U. Dayl, M. Hsu, R. Ladin, A Transactional Model for Long-Running Activities, Proceedings of the VLDB Conference, 1991.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....debits are made from the account over the same period. Therefore, we may need to selectively relax the ACID properties for multisystem transactions to capture precisely the synchrony and coupling requirements based on the true application semantics. While relaxed or advanced transaction models [9, 10, 24, 28, 29] have been proposed, there is continuing debate whether they are appropriate to support multisystem workflow applications [34, 26] In any case, intertask dependencies provide a generic means to capture the constraints among tasks in a relaxed manner, independent of whether we follow a transaction ....

....briefly discusses the concurrency control, safety and recovery issues. A description of CTL and a rigorous proof of correctness of the scheduling algorithm are given in the appendices. 2. Background The specification and enforcement of intertask dependencies has recently received much attention [5, 9, 10, 22, 25]. Following [5] we specify intertask dependencies as constraints on the occurrence and temporal order of certain significant events. Klein has proposed the following two primitives [22] i) e 1 e 2 : If e 1 occurs, then e 2 must also occur. There is no implied ordering on the occurrences of e ....

U. Dayal, M. Hsu, and R. Ladin, "A Transactional Model for Long-running Activities," Proceedings of the 17th VLDB Conference, September 1991.

....to have some type of dependencies among them. # Lock mechanism reduces the throughput or concurrency. The longer the duration, the larger the reduction. To address the above problems, several extended transaction models [8,11] have been proposed, including Sagas [10] longrunning activities [5,6], ASSET [3] multi databases [9,16] and so on. Usually, they are called advanced transaction models (ATM) to distinguish from the traditional one. Many of these models are developed from a database point of view and are too databasecentric to provide adequate flexibility. In this paper, a ....

....applications or tools developed to support cooperations between users such as workflow management systems(WfMS) An activity or subtransaction in CovaTM may be reactivated after its submission. Therefore, activities of a transaction form a graph other than a tree like in long running activities [5,6]. Based on the description of the application, the run time system can guarantee the reliability of execution to its best. The rest of the paper is organized as follows. Section 2 presents a brief review of ATMs, which provide a solid base for developing new models. Then CovaTM model is described ....

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U. Dayal, M. Hsu and R. Ladin. A Transactional Model for Long-Running Activities, in proceedings of VLDB'91(Barcelona, September 1991), 113-122

....the flow of data between different modules. However, the specification of intertask control dependencies is somewhat restrictive since it is assumed that all leaf level tasks are transactional. Some important issues related to workflow models are addressed in the work on long running activities [11, 12]. A long running activity is modeled as a set of execution units that may consists of other activities or transactions. The ATM model (introduced in [12] and stands for Transaction Model for Activities) extends the nested transaction model and provides a language for describing long running ....

....leaf level tasks are transactional. Some important issues related to workflow models are addressed in the work on long running activities [11, 12] A long running activity is modeled as a set of execution units that may consists of other activities or transactions. The ATM model (introduced in [12] and stands for Transaction Model for Activities) extends the nested transaction model and provides a language for describing long running activities. The description includes a procedural static specification of the high level workflow, and rules for the dynamic evolution of the workflow. The ATM ....

U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-Running Activities. In Proceedings of the 17th VLDB Conference, September 1991.

....dependencies among transactions. ATM uses ECA rules to specify complex and parallel workflows. It is an interesting application for active rules. The original HiPAC execution model is well suited for advanced transaction models. ATM is a theoretical model without implementation. References: [DHL90], DHL91] 2.6 Cactis Cactis was developed at the University of Colorado by Hudson and King. It is an extended, object oriented DBMS, designed for CASE and VLSI design. It provides functionally described attributes, which are evaluated immediately, lazy or on demand. These mechanisms are not ....

....among transactions. ATM uses ECA rules to specify complex and parallel workflows. It is an interesting application for active rules. The original HiPAC execution model is well suited for advanced transaction models. ATM is a theoretical model without implementation. References: DHL90] DHL91] 2.6 Cactis Cactis was developed at the University of Colorado by Hudson and King. It is an extended, object oriented DBMS, designed for CASE and VLSI design. It provides functionally described attributes, which are evaluated immediately, lazy or on demand. These mechanisms are not explicitly ....

