Patent Publication Number: US-2002007374-A1

Title: Method and apparatus for supporting a multicast response to a unicast request for a document

Description:
[0001] The present U.S. patent application is related to U.S. patent application Ser. No. 09/XXX,XXX (P001), entitled “Optimizing Bandwidth Consumption for Document Distribution Over a Multicast Enabled Wide Area Network,” which is assigned to the corporate assignee of the present invention. 
    
    
     
       FIELD OF THE INVENTION  
       [0002] The present invention relates to a computer network used for transmitting and dynamically distributing documents. More specifically, the present invention relates to a method and apparatus for supporting a multicast response to a unicast request for a document.  
       BACKGROUND OF THE INVENTION  
       [0003] There are three different techniques utilized by traditional network computing applications for transmitting documents between computers: unicasting, broadcasting, and multicasting. Document transmission may include the transmission of data files or a collection of data files. It may include the transmission of text, audio, media, embedded programs, executable code, or other data that is published at a host server. Unicasting involves communication between a single sender and a single receiver over a network at one time. When unicasting the same document either simultaneously or over a period of time to multiple receivers, an application is required to send one copy of each packet of data in the document to each of the receivers. This technique has significant scaling complications and inefficiencies. If the group of redundant requests for a document is large, it requires extra bandwidth because the same information must be served and be carried over the network multiple times regardless of the topological location of the receivers. Broadcasting involves communication between a single sender and all receivers on a network that are tuned in. Broadcast applications can send one copy of each packet and address it to a broadcast address. However, when using broadcast techniques, the network must either stop broadcasts at the local area network (LAN) boundary or send the broadcast to every receiver on the network. Sending the broadcast to every receiver requires significant usage of network resources if only a small group actually needs to receive the packet(s). In addition, broadcasting is a sender initiated action, not a reactive reply to a request. Multicasting also involves communication between a single sender and multiple receivers on a network. Multicast applications transmit one copy of each packet of the document and address it to a select group of recipients on the network again by addressing the packets to a shared address. Generally, Multicasting is the same as Broadcasting, with the exception that the routers in-between the sender and receiver in a Multicast format are able to “Know” if anyone on the other end is listening, and forward the packets as required.  
       [0004] Internet service providers (ISPs) and corporate WANs typically utilize unicast techniques for transmitting documents to connected client systems. When a plurality of clients request the same document from a server, the server must transmit the identical document multiple times. When the requested document requires a large amount of bandwidth, delay and contention may occur which results in a bottleneck that slows network performance. Thus, what is needed is a method and apparatus for reducing delay and contention associated with transmitting documents over a wide area network.  
       [0005] It is generally true that wide area network (WAN) connections are more expensive and have lower bandwidth than LAN connectivity. ISPs and corporate WANs often utilize caching proxy technology in their main network operations centers (NOCs) to reduce WAN or “back-end/gateway” network traffic and cost by storing documents requested by one client terminal connected to the network for re-use by other client terminals should they also request the document. These caching devices are usually located within the main NOC but still deliver information in a unicast format. The efficiency comes by storing the documents “Closer” to the client terminals. For even better efficiency, ISPs and corporations can also use regional or branch office caching devices. However, distributing redundant information to many remote clients or caching proxies still requires unicast transmissions to each over the expensive WAN or the information must be packaged or aggregated and multicasted on broadcasted across the WAN pro-actively before it is requested by any local users. This is what cache leveling protocols like ICP (Intercache protocol) facilitate. In either case, the network is still inefficient because redundant information is transmitted over the WAN, and extra documents are likely to be transmitted over the network and stored locally that are never consumed but still take up network resources.  
       [0006] In many WANs, users in different remote locations consume similar or the same information. Furthermore, much of this information is temporal and requires frequent refreshing. What is needed is an efficient distribution technology that distributes information as it is consumed by one user in one location to all locations in the WAN likely to consume the information.  
       SUMMARY  
       [0007] A method for managing a document according to a first embodiment of the present invention is disclosed. The document is retrieved in response to a request made by a first computer system at a first location. The document is multicasted to the first computer system at the first location and a second computer system at a second location.  
       [0008] A method for managing a document according to a second embodiment of the present invention is disclosed. The document is retrieved in response to a request made by a first computer system at a first location. The document is unicasted to the first computer system at the first location. The document is multicasted to a second computer system at a second location.  
       [0009] A method for managing a document according to a third embodiment of the present invention is disclosed. The document is received in response to a request made by a first computer system at a first location. The document is multicasted to the first computer system at the first location and a second computer system at a second location.  
       [0010] A network operations center according to a fourth embodiment of the present invention is disclosed. The network operations center includes a master proxy server that retrieves a document in response to a request made by a first computer system at a first location. A multicast server is coupled to the master proxy server. The multicast server transmits the document to the first computer system at the first location and a second computer system at a second location.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011] The present invention is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which:  
     [0012]FIG. 1 is a block diagram of a configuration of a network according to an embodiment of the present invention;  
     [0013]FIG. 2 is a block diagram of a local computing resource according to an embodiment of the present invention;  
     [0014]FIG. 3 is a block diagram of a network operations center according to an embodiment of the present invention;  
     [0015]FIG. 4 is a block diagram of a computer system according to an embodiment of the present;  
     [0016]FIG. 5 is a block diagram of a document manager residing in a master proxy server according to an embodiment of the present;  
     [0017]FIG. 6 is a block diagram of a filtering agent residing in a local computing resource according to an embodiment of the present invention;  
     [0018]FIG. 7 is a flow chart illustrating a method for managing documents in a local computing resource according to an embodiment of the present invention;  
     [0019]FIG. 8 is a flow chart illustrating a method for filtering documents in a local computing resource according to an embodiment of the present invention; and  
     [0020]FIG. 9 is a flow chart illustrating a method for managing documents in a network operations center according to an embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION  
     [0021] A method and apparatus for supporting a multicast response to a unicast request for a document is disclosed. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It would be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the present invention.  
     [0022]FIG. 1 is a block diagram of a configuration of a network  100  according to an embodiment of the present invention. Block  140  represents a transmission medium. The transmission medium  140  transmits documents between computer systems coupled to the transmission medium  140 . The transmission medium  140  may be implemented by a twisted pair telephone line, cable, fiber optics line, satellite transmission medium, or other transmission medium or combination of media. According to an embodiment of the present invention, the transmission medium  140  is the Internet.  
     [0023] Block  150  represents a server computer system connected to the Internet  140 . The server computer system  150  may be, for example, be one or several Hyper Text Transfer Protocol (HTTP) servers that store HTML and HTML associated files. Alternatively, the server computer system  150  may be another type of server that stores other types of network resources and operates as a content host that transmits documents via other protocols.  
