G.E. Kaiser, "Cooperative Transactions for Multiuser Environments, " Modem Database Systems, W. Kim, ed., pp. 409-433, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....as an access filter upon all repository accesses, so called transparent versioning. Finally, the work performed by one user (or a group thereof) may be embedded in a transaction. Throughout this paper, the term transaction will primarily refer to cooperative, long lasting transactions [21] [22], which may be associated to change requests or change sets. We will not focus on classical short ACID transactions ( ACID stands for atomicity, consistency, isolation, and durability; see [23] Each transaction owns a subdatabase, which contains a part of the overall versioned database. ....

G.E. Kaiser, "Cooperative Transactions for Multiuser Environments, " Modem Database Systems, W. Kim, ed., pp. 409-433, 1995.

....serves as an access filter upon 411 repository accesses, so called transparent vetstoning. Finally, the work performed by one user (or a group thereof) may be embedded in a transaction. Throughout this paper, the term transaction will always refer to co operative, long lasting transactions [21] [22], which may be associated to change requests or change sets. We will ignore classical short ACID transactions completely ( ACID stands for atomJetty, consistency, isolation, and durability; see [23] Each transaction owns a subdatabase, which contains a part of the overall versioned database. ....

Gail E. Kaiser, "Cooperative transactions for multiuser envi- ronments," in Modern Database Systems, Won Kim, Ed., pp. 409-433. Addison Wesley, Reading, Massachusetts, 1995.

....the context of different semantic relations. Keywords: cooperative transactions, semantic transaction processing 3 i Introduction New application areas of the transaction concept, like CAD, CASE, or groupware applications like cooperative authoring impose new requirements on transaction models [Kai95, Kor95]. In all of these non standard database applications there is a need to sup port the collaboration of human actors engaged in common tasks and working towards a common goal. A transaction model supporting cooperative applications should make the sharing and exchange of information among ....

.... to shared data in a more or less ad hoc manner using user controlled locking, different lock modes, and notifications [WL93, TW95] Like CSCW systems, most of the approaches in the CAD domain are based on an intuitive model of interaction and do not explicitly address cooperation among co workers [Kai95]. Semantics based transaction processing techniques seem to be a promising approach to overcome concurrency limitations of traditional transaction models [SS84, Wei88, F)89, WS92, MRW 93, WC95] These techniques exploit either the semantics of meth ods defined on objects (data oriented ....

[Article contains additional citation context not shown here]

G.E. Kaiser. Cooperative transactions for multiuser environments. In Kim [Kim95], chap- ter 20, pages 409-433.

....the safety and consistency requirements. 2.5. 2 TransactionShells It is apparent that a wide range of transactional behaviours are useful in different applications [Bancilhon et al. 85, Garcia Molina and Salem 87, Pu et al. 88, Chrysanthis and Ramamritham 91, Kaiser and Pu 92, Gray and Reuter 93, Kaiser and Pu 95] The support for transactions in PJava is an experiment to test whether a wide range of these transactions can be made available by providing a small set of primitives that can be composed to achieve the transactional behaviours. The logical properties of these compositions have already been ....

G.E. Kaiser and C. Pu. Cooperative Transaction for Multiuser Environments. chapter 20, pages 409--433, in W. Kim, editor. Modem Database System -- The Object Model, Interoperability and Beyond. Addison Wesley/ACM Press, 1995.

....serves as an access lter upon all repository accesses, so called transparent versioning. Finally, the work performed by one user (or a group thereof) may be embedded in a transaction. Throughout this paper, the term transaction will primarily refer to cooperative, long lasting transactions [21] [22], which may be associated to change requests or change sets. We will not focus on classical short ACID transactions ( ACID stands for atomicity, consistency, isolation, and durability; see [23] Each transaction owns a subdatabase, which contains a part of the overall versioned database. ....

Gail E. Kaiser, \Cooperative transactions for multiuser environments, " in Modern Database Systems, Won Kim, Ed., pp. 409-433. Addison Wesley, Reading, Massachusetts, 1995.

