A glossary of OGSA-DAI terms and those of related technologies.
| A | |
| ACID | Atomic, Consistent, Isolated and Durable. A set of properties of a transaction that facilitate application use of databases. |
| Action | A single unit of work, considered indivisible by the client that wishes to have that action performed, for example, the evaluation of one query against one database. |
| Activity | An activity is a component within the OGSA-DAI software which provides a particular piece of functionality. For example, an activity is provided to perform an SQL query. A data service resource supports a particular set of activities. |
| Activity Pipeline | An activity pipeline is a chain of two or more activities where the output of one activity is connected to the input of another. Data can be streamed between the activities of an activity pipeline. |
| ANT | Another Neat Tool. A Java-based build-tool. |
| Atomic Action | An action that the implementation system undertakes to perform atomically. That is, the whole action is performed or the effects on the system give subsequent actions the same results as if no part of that action had been performed. |
| Axis | Apache eXtensible Interaction System. A SOAP engine produced by the Apache software foundation. |
| B | |
| Block | An object of data that is consumed or produced by an activity. Most activities consume and produce String, Document or byte[] data, but an activity implementation is free to consume or produce whichever type of data it desires. |
| C | |
| Client | An application or computation that is interacting with an OGSA-DAI data service. |
| Consumer | A computation, sometimes also a client, that is receiving the results of actions requested by a client. |
| Context | A set of data that provides references to the computational environment and other information about the current computation, for example, the authentication, policy and authority under which the computation runs. |
| Controlled Data Repository | A data repository that is at least partially managed by a VO that is using OGSA-DAI components, but which may also have external constraints on its structure. |
| Curated Data Repository | A data repository that is assembled from other data sources and new data and is managed to maintain some particular quality and topic goals. |
| D | |
| DAI | Data Access and Integration. |
| DAIS |
Database Access and Integration Services. A GGF Working Group.
http://forge.gridforum.org/projects/dais-wg/ |
| Data Access Component | A component that allows the data in some structured store to be accessed. This access may include read access, update access, schema access, schema update, bulk operations and administrative operations, depending on what is supported by the store and component and what is permitted. |
| Database | Data held in a structured data storage system, such as that in a DBMS or an XML document repository. It extends to any stored data that is sufficiently described and structured such that database operations based on structure, such as queries, are supported. |
| Data Federation | A combination of data from multiple data sources manipulated to be presented as a single consistent data source. |
| Data Integration Component | A component that transforms the logic or format of data in some way and or combines data from multiple sources using such operations. |
| Data Repository | A structured data storage system that is a database (in the OGSA-DAI sense) that can be used to store and retrieve data. |
| Data Resource | A system external to OGSA-DAI from which data can be read (and often also written). For example a relational database management system such as MySQL or Oracle. |
| Data Resource Accessor | A component used by data service resources to manage accesses to a specific data resource. |
| Data Service | A data service is an OGSA-DAI web service which exposes 0 or more Data Service Resources. Clients interact with data service resources through the operations of the web service. These operations are described using WSDL. |
| Data Service Resource | A data service resource implements the core OGSA-DAI functionality. It accepts perform documents from data services, parses and validates them, executes the data-related activities specified within them and constructs response documents. It can also cache data for retrieval by third-parties (if the data service resource is configured to support asynchronous data delivery). Data service resources are accessed via data services. |
| Data Source | A source of structured data, often read only and often autonomously managed. |
| Data Translation / Transformation Service |
A web service that takes an input and yields an output that is a translation or transformation of its input:
|
| Data Transport | A class of mechanisms for moving data between a source and target preserving information. |
| DBMS | Database Management System. |
| DQP | Distributed Query Processing. |
| DT | See Data Transport. |
| DTD | Document Type Definition - see XML. |
| E | |
| Engine | A central components of a data service resource responsible for processing perform documents. |
| end-point | An end-point is an activity output defined in a perform document that is not connected to the input of another activity. Data written into such an output is delivered back to the client in the response document. |
| EPCC | Edinburgh Parallel Computing Centre. |
| eXist | An XML database. |
| F | |
| G | |
| GGF | Global Grid Forum. |
| Glide-in Database | A database that is created when a job is started on some platform, used while the job is running, for example to collect intermediary results, and is deleted when the job completes, presumably after sending derived data to some other location. |
| Globus | The Globus Project is developing fundamental technologies needed to build computational grids. |
| Globus Toolkit | A Grid middleware solution. The Globus Toolkit version 4 is WSRF-compliant. |
| Grid | Grids are persistent environments that enable software applications to integrate instruments, displays, computational and information resources that are managed by diverse organizations in widespread locations. |
| H | |
| HTTP | Hypertext Transfer Protocol. |
| I | |
| Internal Data Repository | This is a data repository that is totally under the control of the VO that is using OGSA-DAI components, so that its life-cycle, structure and use are within the VO's control. |
