Please wait, while we are loading the content...
Please wait, while we are loading the content...
| Content Provider | ACM Digital Library |
|---|---|
| Author | Lisboa, Elaine |
| Abstract | Supporting heterogeneous database systems in a distributed database environment requires the translation between different forms of data representation and of data manipulation while transmitting data within the network. A generally accepted approach to this translation is to define a standard database system interface (data model and data manipulation language) and to build a global schema of the distributed data. If there is a need to move data from one network node to another, the request for data is first translated into the standard interface, and then converted into the destination database interface to be evaluated. The general problem of translations between different database interfaces is known as the "mapping problem". In this paper, we consider the mapping problem in a heterogeneous distributed database environment.First, two components of database mappings are considered: the data mapping that expresses the source data structure's elements in terms of the target data structure's elements, and the operator mapping that translates the source operators into the corresponding target operators using as reference the data mapping.Four different types of mapping are identified according to the relationship between the source and the target data strucutes. First, the trivial mapping where both the source and the target data structure express exactly the same data structure using the same data model. In this case, the data mapping, as well as the operator mapping, is totally expressed by an identity function. Second, the schema mapping where the source and target data structure differ, even though the underlying data model is the same. Third, the model mapping where the data structures expressed in both schemas are exactly the same, but are described using different data models. Finally, the total mapping occurs when both source and target data models and data structures differ. Each of these four mapping cases presents its own inherent difficulties that are analyzed through the paper.Then mappings are considered within Distributed Data Base Systems. We propose an architectural arrangement that localizes total and schema mappings between the user and the standard interfaces, and limits mappings between the standard and local interfaces to the trivial and model mapping cases. Several advantages result from this arrangement (which does not lessen the mapping flexibility between user and local interfaces). The mappings between the standard and local interfaces are certified feasible and in their simplest form, the design and evaluation of the standard schema is facilitated and the operator decomposition and scheduling are rendered independent of schema mappings.Lastly, the paper presents the architectural framework and the mapping capabilities of a heterogeneous distributed database system being implemented at the University of Southwestern Louisiana. |
| Starting Page | 98 |
| Ending Page | 98 |
| Page Count | 1 |
| File Format | |
| ISBN | 0897910141 |
| DOI | 10.1145/503838.503877 |
| Language | English |
| Publisher | Association for Computing Machinery (ACM) |
| Publisher Date | 1980-03-24 |
| Publisher Place | New York |
| Access Restriction | Subscribed |
| Content Type | Text |
| Resource Type | Article |
National Digital Library of India (NDLI) is a virtual repository of learning resources which is not just a repository with search/browse facilities but provides a host of services for the learner community. It is sponsored and mentored by Ministry of Education, Government of India, through its National Mission on Education through Information and Communication Technology (NMEICT). Filtered and federated searching is employed to facilitate focused searching so that learners can find the right resource with least effort and in minimum time. NDLI provides user group-specific services such as Examination Preparatory for School and College students and job aspirants. Services for Researchers and general learners are also provided. NDLI is designed to hold content of any language and provides interface support for 10 most widely used Indian languages. It is built to provide support for all academic levels including researchers and life-long learners, all disciplines, all popular forms of access devices and differently-abled learners. It is designed to enable people to learn and prepare from best practices from all over the world and to facilitate researchers to perform inter-linked exploration from multiple sources. It is developed, operated and maintained from Indian Institute of Technology Kharagpur.
Learn more about this project from here.
NDLI is a conglomeration of freely available or institutionally contributed or donated or publisher managed contents. Almost all these contents are hosted and accessed from respective sources. The responsibility for authenticity, relevance, completeness, accuracy, reliability and suitability of these contents rests with the respective organization and NDLI has no responsibility or liability for these. Every effort is made to keep the NDLI portal up and running smoothly unless there are some unavoidable technical issues.
Ministry of Education, through its National Mission on Education through Information and Communication Technology (NMEICT), has sponsored and funded the National Digital Library of India (NDLI) project.
| Sl. | Authority | Responsibilities | Communication Details |
|---|---|---|---|
| 1 | Ministry of Education (GoI), Department of Higher Education |
Sanctioning Authority | https://www.education.gov.in/ict-initiatives |
| 2 | Indian Institute of Technology Kharagpur | Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project | https://www.iitkgp.ac.in |
| 3 | National Digital Library of India Office, Indian Institute of Technology Kharagpur | The administrative and infrastructural headquarters of the project | Dr. B. Sutradhar bsutra@ndl.gov.in |
| 4 | Project PI / Joint PI | Principal Investigator and Joint Principal Investigators of the project |
Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon |
| 5 | Website/Portal (Helpdesk) | Queries regarding NDLI and its services | support@ndl.gov.in |
| 6 | Contents and Copyright Issues | Queries related to content curation and copyright issues | content@ndl.gov.in |
| 7 | National Digital Library of India Club (NDLI Club) | Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach | clubsupport@ndl.gov.in |
| 8 | Digital Preservation Centre (DPC) | Assistance with digitizing and archiving copyright-free printed books | dpc@ndl.gov.in |
| 9 | IDR Setup or Support | Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops | idr@ndl.gov.in |
|
Loading...
|