....the user must manually checkin the data item back to the global repository. Some systems, notably NSE [61] and BiiN [97] provide tools that aid in merging multiple parallel versions to the same data. The checkout model can hinder cooperation since each user works separately in isolation [63]. Extensions to this technology include hierarchical workspaces and checkout across multiple workspaces (such as Infuse [66] 2.2.2 Concurrency Control Mechanisms Some multi user environments offer no concurrency control, either because there is no database (i.e. all data is simply stored on ....

Gail E. Kaiser. Cooperative Transactions for Multi-User Environments. In Won Kim, editor, Modern Database Systems: The Object Model, Interoperability, and Beyond, chapter 20, pages 409--433. ACM Press, New York NY, 1994.

....the context of different semantic relations. Keywords: cooperative transactions, semantic transaction processing 1 Introduction New application areas of the transaction concept, like CAD, CASE, or groupware applications like cooperative authoring impose new requirements on transaction models [Kai95, Kor95] In all of these non standard database applications there is a need to support the collaboration of human actors engaged in common tasks and working towards a common goal. A transaction model supporting cooperative applications should make the sharing and exchange of information among ....

.... to shared data in a more or less ad hoc manner using user controlled locking, different lock modes, and notifications [WL93, TW95] Like CSCW systems, most of the approaches in the CAD domain are based on an intuitive model of interaction and do not explicitly address cooperation among co workers [Kai95] Semantics based transaction processing techniques seem to be a promising approach to overcome concurrency limitations of traditional transaction models [SS84, Wei88, F O89, WS92, MRW 93, WC95] These techniques exploit either the semantics of methods defined on objects (data oriented ....

[Article contains additional citation context not shown here]

G. E. Kaiser. Cooperative transactions for multiuser environments. In Kim [Kim95], chapter 20, pages 409--433.

....between users and discuss our cooperation mechanism in the context of different semantic relations. 1 Introduction Modern application areas of the transaction concept, such as CAD, CASE, or groupware applications like cooperative authoring impose new requirements on transaction models [Kai95, Kor95] In all of these non standard database applications there is a need to support the collaboration of human actors engaged in common tasks and working towards a common goal. A transaction model supporting cooperative applications should make the sharing and exchange of information among ....

.... to shared data in a more or less ad hoc manner using user controlled locking, different lock modes, and notifications [WL93, TW95] Like CSCW systems, most of the approaches in the CAD domain are based on an intuitive model of interaction and do not explicitly address cooperation among co workers [Kai95] Semantics based transaction processing techniques [SS84, Wei88, F O89, WS92, MRW 93, WC95] seem to be a promising approach to overcome concurrency limitations of traditional transaction models. These techniques exploit either the semantics of methods defined on objects (data oriented ....

[Article contains additional citation context not shown here]

G. E. Kaiser. Cooperative transactions for multiuser environments. In Kim [Kim95], chapter 20, pages 409--433.

....models in general are guaranteeing fault tolerance and synchronize concurrent access to shared persistent data. To support cooperative applications, several advanced transaction models have been proposed in the recent years. For an overview of these models we refer the reader to [Elm92, Hsu93, Kai95] A general approach to support cooperation is to divide the database in public and private areas [KW84, LP83] Objects are copied from the public database by check out into private areas. When the transaction is finished the modified objects are checked in into the public database. Check out ....

....transaction into two new (serial or independent) transactions while a joinoperations allows to incorporate two transactions into a new transaction. These mechanisms enable a cooperative behaviour by exchanging parts of transactions between concurrent users. The participant transaction model [Kai95] defines each transaction as a participant in a specified domain. The domain represents the set of user transactions controlled by users collaborating on a common task. Participant transactions in the same domain need not to be serializable. Only transactions of different domains have to be ....

[Article contains additional citation context not shown here]

G. E. Kaiser. Cooperative transactions for multiuser environments. In Kim [Kim95], chapter 20, pages 409--433.

....2 The Cooperative Activity Model In this section, we first give an overview of the COACT model. In the following, we describe the concept of history merging in more detail. 2. 1 Overview of CoAct In general, cooperative work is characterized by alternating periods of individual and joint work [1, 29, 15]. During individual work periods, users try out alternative problem solutions while co workers may work simultaneously on the same subject. Access to and use of shared data should nei ################# ################# ################# ####### ....

