Google Inc.

Eric Russell Fredricksen

Bay-Wei W Chang

Georges R Harik

Jeffrey Adgate Dean

Sanjay Ghemawat

Fritz Schneider

Niels Provos

Hanping Feng

Naga Sridhar Kataru

Paul Thomas Buchheit

Jeffrey Glen Rennie

Embodiments of this invention allow a user to navigate through previously viewed documents. These documents may be associated with a key, e.g. a search or a document. In response to re-entering the search or detecting subsequent interaction with the document, the navigation may be provided. In certain embodiments, the navigation is provided through a button on a toolbar or through a menu listing.

System and method for navigating documents

The present invention is directed to a client-server network system implementing a multi-tier caching strategy for a user to access a document efficiently. When serving a document to client, the document is examined for embedded references to other documents. The embedded references are extracted and then assigned a priority. The referenced documents are preloaded to the client prior to receiving a request for them. The referenced documents are obtained locally from the server cache or obtained from their respective web hosts and transmitted according to the assigned priority.

Prioritized preloading of documents to client

Upon receipt of a document request, a client assistant examines its cache for the document. If not successful, a server searches for the requested document in its cache. If the server copy is still not fresh or not found, the server seeks the document from its host. If the host cannot provide the copy, the server seeks it from a document repository. Certain documents are identified from the document repository as being fresh or stable. Information about each of these identified documents is transmitted to the server which inserts entries into an index if the index does not already contain an entry for the document. If and when this particular document is requested, the document will not be present in the server, however the server will contain an entry directing the server to obtain the document from the document repository rather than the document's web host.

System and method of accessing a document efficiently through multi-tier web caching

The present invention is directed to a method for updating a cache. A server identifies whether certain preconditions have been met for a document in a cache from freshness parameters associated with a document identifier for the document. Then when the preconditions have been met, a first document content is retrieved from a remote host. A first content fingerprint for the first document content is calculated. The first document content is stored in the cache. Then a content difference is calculated between the first document content and a second document content, both associated with the document identifier. The content difference is stored. Then the document identifier is associated with the content difference.

Refreshing cached documents and storing differential document content

Upon receipt of a document request, a client assistant examines its cache for the document. If not successful, a server searches for the requested document in its cache. If the server copy is still not fresh or not found, the server seeks the document from its host. If the host cannot provide the copy, the server seeks it from a document repository. Certain documents are identified from the document repository as being fresh or stable. Information about each these identified documents is transmitted to the server which inserts entries into an index if the index does not already contain an entry for the document. If and when this particular document is requested, the document will not be present in the server, however the server will contain an entry directing the server to obtain the document from the document repository rather than the document's web host.

The present invention is directed to a client-server network system implementing a multi-tier caching strategy for a user to access a document efficiently. The system comprises a client cache assistant serving as proxy for web browsers, a remote cache server managing user-requested documents and a search engine repository storing a huge number of documents as a backup for the remote cache server. Upon receipt of a document request, the client cache assistant examines its client cache to identify the requested document. If not successful, the remote cache server then identifies a copy of the requested document in its own cache and transmits a content difference between the two copies to the client cache assistant. If the server copy is still not fresh or not found, the remote cache server seeks another copy of the requested document from the search engine repository and transmits another content difference to the client cache assistant. The client cache assistant merges the content differences and the original copy into a new copy of the requested document.

The present invention is directed to a system and method of performing a lookup, self-refreshing and prefetching against a DNS provider that includes a DNS cache and a DNS master. The DNS cache includes a set of address records which are presumptively fresh and the DNS master includes another set of address records which may be updated if their respective IP addresses are not deemed fresh or identified for update based on other factors. A hostname resolution request is first processed by the DNS cache and then by the DNS master to identify a valid IP address for a hostname. If no valid IP address is found, the DNS master retrieves a new IP address for the hostname from a third-party DNS server and then updates the addresses records in the DNS cache and master with the new IP address. Entries in the DNS master are updated from time to time increasing the likelihood that fresh addresses are predominately present and to update the DNS cache.

A client assistant, sometimes called a browser helper, runs on a client computer. The client assistant monitors a user's browsing activities and infers one or more next documents that are most likely to be requested by the user. The client assistant attempts to locate a fresh copy of the inferred next document within a client cache. If a fresh copy of the inferred document is not found in the client cache, the client assistant submits a document download request to a document server.

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San Francisco, CA, United States of America

Eric Russell Fredricksen