G. Wiederhold. Mediation in information systems. ACM Computing Surveys (CSUR), 27(2):265--267, 1995.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....semantic information about its objects. Standardizing this facility, improving its general availability, and enhancing current traders and brokers to make e#ective use of it seems like a very promising way to go in component based development environments. 7. 6 Mediation The concept of mediation [48] appears when we want to get components to work together when they are functionally compatible, but not necessarily signature and or protocol compatible. By functionally compatible we mean that, at high enough level of abstraction, the service provided by one component is equivalent to the service ....

G. Wiederhold. Mediation in information systems. ACM Comput. Surv., 27(2):265-- 267, June 1995.

....recent related works on service composition. Finally, Section 2.5 reviews the current Web services technology. 2.4. 1 Mediator Technology A generic architecture for the integration of information sources involves the systems based on Mediators (Intelligent Information Integration (I3) Mediation) [147]. Such architecture is based on components named Mediators. According to Wiederhold [147] a Mediator is a software component, which explores the knowledge represented in a set or subset of data, to generate information for applications residing in an upper layer. Each Mediator encapsulates the ....

....services technology. 2.4.1 Mediator Technology A generic architecture for the integration of information sources involves the systems based on Mediators (Intelligent Information Integration (I3) Mediation) 147] Such architecture is based on components named Mediators. According to Wiederhold [147], a Mediator is a software component, which explores the knowledge represented in a set or subset of data, to generate information for applications residing in an upper layer. Each Mediator encapsulates the representation of multiple data sources and provides the functionality of uniform access to ....

Wiederhold, G., "Mediation in Information Systems", ACM Computing Surveys,v. 27, n. 2, pp. 265-267, 1995.

.... FreeMiles, Unlimited Fig. 5. Unified MIX Representation 3 Metadata based Prototype To evaluate the MIX model we implemented an application independent Java framework that manages and exchanges semantic metadata. The implementation follows the mediator approach introduced in [9] and is shown in Fig. 6. The bottom layer of the architecture consists of autonomous data sources that may be structured or semistructured. The current prototype supports the mapping of relational databases and XML documents. Wrappers map local data structures from the source to the concepts ....

Wiederhold, G.: Mediation in Information Systems, ACM Comp. Surv., 27(2), 1995

....taken from a commonly known ontology. Thus, the concept label and the semantic context of a semantic object help to describe the supposed meaning of the data. An example of how data is represented using MIX is given in Figure 3. Our framework follows the classical mediator approach introduced in [22], and is shown in Figure 2. For the time being, components such as federation manager, and wrapper and ontology servers are colocated with the application processing the data. However, it is feasible to view these as generic Internet services that may be located remotely in the future. The bottom ....

Wiederhold, G.: Mediation in Information Systems, ACM Computing Surveys, Vol. 27, No.2, 1995 8

....middleware is connected to but one underlying database. Hence, in heterogeneous databases, data integration, both conceptually and operationally, is a prime concern; this is a non issue for temporal middleware. More recently, there has been a great deal of work in the related area of mediators [GP98, Wie92, Wie95] and, more generally, on integration architectures. Roughly, a mediator offers a consistent data model and accessing mechanism to disparate data sources, many of which may not be traditional databases. As such, the focus is on resolving schema discrepancies, semi structured data access, data ....

G. Wiederhold. Mediation in Information Systems. ACM Computing Surveys, 27(2): 265--267 (1995).

....middleware is connected to but one underlying database. Hence, in heterogeneous databases, data integration, both conceptually and operationally, is a prime concern; this is a non issue for temporal middleware. More recently, there has been a great deal of work in the related area of mediators [GP98, Wie92, Wie95] and, more generally, on integration architectures. Roughly, a mediator offers a consistent data model and accessing mechanism to disparate data sources, many of which may not be traditional databases. As such, the focus is on 21 20 40 60 80 100 120 140 8K 17K 27K 36K 46K 55K 64K 74K 84K ....