[Article contains additional citation context not shown here]

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proc. 17th Annotation: This paper introduces ATM and emphasizes on transaction management and briefly repeats

....dependencies among transactions. ATM uses ECA rules to specify complex and parallel workflows. It is an interesting application for active rules. The original HiPAC execution model is well suited for advanced transaction models. ATM is a theoretical model without implementation. References: [DHL90], DHL91] 2.5 Cactis Cactis was developed at the University of Colorado by Hudson and King. It is an extended, object oriented DBMS, designed for CASE and VLSI design. It provides functionally described attributes, which are evaluated immediately, lazy or on demand. These mechanisms are not ....

....among transactions. ATM uses ECA rules to specify complex and parallel workflows. It is an interesting application for active rules. The original HiPAC execution model is well suited for advanced transaction models. ATM is a theoretical model without implementation. References: DHL90] DHL91] 2.5 Cactis Cactis was developed at the University of Colorado by Hudson and King. It is an extended, object oriented DBMS, designed for CASE and VLSI design. It provides functionally described attributes, which are evaluated immediately, lazy or on demand. These mechanisms are not explicitly ....

[Article contains additional citation context not shown here]

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proc. 17th Annotation: This paper introduces ATM and emphasizes on transaction management and briefly repeats

....of the split operation. This is central to the idea of a Kangaroo Transaction. We thus feel that the split transaction concept can be used to capture the hopping nature of a mobile transaction. There are some similarities between our view of mobile transactions and workflow activity models [6,19,20]. A workflow is a set of related tasks which are executed to satisfy a business requirement. It has been argued that transaction and workflow models should be integrated into one architecture [1] In this article, it was pointed out that multidatabase transactions indicate how data operations can ....

U. Dayal, M. Hsu and R. Ladin, A transactional model for longrunning activities, in: Proceedings of the International Conference on Very Large Data Bases (1991).

....automatically and therefore the concepts of advanced transaction models cannot be applied directly. Major work in expanding advanced transaction models for workflow requirements was done in the area of transactional workflows (e.g. RS93, Hsu93, BDS 93] and long running activities (e.g. DHL91, WR92] Nevertheless, this work still is mainly influenced by a database point of view and therefore not direct applicable for workflow systems. Modern WFMSs have to support complex, long running business processes in a heterogeneous and or distributed environment. It has been pointed out in ....

U. Dayal, H. Hsu, and R. Ladin. A transactional model for long-running activities. In Proc. of the 17th Int. Conference on VLDBs, Barcelona, September 1991.

....of the split operation. This is central to the idea of a Kangaroo Transaction. We thus feel that the split transaction concept can be used to capture the hopping nature of a mobile transaction. There are some similarities between our view of mobile transactions and workflow activity models [6, 20, 21]. A workflow is a set of related tasks which are executed to satisfy a business requirement. It has been argued that transaction and workflow models should be integrated into one architecture [1] In this article, it was pointed out that multidatabase transactions indicate how data operations can ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the International Conference on Very Large Data Bases, 1991.

....user transactions and other events (such as method execution, time) are reported to the event detector. If a rule fires, the C A part may be executed as database transactions, if C and A contain database operations. Various transactions models for rule execution have been proposed [Cea89, HLM88, DHL91] that deal with the coupling and synchronization of user invoked transactions and system triggered rules. For example, the triggering and triggered transaction can be coupled as immediate, deferred and separate. In the immediate coupling mode the fired rule is executed immediately as a ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th International conference on very large databases, pages 113--122, 1991.

....in terms of transaction execution. Transaction failure is often localized within such models using retries and alternative actions. We use a similar approach to localize errors in ORBWork. A mechanism for dealing with errors in an ATM for long running activities was proposed in [DHL90, DHL91] It supported forward error recovery such that errors occurring in nonfatal transactions could be overcome by executing alternative transactions. The work on flexible transactions[ELLR90, ZNBB94] discusses the role of alternate transactions that can be executed without sacrificing the atomicity ....

U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-running Activities. In Proc. of the 17th. Intl. Conference on Very Large Data Bases, pages 113--122, Barcelona, Spain, September 1991.

....so that when a failure occurs, an application program rolls the task back to the last successful checkpoint. These task types may have some attributes such as CRITICAL, NON VITAL and CRITICAL NONVITAL. Critical tasks can not be compensated and the failure of a non vital task is ignored (Dayal and et.al. 1991, Chen and Dayal 1996) Besides these attributes, tasks can also have some properties like retriable, compensable, and undoable. A retriable task restarts execution depending on some condition when it fails. Compensation is used in undoing the visible effects of tasks after they are committed. ....