| J | |
| JUnit | Java-based unit testing tool. |
| K | |
| L | |
| Language | A notation in which a script is written defined by an XML Schema and identified by a URI for that schema. |
| Log4j | A library for inserting logging statements into your code. |
| M | |
| Metadata |
|
| N | |
| NeSC | UK National e-Science Centre. |
| O | |
| OGSA | Open Grid Services Architecture. An emerging architecture for Grids that draws on Web services. |
| OGSA-DAI | Open Grid Services Data Access and Integration. A UK e-Sciences Core Programme project developing generic middleware designed to support database access and integration in the context of OGSA. |
| OGSA-DAI Developer | A software engineer who is developing components that comply with the OGSA-DAI architecture. Typically they will be developing OGSA-DAI components. |
| OGSA-DAI User | A person, typically an application scientist or engineer, who uses an application that has been built using OGSA-DAI components. |
| OMII |
The UK Open Middleware Infrastructure Institute
http://www.omii.ac.uk |
| P | |
| Perform Document | A document describing the activities to be performed by a data service resource. This may include database query activities, data transformation activities and data delivery activities, as well as any other kinds of activities. |
| Primitive Action | An action that can be performed by a represented DBMS that is indivisible. |
| portType | A WSDL element that groups together a collection of WSDL operations. |
| Producer | A service that is generating data. |
| Property | An attribute or value holding some information relating to the state of a resource or other entity. For example data service resources have properties which hold information on the data resource they expose, the activities they can execute and the status of any requests currently being executed. A client-service connection may have properties that hold the timeout for client connections and security-related configuration information. |
| Q | |
| R | |
| RAMPS | Reliability, Availability, Manageability, Performance and Scalability. |
| RDBMS | Relational Database Management System. |
| Receiver | A service that is the target of a Data Transport application and is actively receiving its data. |
| Resource Property | An attribute or value holding some information relating to the state of a resource. For example data service resources have properties which hold information on the data resource they expose, the activities they can execute and the status of any requests currently being executed. In WSRF-compliant web services, resource properties are accessed via operations defined by the WSRF WS-ResourceProperties specification. |
| S | |
| Sender | The service that is the source of data in a Data Transport application. |
| Session | An object that allows state to be stored across multiple requests to a data service resource. Each data service resource has its own session manager responsible for creating, accessing and terminating sessions. Sessions have a finite lifetime after which they are said to have expired. |
| Session Attribute | An object of state stored inside a session. Activities are able to store new session attributes as well as accessing and updating existing session attributes. |
| Session Stream | A stream that is stored in a session and can be accessed using the data transport functionality of a data service. |
| SOAP | Simple Object Access Protocol. |
| SQL | Structured Query Language. |
| Statement | An atomic action on a data source, such as a query, update, insert or delete. |
| Static Session Attribute | A special kind of session attribute that automatically exists within every new session created by a session manager. These are specified in the session configuration file and cannot be modified or deleted by activities. |
| Stream | An input or output which can consume or produce data in a succession of blocks. |
| T | |
| Tomcat | Tomcat is the servlet container that is used in the official Reference Implementation for the Java Servlet and JavaServer Pages technologies. |
| Transaction | A sequence of one or more actions that is implemented as an atomic action. That is, it will either be wholly completed or will terminate leaving no effect on the persistent data state. The transaction may often have ACID properties. |
| U | |
| UML | Unified Modelling Language. An object-oriented product design, modelling and documentation language. |
| URI | Uniform Resource Identifier. |
| URN | Uniform Resource Name. |
| URL | Uniform Resource Locator. |
| V | |
| VD | Virtual Data. Data that may be stored or may be automatically generated according to a recipe; consumers of that data should not be aware whether it is stored or generated. |
| Virtual Database | A data federation that presents multiple collections of data as one uniformly organised collection of data. |
| VO | Virtual Organisation. A virtual organisation integrates services and resources across distributed, heterogeneous, dynamic organisations to allow service and resource sharing when co-operating on the realisation of a joint goal. |
| W | |
| W3C | World Wide Web Consortium. |
| WSDL | Web Services Description Language. |
| WS-I | Web Services Interoperability |
| WSRF |
Web Services Resource Framework
http://www.oasis-open.org/committees/tc_home.php?wg_abbrev=wsrf |
| X | |
| Xalan | XSLT Processor. |
| Xerces | XML compliant parser and processor. |
| Xindice | An XML database. |
| XML | eXtensible Markup Language. |
| XML:DB | XML:DB Initiative for XML Databases. |
| XML Namespaces | XML namespaces provide a simple method for qualifying element and attribute names used in XML documents by associating them with namespaces identified by URI references. |
| XML Schema |
An XML language to specify XML document structure.
|
| XPath | A W3C recommendation. XPath is an XML language used to addressing parts of an XML document. The current version of the 1.0 standard can be found at: |
| XSL-T | Extensibility Stylesheet Language Transformation. A language for transforming XML documents into other XML documents. A W3C recommendation. The standard (version 1.0) can be found at: |
| XUpdate | An XML-based language for specifying updates to XML documents held within XML databases. |
| Y | |
| Z | |
| Up: OGSA-DAI User Guide | ||
| © International Business Machines Corporation, 2002-2006 | © The University of Edinburgh, 2002-2006 |