     [0024] Blocks  110  and  111  represent local computing resources. Each of the local computing resources  110  and  111  may include a single computer system, or a plurality of computer systems connected together in a local area network or wide area network. The local area network or wide area network may be managed by a local server.  
     [0025] A network operations center  130  is coupled to the local computing resource  110  via connection  120  and the local computing resource  111  via connection  121 . The connections  120  and  121  may be implemented individually as a twisted pair telephone line, cable, fiber optics line, satellite transmission, or other connection media. Each connection  120  and  121  may include one of or a combination of the described connection media so long as the connection supports the routing of multicast packets on assigned multicast channels or addresses. The network operations center  130  is also coupled to the Internet  140 . The network operations center  130  operates to provide the local computing resources  110  and  111  with access to the Internet  140  and access to network resources. The network operations center  130  may operate as an ISP to the local computing resources  110  and  111 . According to an embodiment of the present invention, the network operations center  130  fetches and caches and latter-on delivers documents from the server  150  to the local computing resources  110  and  111  when requested. The network operations center  130  multicasts documents requested by one of the local computing resource  110  or  111  to the non-requesting local computing resource  110  or  111 . By sharing documents that contains relevant information to the non-requesting local computing resource, the network operations center  130  provides the local computing resource  110  and  111  with documents that users on both the local computing resources  110  and  111  are likely or guaranteed to consume at some point of time. Sharing documents allows accessing documents in the network  100  to be more efficient. It also delivers a more responsive user experience and facilitates the delivery of high bandwidth and/or time dependent documents. The local computing resources  110  and  111  filter the incoming documents from the network operations center  130 . Before storing and/or forwarding documents received from the network operations center  130 , the local computing resources  110  and  111  make sure that the documents are relevant for the purposes of the local computing resources  110  and  111  and has a probability of being used or has been transmitted in response to a local user&#39;s request. This allows the storage device in the local computing resources  110  and  111  to be used efficiently.  
     [0026] It should be appreciated that any number of local computing resources may be connected to the network operations center  130  and that any number of network operations centers may be connected to the Internet  140 . It should also be appreciated that any number of server computer systems may be connected to the Internet  140 .  
     [0027]FIG. 2 is a block diagram of the local computing resource  110  according to an embodiment of the present invention. The local computing resource  110  shown in FIG. 2 may also be implemented as the local computing resource  111  (shown in FIG. 1). The local computing resource  110  includes a plurality of client terminals  210 - 213 . The client terminals  210 - 213  may be general purpose computer systems, set-top boxes, or other types of client terminal devices. Each client terminal includes at least an input device and a display device. Client terminals  210 - 213  are connected together in a network via network connection  220  which should, but does not necessarily need to support multicast transmissions.  
     [0028] The local computing resource  110  includes a local server  230  which in another embodiment could be a logical process on a single user&#39;s machine. The local server  230  operates as a local caching proxy server that runs communications proxy and storage/cache services for the client terminals  210 - 213 . The proxy services take requests for Internet services, such as HTTP, FTP, and Telnet, from the client terminals  210 - 213  and forwards them to the network operations center  130  (shown in FIG. 1) as appropriate according to the protocol of the local computing resource  110 . The proxies provide replacement, re-directed or intermediary connections and act as gateways to the services. According to an embodiment of the present invention, the local server  230  includes a storage device (not shown) that stores documents pre-fetched or previously fetched by the network operations center  130 . When a HTTP request is made by a client terminal, the proxy service run by the local server  230  checks the storage device to determine whether the documents requested by the client terminal are cached in the storage device. If the documents are cached in the storage device, the documents from the storage device are sent to the client terminal. If the documents are not cached in the storage device, the proxy service forwards the request to the network operations center  130 . In an alternate embodiment, the network connection  120  itself is interconnected to the Internet  140 , with a reply-to address of a network communications unit  250 .  
     [0029] The network communications unit  250  is coupled to the local server  230 . The network communications unit  250  operates to connect the local server  230  to the network operations center  130  via connection  120 . The network communications unit  250  may include a telephone modem, cable modem, satellite receiver/transmitter, router, or other communication devices. The network communications unit  250  may include one or a plurality of the described communication devices. The network communications device supports both unicast and multicast connections.  
     [0030] The local computing resource  110  may optionally include an input/output device  240 . The input/output device  240  may be coupled to the local server  230  as shown in FIG. 2. Alternatively, the input/output device  240  may be coupled to the network connection  220 , to the network communication unit  250 , or to a client terminal  210 - 213 . The input/output device  240  may include one or more printers, display video monitors, video cameras, or other input/output devices.  
     [0031]FIG. 3 is a block diagram of a network operations center  130  according to an embodiment of the present invention. The network operations center  130  includes a router/firewall  310 . The router/firewall  310  connects the network operations center  130  to the Internet  140 . The router/firewall  310  operates to prevent unauthorized access to the network operations center  130 . The router/firewall  310  analyzes all messages entering the network operations center  130  to determine whether they meet specified security criteria.  
     [0032] The network operations center  130  includes a network communications unit  315 . The network communications unit  315  operates to connect the network operations center  130  to the local computing resources  110  and  111  via connections  120  and  121 . The network communications unit  315  may include a telephone modem, cable modem, satellite receiver/transmitter, router, or other communication devices. The network communications unit  315  may include one of or a plurality of the described communication devices. The network communications device supports both unicast and multicast connections.  
     [0033] The network operations center  130  includes a plurality of servers that perform specific functions at the network operations center  130 . According to an embodiment of the present invention where the network operations center  130  includes a plurality of computer systems connected in a network, each server may be implemented by a single or a plurality of computer systems. Alternatively, in an embodiment of the present invention where the network operations center  130  is a single computer system, the servers may be implemented in software as software modules or in hardware as individual hardware components.  
     [0034] In one embodiment, the network operations center  130  includes a database server  320  that manages data in a network operations center data storage  325 . Data in the network operations center data storage  325  may include data corresponding to users with access to client terminals, statistical data on and profiles of the users, privileges granted to the users, advertisement data, logs corresponding to user activities, billing status data, preference data, and other types of data. In one embodiment, this database would likely also hold the list of trusted sources of data/documents.  
     [0035] In one embodiment, the network operations center  130  includes a statistics server  330 . The statistics server  330  interfaces with data stored in the network operations data storage  325  to generate real-time usage statistics. For example, the statistics server  330  may access an activity log and a statistics database in the network operations center data storage  325  and generate real-time usage statistics.  
