Electrical computers and digital processing systems: multicomput – Computer-to-computer data routing – Decentralized controlling
Reexamination Certificate
1997-06-24
2001-06-05
Rinehart, Mark H. (Department: 2756)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data routing
Decentralized controlling
C709S201000
Reexamination Certificate
active
06243760
ABSTRACT:
FIELD OF INVENTION
This invention relates generally to the distribution of large amounts of data over a network, such as the Internet, and more particularly to a satellite based Internet caching system.
In recent years the Internet has become widely used as a means of disseminating information to a large number of people. Users, who may have access to the Internet via an Internet Service Provider (ISP) can access web pages residing on servers that may be located anywhere around the globe. As usage increases, so do the demands on bandwidth, leading to congestion in the network, which results in frustrating delays for the users.
One solution to the problem of ever increasing bandwidth requirements is to bring web content to locations close to users by means of a cache.
All caching systems attempt to move content closer to the client. Two principal types of caching systems, demand and mirrored caching, are currently being deployed throughout the Internet.
In demand caching, clients request web material though a shared intermediary known as a proxy server, usually located at the Internet Service Provider (ISP). If the material is located on the proxy server, the proxy server returns the material to the client. If not, the proxy server retrieves the material from the remote server, returns it to the client and caches it for later access by other clients. The material cached at the proxy server can in turn be accessed by other subscribers so that there is no need for them to access it through the network.
Demand caching is passive to the content provider, users determine what is cached by their access patterns. Demand caching also involves a chain of caches: the client's cache, local to a client's browser, the proxy cache and sometimes intermediate network cache points. As the cache becomes full, stale material is removed on a least use basis or by use of time-to-live parameters.
Demand caching suffers from several problems. As the content provider is a passive participant in the scheme, it is often unaware that its material is being copied and stored—demand caching often violates copyright laws; as cached copies and originals are not synchronized, the copy returned to other users is sometimes not the content provider's most recent copy but the previously cached version; as well, demand caching hierarchies, along with making routing difficult and being complex to maintain and implement, make it difficult for content providers to control access to their sites, to get an accurate picture of how often their pages are being accessed or to provide custom support to local databases.
In mirrored caching the content provider has a more active role. The content provider manages, or selects an agent to manage, a distributed system of mirrored sites. The sites are placed strategically through the network and the content provider or his agent pro-actively maintains synchronization amongst these sites by distributing material over the Internet.
Though providing more control to the web page owner, mirrored caching has its problems. The mirroring of sites is complex to maintain; the system forces end users to explicitly choose one of the mirrored sites; and, lastly, the sites are often remote from an ISP's point of presence; hence clients can still suffer from network delays.
An object of the invention is to alleviate the afore-mentioned problems in the prior art.
According to the present invention there is provided a system for disseminating information over a wide area network, comprising at least one site for disseminating data to remote users on said network, said at least one site having a network address associated therewith and being accessible over said wide area network, and said data including cacheable and non-cacheable parts; a central caching unit having a network address associated therewith for storing cacheable data from said at least one site; means for establishing communication between said at least one site and said central caching unit for transferring cacheable data to said central caching unit; a plurality of local access nodes for permitting said remote users to access said wide area network; distributed local caching units associated with said local access nodes for locally storing cacheable data; a communications system distinct from said wide area network for establishing communication between said central caching unit and said local caching units for the transfer of cacheable data directly from said central caching unit to said local caching units; and routing means at said local access nodes for responding to user requests for data by establishing a connection to a destination address on said network where the requested data is located, said routing means including local routing tables containing the network address of said central caching unit and responding to connection requests from said remote users to retrieve data located at said central caching unit by first establishing a connection with the local caching unit at the associated local node to retrieve the requested data therefrom if present, and if the requested data is not present at said local caching unit, establishing a connection over said network with said central caching unit to retrieve said requested data over the wide area network.
The communications systems is typically satellite-based, but could also be a terrestrial-based broadcast or multicast system.
The invention is particularly applicable to the Internet, but may also be applied to other wide area networks, such as Intranets.
The system in accordance with the invention allows Internet web content to be stored at the local Internet provider level. The system, referred to as Managed Distributed Caching (MDC), permits the use of differential referencing of web page content, software filters and acknowledged satellite or terrestrial multicast to provide a low cost, easy to manage and copyright transparent, push caching service for the Internet. More specifically, an aspect of the invention relates to a scheme of combining differential referencing and static routing of web page content that provides content providers with a seamless and controllable caching system.
This invention addresses the problems of control, synchrony, complexity and performance that plagued the prior art.
To give complete control to the content provider, system allows the content provider to split web content into cacheable and non-cacheable elements. The splitting is completely under the control of the content provider. The non cacheable elements are stored at the content provider's site or, for small content providers through a virtual hosting mechanism at a central site. The content provider can now control and monitor access to its site and where direct contact with the user is required, provide access to non cached databases (e.g., cgi) and other custom features. Cached items, on the other hand, are transferred to the central cache site.
To ensure that the cached copies are up-to-date and synchronized across a network, the cacheable items, stored at the central cache site, are distributed, by satellite or terrestrial multicast, to caches at the subscribing ISPs.
To ensure that routing between cached and uncached elements is as simple as possible and easy to maintain, proxyless routing, through the use of static routes, is typically used at the ISP router.
The invention also provides a method of disseminating information over a wide area network, comprising the steps of providing at least one site for disseminating data to remote users on said network, said at least one site having a network address associated therewith and being accessible over said wide area network, and said data including cacheable and noncacheable parts; storing cacheable data from said at least one site at a central caching unit having a network address associated therewith; transferring said cacheable material over a communications system distinct from said wide area network directly to distributed local caching units associated with local access nodes giving remote users
Armbruster Brian
Brown Jeff
Wall Peter
(Marks & Clerk)
Rinehart Mark H.
Vistar Telecommunications Inc.
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