G. Wiederhold. Mediation in Information Systems. ACM Computing Surveys, 27(2): 265--267 (1995).

....from the user s point of view. Underlying DBMS Stratum Error Result Temporal Statement SQL 92 Statement Code Generator Parser Scanner Output Processer Management Metadata Figure 1: The Stratum Architecture The stratum approach is similar in some ways to the related area of mediators [29, 30] and, more generally, of integration architectures. Broadly speaking, a mediator offers a consistent data model and accessing mechanism to a range of disparate data sources. The two approaches share an emphasis on interposing a layer, termed the mediator (also called a wrapper [19] that changes ....

G. Wiederhold. Mediation in Information Systems. ACM Computing Surveys 27(2):265--267, June 1995.

....user has to repeat the process with alternative input selections. To make matters worse, there is little commonality across WEB applications offering services in a domain. Any two applications in a given domain may use different terminology and interaction models for similar services. Mediation [9, 10, 14] is the integration of diverse and heterogeneous information sources by abstracting away the representation differences among them, and by integrating their individual views of the application domain into a common model. A mediator interacts with the users, translates the users requests into ....

G. Wiederhold. Mediation in Information Systems. ACM Computing Surveys. 27(2):265-267, June 1995.

....service providers and re divert to them the incoming service requests not implemented by the component. Regarding interoperability and interface adaptation, they try to find translators for the outgoing messages they handle, components with a similar functionality to Wiederhold s mediators [24]. Integrity. Controllers of this property check pre requisites on the component interface. Typical examples are user defined pre conditions on the incoming and outgoing messages, like control over their partial order or the time intervals between them, or the addition of security controls to the ....

G. Wiederhold, Mediation in information systems, ACM Comp. Surveys, 27 (June 1995) 265--267. 28

....(API) However, naive application partitioning can result in high maintenance costs and even a lack of openness if each client server pair has its own interface. As the number of clients n and the number of servers m expand, the number of potential relationships is of course n Theta m. Mediators [51] are a well known mechanism for reducing this interoperability problem. Mediators are used in the commonly used (and mentioned) three tiered architecture model in business applications of presentation logic, business rules, and database backend; this could be realized through a windows GUI, a ....

G. Wiederhold. Mediation in information systems. ACM Computing Surveys, 27(2), 1995. 35

....of the Data and Calculation Services (DCS) mediator product described here was to bring together six highly competitive firms to cooperate in providing decision support information to their customers while retaining autonomous control of proprietary data and analytic resources. Wiederhold [1][2] described mediators as an extra software layer to provide client applications with access to the integrated knowledge available from heterogeneous, autonomous data servers. The DCS mediator extended the definition to include computational resources as well as data sources. Context refers to the ....

G. Wiederhold, "Mediation in information systems," ACM Comp. Surveys vol. 27, no.2, June 1995, pp. 265-267.

....this property find available service providers and re divert to them the incoming service requests not implemented by the component. Regarding interoperability and interface adaptation, they try to find translators for the outgoing messages they handle, entities similar to Wiederhold s mediators [15]. Integrity: Controllers of this property check prerequisites on the component interface. Typical examples are user defined pre conditions on the incoming and outgoing messages, like control over their partial order or the time intervals between them, or de addition of security controls to the ....

G. Wiederhold. Mediation in Information Systems. ACM Computing Surveys, Vol.27, No.2, June 1995. 10

....closed environments by open solutions, characterised by different platforms, applications and databases that interoperate in real time. These solutions are found under several denominations: multidatabases (MDB) mediators, federated databases and interoperable systems [2] 4] 5] 16] [21]. They have the objective of preserving the existent systems, maintaining its autonomy, through solutions that possesses means to access and share the existing data. The extension of these solutions for GIS provides the effective sharing of geographic data. These solutions offer an environment ....

