US 5,611,049 AGranted

System for accessing distributed data cache channel at each network node to pass requests and data

OwnerWilliam M. Pittsinventor

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Abstract

Network Distributed Caches ("NDCs") (50) permit accessing a named dataset stored at an NDC server terminator site (22) in response to a request submitted to an NDC client terminator site (24) by a client workstation (42). In accessing the dataset, the NDCs (50) form a NDC data conduit (62) that provides an active virtual circuit ("AVC") from the NDC client site (24) through intermediate NDC sites (26B, 26A) to the NDC server site (22). Through the AVC provided by the conduit (62), the NDC sites (22, 26A and 26B) project an image of the requested portion of the named dataset into the NDC client site (24) where it may be either read or written by the workstation 42. The NDCs (50) maintain absolute consistency between the source dataset and its projections at all NDC client terminator sites (24, 204B and 206) at which client workstations access the dataset. Channels (116) in each NDC (50) accumulate profiling data from the requests to access the dataset for which they have been claimed. The NDCs (50) use the accumulated profile data stored in channels (116) to anticipate future requests to access datasets, and, whenever possible, prevent any delay to client workstations in accessing data by asynchronously pre-fetching the data in advance of receiving a request from a client workstation.

Claims30

Dependent claims

In a network of digital computers that includes a first plurality of Network Distributed Cache ("NDC") sites, each NDC site including an NDC that has an NDC buffer, a method for projecting images of a stored dataset from an NDC server terminator site into a second plurality of NDC client terminator sites in response to requests to concurrently access such stored dataset transmitted from a third plurality of client sites respectively to the second plurality of NDC client terminator sites, the method comprising the steps of:

(a) the NDC receiving the request to access data in the stored dataset;
(b) the NDC checking the NDC buffer at this NDC site to determine if a projected image of data requested from the stored dataset is already present there;
(c) if the NDC buffer of this NDC site does not contain a projected image of all data requested from the stored dataset, and if the NDC site receiving the request is not the NDC server terminator site for the stored dataset, the NDC of this NDC site transmitting a request for data from this NDC site downstream to another NDC site closer to the NDC server terminator site for the stored dataset than the present NDC site;
(d) if the NDC buffer of this NDC site does not contain a projected image of all data requested from the stored dataset, and if the NDC site receiving the request is the NDC server terminator site for the stored dataset, the NDC of the NDC server terminator site accessing the stored dataset to project an image of the requested data into the NDC buffer of the NDC server terminator site;
(e) repeating the steps (a) through (d) until the NDC buffer of the downstream NDC site receiving the request contains a projected image of all requested data;
(f) each successive NDC site, having obtained a projected image of all the requested data, returning the requested data upstream to the NDC site from which the NDC site received the request until the requested data arrives at the NDC client terminator site, each NDC site that returns data upstream to the requesting NDC site retaining a copy of the returned data that the returning NDC site may subsequently transmit to an NDC site other than the NDC site to which the returning NDC site first returned the data, whereby images of the stored dataset may be projected concurrently from a single NDC site into the second plurality of NDC client terminator sites;
and
(g) the NDC client terminator site, upon receiving the requested data, returning the requested data to the client site that requested access to the stored dataset.

5 more elements

A network of digital computers that includes a first plurality of client sites which request access to a stored dataset that is stored at a location that can be accessed through the network, the network comprising:

a second plurality of NDC sites, the stored dataset whose access is requested by the client sites being stored at an NDC server terminator site, a request from the client sites for access to the stored dataset being received by a third plurality of NDC client terminator sites, each NDC site including:
(a) an NDC that has an NDC buffer;
(b) means for the NDC to receive the request to access the stored dataset;
(c) means for the NDC to check the NDC buffer at this NDC site to determine if a projected image of data requested from the stored dataset is already present there, wherein:
i. if the NDC buffer of this NDC site does not contain a projected image of all data requested from the stored dataset, and if this NDC site is not the NDC server terminator site for the stored dataset, the NDC includes means for transmitting a request for data from this NDC site downstream to another NDC site closer to the NDC server terminator site for the stored dataset than the present NDC site;
ii. if the NDC buffer of this NDC site does not contain a projected image of all data requested from the stored dataset, and if this NDC site is the NDC server terminator site for the stored dataset, the NDC including means for accessing the stored dataset to project an image of the requested data into the buffer of this NDC;
and
iii. if the NDC buffer of an NDC site contains a projected image of all requested data, the NDC including means for returning the data requested from this NDC site upstream to the NDC site from which this NDC site received the request, whereby through a succession of such returns of data from one NDC site to the next upstream NDC site the requested data ultimately arrives at the NDC client terminator site, each NDC site that returns data upstream to the requesting NDC site retaining a copy of the returned data that the returning NDC site may subsequently transmit to an NDC site other than the NDC site to which the returning NDC site first returned the data, whereby images of the stored dataset may be projected concurrently from a single NDC site into the third plurality of NDC client terminator sites;
and
(d) means for the NDC client terminator site to return the requested data to the client site that requested access to the stored dataset.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/343,477Filed 28 Nov 1994
Granted: 11 Mar 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G06F 12/0813
Multiuser, multiprocessor or multiprocessing cache systems: with a network or matrix configuration
G06F 16/10
Information retrieval; Database structures therefor; File system structures therefor: file systems; File servers
H04L 67/568
Provisioning of proxy services: storing data temporarily at an intermediate stage, e.g. caching
H04L 69/329
Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions: in the application layer [OSI layer 7]