Method and system for distributed caching, prefetching and replication

In a system containing a plurality of computers which communicate over a network using a layered communication protocol, with the computers at certain nodes in the network acting as home servers for storing information in the form of documents, and with certain other computers acting as clients that send document request messages to the servers at an application layer level, the document request messages being requests for documents stored at the home servers, a method of fulfilling document request messages by transparent proxying comprising the steps of:

• (a) storing local cache copies of documents at a plurality of intermediate node locations in the network;
• and
• (b) in response to a particular one of the clients generating a particular application layer document request message intended to be sent to a particular one of the home servers, fulfilling the particular application layer document request message at one of the intermediate node locations along a path from the client to the home server through which the document request would naturally flow in the absence of any cache servers, by intercepting the document request message and returning one of the local cache copies in a response message to the application layer at the client, such that the application layer request message is intercepted at the intermediate node and such that a network connection is not established with the application layer on the home server and such that the addresses in a response message are the same as if the home server had fulfilled the document request message.

In a system containing a plurality of computers which communicate over a network, with certain computers acting as home servers for storing information in the form of documents, and with certain other computers acting as clients that send messages which are requests for documents stored at the home servers, a method of fulfilling document request messages by distributed caching comprising the steps of:

• (a) routing document request messages from a client to a home server along a path from the client to the home server, the path comprising a plurality of hops including a plurality of intermediate node locations in the network through which the document request would naturally flow through in the network in the absence of cache servers;
• (b) at selected intermediate nodes,
• (i) storing local cache copies of selected documents at intermediate nodes;
• (ii) filtering document request messages to determine if a particular document request message made by a client can be fulfilled by providing one of the local cache copies to the client, and if so, returning the local cache copy to the client;
• and
• (iii) if not possible to so fulfill the document request message forwarding the document request message to the home server along the path which the document request message would naturally follow through the network.

In a system containing a plurality of computers which communicate over a network, with the computers at certain nodes in the network acting as home servers for storing information in the form of documents, and with certain other computers acting as clients that send document request messages which are requests for documents stored at the home servers, a method of fulfilling document request messages at node through which the document request messages travel comprising the steps of:

• (a) storing local cache copies of documents at a plurality of intermediate node locations in the network;
• (b) in response to a particular one of the clients generating a particular document request message intended to be sent to a particular one of the home servers;
• (i) determining a path for the particular document request message to travel from the particular client to the particular home server along a path of nodes located in the network between the particular client and the particular home server, the path being determined by an address of the home server and the path comprising a plurality of the intermediate node locations in the network;
• (ii) forwarding the request message along the path as determined by the home server address in the request message;
• and
• (iii) fulfilling the particular document request message at one of the plurality of intermediate node locations in the determined path of nodes by the steps of, if a local cache copy is available at the intermediate node, returning one of the local cache copies corresponding to a document specified in the particular document request message, and otherwise if a local cache copy is not available at the intermediate node, forwarding the request message in the direction of the home server along the path.

A method of fulfilling requests for information in a network of computers, with at least some of the computers in the network acting as home servers for storing information, and at least some of the computers acting as clients that send request messages to the home servers, the method comprising the steps of:

• (a) distributing cache copies of the information through the network by storing copies of the information in a plurality of computers in the network that act as cache servers;
• (b) routing request messages from the client to the home server along a path consisting of a plurality of intermediate computers in the network, the path including computers through which the request messages travel in the absence of any cache servers with at least some of the intermediate computers also acting as cache servers, the request messages initiated by a particular one of the clients to obtain information from a particular one of the home servers;
• and
• (c) transparently processing request messages as they are routed through the cache servers, such that request messages that can serviced by the cache servers instead of the home servers are serviced by the cache servers, in a manner which is transparent to the clients and the home servers.