G. E. Kaiser. Cooperative transactions for multiuser environments. In Kim [16], chapter 20, pages 409--433.

....Activity Model In this section, we first give an overview of the COACT model. In the following, we describe the concept of history merging in more detail. 2. 1 Overview of CoAct In general, cooperative work is characterized by alternating periods of individual and joint work [AKT 96, TW95, Kai95] During individual work periods, users try out alternative problem solutions while co workers may work simultaneously on the same subject. Access to and use of shared data should neither block other users nor should it affect co workers unintendedly. During joint work, co workers should be able ....

G. E. Kaiser. Cooperative transactions for multiuser environments. In Kim

....safety and consistency requirements. 2.5. 2 TransactionShells It is apparent that a wide range of transactional behaviours are useful in different applications [Bancilhon et al. 85, Garcia Molina and Salem 87, Pu et al. 88, Chrysanthis and Ramamritham 91, Kaiser and Pu 92, Gray and Reuter 93, Kaiser and Pu 95] The support for transactions in PJava is an experiment to test whether a wide range of these transactions can be made available by providing a small set of primitives that can be composed to achieve the transactional behaviours. The logical properties of these compositions have already been ....

G.E. Kaiser and C. Pu. Cooperative Transaction for Multiuser Environments. chapter 20, pages 409--433, in W. Kim, editor. Modern Database System -- The Object Model, Interoperability and Beyond. Addison Wesley/ ACM Press, 1995.

.... Integrated Publication and Information Systems Institute (GMD IPSI) Dolivostra e 15, D 64293 Darmstadt, Germany http: www.darmstadt.gmd.de waesch Introduction New application areas, such as CAD, CASE, cooperative authoring, or mobile computing, impose new requirements on a transaction model [6, 8, 5]. Transactions in such environments need to support interactive activities of long duration, in which competition for resources is replaced by the need to cooperate. The emphasis, therefore, is not on preventing access to resources, but rather on the interoperation, i.e. the semantically ....

.... Most approaches found in the CSCW area synchronize cooperative access to shared data in a more or less ad hoc manner [8] Like CSCW systems, most of the approaches in the CAD domain are based on an intuitive model of interaction and do not explicitly address cooperation among co workers [6]. For an overview of extended transaction models that address (more or less) multi user cooperation we refer the reader to [3] The CoAct model In [7] we have proposed the CoAct model which provides a framework for cooperative activities in interactive, multi user environments. In CoAct each ....

G. E. Kaiser. Cooperative transactions for multiuser environments. In W. Kim, editor, Modern Database Systems: The Object Model, Interoperability, and beyond, chapter 20, pages 409--433. Addison-Wesley Publishing Company, 1995.

....the ACID model comes with a scheduling discipline, namely, serializability, the newer extended transaction models do not typically have as clear a scheduling approach associated with them. This has led to calls for generic facilities for specifying and scheduling extended transaction models, e.g. [Kaiser, 1994, pp. 428 429] Contributions We present an approach through which workflows can be efficiently scheduled in a distributed manner. We base our approach on an algebra of events that we previously developed for representing and reasoning about intertask dependencies. 1 Formal specifications ....

....e.g. when they require an infinitely many events to be triggered because of a single event occurrence. Determining the safe sublanguages is a problem we leave to future research. 8 Overview of the Literature Several extended transaction models have been proposed [Barghouti Kaiser, 1991; Kaiser, 1994; Elmagarmid, 1992] These are typically nested but open in that results of subtransactions are visible before the global activity terminates. Sagas are c flMunindar P. Singh 48 12 September composed of several subtransactions or steps [Garcia Molina Salem, 1987] which can be optimistically ....

Kaiser, Gail E.; 1994. Cooperative transactions for multi-user environments. In [Kim, 1994]. Chapter 20.

....applicable in various fields beyond CSCW systems, e.g. in the area of mobile computing to manage disconnected operation. 1 Introduction New application areas, such as CAD, CASE, design for manufacturing, cooperative authoring, or mobile computing, impose new requirements on a transaction model [16, 31, 32, 2, 15]. Transactions in such environments need to support interactive activities of long duration, in which competition for resources (on which the locking protocols are based) is replaced by the need to cooperate. The emphasis, therefore, is not on preventing access to resources, but rather on the ....