     [0036] In one embodiment, the network operations center includes an applications server  340 . The applications server  340  supports web-based services such as an HTML enabled e-mail systems, chat systems, discussion boards, and communication gateways. The application server  340  may also support the server side of client/server applications. The applications server  340  may reside inside the network operations center  130  as shown in FIG. 3, or alternatively reside outside of the network operations center  130 .  
     [0037] In one embodiment, the network operations center  130  includes an advertisement server  350 . The advertisement server  350  schedules and manages advertisement placements that are displayed on client terminals  210 - 213  (shown in FIG. 2) at local computing resources  110  and  120  (shown in FIG. 1). It should be appreciated that in an alternate embodiment of the present invention, the functionality of the advertisement server  350  may be implemented in a middleware server  370 . Additional uses and details of the advertisement server  350  can be found in U.S. Patent application Ser. No. 09/XXX,XXX (P003), entitled “Micro Targeted Advertising,” which is assigned to the corporate assignee of the present invention.  
     [0038] In one embodiment, the network operations center  130  includes a web server  360 . The web server  360  publishes HTML documents and related files via TCP/IP, HTTP, FTP, UDP, and other protocols.  
     [0039] In one embodiment, the network operations center  130  includes a middleware server  370 . The middleware server  370  interfaces with the database server  320 , statistics server  330 , applications server  340 , usually via the web server  360 , in response to requests from the client terminals  210 - 213  to dynamically publish web pages, send and receive documents to and from client terminals, as well as to establish and track user sessions on client terminals. The middleware server  370  interfaces with the database server  320  to store, log, retrieve, and process session related data. The middleware server  370  also acts as a communication log-in proxy for remote applications and serves to associate sessions with users, and terminal entities so as to associate logged usage with users. Additional uses and details on the identification of sessions can be found in U.S. patent application Ser. No. 09/XXX,XXX (P005), entitled “ENTITY MODEL RELATIONSHIP ENABLING PRIVILAGE TRACKING ACROSS MULTIPLE TERMINALS,” which is assigned to the corporate assignee of the present invention.  
     [0040] In one embodiment, the network operations center  130  includes a master proxy server  380 . The master proxy server  380  handles and redirects requests to appropriate locations and servers. The master proxy server  380  interfaces with the master web cache  385 . According to an embodiment of the present invention, the master proxy server  380  receives a request for a document from a local computing resource. The master proxy server  380  determines whether the document is stored in the master web cache  385 . If the document is stored in the master web cache  385 , the document from the master web cache is delivered to the local computing resource by the master proxy server  380 . If the document is not stored in the master web cache  385 , or is out of date, the master proxy server  380  retrieves the document on behalf of the local computing resource. The master proxy server  380  may cache a copy of the document in the master web cache  385 . The master proxy server  380  determines where and how the document is transmitted. It should be appreciated that the master web cache  385  may be implemented by any known caching device. The document may be either unicasted or multicasted to the requesting local computing resource and other local computing resources as described in more detail below.  
     [0041] In order to reply to a unicast request via a multicast channel and recover potential packet loss, a sender (the master proxy server  380  ) buffers sent packets and re-sends on a negative acknowledgment. By removing unneeded replies for receipt acknowledgment while assuring complete intact delivery, IP ramp-up lag is minimized.  
     [0042] The network operations center  130  includes a multicast server  390 . The multicast server  390  sends documents or any file or group of files to specified directories on predefined local servers via Internet Protocol (IP) Multicast protocols or other one-to-many transmission protocols. The multicast server  390  manages multicast channels on which the documents are transmitted. According to an embodiment of the invention, the local server  230  (shown in FIG. 2) where functions and resources of the network operations center  130  may be replicated, the multicast server  390  packages and schedules reliable multicast file transfers of documents, such as documents stored in the web cache  385  and in the network operations center data storage  325  onto the local server  230 . It should be appreciated that the multicast server  390  may also multicast replicated web sites such as a directory tree of HTML and associated HTML files, such as JPEG, GIF, JAVA, and other files, from the web server  360 , applications such as installable software packages from the applications server  340 , and data and resources from other servers on the network operations center  130  or servers  150  connected to the Internet  140  onto the local server  230 .  
     [0043] It should be appreciated that not all of the servers described are necessary for implementing the network operations center  130 . According to an embodiment of the present invention, the network operations center  130  may be implemented using only the master proxy server  380 , the middleware server  370 , and the database Server  320  with its associated data storage  325 .  
     [0044]FIG. 4 is a block diagram of a computer system  400  according to an embodiment of the present invention. The computer system  400  may be used to implement the network operations center  130  (shown in FIG. 1) in an embodiment of the present invention where the network operations center  130  is implemented by a single computer system. The computer system  400  may be used to implement or one or more of the servers in the network operations center  130  in an embodiment of the present invention where the network operations center  130  is implemented by a network of computer systems. It should be appreciated that the computer system  400  may also be used to implement one of the client terminals  210 - 213  (shown in FIG. 2) and the local server  230  (shown in FIG. 2).  
     [0045] The computer system  400  includes a bus  410 . The bus  410  may be a single bus or a combination of multiple buses. As an example, the bus  320  may include a Peripheral Component Interconnect (PCI) bus, an Industry Standard Architecture (ISA) bus, or a combination of other buses. A processor  420  is coupled to the bus  410 . The processor  420  processes data signals.  
     [0046] A memory  430  is coupled to the bus  410 . The memory  430  may store instructions and code represented by data signals that may be executed by the processor  420 . A network controller  440  is coupled to the bus  410 . The network controller  440  links the computer system  400  to a network of computers (not shown in FIG. 4) via a connection (not shown) or a network communications unit (not shown in FIG. 4) and supports communication among the machines. A display device controller  450  may be coupled to the bus  410 . The display device controller  450  allows coupling of a display device to the computer system  400  and acts as an interface between the display device and the computer system  400 . A data storage device  460  is coupled to the bus  410 . The data storage device  460  may be a hard disk drive, a floppy disk drive, a CD-ROM device, a flash memory device or other mass storage device or any combination thereof. An input device interface  470  is coupled to the bus  410 . The input device interface  470  allows coupling of a keyboard, pointing device, or other input device to the computer system  400  and transmits data signals from an input device to the computer system  400 .  
     [0047] It should be appreciated that not all the components described in the computer system  400  may be necessary for implementing one of the network operations center  130 , a server on the network operations center  130 , a local server  230 , or a client terminal at the local computing resource  110 . The present invention is related to the use of the computer system  400  to manage documents. According to one embodiment, managing documents is performed by the computer system  400  in response to the processor  420  executing a sequence of instructions in memory  430 . Such instructions may be read into memory  430  from another computer-readable medium, such as data storage device  460 , or from another source via the network controller  440 . Execution of the sequence of instructions causes the processor  400  to manage a document, as will be described hereafter. In an alternate embodiment, hardwired circuitry may be used in place of or in combination with software instructions to implement the present invention. Thus, the present invention is not limited to any specific combination of hardware circuitry and software.  