Dayal, U., Hsu M., and Ladin R., "A Transactional Model for Long-running Activities", in Proceedings of the 17th International Conference on Very Large Data Bases (VLDB'91), Barcelona 1991.

....not shared. Using this set of information systems is an ever changing set of enterprise wide operations. As business requirements change, new procedures are introduced and others become obsolete. Many of these procedures are composed of activities that manipulate information at different sites [2, 4, 12, 13]. While many of the tasks in these activities are automated, they are frequently invoked at different times and by different parts of the organization. In some cases, certain dependencies between the applications can be modeled and should be enforced [2, 33] In other cases, these applications can ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of 17th International Conference on Very Large Data Bases, August 1991. 23

....by the users themselves, not by the process guru . 3 The ADDD PSEE ADDD is a PSEE which integrates process technology and configuration management [Kobi93a, Kobi98a] Active process support is based on triggers. Triggers are eventcondition action rules, as known from active database systems [Daya91]. In section 3.1, we give a short introduction to the concepts of ADDD and its PML, called ALADYN. The rest of this section focuses on the user interface of ADDD. 3.1 Basic Concepts In ADDD, work is organized in a task hierarchy which can be extended dynamically. A task is a concrete piece of ....

Umeshwar Dayal, Meichun Hsu, and Rivka Ladin. "A transactional model for longrunning activities." In Proceedings of the 17th Conference on Very Large Databases. Morgan Kaufmann, September 1991.

....To demonstrate the usefulness of the proposed framework, we have applied this activity restructuring framework to a number of example applications drawn from the real world domains. See [14] for further detail. 4 Related Work and Conclusion Several activity models have been proposed [5, 4, 19] to support declarative specification of control flows within activities. Features of long running activities [5, 4] include an automatic compensation capability and the use of ECArules for monitoring activities. The cooperative model [19] A B C D E A B C D A B F G A B F E G A B C D ....

....to a number of example applications drawn from the real world domains. See [14] for further detail. 4 Related Work and Conclusion Several activity models have been proposed [5, 4, 19] to support declarative specification of control flows within activities. Features of long running activities [5, 4] include an automatic compensation capability and the use of ECArules for monitoring activities. The cooperative model [19] A B C D E A B C D A B F G A B F E G A B C D A B F C D A B C D E A B F E C D (a) AJoin(F, g, C, D) at leaf node (b) AJoin(F, g, C, D) at internal node ....

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U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th Very Large Databases, pages 113--122, 1991.

....Another feature supported by TAM is the promotion of enhanced intra activity parallelism by allowing an activity to be modified dynamically through the invocation of system supplied activity restructuring operations. In addition to our early proposal [13] other activity models have been proposed [8, 21] to support declarative specification of control flows within activities. Features of long running activities [8, 7] include an automatic compensation capability that offers some level of failure atomicity for the activity and the use of ECA rules for monitoring activities. The cooperative model ....

....be modified dynamically through the invocation of system supplied activity restructuring operations. In addition to our early proposal [13] other activity models have been proposed [8, 21] to support declarative specification of control flows within activities. Features of long running activities [8, 7] include an automatic compensation capability that offers some level of failure atomicity for the activity and the use of ECA rules for monitoring activities. The cooperative model [21] achieves cooperation by controlled data exchange of the content of workspaces and controlled sharing of a common ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th Very Large Databases, pages 113--122, 1991.

....bring a number of advantages, such as added concurrency, enhanced cooperation, and adaptive recovery, to the composable activity model for organizing cooperative activities in distributed and multi user design and computing environment. 4 Related Work Several activity models have been proposed [7, 6, 22] to support declarative specification of control flows within activities. Features of long running activities [7, 6] include an automatic compensation capability that offers some level of failure atomicity for the activity and the use of ECA rules for monitoring activities. The cooperative model ....

....activity model for organizing cooperative activities in distributed and multi user design and computing environment. 4 Related Work Several activity models have been proposed [7, 6, 22] to support declarative specification of control flows within activities. Features of long running activities [7, 6] include an automatic compensation capability that offers some level of failure atomicity for the activity and the use of ECA rules for monitoring activities. The cooperative model [22] achieves cooperation by controlled data exchange of the content of workspaces and controlled sharing of a common ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th Very Large Databases, pages 113--122, 1991.

....activity. The steps within a ConTract are forward recoverable. ConTracts provide relaxed isolation and atomicity so that it may be interrupted and re instantiated in the event of errors or failures. A mechanism for dealing with errors in an ATM for long running activities was proposed in [DHL90, DHL91] It supported forward error recovery, so that errors occurring in non fatal transactions could be overcome by executing alternative transactions. In [Wei93] the author suggests that semantic transaction concepts be merged with workflow concepts to promote workflow systems that are consistent ....