....cooperate only via the common workspace. However, we decided to provide this option since it allows a (dynamically determined) subset of users to cooperate. The design rationale for CoAct s computational model is that a major part of work within a cooperation is done in isolation by the co workers [16, 32, 31]. Users try out alternative problem solutions while other co workers are working simultaneously on the same subjects. Access to and use of shared objects should neither block other users work nor should updates on objects affect co workers immediately (if this is not intended) Another reason is ....

[Article contains additional citation context not shown here]

G. E. Kaiser. Cooperative transactions for multiuser environments. In W. Kim, editor, Modern Database Systems: The Object Model, Interoperability, and beyond, chapter 20, pages 409--433. Addison-Wesley Publishing Company, 1995.

....Transactions Figure 1: Cooperative Transaction Manager 3. Transactional Cooperative Model Advanced applications like CAD CAM or CASE require long duration transactions, interactive user control and cooperation on partial results among transactions in order to bypass serializability constraint [Kais95, BaKa91]. The meta model ACTA introduces a formalism to define such new 4 extended transaction models and provides tools to characterize structure and behavior of transactions. The toolkit ASSET [BDGJR94] is a first step in providing ACTA based services to developers. A designer can freely create ....

....spheres can be used to add SCD and AD dependencies in order to emulate various transaction models, as pictured in Figure 3. Note: Abort Sphere : Commit Sphere Tp Tc Tp Tc Tp Tc Tp Tc Distributed Closed Nested Open Nested (e.g, OSI TP92] e.g, Moss85] e.g. WeSh92, GaSa87] Cooperative (e. g, [Kais95]) SCD Flexibility SCD AD AD Flat Transaction vital non vital contingency compensating and Model data sharing Environment (e.g, BeHG87] T Figure 3: Model Generality 6 3.2 Workspaces Management Cooperative environments where transactions act more as partners than as concurrent require new ....

[Article contains additional citation context not shown here]

Kaiser G., Cooperative Transactions for Multiuser Environments, in W. Kim (Ed.), Modern Database System - The Object Model, Interoperability, and Beyond, Addison Wesley, ACM Press, 1995.

....models. Transaction models guarantee fault tolerance and synchronise concurrent access to shared persistent data. To support cooperative applications, several advanced transaction models have been proposed in the recent years. For an overview of these models we refer the reader to [Elm92, Hsu93, Kai95] A general approach to supporting cooperation is to divide the database into public and private areas [KW84, LP83] Objects are then copied from the public database by check out into private areas. When a transaction is finished, the modified objects are checked in into the public database. ....

.... facilities The Cooperative Activity Model (COACT) comprises the core of the TRANSCOOP transaction model [RKT 95, WK96, KTW96b] The model builds on the observation stated in Section 2 that cooperative work is characterised by alternating periods of individual and joint work [TV95, TW95, Kai95] During individual work periods, users try out alternative problem solutions while coworkers may work simultaneously on the same subject. Access to and use of shared data should neither block other users, nor should it affect co workers unintendedly. During joint work, co workers should be able ....

G. E. Kaiser. Cooperative transactions for multiuser environments. In Kim [Kim95], chapter 20, pages 409--433.

.... paradigm addresses long duration and open ended activities, but is weak on collaboration since user tasks are performed in a private workspace; version merging, notification, group workspaces, and other work arounds that attempt to extend checkout to collaborative work are discussed elsewhere [17]. SDE applications probably require what are sometimes termed cooperative transactions . A variety of collaborative concurrency control mechanisms have been proposed in the literature; see [3] for a survey. In general, cooperative transactions make it possible to guarantee atomicity (rollback ....

Gail E. Kaiser. Cooperative transactions for multi-user environments. In Won Kim, editor, Modern Database Systems: The Object Model, Interoperability, and Beyond. ACM Press, New York NY, 1994. In press.