     [0048]FIG. 5 is a block diagram of a document manager unit  500  residing in the master proxy server  380  (shown in FIG. 3) according to an embodiment of the present invention. In a preferred embodiment of the present invention, the document manager unit  500  is implemented by software and resides in main memory  430  (shown in FIG. 4) as a sequence of instructions in a computer system  400  that may be implemented as an extension of the master proxy server  380  or a network operations center  130  having a master proxy server  380 . It should be appreciated that the document manager unit  500  may also be implemented by hardware as components coupled to the bus  410  (shown in FIG. 4), a combination of both hardware and software, or a plurality of computers working together as performance and traffic requirements dictate.  
     [0049] The document manager  500  includes a session profile unit  510 . The session profile unit  510  interfaces with the middleware server  370  (shown in FIG. 3) to obtain session information relating to the session run at a local computing resource that is requesting a document and currently active user sessions as well as user and session information associated with the specific request for a document. In an alternate embodiment, the session profile unit  510  might query the database server  320  (shown in FIG. 3) directly to obtain this information. The real purpose of the middleware server  370  is to simplify getting information out of the database server  320 , each server and client actually could talk to the database server  320  directly, but this would be a lot more work and load on each of these systems. In one embodiment, the middleware server  370  reports to the master proxy server  380  all new session ID as they are assigned as well as the associated user and session privileges and any other relevant data. The master proxy server  380  also messages at the end of a session to purge the session ID from the master proxy server&#39;s “Current session” table in memory. The session information includes information relating to a user that is requesting the document and a set of access privileges that belongs to the user or session. The session profile unit  510  transmits the session information to the document transmission unit  550 .  
     [0050] In one embodiment, the document manager  500  includes a document profile unit  520 . The document profile unit  520  receives a copy of the document that constitutes the document requested by the local computing resource. The document profile unit  520  obtains, generates and formats meta data relating to the content of each document that has been requested and allows the document transmission unit  550  to determine where and how to transmit the documents. According to a first embodiment of the present invention, the document profile unit  520  reads and re-formats recognized meta tags in the document that were placed there by the original publisher of the document and provide subject matter, size, source, rating, keyword, or other information relating to the document and forwards the meta data to the document transmission unit  550 . According to a second embodiment of the present invention, the document profile unit  520  reads the content of the document to determine relevant subject matter, size, source, or other information relating to the document and forwards the meta data to the document transmission unit  550 . In another example, the document profile unit  520  may also interface with the master proxy server  380  (shown in FIG. 3) on the network communications interface to determine if the document being requested by a user has been “popular” with a specific class of local computing resources and forwards this meta data to the document transmission unit  550 . According to this embodiment of the present invention, the document profile unit  520  may generate its own meta tags in its own format that are transmitted with the document or in some other way append or associate its aggregated formatted meta data to the source document. Some of the data, like source information, could be evaluated even before the document is received and help speed the evaluation process. For example, an excluded source could redirect to a unicast reply even before the source document arrives for evaluation by the other units. The meta tags may be transmitted in the header of the document, the body of the document, or using other techniques.  
     [0051] In one embodiment, the document manager  500  includes a local computing resource (LCR) profile unit  530 . The local computing resource profile unit  530  interfaces with the middleware server  370  to obtain profile information relating to local computing resources that are connected to the network  100  (shown in FIG. 1). The profile information includes information relating to the subject matter, size, source of the document, or other content associative parameters that a local computing resource would like to receive or explicitly rejects (e.g. documents published from a suspect source). The profile information may also include the identity of content class associated multicast channels on which to transmit the document to the local computing resource. The local computing resource profile unit  530  transmits the profile information to the document transmission unit  550 .  
     [0052] In one embodiment, the document manager  500  includes a system status profile unit  540 . The system status profile unit  540  includes a list of local computing resources and the multicast channels each local computing resource are listening to. The system status profile unit  540  also includes associated target content profiles for each of the active multicast channels. The system status profile unit  540  operates to inform the document transmission unit  560  of current transmission latencies for all active multicast channels. According to one embodiment, the system status profile unit  540  monitors activity on multicast channels and transmits traffic information to the document transmission unit  560 . The system status profile unit  540  informs the document transmission unit  560 , via the traffic information, if the multicast channel to which a document is to be re-directed is backed-up beyond some maximal latency. In response, the document transmission unit  560  may generate a unicast reply to the original requester since a multicast reply would require too much time due to an over subscribed multicast channel. In one embodiment, a document may be placed in a queue for evaluation and possible multicast when traffic subsides.  
     [0053] A document transmission unit  550  is coupled to the session profile unit  510 , the document profile unit  520 , and the local computing resource profile unit  530 , and the system status profile unit  540  in a way such that transferred information (meta data) from the sources arrives with or is associated with the document for each requested document. Some might be appended as meta tags in the body, and others as announcements prior to the arrival of the document. Some of this compiled meta data should be passed on to the receivers so as to keep them from having to re-generate the meta data. This is further described below in relation to FIG. 6. The document transmission unit  550  operates to determine where and how to transmit the requested document and facilitates the transmission. The document transmission unit  550  receives session information from the session profile unit  510 . The session information may be used by the document transmission unit  550  to determine whether to transmit the document requested by a user at a local computing resource to the requesting local computing resource only using unicast techniques, to transmit the document requested to the requesting local computing resource and to other non-requesting local computing resources at the same time using multicast techniques, or to transmit the document requested to the requesting local resource using unicast techniques and to other non-requesting local computing resources using multicast techniques at a later time or upon further determination. This decision might also take into account network traffic and capacity as reported by the system status unit ( 540 ), (e.g. the multicast channel is backed-up and has a delivery latency greater them a maximal value.) In such a case the document must be sent back to the original requester via unicast in order to avoid a request time-out on the client end. The document can then be placed in a queue for evaluation and possible multicast latter on when traffic subsides. The session information may include information relating to the user and access privileges that belong to the user. For example, a request for a document by a user with a high level of access privileges such as “instructor class access privileges” may effectuate the document requested to be multicasted to the requesting and non-requesting computing resources at the same time and perhaps on a priority or reserved channel/address. A user with middle level access privileges such as “contributor class access privileges” may effectuate the document requested to be unicasted to the requesting local computing resource and multicasted to non-requesting local computing resources at a later time or upon further determination or sent on a lower priority channel. A user with low level access privileges such as “viewer class access privilege” may effectuate the document requested to be unicasted only to the requesting local computing resource or only multicasted if the document itself triggers a multicast as described below. It should be appreciated that other schemes of determining where and how the document is transmitted may be utilized. Such schemes may relate directly to the purpose and use of the network and the type of document being consumed.  
