This invention relates to indexing and searching in a distributed (e.g., Internet-based) system.
In the field of this invention it is known that storing newly-acquired information is a routine process, but unless appropriate steps are taken, a wider user community that wants to use that information can remain unaware of its existence. Existing methods rely on suitably structured queries to databases that might hold objects relevant to the information needs that prompted the query. The drawback is evident: no information is forthcoming unless a query is issued. These existing methods may be considered as ‘pull’ methods: interested parties have to “data mine” for information that might be of interest, by pulling it from a range of database sources. If the sources are primary, users typically employ a search engine, but indexing services that “enrich” the information provide a more effective approach to information discovery, and are likely also to be more efficient. The growth in the amount of information available online must inevitably lead to an increase in the availability of indexing services. These will typically comprise of a range of indexing servers distributed across a computer network.
An example of the need for an active method of information management/mining is described in the publication “Information grids: managing and mining semantic data in a grid infrastructure; open issues and application to geno-medical data”, Brunie et al, pp.509-515, Proc. 14th International Workshop on Database and Expert Systems Applications (DEXA '03), 2003.
In the publication “Distributed Indexing and Searching: A Big Picture” by Daigle and Mazzucato (available at website http://www.w3.org/Search/9605-Indexing-Workshop/Papers/Daigle@bunyip.html) it is suggested for indexing servers to be distributed. However, although this publication suggests that rather than allowing indexers to ‘pull’ the indexing data the server would be better served by making agreements with indexing services to which the data could be ‘pushed’, it offers no suggestions about how such “agreements” might be implemented.
A need therefore exists for a system and method for general notification of newly-acquired information wherein the abovementioned disadvantage(s) may be alleviated.
In accordance with a first aspect of the present invention there is provided a system for general notification of newly-acquired information as claimed in claim 1.
In accordance with a second aspect of the present invention there is provided a method for general notification of newly-acquired information as claimed in claim 8.
One system and method for general notification of newly-acquired information incorporating the present invention will now be described, by way of example only, with reference to the accompanying drawing(s), in which:
As will be explained in greater detail below, a novel system and method incorporating the present invention publishes to the wider community the fact that a fresh information object has been acquired and stored, rather than expecting members of the community to pull the information on their own initiative. For the purposes of this description, the term ‘wider community’ is used to mean both end users and indexing services that perform an enrichment role for newly stored information objects.
As illustrated in
In this architecture, there is a tight relationship between the three components 110, 120 and 130. Typically, the creation of new information objects within an Object Server 110 is managed by the Indexing Service 120. All objects are indexed before being stored on an appropriate Object Server 110 whose location is determined by the Indexing Service 120. There may be many Object Servers distributed throughout a network but typically there is a single Index Service that manages and provides access to the information objects. End User Clients 130 retrieve information objects by submitting a query to the Indexing Service 120 which returns a set of hits that include references to the information objects. A user then retrieves the information object by selecting the appropriate hit. In some cases (as in Content Management systems) the user's request for the object is validated by the Indexing Service before instructing an Object Server to return the information object to a user. In other indexing systems such as Google™ the hits include the URL (Uniform Resource Locator) of the appropriate page that the user accesses directly (though Internet search engines employ crawlers to assemble the indexes rather than the formal index/store process used in large content management systems).
Although it might be thought that known publication indexing services provided by third parties are the equivalent of this method's indexing servers, it must be understood that these known services essentially involve the amalgamation and remarketing of indexing information (typically a set of keywords) provided by the publishers of the original information. The novel method described herein is significantly more flexible and adds selectivity to the indexing process, as described below.
In this novel method, the Indexing Services receive metadata published by the Object Servers through a subscription service. The Indexing Services are then able to create entries into structured indexes that create enriched metadata for the information objects stored elsewhere. If necessary, the Indexing Services can use the tokens published by the Object Servers to retrieve an object for further indexing and analysis. It will be understood that the tokens are unique locators, for example URIs (Uniform Resource Indicators). However, an important attribute of the ‘triangle architecture’ of this embodiment is the access control afforded to the object servers. Clients route their requests through the indexing servers, which notify the relevant objects server to send the required information object (as identified by the token) to the clients (probably identified by an IP—Internet Protocol—address). It will further be understood that the metadata is of two kinds: (a) the classification information published by the object server to the broker, and (b) the indexing metadata created by the indexing servers. Both comply with the standard definition of metadata: “data about data”. The classification information might, for example, be a topic string, such as /news/sport/tennis/Wimbledon/final/winner or it might be a fragment of XML (extensible Markup Language) that conforms to a controlled classification vocabulary. The indexing metadata is likely to be a function of the indexing method employed. For example, for a picture it might comprise a set of feature vectors derived by computations performed on the image content.
Referring now to
The architectural advantages of distributed versus centralised systems are well known and accepted. Centralised indexing introduces bottlenecks both from a performance, algorithmic and management point of view. Furthermore, the publish/subscribe model introduces anonymity so that new publishers and subscribers in the form of Object Servers and Indexing Services can be added at. will without affecting the existing system. Each of the distributed indexers can be optimised to a particular form of content or style (e.g., audio, video, structured or unstructured text etc.), which would be considerably more difficult in a simple centralised configuration.
It will be understood that the novel method described herein is explicitly selective in that the subscription mechanism enables each indexing service to prescribe its area of interest, and the Broker provides a notification service and delivers only the object metadata that matches the subscription. The Broker performs a relatively neutral function: forwarding publications to interested subscribers. The Broker is aware only that some application is interested in a particular topic, not the reason why there was interest. The Broker is simply providing a notification service for indexers to access objects or indexes if necessary. The combination of anonymous publish/subscribe technology to integrate the otherwise centralised indexing and object storage allows content to be “pushed” to end user clients.
It will be appreciated that the method can be extended further to allow for the Indexing Services themselves to publish metadata. In addition to allowing content to be “pushed” to End User Clients, this metadata enables other Indexing Services to be provided at a richer semantic level. For example, the Indexing Services might include one that specializes in images and another that specializes in textual descriptions of objects. A higher-level service subscribes to the metadata published by the image and text indexing services to construct a richer index that contains semantic links between the image and the text.
Referring now also
Indexing services that are configured for higher-level semantic enrichment inspect the enhanced metadata received from the lower-level indexing services via the Broker. If the metadata is relevant to the higher-level indexing service, then the service creates an entry in its structured index. If the higher-level indexing service relies on more extensive analysis of the fresh information object, then it may use the retrieval tokens for the information object to retrieve a copy for further analysis. This method of enrichment is not restricted to a two-tier model as described in this example, but may be extended to an n-tier model with the nth tier inspecting metadata from the lower n-1 tiers. Higher-level semantic indexing services will employ more complex index structures and algorithms, but the nature of these, and the means whereby index entries are created, need not be discussed herein.
It will be understood that the system and method for general notification of newly-acquired information described above provides a combination of anonymous publish/subscribe technology to integrate otherwise centralised indexing and object storage, allowing content to be “pushed” to end user clients.
Number | Date | Country | Kind |
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0506532.1 | Mar 2005 | GB | national |