.... allows multiple writers of the object containing the edited file attribute(s) this is achieved in Oz by defining and loading application specific concurrency control policies, written in a notation [32] that permits definition of extended transaction models including cooperative transactions [35]. Concurrency control, per se, is not in the strictest sense part of the wrapping facility, but is nevertheless essential in order to fully integrate this class of tools. Further discussion of this topic is outside the scope of this paper. 6. Related Work As we pointed out in the previous ....

Gail E. Kaiser. Cooperative transactions for multi-user environments. In Won Kim, editor, Modern Database Systems: The Object Model, Interoperability, and Beyond, chapter 20, pages 409--433. ACM Press, New York NY, 1994.

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#22# Gail E. Kaiser. Cooperative transactions for multi-user environments. In Won Kim, editor, Modern Database Systems: The Object Model, Interoperability, and Beyond,chapter 20, pages

.... to support a concurrency control policy that allows multiple writers of the object containing the edited file (this is achieved in Oz by defining and loading application specific concurrency control policies, written in a notation [16] that permits definition of cooperative transactions [19]) Concurrency control, per se, is not in the strictest sense a part of the wrapping facility, but is nevertheless essential in order to fully integrate this class of tools. 6. Contributions and Future Work We have fully implemented all the facilities discussed in this paper, except as noted in ....

Gail E. Kaiser. Cooperative transactions for multi-user environments. In Won Kim, editor, Modern Database Systems: The Object Model, Interoperability, and Beyond, chapter 20, pages 409--433. ACM Press, New York NY, 1994.

....the TM and the task manager. If the TM cannot suspend transactions, for example, the administrator writing these cord rules must refrain from using this action in cord rules or add this functionality to the TM. The most novel feature of cord is its ability to dynamically restructure transactions [21]; the operations split ( T, subset) and join ( T1, T2) effect this behavior. To provide a framework for reasoning about such restructuring, we developed the Prefix Continuation (P C) transaction model [18] cord is simply a realization of this model. P C views each transaction as having a ....

....operate on private copies of data that are checked out from a repository. The only contention for shared objects occurs when a transaction checks in out an object. We view checkout, versions, and configurations as the domain of the application rather than something to be imposed by the TM. See [21] for a survey of extended checkout models. 8 Contributions and Future Work Advanced database applications use databases to store information but they require more sophisticated concurrency control policies than standard DBMSs provide. Fortunately, such applications contain semantic information ....

Gail E. Kaiser. Cooperative transactions for multi-user environments. In Won Kim, editor, Modern Database Systems: The Object Model, Interoperability, and Beyond, chapter 20, pages 409--433. ACM Press, New York NY, 1994.

.... following the checkout model , there is little concept of transactions 2 , with either the classical atomicity, consistency, isolation and durability properties, or permitting relaxations proposed for long duration, interactive, and or cooperative work [22, 18] The first author argues in [32] why the checkout model is less attractive for collaborative efforts than the emerging variety of cooperative transaction models. Concurrency control of some sort is a key requirement for managing concurrent access to shared information. Both collaborative and solo work involve more than browsing ....

Gail E. Kaiser. Cooperative transactions for multi-user environments. In Won Kim, editor, Modern Database Systems: The Object Model, Interoperability, and Beyond, chapter 20, pages 409--433. ACM Press, New York NY, 1994. ftp://ftp.psl.cs.columbia.edu/pub/psl/CUCS-006-93.ps.Z.

....PCE implementation, probably more expensive) to whatever format is needed. It does not seem to matter much whether the task was previously posted, or the notification only informs the history manager, except that if it was previously posted it is reasonable to assume some kind of checkout model [33] whereby the SubEnv indicates that it intends to perform a given task and then acquires the data and other resources it needs to perform the work; later a checkin is achieved via the notification. An alternative to checkout is that the first (or last) notification wins, with respect to what ....

Gail E. Kaiser. Cooperative transactions for multi-user environments. In Won Kim, editor, Modern Database Systems: The Object Model, Interoperability, and Beyond, chapter 20, pages 409--433. ACM Press, New York NY, 1994.

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G. E. Kaiser. Cooperative transactions for multiuser environments. In Kim 29 , chapter 20, pages 409--433.

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