     [0054] The document transmission unit  550  receives meta data from the document profile unit  520  and local profile information from the local computing resource profile unit  530 . The meta data and the profile information may be used by the document transmission unit  550  to determine whether or not to cache a copy of a requested document onto the web cache  385 . The meta data and profile information may also be used by the document transmission unit  550  to determine whether or not to multicast the document to non-requesting local computing resources and if so to which ones by selecting one or more active multicast channels. In one embodiment, the network operations center  130  announces channel changes or temporary channel assignments to the appropriate local computing resources. For example, an “Instructor” in one location tells 10 students at ten different locations to look at a specific document which may contain a live multicasted video stream. The master proxy server  380  dynamically assigns a multicast channel to send the instructor&#39;s document back on, and at the same time, inform the ten other locations of this dynamic channel assignment (via a separate “Announcement” channel.). According to an embodiment of the present invention, the document transmission unit  550  multicasts a document to a non-requesting local computing resource if the meta data corresponding to the document matches the profile information for a currently active multicast channel. It should be appreciated that other schemes for determining whether or not to multicast the document to non-requesting local computing resources may be utilized. According to an alternate implementation, the network operations center  130  reports to all matching local computing resources what channel that matching document is going to be sent on, and when on a separate “Announcement” multicast channel that all local computing resources listen to. According to one aspect of this embodiment, the network operations center  130  waits for “I&#39;m listening” acknowledgements from all target local computing resources before sending the document.  
     [0055] It should be appreciated that how, when and in what order meta data is sent to the local computing resource  110  may be important. Some meta data may be appended as reformatted meta tags, others may be sent prior to the receipt of the document so as to allow the computing resource  110  to make a fast decision that will allow the local computing resource to run more efficiently.  
     [0056] The document transmission unit  550  also facilitates the transmission of documents. For example, if a determination is made that the document being requested is to be unicasted back to the requesting local computing resource, even if it is also to be multicasted to a set of non-requesting local computing resources, the document transmission unit  550  may redirect the server sourcing (serving/hosting) the document to transmit the document directly to the requesting local computing resource or though a separate proxy server or connection. On the other hand, if it is determined that the network operations center  130  (shown in FIG. 1) should multicast a copy of the requested document or examine the requested document, the document transmission unit  550  may direct the server sourcing the document to transmit the document to both the requesting local computing resource and the network operations center  130  or alternatively have the document transmitted only to the network operations center  130  and have the network operations center  130  transmit the document to the requesting local computing resource. If a determination is made that the document being requested is to be multicasted, the document transmission unit  550  transmits the document and an identity of an appropriate multicast channel in which the document is to be sent on to the multicast server  390  (shown in FIG. 3). The session identification as well as some or all of the aggregated meta data, and perhaps other session data like the class of the original requester, (e.g. “an instructor you trust asked for this document”) is included with the document as it is transmitted. In an alternate embodiment, the master proxy server  380  may operate as the multicast server  390  directly by extending its features to handle re-sending packets on a negative acknowledgement. According to an embodiment of the present invention, the session identification is appended in a header of the document as a cookie. According to an alternate embodiment of the present invention, the session identification is appended as a CGI variable. It should be appreciated that the session identification may be transmitted with the document using other techniques.  
     [0057] It should be appreciated that the document manager  500  may transmit a document to local computing resources with or without transmitting meta tags corresponding to the document. It should also be appreciated that the document manager  500  may multicast the document to local computing resources without taking into account the session information associated with the original request, meta data in the document, or profiles of local computing resource where the document is to be multicasted. As described, the document profile unit  520  may generate and append meta data. It should also be appreciated that the session profile unit  510 , the local computing resource profile unit  530 , and the system status profile unit  540  may also generate and append meta data.  
     [0058] The session profile unit  510 , document profile unit  520 , local computing resource profile unit  530 , and the document transmission unit  550  may be implemented using any known circuitry or technique. In an embodiment of the present invention where the document manager unit  500  is implemented in hardware, the session profile unit  510 , document profile unit  520 , local computing resource profile unit  530 , and the document transmission unit  550  all reside in a single semiconductor substrate. In a preferred embodiment of the present invention, the document manager  500  is implemented by software proxy server plug-ins or extensions, and/or packet filter processes.  
     [0059]FIG. 6 is a block diagram of a filtering agent  600  residing in the local server  230  (shown in FIG. 2) according to an embodiment of the present invention. The filtering agent  600  operates to filter documents received on one or more multicast channels by the network communications unit  250  (shown in FIG. 2) of the local computing resource  110  (shown in FIG. 2). In a preferred embodiment of the present invention, the filtering agent  600  is implemented by software and resides in main memory  430  (shown in FIG. 4) as a sequence of instructions in a computer system  400  that may be implemented as the local server  230  (shown in FIG. 2). It should be appreciated that the filtering agent  600  may also be implemented by hardware as components coupled to the bus  410  (shown in FIG. 4), a combination of both hardware and software, or a plurality of computers working together.  
     [0060] The filtering agent  600  includes a network communications interface  610 . The network communications interface  610  interfaces with the network communications unit  250  and receives multicast documents transferred over multicast channels from the network operations center  130 . The network communications interface  610 , could also receive broadcast notification and channel activation, de-activation, and content assignment changes. In addition it should report new local computing resource channel subscriptions (e.g. multicast channel that are monitored at the local site) and profile changes to the network operations center  130 .  
     [0061] A session identification reading unit  620  is coupled to the network communications interface  610 . The session identification reading unit  620  receives the document from the network communications interface  610 . This process may be “made aware” to listen for a session ID or specific document via an pre-announcement from the network operations center  130 . In one embodiment, there is a separate announcement and schedule multicast channel. In another embodiment announcements are send via unicast. The session identification reading unit  620  analyzes the document for a session identification associated with the document and forwards the session identification to an evaluation unit  650 . The session identification may be used by the filtering agent  600  to determine whether the document is the reply to a local user&#39;s request or includes relevant information and how to process the document. The session identification reading unit  620  may be configured to recognize that the session identification may be transmitted with the document as a cookie appended in the header of the document, as appended custom meta tags, or in a separate transmission announcement, or using other techniques and search for the session identification accordingly.  
