Abstract:
A plurality of sources are registered. A plurality of schemas are constructed, based on the plurality of sources. A desired output is obtained as a conjunctive query. A list of potential connections between at least selected ones of the sources is provided. A plurality of join plans are developed, based on the connections.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application is related to a commonly assigned U.S. application entitled “Method For Assembly Of Personalized Enterprise Information Integrators Over Conjunctive Queries,” U.S. Ser. No. 11/946,130, filed on Nov. 28, 2007, the disclosure of which is incorporated by reference herein in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to the electrical, electronic and computer arts, and, more particularly, to enterprise information integration (EII) systems and the like. 
     BACKGROUND OF THE INVENTION 
     Current EII systems are generally aimed at scenarios with a large user base. These systems are often complex, and may require manual reconciliation of schemas. With current systems, the large demand typically justifies the relatively large costs involved. End-users of current systems usually expect precise answers for their queries. The SEMEX System, as discussed in X. Dong and A. Halevy, A Platform for Personal Information Management and Integration, CIDR 2005, offers users a flexible platform for personal information management by creating associations between data items on the users&#39; desktop. However, SEMEX can only support building of integration systems for sources residing on the user&#39;s workstation. This implicitly makes the user “an expert” and also the “admin” for all the sources to be integrated. The solution is not appropriate when the user wants to combine sources operated by other users and accessible remotely. 
     The references (i) W. Shen, P. DeRose, L. Vu, A, Doan, R. Ramakrishnan, Source-aware Entity Matching: A Compositional Approach, ICDE 2007, and (ii) M. Sayyadian, H. LeKhac, A. Doan, L. Gravano, Efficient Keyword Search across Heterogeneous Relational Databases, ICDE 2007 support relational databases and do not provide support for quickly setting up a personalized mediator over autonomous sources. 
       FIG. 1  shows a prior-art EII system  100 . User  102  seeks to find employees with four years experience in the Java programming language. User  102  accesses global schema  104  which in turn accesses a plurality of source schemas  106 ,  108 , and  110 . Each of these in turn accesses a database  112 ,  114 ,  116  through a corresponding wrapper  118 ,  120 ,  122 . The original motivation for system  100  may be, for example, an enterprise application, such as payroll, human resources, banking, and the like. Such systems typically require “Precise Integration,” target a large user base with long-term needs, and are time consuming and costly to build and maintain. 
     SUMMARY OF THE INVENTION 
     Principles of the present invention provide techniques for assembly of personalized enterprise information integrators over conjunctive queries. In one aspect, an exemplary method (which can be computer implemented) for assembly of personalized enterprise information integrators over conjunctive queries, includes the steps of registering a plurality of sources; constructing a plurality of schemas based on the plurality of sources; and obtaining a desired output as a conjunctive query. The method further includes providing a list of potential connections between at least selected ones of the sources; and developing a plurality of join plans based on the connections. 
     One or more embodiments of the invention or elements thereof can be implemented in the form of a computer product including a computer usable medium with computer usable program code for performing the method steps indicated. Furthermore, one or more embodiments of the invention or elements thereof can be implemented in the form of an apparatus including a memory and at least one processor that is coupled to the memory and operative to perform exemplary method steps. Yet further, in another aspect, one or more embodiments of the invention or elements thereof can be implemented in the form of means for carrying out one or more of the method steps described herein; the means can include hardware module(s), software module(s), or a combination of hardware and software modules. As used herein, “facilitating” an action includes performing the action, making the action easier, helping to carry the action out, or causing the action to be performed. Thus, by way of example and not limitation, instructions executing on one processor might facilitate an action carried out by instructions executing on a remote processor, by sending appropriate data or commands to cause or aid the action to be performed. 
     One or more embodiments of the invention may offer one or more technical benefits; for example, an infrastructure that proactively helps an enterprise user in assembling an information integration system for answering queries that only the user may want to ask. One or more embodiments of the invention can be used in building and updating models of shared understanding, called Ontologies, as the information technology (IT) system evolves with time. One or more embodiments of the invention can also be used to detect emergent behavior in IT systems, and this also leads to better intelligence for enterprises. 