U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-running Activities. In Proc. of the 17th. Intl. Conference on Very Large Data Bases, pages 113--122, Barcelona, Spain, September 1991.

....continue. In addition to the relaxed isolation, ConTracts provide relaxed atomicity so that a ConTract may be interrupted and re instantiated. Workflow applications are typically long lived compared to database transactions. A workflow is seen as a Long Running Activity in [Dayal et al. 1990, Dayal et al. 1991] A Long Running Activity is modeled as a set of execution units that may consist recursively of other activities, or top level transactions (i.e. transactions that may spawn nested transactions) Control flow and data flow of an activity may be specified statically in the activity s script, or ....

....to the error thereby not requiring an undo operation. Therefore, the error handling semantics of traditional transactional processing systems are too rigid for workflow systems. A mechanism for dealing with errors in an ATM for long running activities was proposed in [Dayal et al. 1990, Dayal et al. 1991] It supported forward error recovery, so that errors occurring in non fatal transactions could be overcome by executing alternative transactions. Although, this model provides well defined constructs for defining alternative flow of execution in the event of errors, it is restrictive in terms of ....

Dayal, U., Hsu, M., and Ladin, R. (1991). A Transactional Model for Long-running Activities. In Proc. of the 17th. Intl. Conference on Very Large Data Bases, pages 113--122, Barcelona, Spain.

.... literature to relax some requirements of the traditional trans1 action model, such as atomicity or isolation, that may be too restrictive in a multidatabase environment [GS87, Elm92] The management of work flows and long running activities has been addressed, among others, in [Reu89, GGK 90, DHL91, Kle91] During a cooperative research project involving Bellcore and the University of Houston, a prototype transaction processing system based on an extended transaction model was developed. The system was then used to implement a telecommunication application that served as a testbed for the ....

U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-Running Activities. In Proceedings of the 17th VLDB, September 1991.

....the state of the ConTract must be restored and its execution may continue. In addition to the relaxed isolation, ConTracts provide relaxed atomicity so that a ConTract may be interrupted and re instantiated. Some issues related to workflows were addressed in the work on Long Running Activities [11, 12]. A Long Running Activity is modeled as a set of execution units that may consist recursively of other activities or (top) transactions (i.e. transactions that may spawn nested transactions) Control flow and data flow of an activity may be specified statically in the activity s script, or ....

....The dependencies may be enforced by checking relevant dependency automata. Other terms used in the database and related literature to refer to workflows are task flow, multi system applications [1] application multiactivities [34] networked applications [13] and long running activities [12]. Related topics are also discussed in the context of cooperative activities [35] or cooperative problem solving [7] 3 Specification of Workflows The following are key issues in specifying a workflow: ffl Task specification: The execution structure of each task is defined by providing a set of ....

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U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-Running Activities. In Proceedings of the 17th VLDB Conference, September 1991.

....The extensions allow the designer of a multitask activity to specify the data and control flow among tasks and to selectively choose transactional characteristics of the activity, based on its semantics. The work in this area has been influenced by the concept of long running activities [3]. Workflows discussed in this paper may be long running or not. Other related terms used in the database literature are task flow, multitransaction activities [7] multi system applications [1] application multiactivities, and networked applications [4] Some related issues are also addressed ....

....are used in the literature to refer to various scheduling preconditions. In the dynamic case, the task dependencies are created during the execution of a workflow, often by executing a set of rules. Examples of this kind of dependency specifications are found in long running activities [3] and polytransactions [12] The tasks of a workflow can communicate with each other through variables, local to the workflow and made persistent by the workflow system. These variables (including temporal variables) may also hold parameters for the task programs. The data flow between tasks is ....

U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-Running Activities. In Proceedings of the 17th VLDB Conference, September 1991.

....compensatable, retriable, or pivot, and at most one subtransaction can be pivot. In [ZNBB94] it was shown that this class can be extended by specifying global transactions as exible transactions. Flexible transaction models, such as ConTracts, Flex Transactions, S transactions, and others [DHL91, ELLR90, BDS 93] increase the failure resilience of global transactions by allowing alternate subtransactions to be executed when an LDBS fails or a subtransaction aborts. In a non exible transaction, a global subtransaction abort is followed either by a global transaction abort decision or ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. 17th VLDB Proceedings, pages 113-122, 1991.