     [0062] An information classification unit  630  is coupled to the network communications interface  610 . The information classification unit  630  receives the document from the network communications interface  610 . The information classification unit  630  analyzes the document for meta data relating to the content of the document. The meta data may be used by the filtering agent  600  to determine whether the document includes relevant information and how to process the document. All meta data needed may be appended to the transmission or announced separately by  550  from  520 . According to a first embodiment of the present invention, the information classification unit  630  reads meta tags in the document that provide subject matter, size, source, rating, keyword, or other information relating to the document and forwards the meta data to the evaluation unit  650 . The meta tags may be published with the document, appended the network operations center  130 , or other entity process. According to a second embodiment of the present invention, the information classification unit  630  reads the content of the document to determine relevant subject matter, size, source, rating, keyword or other information relating to the document and forwards the meta data to the evaluation unit  650 . It should be appreciated that the second embodiment of the present invention may be implemented when meta tags with meta data are not supplied by the source of the document, the network operations center  130 , or other process. The second embodiment of the present invention may also be implemented as a redundant operation or secondary meta data gathering process that may differ from the meta data gathering process in the network operations center  130 .  
     [0063] A source unit  640  is coupled to the network communications interface  610 . The source unit  640  receives the document from the network communications interface  610 . The source unit  640  analyzes the document for source information relating to where the document originated. The source information may be used by the filtering agent  600  (via the evaluation unit  650 ) to determine whether the document includes relevant information and how to process the document. The source information may include a URL, domain or other source information that may be written in the body of the document. The source unit  640  transmits the source information to the evaluation unit  650 .  
     [0064] The evaluation unit  650  is coupled to the session identification reading unit  620 , the information classification unit  630 , and the source unit  640 . The evaluation circuit  650  receives the session identification associated with the document from the session identification reading unit  620 . The evaluation circuit  650  determines whether the session identification corresponds to a session being run by a client terminal on the local computing resource. According to an embodiment of the present invention, the evaluation circuit  650  accesses a session log to determine whether the session identification associated with the document matches the session identifications that are active on the local computing resource. In one embodiment, an announcement informs the evaluation unit  650  to look for a reply on a specific multicast channel. In an alternate embodiment, the session may be associated with a “Trusted User” like an “Instructor class user” to effect a push into cache. If the session identification associated with the document corresponds to a session being run by a client terminal on the local computing resource, the evaluation unit  650  recognizes that the document is a multicast response to a unicast request for the document made by the local computing resource. The evaluation circuit  650  forwards the document to the appropriate client terminal.  
     [0065] The evaluation unit  650  receives meta data associated with the document from the information classification unit  630 . The evaluation unit  650  determines whether the document includes meta data that matches a local information profile of the local computing resource. According to an embodiment of the present invention, the evaluation unit  650  accesses a local information profile to determine whether the meta data associated with the document matches meta data. The evaluation unit  650  may decide whether to cache or discard the document based on the determination. In one embodiment, the local information profile may include inclusionary meta data that would prompt the evaluation unit  650  to cache the document. The inclusionary meta data may include anything on the subject Advanced Algebra for example. The meta data in the local information profile may also include exclusionary meta data that would prompt the evaluation unit  650  to discard the document. The exclusionary meta data may include keywords that include profanity, or subject matter that may be considered offensive or inappropriate to the users at the local computing resource. It should be appreciated that the local information profile may be configured by a system administrator, compiled dynamically based on prior requests for the document, or using other techniques or combinations of techniques.  
     [0066] The evaluation unit  650  receives source information associated with the document from the source unit  640 . The evaluation unit  650  determines whether the document originated from a “Trusted” source that is recognized by the local computing resource. According to an embodiment of the present invention, the evaluation unit  650  accesses the local information profile to determine whether the source information associated with the document matches source information in the local information profile. The evaluation unit  650  may decide whether to cache or discard the document based on the determination. In one embodiment, the source information in the local information profile may include inclusionary source information that would prompt the evaluation unit  650  to cache the document. The inclusionary source information may include a private index of web sites, URLs, domain, sub domains, IP addresses or ranges of addresses, etc. (e.g. a database of educational web sites such as the National Geographic Society, and the NASA web site etc.) The meta data in the local information profile may also include exclusionary source information that would prompt the evaluation unit  650  to discard the document. The exclusionary source information may include adult oriented web sites, or web sites containing information that may be considered inappropriate for the users at the local computing resource. It should be appreciated that the local information profile may be configured by a system administrator, compiled dynamically based on prior requests for the document, or using other techniques such as AI and/or pattern recognition and matching. For example, the local information profile may be configured dynamically by an agent on the local server that includes URLs frequently accessed by users on the local computing resources as inclusionary source information. The local information profile may be later edited by a system administrator who may delete source information that may be inappropriate.  
     [0067] According to an embodiment of the present invention, the evaluation unit  650  includes a redirection unit  655 . It should be appreciated that the redirection unit  655  may reside inside the evaluation unit  650  as shown in FIG. 6 or alternatively reside external to the evaluation unit  650 . The redirection unit  655  “spoofs” or plays the role of a host server that sources requested documents. According to an embodiment of the present invention, the redirection unit  655  “feeds” or “serves” packets of data that constitute that document to a proxy at the local computing resource that believes it is talking to the host server. This allows the proxy to operate as it would if it had made a unicast HTTP connection with the host server. According to an alternate embodiment of the present invention, the redirect unit  655  messages the proxy at the local computing resource that it has the document that was requested. In response, the proxy stops attempting to connect to the host server. The proxy then plays the role of the host server to the client terminal requesting the document.  
     [0068] It should be appreciated that the filtering agent  600  may utilize one or all of the session identification reading unit  620 , information classification unit  630 , and source unit  640  when determining whether a document includes relevant information and whether to forward the document to a client and whether to cache the document. For example, the meta data from the information classification unit  630  and the source information from the source unit  640  may be used to deny a client terminal access to the requested document regardless of whether a session identification match exists. Alternatively, a weighting protocol may be utilized in situations when the meta data and source information generates conflicting inclusionary/exclusionary results.  
     [0069] The network communications interface  610 , session identification reading unit  620 , information classification unit  630 , source unit  640 , and evaluation unit  650  may be implemented using any known circuitry or technique. In an embodiment of the present invention where the filtering agent  600  is implemented in hardware, the network communications interface  610 , session identification reading unit  620 , information classification unit  630 , source unit  640 , and evaluation unit  650  all reside on a single semiconductor substrate. In a preferred embodiment of the present invention, the filtering agent  600  is implemented by software proxy server plug-ins or packet filtering extensions.  
     [0070]FIG. 7 is a flow chart illustrating a method for managing a document at a local computing resource according to an embodiment of the present invention. At step  701 , a request for a document is received from a client terminal. The request for the document may be a request to receive an HTML file from a remote server. The request may include an URL that corresponds to where the HTML file is located.  