     These and other features, aspects and advantages of the present invention will become apparent front the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts enterprise integration according to the prior art; 
         FIG. 2  depicts exemplary schema registration and building according to an aspect of the invention; 
         FIG. 3  depicts exemplary filtering joins and building join plans according to an aspect of the invention; 
         FIG. 4  depicts an exemplary inventive integration framework; 
         FIG. 5  is a flow chart showing exemplary assembly of a personalized EII system, according to an aspect of the invention; 
         FIG. 6  is a flow chart showing exemplary querying of a personalized EII system, according to an aspect of the invention; and 
         FIG. 7  depicts a computer system that may be useful in implementing one or more aspects and/or elements of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     On-the-fly information integration refers to lightweight data management tasks that require combining information from multiple sources to achieve a task. One or more embodiments of the invention enable the non-technical users in an enterprise to easily integrate diverse sources, in some instances, even for transient tasks. Given a high level information need—specified as a conjunctive query suggesting a “desired output,” one or more embodiments of the invention help the user in quickly identifying the sources in the enterprise that can together answer the query. Further, one or more instances of the invention will help the user by suggesting possible associations between the various chosen datasets, and will enable users to easily incorporate new data sources into the database using an inventive source registration step, discussed below. One or more aspects of the invention also help in priming up the dataset for integration with other (tobe) registered sources. Thus, various instances or aspects of the invention enable a user to quickly build an integrator to find answers to (often personal) information needs from enterprise-wide data sources. 
     One or more embodiments of the invention provide a novel framework for building personalized mediation systems for answering conjunctive queries using enterprise-wide sources and services. Instances of the inventive domain-independent framework support publishing Source Information (data and services) without knowing the complete global model, e.g., schema models. A “desired output” model is then accepted and an integration scheme is suggested. Techniques are provided to recommend mapping between source schema and global schema to publisher. Additional techniques provide easy information extraction from the integration scheme, support keyword searches over the personalized integration scheme, provide ranked results and explanations, and/or automatically gather cost-metrics and performance statistics. 
     In another aspect, a domain independent method is provided for mapping data sources that have been registered by different users, without the presence of a single global schema. The mappings may be identified, for example, using syntactic matching techniques or derived from past linkage models in turn derived from integration systems built by other users. Once the mappings are approved by the user, one or more embodiments of the invention will then suggest various possible plans for combining the information from the sources along with a cost based ranking of such plans. The user can pick an appropriate plan, and preferably, the best plan, to set up the personalized integration system and then issue conjunctive queries over the system. One or more inventive techniques can be easily extended to support a variety of querying formats and languages, including keyword search and support for ranked answers for queries issued by the users. 
     Aspects of the invention will be illustrated using a non-limiting example. Consider a mid-level Project Manager who is interested in identifying the average cost of setting up a new 10 member team for developing a custom software application. Also, he or she would like to identify potential team members and their availability. It will be appreciated that this example is one which addresses satisfaction of an immediate need, of interest to a single user or a very small subset of users. The user may well be ready to trade completeness for speed and lower cost. With reference to  FIG. 2 , in terms of sources  202 , cost metrics for various stages of the project can be estimated by querying a projects database  204 . Team member identification can be done using an employee profile database  206  and also a new applicant database  208 . 
     The skilled artisan is familiar with the basics of databases. A database is a repository of data whose structure is explicitly defined in a standardized representation called a schema. All data instances in the database would conform to the defined schema of the database. Data can be stored outside databases also, like on a file system. In this case, the structure is unknown up-front, and such data is called unstructured data. Data can be also represented in semi-structured format like extensible mark-up language (XML) where its structure is not restricted up-front but can be automatically extracted out by the syntax in which the data is stored. One or more embodiments of the invention address data in one, some, and/or all of the three forms. 
     In terms of constraints, there will likely be many sources with varying schemas. The need being immediate, and not generic enough, makes it infeasible to build a system to integrate the sources from scratch. Even assuming the sources have easily reconcilable schema, the project manager may not have time and the necessary expertise to integrate the sources. Schema building, based on registration suggestions and content, is shown at  210 , is discussed in greater detail below. 