WIEDERHOLD, G., 1995, "Mediation in Information Systems", ACM Computing Surveys, v. 27, n.2 (Jun.), pp. 265-267

....property try to find available service providers and re divert to them the incoming service requests not implemented by the component. Regarding interoperability and interface adaptation, they try to find translators for the outgoing messages they handle, entities similar to Wiederhold s mediators [18] or to Yellin and Storm s adaptors [20] Mediation is a smart way to achieve evolutionary adaptation of interfaces, since it separates the controllers from the adapters themselves, improving the reusability of the controllers and the independent evolution of the adapters. The remainder of this ....

G. Wiederhold. Mediation in Information Systems. ACM Comp. Surveys, 27(2):265--267, June 1995.

....of the fixed income securities industry. The challenge of the DCS mediator was to bring together six highly competitive firms to cooperate in providing decision support information to their customers while retaining autonomous control of proprietary data and analytic resources. Wiederhold[1,2] described mediators as an extra software layer to provide client applications with access to the integrated knowledge available from heterogeneous, autonomous data servers. The DCS mediator extended the definition to include computational resources as well as data sources. Context refers to the ....

G. Wiederhold, "Mediation in information systems," ACM Comp. Surveys vol. 27, no.2, June 1995, pp. 265-267.

....but usually for identifying product sources rather than for fully executing the purchase. Some auction sites allow automatic bidding (e.g. Bidmaker at OnSale.com) This is a good starting point, but the technology is not ready for unattended operation. Wiederhold s projections about mediators [Wie95] suggest a starting point. Security Resource coalitions require authentication of identity, privacy of content, and integrity of certain parts of the resource information. The identity may be a link to a responsible agent, not necessarily to an identifiable human. Some resources exist, such as ....

Gio Wiederhold. Mediation in Information Systems. ACM Computing Surveys. 27(2):265267, June 1995.

....to the stratum, which then displays the result of the statement to the user. The user cannot see that the data is actually stored in a conventional DBMS the stratum encapsulates the DBMS from the user s point of view. The stratum approach is similar in some ways to the related area of mediators [27, 28] and, more generally, of integration architectures. Broadly speaking, a mediator offers a consistent data model and accessing mechanism to a range of disparate data sources. The two approaches share an emphasis on interposing a layer, termed the mediator (also called a wrapper [18] that changes ....

G. Wiederhold. Mediation in Information Systems. ACM Computing Surveys 27(2):265--267, June 1995.

....(API) However, naive application partitioning can result in high maintenance costs and even a lack of openness if each client server pair has its own interface. As the number of clients n and the number of servers m expand, the number of potential relationships is of course n Theta m. Mediators [6] are a well known mechanism for reducing this interoperability problem. Mediators are used in the commonly used (and mentioned) three tiered architecture model in business applications of presentation logic, business rules, and database backend; this could be realized through a windows GUI, a ....

G. Wiederhold. Mediation in information systems. Computing Surveys, 27(2), 1995.

....complexity. Clients and servers from different software platforms or programming languages can talk to each other through mediators (adapters) that convert data formats. Mediation in information systems as an organizing principle for interoperation of heterogeneous components is reviewed in [Wi]. Though mediators can handle a wide range of differences in data formats and recognized differences of representation, like that between Cartesian and polar coordinates, the general problem of reusing procedure functionality is unsolvable, since functional equivalence is undecidable. The two ....

Gio Wiederhold, Mediation in Information Systems, Computing Surveys, June 1995.

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G. Wiederhold. Mediation in information systems. ACM Computing Surveys (CSUR), 27(2):265--267, 1995.

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G. Wiederhold. Mediation in information systems. ACM Comput. Surv., 27(2):265--267, 1995.

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G. Wiederhold. Mediation in Information Systems. ACM Computing Surveys, 27(2): 265--267 (1995).

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Gio Wiederhold. Mediation in Information Systems. Computing Surveys, June 1995.

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