     [0071] At step  702 , it is determined whether the document requested is stored locally at the local computing resource. Determining whether the document requested is stored locally may be achieved by checking a web cache or other storage device at the local computing resource, which may need to check with the original host to see if the cached copy is up-to-date. If the document requested is stored locally and is not expired or out-of-date, control proceeds to step  703 . If the document requested is not stored locally or is expired or out-of-date, control proceeds to step  704 .  
     [0072] At step  703 , the document requested is forwarded from the storage device to the client terminal and a “Hit” notification is sent to the original host, usually via the master proxy server. The request for the document is not transmitted to the source of the document. According to an embodiment of the present invention, the request is logged in a local computing resource information profile.  
     [0073] At step  704 , the request for the document is transmitted or redirected to an external system. According to an embodiment of the present invention, the request for the document is transmitted to a master proxy server on a network operations center which has a connection to the source of the document or its own cached copy of the document or a mirror of the original host server. The network operations center may operate as a master proxy server or an ISP for the local computing resource. When transmitting the request for a document to the network operations center, the local computing resource may also transmit session information that includes or points to information about the user requesting the document such as a session identification. According to an alternate embodiment of the present invention where the local computing resource has a connection to the source of the document, the request for a document is transmitted to the source of the document with instructions to return the requested document to the network operations center  130 , such request containing the session identifier to be read by the session profile unit ( 510 ) and session ID reading unit ( 620 ).  
     [0074] At step  705 , a document received from a unicast channel is forwarded to a client terminal requesting the document or a unicast or multicast announcement of a multicast transfer of the requested document “Alerts” the session identification reading unit to look-out. Alternately or simultaneously, as part of step  704 , the session ID and document request are placed in a “Waiting for reply” queue that is read by the session identification reading unit and acts as the announcement to look-out for that same session ID on all monitored multicast channels.  
     [0075] At step  706 , it is determined whether a document received from a multicast channel contains relevant information and/or is a reply to a local user&#39;s request and has a session ID associated with a client terminal that location. According to an embodiment of the present invention, determining whether the document received includes relevant information includes determining whether the document may be used by a client terminal associated with a local computing resource. If the document received does not contain relevant information, control proceeds to step  707 . If the document received contains relevant information, control proceeds to step  708 . FIG. 8 is a block diagram illustrating the steps of how determining whether a document received contains relevant information is achieved according to an embodiment of the present invention.  
     [0076] At step  707 , the document is discarded.  
     [0077] At step  708 , the document is consumed or stored for latter consumption by the local computer resource. According to an embodiment of the present invention, the document received is determined to be requested by a client terminal and is forwarded to the client terminal. The document requested may be received from either the network operations center or the source of the document directly depending on how the request was made. It should be appreciated that the document requested may be unicasted or multicasted to the local computing resource and that the local computing resource may examine the requested document using known techniques to determine the identity of the client terminal to forward the document. The document received may also be cached locally on a storage device.  
     [0078]FIG. 8 is a flow chart illustrating a method for filtering a document at a local computing resource according to an embodiment of the present invention. At step  801 , a session identification is obtained from the document or an associated announcement. According to an embodiment of the present invention, the session identification may be obtained by a session identification reading unit  620  (shown in FIG. 6). The session identification reading unit  620  analyzes the document for a session identification associated with the document. The session identification reading unit  620  may be configured to recognize that the session identification may be transmitted with the document as a cookie appended in the header of the document, unique meta tags in the body, or using other techniques and search for the session identification accordingly.  
     [0079] At step  802 , it is determined whether the session identification associated with the document corresponds with an active session run by a client terminal on a local computing resource. According to an embodiment of the present invention, the determination is made by an evaluation circuit  650  (shown in FIG. 6). The evaluation circuit accesses a session log to determine whether the session identification associated with the document matches the session identifications that are active on the local computing resource. If the session identification associated with the document matches a session run by a client terminal, control proceeds to step  803 . If the session identification associated with the document does not match a session run a the client terminal, control proceeds to step  804 .  
     [0080] At step  803 , the document is forwarded to the client terminal. If the session identification associated with the document corresponds to a session being run by a client terminal on the local computing resource, the document is recognized as a multicast response to a unicast request for the document made by the client terminal. The local proxy must spoofs a unicast reply to the original request.  
     [0081] At step  804 , meta data associated with a transferred document is obtained. According to an embodiment of the present invention, the meta data may be obtained by an information classification unit  630  (shown in FIG. 6). The information classification unit  630  may obtain meta data from the document from meta tags in the document or by reading the content of the document to determine relevant subject matter, size, source, rating, keyword or other information relating to the document.  
     [0082] At step  805 , it is determined whether the meta data associated with the document is of interest to the local computing resource. According to an embodiment of the present invention determining whether the meta data is a match for local interests is performed by the evaluation unit  650 . The evaluation unit  650  accesses a local information profile to determine whether the meta data associated with the document matches meta data in the local information profile. The evaluation unit  650  may decide whether to cache or discard the document based on the determination. The local information profile may include inclusionary or exclusionary meta data that may be configured by a system administrator, dynamically based on prior information consumption, or using other techniques or combination of techniques. If the meta data associated with the document is recognized as inclusionary, control proceeds to step  806 . If the meta data associated with the document is not recognized, control proceeds to step  807 . It should be appreciated that even if the document is of interest to the local computing resource, if the document includes a meta tag which indicates that the document should not be cached, control proceeds to step  809 .  
     [0083] At step  806 , the document is pushed into cache. According to an embodiment of the present invention when the proxy at the local computing resource believes it has a unicast connection with the host server, the document is pushed into the cache. In an alternate embodiment of the present invention, the redirect unit  655  (shown in FIG. 6) pretends to be a client terminal and requests the document from the proxy at the local computing resource. The redirect unit  655  intercepts the proxy&#39;s forwarded request for the document and pretends to be a host server having the document. The proxy caches the document as it forwards the document back to the redirect unit, which just discards it.  
     [0084] At step  807 , source information is obtained. According to an embodiment of the present invention, the source information may be obtained by the source unit  640  (shown in FIG. 6). The source unit  640  analyzes the document for source information relating to where the document originated from.  
     [0085] At step  808 , it is determined whether the source information associated with the document is of interest to the local computing resource. According to an embodiment of the present invention, determining whether the source information is of interest to the local computing resource is performed by the evaluation unit  650 . The evaluation unit  650  accesses a local information profile to determine whether the source information associated with the document matches source information in the local information profile. The evaluation unit  650  may decide whether to cache or discard the document based on the determination. The local information profile may include inclusionary or exclusionary source information that may be configured by a system administrator, dynamically based on prior information consumed, or using other techniques or combination of techniques. If the source information is recognized as inclusionary, control proceeds to step  806 . If the source information is not recognized or is recognized as exclusionary, control proceeds to step  809 .  