     It should be noted that information sources may be partially or completely autonomous. The number of sources is typically in the hundreds. There may be structured sources, e.g., relational databases (used by EII systems); semi-structured sources, e.g. spreadsheets, emails, web pages, web logs (“blogs”), and the like; and unstructured sources, e.g. reports, publications, manuals and so on. The source schema and content may change, and sources may enter and/or leave the integration environment 
       FIG. 3  shows the schema building aspect  210  of  FIG. 2 , wherein joins have been filtered, as indicated by the “X” notation next to certain entries. As shown at  312 , there are three suggested join plans in this instance, namely. Schema  1 , Schema  2 , and Schema  3 . A possible query from Schema  3  is shown at block  314 . 
     Attention should now be given to  FIG. 4 , depicting exemplary framework  400 , and to flow chart  500  of  FIG. 5 . Initially, a step of source registration and schema building is carried out, as per blocks  402  and  404  in  FIG. 4  and steps  502  and  504  in  FIG. 5 . The user  406  can register the source (such as  408 ,  410 , or  412 ) by providing an access path and then selecting the schema to publish. The various elements (attributes) in the schema can be enhanced by providing metadata such as the type of attribute, a sample instance, etc. Providing such information will help the framework in finding potential combinations. This step is optional if the user has no new source to contribute. Registered sources can be stored in sourcebase  414 . Source registration block  402  may carry out both registration and annotation functions, as indicated, at blocks  416 ,  418 . 
     One exemplary inventive approach to iteratively building a “Desired Output” based personalized enterprise information integrator will now be set forth. The user  460  provides a “desired output” to the system in the form of a “conjunctive query”. For illustrative purposes, the exemplary embodiment employs a simple syntax for such a query, like the widely accepted SQL. Given the high level goal, potential sources that can be used to answer such a query are identified. The user  460  can optionally add and/or remove sources to the identified list. Once the sources are accepted by the user, using schema matching techniques along with information from the plan libraries, a list of potential connections (joins) between the sources is provided. The user can filter out the connections if need be and then proceed towards a join plan creation at step  520 . The system can then automatically generate various join plans and use statistical information about the sources to provide cost metrics for each such plan. The user  460  can pick the best plan as per his understanding which will then be registered as the schema for the user&#39;s personalized information integrator. The user  406  can be same as the user  460 ; however, in a general case, he may be a totally different user who just decided to register the source. Hence,  FIG. 4  shows a different user icon  406  to represent a separate user from user  460 . 
     Schema builder  404  can include a personalized schema designer  430  and a mapper  432 . Thus, builder  404  accesses the source schema and selects appropriate users&#39; schema for the user  460 . The metadata mentioned elsewhere herein can be contained in metabase  434 . The user&#39;s query can be provided to query engine  436 , including intelligent query builder  438  and dynamic executor  440 . Engine  436  outputs the results as shown. Learner  442  includes source monitor  444  and metadata miner  446 , and may be accessed by query engine  436  when processing queries to obtain results. 
     The details of functionality for source registration  402  and for the schema builder  404  are shown in  FIGS. 2 and 3 . The query engine  436  allows users to query over the personalized mediator. The query could be, for example, in SQL or just keywords, and these will be converted into the necessary format by the intelligent query builder  438 . The dynamic executor will use the source statistics provided by the learner  442  to schedule execution of the query. This involves ordering the call sequence of the sources, eliminating duplicates and creating the final output to be sent to the user. 
     With attention now to flow chart  600  of  FIG. 6 , an example of executing queries over the personalized information integrator will now be set forth. The system allows user to execute an SQL and/or keyword query over the personalized integrator registered by the user. If new matching sources are found after registration then those will be shown to the user and user can opt to add them into the source querying pool for answering the queries. The system will automatically create a query plan for the new source identified for the integrator, as shown at step  602 . Ranked answers with explanations can be provided by plugging in various ranking models, as shown at step  604 . 