....the ow of data between di erent modules. However, the speci cation of intertask control dependencies is somewhat restrictive since it is assumed that all leaf level tasks are transactional. Some important issues related to work ow models are addressed in the work on long running activities [11, 12]. A long running activity is modeled as a set of execution units that may consists of other activities or transactions. The ATM model (introduced in [12] and stands for Transaction Model for Activities) extends the nested transaction model and provides a language for describing long running ....

....leaf level tasks are transactional. Some important issues related to work ow models are addressed in the work on long running activities [11, 12] A long running activity is modeled as a set of execution units that may consists of other activities or transactions. The ATM model (introduced in [12] and stands for Transaction Model for Activities) extends the nested transaction model and provides a language for describing long running activities. The description includes a procedural static speci cation of the high level work ow, and rules for the dynamic evolution of the work ow. The ATM ....

U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-Running Activities. In Proceedings of the 17th VLDB Conference, September 1991.

....compensatable, retriable, or pivot, and at most one subtransaction can be pivot. In [ZNBB94] it was shown that this class can be extended by specifying global transactions as flexible transactions. Flexible transaction models, such as ConTracts, Flex Transactions, S transactions, and others [DHL91, ELLR90, BDS 93] increase the failure resilience of global transactions by allowing alternate subtransactions to be executed when an LDBS fails or a subtransaction aborts. In a non flexible transaction, a global subtransaction abort is followed either by a global transaction abort decision ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. 17th VLDB Proceedings, pages 113--122, 1991.

....state inaccurate, thus removing the conventional database safety net of resorting to the latest persistent state. This problem is handled in Section 4.2.1. The use of rules and the involvement of the designer as the initiator of events indicate the existence of long running activities [7]. Advanced transaction models, e.g. Nested transactions [26] and Split transactions [31] provide various mechanisms for minimizing the impact of vast and prolonged lockings in databases; therefore, these transaction models allow for the increase in the parallel execution of long running ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th VLDB, pages 113--122, Sep 1991.

....be applied to the workflow coordination model in [2] which has the nice theoretical property that one can analyze when it is safe to make changes. A second class of work, which usually deals with anticipated exceptions, involves so called advanced transaction models . From the seminal work in [17] to such recent papers as [23] and [35] this work has normally addressed issues such as failure recovery and co ordination between multiple workflows. Following the example of the wide project [13] we have chosen to separate these issues from the more local exceptional occurrences studied in ....

U. Dayal, M. Hsu, R. Ladin: "A Transactional Model for Long-Running Activities". Proc. VLDB'91: 113-122.

....among transactions. ATM uses ECA rules to specify complex and parallel workflows. It is an interesting application for active rules. The original HiPAC execution model is well suited for advanced transaction models. ATM is a theoretical model without implementation. References: DHL90] DHL91] Secondary: 2.5 Cactis Cactis was developed at the University of Colorado by Hudson and King. It is an extended, objectoriented DBMS, designed for CASE and VLSI design. It provides functionally described attributes, which are evaluated immediately, lazy or on demand. These mechanisms are not ....

.... of parameters for basic events, and context information for complex events are described in: References: CM93] Transactions The following papers address rule execution in the presence of regular transactions within the DBMS: References: BBKZ92] BBKZ93] BOGM92] CR90] CR93] DHL90] DHL91] DR93] GD93c] HLM88] IK93] SPAM91] WF90] ZB90] Rule Analysis In active database applications usually more than one rule is triggered at a time. Important aspects of rule execution are execution order, confluence and termination of rule execution. References: ACL91] AWH92] ....

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U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proc. 17th Int'l. Conf. on Very Large Data Bases, Barcelona, September 1991.

....the management of workflow applications are proposed in [25] Some further currently discussed transaction models can be found in [16] The transaction model [6] is dedicated to active DBMS and integrates the notion of compensating transactions and vital tasks. Some other suggestions are given in [13], where a relaxed transaction model for long running activities in an active DBMS is proposed. 3 Advanced Workflow Management and Time Aspects In several application domains of workflow management systems the supervision of firm deadlines is inevitable, e.g. for the medical treatment of ....

....of workflows, the scheduling problem shows some differences when compared with classical real time database systems. First, the (trans )actions performed by the active DBS are of rather long duration and must use a different transaction model than conventional transactions, see [12] and [13]. Secondly, we have a fuzzy predictability of the duration of individual tasks available from the designer of the workflow who collected this information during the modelling of the workflow. The designer usually associates estimations of a duration with each task. Sometimes, he also supplies a ....