     [0086] At step  809 , the document is discarded.  
     [0087] It should be appreciated that the steps in FIG. 8 may be performed in an order other than that which is illustrated. For example, the steps of determining whether the meta data is recognized and whether the source information is recognized may be performed at the same time or in opposite order. A process that resolves any discrepancies in the results may be implemented.  
     [0088]FIG. 9 is a flow chart illustrating a method for managing a document at a network operations center according to an embodiment of the present invention. At step  901 , a request for a document is received from a local computing resource. The request for the document may be a request to receive an HTML file from a remote server. The request may include an URL that corresponds to where the HTML file is located.  
     [0089] At step  902 , it is determined whether the document requested is stored locally at the network operations center. Determining whether the document requested is stored locally may be achieved by checking a web cache or other storage device at the network operations center to determine whether the document requested was previously stored locally. If the document requested is stored locally, control proceeds to step  903 . In one embodiment the original host is checked to assure the cache copy is fresh (Up-to-date) before proceeding to  903 . If the document requested is not stored locally, or is out-of-date, control proceeds to step  904 .  
     [0090] At step  903 , the document requested is forwarded from the storage device to the client terminal. The document is not retrieved from the source. In one embodiment, a “Hit” may be sent to the host to allow the host to account for the fact that the document was requested. According to an embodiment of the present invention, the stored document may be checked to see if its time stamp is up to date by checking with the original host. If the time stamp is not up to date, control may proceed to step  904 . In another embodiment, step  903  might additionally check to see if the document has been evaluated for multicasting, and if not jump to step  907  in order to consider multicasting the cached document to non-requesting local computing resources. In this case, if  907  returns a no, then  903  proceeds as normal.  
     [0091] At step  904 , a determination is made as to whether the user requesting the document has appropriate access privileges to effectuate multicasting the document to other local computing resources upon receipt of the document. The determination may be made by examining session information corresponding to the request. The session information includes information about the user and access privileges that belong to the user. If there are insufficient access privileges to effectuate multicasting the document upon receipt, control proceeds to step  905 . If there are sufficient access privileges to effectuate multicasting the document upon receipt, control proceeds to step  906 . According to an embodiment of the present invention, the examining session information may be achieved by a session profile unit  510  (shown in FIG. 5).  
     [0092] At step  905 , the request for the document is forwarded to the source host for unicast return to the original requesting terminal. The session identification should still be appended by the client.  
     [0093] At step  906 , the request for the document is transmitted to the source of the document with directions to direct the requested document back to the network operations center, such as a reply address. Session identification is still appended.  
     [0094] At step  907 , it is determined whether the multicast channel which the document is to be transmitted on is in proper working order. If for example, the multicast channel is not active or is experiencing large latency, control proceeds to step  905 . If the multicast channel is in proper working order control proceeds to step  908 . According to an embodiment of the present invention, determining whether the multicast channel is in proper working order may be achieved by the system status profile unit  540  (shown in FIG. 5).  
     [0095] At step  908 , a determination is made as to whether the user requesting the document has appropriate access privilege to effectuate multicasting the requested document to some or all local computing resources on the network by sending on one or more active multicast channels. The determination is made by examining session information corresponding to the request. If sufficient access privileges exist, control proceeds to step  913 . If sufficient access privileges do not exist, control proceeds to step  909 . According to an embodiment of the present invention, examining session information corresponding to the request may be achieved by the session profile unit  510 . In an alternate embodiment, control may proceed to step  913  directly and select from a list of active multicast channels to transmit the document.  
     [0096] At step  909 , meta data relating to the requested document is obtained. Step  909  can not proceed until the entire document is received in response to step  906 . The meta data may include information relating to the subject matter, size, source, keyword, format, rating, or other data. According to an embodiment of the present invention, the meta data may be obtained from meta tags in the requested document. According to an alternate embodiment of the present invention, meta data may be obtained by reading the content of the document. In one embodiment, obtaining meta data may be achieved by a document profile unit  520  (shown in FIG. 5).  
     [0097] At step  910 , profile information relating to the local computing resources on the network are obtained. The profile information may include information relating to the subject matter, size, source, key word, rating or other data that the local computing resources would like to receive. The profile information may also include the identity of multicast channels on which to transmit the document to the local computing resources. According to one embodiment of the present invention, obtaining profile information may be achieved by a local computing resource profile unit  530  (shown in FIG. 5).  
     [0098] At step  911 , a determination is made as to whether the requested document is a relevant document to multicast to non-requesting local computing resources on one or more active multicast channels. According to an embodiment of the present invention, the determination is made by comparing the meta data with active multicast channel profile information for matches and/or exclusions. It should be appreciated that other techniques for making the determination may also be utilized. If it is determined that the requested document does not include relevant data to any group or class of local users nor match any active multicast channel profile, control proceeds to step  912 . If it is determined that the requested document includes relevant data, control proceeds to step  913 . According to one embodiment of the present invention, determining whether the requested document includes relevant data is achieved by a document transmission unit  550  (shown in FIG. 5).  
     [0099] At step  912 , the requested document is not multicasted to non-requesting local computing resources. Instead, the requested document is transmitted to the requesting local computing resource using unicast techniques.  
     [0100] At step  913 , the requested document is multicasted on appropriate multicast channel(s) to appropriate local computing resources. Step  913  can not proceed until the entire document is received in response to step  906 . In an alternate embodiment, the document can be sent to all matching local computing resource by announcing to them the channel and time of multicasting of that document and perhaps the associated session identification to look for. The local computing resources may filter the document to determine for itself whether the document includes relevant information. The requested document is also multicasted to the local computing resource requesting the document. Alternately, the document could be unicasted back to the original requesting local computing resource. The multicasting may be achieved by using batch processing where other documents stored locally on the web cache are multicasted with the requested document to the appropriate local computing resources.  
     [0101] At step  914 , the requested document may be cached locally at the network operations center.  
     [0102] It should be appreciated that the network operations center managing the document may be used only for performing the steps for supporting multicasting and/or unicasting as set out in steps  907 - 913 . In an embodiment of the present invention where a local computing resource has a connection to a source of the requested document, the local computing resource may redirect the source of the requested document to transmit the document to the network operations center where steps  907 - 914  are performed to provide a multicast response to a unicast request.  
     [0103] In the foregoing description, the invention is described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.