     One or more embodiments of the invention thus provide a framework for publishing source information (data and services) without knowledge of the complete global model, e.g., schema models. Further, one or more embodiments also provide an approach that accepts a “desired output” model and suggests an integration scheme, and techniques to recommend, to a user, mapping between a source schema and a user schema. An advantage of the on-the-fly integration over autonomous sources is the significant value-add for information integration tools. 
     Exemplary System and Article of Manufacture Details 
     A variety of techniques, utilizing dedicated hardware, general purpose processors, firmware, software, or a combination of the foregoing may be employed to implement the present invention or components thereof. One or more embodiments of the invention, or elements thereof, can be implemented in the form of a computer product including a computer usable medium with computer usable program code for performing the method steps indicated. Furthermore, one or more embodiments of the invention, or elements thereof, can be implemented in the form of an apparatus including a memory and at least one processor that is coupled to the memory and operative to perform exemplary method steps. 
     One or more embodiments can make use of software running on a general purpose computer or workstation. With reference to  FIG. 7 , such an implementation might employ, for example, a processor  702 , a memory  704 , and an input/output interface formed, for example, by a display  706  and a keyboard  708 . The terra “processor” as used herein is intended to include any processing device, such as, for example, one that includes a CPU (central processing unit) and/or other forms of processing circuitry. Further, the term “processor” may refer to more than one individual processor. The term “memory” is intended to include memory associated with a processor or CPU, such as, for example, RAM (random access memory), ROM (read only memory), a fixed memory device (for example, hard drive), a removable memory device (for example, diskette), a flash memory and the like, in addition, the phrase “input/output interface” as used herein, is intended to include, for example, one or more mechanisms for inputting data to the processing unit (for example, mouse), and one or more mechanisms for providing results associated with the processing unit (for example, printer). The processor  702 , memory  704 , and input/output interface such as display  706  and keyboard  708  can be interconnected, for example, via bus  710  as part of a data processing unit  712 . Suitable interconnections, for example via bus  710 , can also be provided to a network interface  714 , such as a network card, which can be provided to interface with a computer network, and to a media interface  716 , such as a diskette or CD-ROM drive, which can be provided to interface with media  718 . 
     Accordingly, computer software including instructions or code for performing the methodologies of the invention, as described herein, may be stored in one or more of the associated memory devices (for example, ROM, fixed or removable memory) and, when ready to be utilized, loaded in part or in whole (for example, into RAM) and executed by a CPU. Such software could include, but is not limited to, firmware, resident software, microcode, and the like. 
     Furthermore, the invention can take the form of a computer program product accessible from a computer-usable or computer-readable medium (for example, media  718 ) providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer usable or computer readable medium can be any apparatus for use by or in connection with the instruction execution system, apparatus, or device. The medium can store program code to execute one or more method steps set forth herein. 
     The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. Examples of a computer-readable medium include a semiconductor or solid-state memory (for example memory  704 ), magnetic tape, a removable computer diskette (for example media  718 ), a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) and DVD. 
     A data processing system suitable for storing and/or executing program code includes at least one processor  702  coupled directly or indirectly to memory elements  704  through a system bus  710 . The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memories which provide temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk; storage during execution. 
     Input/output or I/O devices (including but not limited to keyboards  708 , displays  706 , pointing devices, and the like) can be coupled to the system either directly (such as via bus  710 ) or through intervening I/O controllers (omitted for clarity). 
     Network adapters such as network interface  714  may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters. 
     In any case, it should be understood mat the components illustrated herein may be implemented in various forms of hardware, software, or combinations thereof, for example, application specific integrated circuits) (ASICS), functional circuitry, one or more appropriately programmed general purpose digital computers with associated memory, and the like. Given the teachings of the invention provided herein, one of ordinary skill in the related art will be able to contemplate other implementations of the components of the invention. 
     It will be appreciated and should be understood that the exemplary embodiments of the invention described above can be implemented in a number of different fashions. Given the teachings of the invention provided herein, one of ordinary skill in the related art will be able to contemplate other implementations of the invention. Indeed, although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be made by one skilled in the art without departing from the scope or spirit of the invention.