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U. Dayal, M. Hsu, and R. Ladin. A transactional model for long--running activities. In Proc. Intl. Conf. on Very Large Data Bases, pages 113--122, Barcelona, Spain, 1991.

....sets (recall Section 2.3) of both the input activity of ASplit and its parent activity, the specialization type of the split, and the additional activity dependencies added through programmer guided split activities. 6 Comparison with Related Work Several activity models have been proposed [9, 8, 26] to support declarative specification of control flows within activities. Features of long running activities [9, 8] include an automatic compensation capability and the use of ECA rules for monitoring activities. The cooperative model [26] achieves cooperation through controlled data exchanges in ....

....the split, and the additional activity dependencies added through programmer guided split activities. 6 Comparison with Related Work Several activity models have been proposed [9, 8, 26] to support declarative specification of control flows within activities. Features of long running activities [9, 8] include an automatic compensation capability and the use of ECA rules for monitoring activities. The cooperative model [26] achieves cooperation through controlled data exchanges in private workspaces and controlled sharing of a common database among users. Although previous activity models ....

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U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th Very Large Databases, pages 113--122, 1991.

....global system is transferred to the user. Federated databases can also be implemented using tightly coupled systems, where a global conceptual schema is used to define the semantics of the global schema. Research in the workflow area has been influenced by the concepts of long running activities [11], multi system applications [1] polytrans multidatabases federated databases distributed databases heterogeneous databases workflows global information systems internet applications multi view systems NONE FULL LOCAL AUTONOMY HIGH LOW DATA STRUCTURE Figure 9. Distribution of information systems ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th VLDB, pages 113--122, Sep 1991.

....One of the main goals is to provide mechanisms for defining and controlling long lived activities, complex and concurrent computations, just like transactions in traditional DBMSs control short computations. During the last years several new interesting transactional workflow models and concepts [3, 4, 5] (see also subsection 2.1) have been introduced and some basic features of these models have also been integrated into our model. However, the main difference to this related work is that our model is much easier to work with as it does not require skilled programmers and it is more flexible ....

....Transactions Model [10] is based on the nested transaction model and has been proposed as a transaction model suitable for a multi database environment. Important issues related to transactional workflow models besides [8, 9, 10] for example, were addressed in the work of Long Running Activities [3], On Transactional Workflows [4] or The ConTract Model [5] In [3] a Long Running Activity consists recursively of multiple application steps each of which is either an activity or a (nested) transaction. Control flow and data flow of an activity may be specified statically in the activity s ....

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Dayal U., Hsu H., Ladin R.: A Transactional Model for Long-Running Activities. Proc. of the 17th Int. Conf. on VLDBs, Barcelona, Sept. 1991.

....are further discussed in [BSW88, Ga83, HW91, LKS91, MGG86, MR91, WHBM90, Wei91] in the extended OODBS context of this paper, recovery issues are not yet addressed. It seems fairly natural to view the method invocation hierarchy of an OODBS transaction as an open nested transaction (cf. also [BM91, DHL91, RGN90]) A concurrent execution of two transactions from the order entry example of Section 2 is shown in Figure 4. The ordering of actions is from left to right; note that some of the non leaf actions are concurrent (i.e. their descendants are interleaved) The example execution is semantically ....

Dayal, U., Hsu, M., Ladin, R., A Transactional Model for Long-Running Activities, VLDB Conf., 1991

....used to support views, procedures, and integrity constraints. Research on constraints using active object oriented databases includes: KDM88] where an extended trigger mechanism is described for the DAMASCUS system) DBM88, CBB 89] introducing E,C,A rules in the HIPAC system) DHL90, DHL91] where rules are studied in the context of long running activities, where the action may be postponed) NQZ90] using rules to help semantic modelling on GemStone) UD89, UD90, UKN92] where rules are used to maintain constraints, and an algorithm is proposed to detect rule cycles) MP91a, ....

U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-Running Activities. In Proceedings 17th VLDB, pages 113--122, 1991.

....ranges from using (and possibly extending) standard specification methods such as Petri net variants to specifically designed languages. Work in the first category includes [KS91, EN93, OSS94] the language approach is pursued, for example, in [BDMQ95, FKB95] In addition, some approaches such as [BMR94, KLRR95, DHL91, RS94] are based on Event Condition Action rules (ECA rules) as used in active database systems [WD94] for describing the control flow between activities. We are not aware of any other project that is based on state transition machines like the state chart method. Most of the research on ....

