (time to live) directive specifies a period (n, in seconds) during which a shortcut token is valid. Similar directives may be included in requests or response to indicate time-to-live values for other data, such as session keys and public keys.   

     The invention may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Apparatus of the invention may be implemented in a computer program product tangibly embodied in a machine-readable storage device for execution by a programmable processor; and method steps of the invention may be performed by a programmable processor executing a program of instructions to perform functions of the invention by operating on input data and generating output. The invention may advantageously be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Each computer program may be implemented in a high-level procedural or object-oriented programming language, or in assembly or machine language if desired; and in any case, the language may be a compiled or interpreted language. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, a processor will receive instructions and data from a read-only memory and/or a random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM disks. Any of the foregoing may be supplemented by, or incorporated in, specially-designed ASICs (application-specific integrated circuits). 
     A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, server, proxy, and client protocols need not use the HTTP protocol. Alternate protocols and data formats may be used such as file transfer protocol (YIP) or network news transfer protocol (NNTP). Accordingly, other embodiments are within the scope of the following claims.

Technology Category: 5