Electrical computers and digital processing systems: multicomput – Remote data accessing – Accessing a remote server
Reexamination Certificate
1999-10-20
2004-05-11
Lin, Wen Tai (Department: 2154)
Electrical computers and digital processing systems: multicomput
Remote data accessing
Accessing a remote server
C709S203000, C345S215000, C345S215000, C707S793000, C707S793000
Reexamination Certificate
active
06735622
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to techniques that transfer information about documents between machines.
BACKGROUND
Flynn et al., EP-A-691 619 (“Flynn”), describe a system for accessing and distributing electronic documents. The system can include any number of workstations, file servers, printers, and other fixed devices such as copiers, fax machines, and multifunction devices, all coupled in a network. The system can also include a number of portable devices, such as handheld or wristwatch computers, that can be carried by users and coupled to the network by infrared (IR) link. Each portable device can emulate its user's personal satchel for documents: The device can be programmed to receive, transmit, and store document references or tokens, such as Web URLs, each of which is associated with an electronic document stored in a database on the network. A document can be distributed from one user's portable device to another's by transmitting the document's URL, and a document can similarly be sent to a fixed device such as a printer by beaming the document's URL to an IR transceiver associated with the device.
Andreoli, J.-M., Borghoff, U. M., Pareschi, R., and Schlichter, J. H., “Constraint Agents for the Information Age”,
Journal of Universal Computer Science
, Vol. 1, No. 12, December 1995, pp. 762-789, describe constraint-based knowledge brokers which are concurrent agents that use signed feature constraints to represent partially specified information and can flexibly cooperate in the management of distributed knowledge.
Andreoli et al. disclose an operation named “scope-splitting”, which relies on the use of negation. Under scope-splitting, a broker can split its scope, creating two brokers. In contrast with a basic feature constraint (BFC), which cannot include negation or disjunction, a signed feature constraint (SFC) is composed of a positive part and a list of negative parts, both of which are basic feature constraints. If the scope of a broker is represented by an SFC and the scope is split by a BFC, the two resulting split scopes can both be represented by SFCs. In an example, a database of documents by non-American authors about art can be split by a constraint “books written after 1950” into art books written after 1950 but not by an American author and art documents not authored by an American but not books subsequent to 1950.
Andreoli et al. also disclose techniques for solving SFCs. Constraint satisfaction over BFCs is defined by conditional rewrite rules, as is conventional. Given an SFC, its positive component is first normalized by the algorithm for BFCs. If the result is a contradiction, the SFC is unsatisfiable. But otherwise, the normalized positive component is inserted into each of the negative components, which are then normalized by the algorithm for BFCs. If a resulting negative component has a contradictory normal form, it is eliminated, but if it has a tautological normal form, the SFC is unsatisfiable. The SFC is thus satisfiable if and only if its normal form is not reduced to a contradiction. Andreoli et al. disclose an implementation in which the SFC solver is realized as a list-transforming algorithm with additional checks for constraint satisfaction.
Andreoli et al. also disclose that a set of initial brokers can be provided, each with predefined scope. In processing requests, new brokers and agent specialists are cloned to handle a subset of their parent scope. In responding to follow-on requests, answers from existing specialists can be used, and the scope splitting mechanism avoids redundant work. Complex requests require interactions with many other agents and information stored in the network. In large information networks, such as the World Wide Web (“WWW” or “the Web”), the reuse of generated and already collected information is especially important.
SUMMARY OF THE INVENTION
The invention addresses problems that arise in transferring information relating to documents between machines, especially between portable computing devices that communicate through infrared links or other low bandwidth channels.
While the use of portable computing devices is becoming more widespread, storage capacity limitations make it impossible for such a device to store the electronic files for all the documents that a typical user may wish to access. Furthermore, the transfer of bulk documents between such devices or between one such device and a desktop computer or other non-portable computing device may be time consuming or difficult for the typical user. Meanwhile, the number of electronic document repositories is growing and document transfer via the Internet is expanding.
Although the system described by Flynn, above, addresses this situation, the Flynn techniques are problematic in several ways.
One problem is that Flynn's system stores and distributes references such as WWW URLs only for individual documents: Each document reference points to or links to a particular document. Flynn's system does not provide references for groups of documents.
Another problem with the Flynn techniques is how to keep track of a continually changing electronic document repository. Document descriptions can change, through updated author lists, updated dates, updated keywords, and so forth, requiring dynamic adjustments. In the Flynn system, however, a user may carry a URL for document A written by author B on the subject of topic C. Unknown to the user, updated document A′ by author B may exist, written two years after A and on the same topic C. Or there may be a further document A″ by author B and on a subject closely related to topic C, perhaps having a keyword in common. Even though A′ and A″ would be of use to the user, the user does not have references to them and could only obtain references through a further searching or browsing exercise to find and retrieve their URLs. The user is likely to continue working oblivious to the existence of A′ and A″.
These and similar problems with conventional techniques for transferring document-related information between machines are referred to herein as “document transfer problems”.
The invention alleviates document transfer problems by providing techniques that transfer constraint. descriptors for documents. A constraint descriptor includes information about a set of one or more constraints that documents could satisfy. Instead of referring or pointing to a single document or to a static set of documents, a constraint descriptor implicitly refers to a set of documents that satisfy the set of constraints. The constraint descriptor can therefore be used to obtain documents in this set, even though the set may be dynamic in the sense that it changes as features of documents change.
The new techniques avoid the lack of dynamicity of existing systems and enable users to hold pointers to a set of documents that may be dynamically changed.
The new techniques can be implemented in methods for transferring information about documents between machines. In general, the methods can involve a transfer of a constraint descriptor from a first machine to a second machine.
A first method implementing the new techniques can operate the first machine to obtain a constraint descriptor that includes information about a set of constraints that documents can satisfy. The first method can then operate the first machine to transfer the constraint descriptor to a second machine that is capable of using it to access documents that satisfy the set of constraints.
In the first method, the first machine can include user interface circuitry for receiving user signals. In obtaining the constraint descriptor, the first machine can receive a series of user signals that define a relation between a document related attribute and a set of at least one value of the attribute. The first machine can use the series of user signals to compile a constraint that includes the relation. The series can, for example, include two or more user signals.
The first machine can be a portab
Andreoli Jean-Marc
Borghoff Uwe M.
Lin Wen Tai
Xerox Corporation
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