U. Dayal, M. Hsu, R. Ladin, A Transactional Model for Long--Running Activities, VLDB Conference, 24

....times conform to these norms. In general, in the current corporate environment, it is vital for organizations to adapt to its ever changing requirements. Such adaptation often requires the re engineering of its business processes. The notions of workflows and workflow management have been proposed [2, 15, 19] as a general means to model, analyze and re engineer business processes. While workflow management has been successfully applied to several different application domains (see section 2 below for references) a general, application independent framework for managing workflows remains to be ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th International Conference on VLDB, 1991.

....and (b) a script or execution plan: a (possibly parallel) program invoking the steps that defines the structural aspects of the ConTract. ConTracts are forward recoverable through failures and interruptions. A long running activity is a set of transactions (possibly nested) and other activities [Dayal et al. 1991]. Control and data flow may be specified in a script or with event condition action rules. Other important models include flex transactions [Bukhres et al. 1993] cooperating transactions [Nodine, 1993] splitand join transactions [Kaiser Pu, 1992] and cooperating activities [Rusinkiewicz ....

Dayal, U.; Hsu, M.; and Ladin, R.; 1991. A transactional model for long-running activities. In Proceedings of the 17th International Conference on Very Large Data Bases.

....ranges from using (and possibly extending) standard specification methods such as Petri net variants to specifically designed languages. Work in the first category includes [KS91, EN93, OSS94] the language approach is pursued, for example, in [BDMQ95, FKB95] In addition, some approaches such as [BMR94, DHL91, RS94] are based on Event Condition Action rules (ECA rules) as used in active database systems [WD94] for describing the control flow between activities. Finally, simple state transition diagrams are employed in [ASSR93, KS95] to specify limited forms of intertask dependencies. However, we are not ....

U. Dayal, M. Hsu, R. Ladin, A Transactional Model for Long--Running Activities, VLDB Conference, 1991

....idea might be of interest also for workflows. Transaction Specification and Management Environment (TSME) GHM 93, GHKM94, GH94] is a complete approach directed towards workflows. As an implementation technique for transactional and other features the ECA model is of interest [DBM88, DHL90, DHL91] and as a specification environment ACTA [CR90, CR91, CR92, CR94] There have been some projects, prototypes and products, where transactional features are addressed, notably the work related to the (further) development of IBM FlowMark [LA94, LR94] done in Exotica project [MAGK95, MAA 95, ....

Umeshwar Dayal, Meichum Hsu, and Rivka Ladin. A transactional model for longrunning activities. In Proceedings of the 17th International Conference on VLDB, Barcelona, Spain, Sep 1991.

....task does return successfully, the function did commit( in the task program is used to determine whether the contract committed or aborted. 6 Related Work We first discuss work in the literature related to workflow activity models [10] These include active database and rule based approaches [7, 8], multidatabase and relaxed extended transaction model based approaches [14, 1, 15] and office and process automation based approaches [17, 23, 24] Somewhat less relevant are the many proposals for multi level and nested transaction models [30] A perspective on combining workflow and ....

....specification of intertask control dependencies is limited, and it is assumed that all the leaf level tasks are transactional. We have adopted a similar data transfer specification in WFSL, but have extended the model to include different task structures and more complex control dependencies. In [7, 8], the ATM extended nested transaction model and language is presented for describing long running activities. Such a description includes a procedural static specification of the high level workflow, and rules (triggers) for the dynamic evolution of the workflow. The WFSL language, is however, ....

U. Dayal, M. Hsu, and R. Ladin. A Transactional Model for Long-Running Activities. In Proc. of the 17th VLDB Conference, September 1991.

....even if the global transaction eventually aborts. The requirements of local database system autonomy place the execution of the local transactions completely out of the control of the GTM. Flexible transaction models, such as ConTracts, Flex Transactions, S transactions, and others [DHL91, ELLR90, BDS 93] increase the failure resiliency of global transactions by allowing alternate subtransactions to be executed when an LDBS fails or a subtransaction aborts. In a nonflexible transaction, a global subtransaction abort is followed either by a global transaction abort decision or ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. 17th VLDB Proceedings, pages 113--122, 1991.

....transaction dependencies, serializability, breakpoints, successions, recoverability. 1. Introduction The need for introducing extended transaction models (ETMs) to support various application requirements has been recognized for some time and numerous ETMs have been proposed, including [19,29,23,10,15,11,13,12,21,14,20]. ETMs extend the traditional (ACID) transaction model to allow: i) nested transaction structure and or transaction grouping, and (ii) use of new correctness criteria for permitting functionality necessary for advanced applications, improving transaction throughput, and or dealing with the ....

.... 22 June ETMs proposed to allow advanced application functionality (e.g. permit transaction cooperation) and improve throughput (e.g. reduce transaction blocking and abortion caused by transaction synchronization) relax the atomicity and isolation properties of the ACID transaction model [19,29, 23,15, 11,12,5,14,20]. However, many of these extensions resulted in application specific ETMs offering adequate correctness guarantees in a particular application, but not others. Furthermore, an ETM may impose unacceptable restrictions in one application but these same restrictions may be required by another. For ....

U. Dayal, M. Hsu, and R. Ladin, A Transactional Model for Long-Running Activities, Proceedings of the 17th International Conference on VLDB, 1991.

.... Based on the work on multidatabase systems there are also interesting research activities in defining general purpose work flow languages [14] Important issues related to transactional workflow models besides [10, 11, 12] for example, were addressed in the work of Long Running Activities [15], On Transactional Workflows [5] or The ConTract Model [16] In [15] a Long Running Activity consists recursively of multiple application steps each of which is either an activity or a (nested) transaction. Control flow and data flow of an activity may be specified statically in the activity s ....

.... research activities in defining general purpose work flow languages [14] Important issues related to transactional workflow models besides [10, 11, 12] for example, were addressed in the work of Long Running Activities [15] On Transactional Workflows [5] or The ConTract Model [16] In [15] a Long Running Activity consists recursively of multiple application steps each of which is either an activity or a (nested) transaction. Control flow and data flow of an activity may be specified statically in the activity s script or dynamically by ECA rules. The model includes compensation, ....

Dayal U., Hsu H., Ladin R.: A Transactional Model for Long-Running Activities. Proc. of the 17th Int. Conf. on VLDBs, Barcelona, Sept. 1991.

....exception management; The Local Transaction Manager (LTM) modules is responsible for middle level transaction management on the individual supertask level. Specifically, it controls the isolation and atomicity property within the boundaries of a supertask, based on a nested transaction concept [DHL91] The LTM module uses the transactional mechanisms of the underlying database management system, and is therefore located in the WIDE interface layer. WIDE 33 7. Example The enrollment WF handles the volunteer enrollment procedure of a military office. The candidate being examined fills in an ....

Dayal, U., Hsu, M., Ladin, R., A Transactional Model for Long-Running Activities, Proc. 17th International Conference on Very Large Databases, Barcelona, Spain, 1991.

....automatically and therefore the concepts of advanced transaction models cannot be applied directly. Major work in expanding advanced transaction models for workflow requirements was done in the area of transactional workflows (e.g. RS93, Hsu93, BDS 93] and long running activities (e.g. DHL91, WR92] Nevertheless, this work still is mainly influenced by a database point of view and therefore not direct applicable for workflow systems. Modern WFMSs have to support complex, long running business processes in a heterogeneous and or distributed environment. It has been pointed out in ....

U. Dayal, H. Hsu, and R. Ladin. A Transactional Model for Long-Running Activities. In Proc. of the 17th Int. Conference on VLDBs, Barcelona, September 1991.

No context found.

U. Dayal and M. Hsu and R. Ladin, "A Transactional Model for long Running Activities", Proc. VLDB'91, 1991.

No context found.

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long running activities. In Proceedings of the Seventh International ConferenceonVery Large Data Bases, 113# 122, 1991.

....for run time system integration, and supports dynamic service construction, modification and movement. A prototype has been developed at HP Labs and made available to several external research groups. 1 Introduction Distributed problem solving is characterized by decentralization and cooperation[18, 5, 4, 12]. By decentralization wemean that the task is handled by multiple distributed autonomous agents without global control. By cooperation we mean that the task is accomplished by those agents through information exchange and task sharing as no one agent has sufficient information to solve the entire ....

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long running activities. In Proc. VLDB'91, 1991.

No context found.

U. Dayl, M. Hsu, R. Ladin, A Transactional Model for Long-Running Activities, Proceedings of the VLDB Conference, 1991.

No context found.

U. Dayal and M. Hsu and R. Ladin, "A Transactional Model for long Running Activities", Proc. VLDB'91, 1991.

No context found.

U. Dayal, M. Hsu, and R. Ladin. A transactional model for long-running activities. In Proceedings of the 17th VLDB Conference, September 1991.

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