Abstract: Embodiments herein provide a fault-handling scheme based on forward recovery for cooperative workflow environments. The fault handling scheme relies on the correct placement of transaction scopes and their associated fault and compensation handlers for maintaining correct application semantics, a fault propagation scheme for forwarding faults to a workflow component that has the corresponding fault handler, and a distributed mechanism for collecting data of completed workflow components to facilitate recovering from faults. The fault handling scheme makes use of control flow messages to facilitate compensation of nested transaction scopes (residing in different components). The workflow components are also modified with additional code for aiding with fault propagation and fault recovery.

Abstract: Decentralized orchestration of composite services results in a number of flow topologies which differ in their messaging patterns and the distribution of flow code amongst different partitions of a topology. Different performance metrics result for different topologies, and this is governed by the availability of resources, such as CPU cycles, memory, network bandwidth, and so on. A performance model is used to evaluate the performance of different topologies based on availability of resources, and dynamically direct client requests between different topologies according to prevailing conditions.

Abstract: In an ASP server farm, requests to use an application are directed to a particular executing instance of the application (or an appropriate component thereof) that is identified as being the least loaded of the available such instances of the application or its component. The number of such instances is dynamically increased or decreased in response to the number of requests for the application or components thereof. Requests may be directed (in accordance with the first aspect) or the instances adjusted (in accordance with a second aspect) on a per client-basis, in which instances of the application and/or components thereof are reserved for the use of a user or a particular group of users. Operation in this manner facilitates compliance with service agreements with respective users or groups of users.

Abstract: A technique for orchestrating composite web services in a constrained data flow environment. Data flow constraints represent the restrictions which the domains involved in composition might want to impose on access to the data they provide or the source from which they can accept data. The data flow constraints are overcome by breaking down an input composite web service specification into topologies (a topology is a set of partitions communicatively connected with one another at runtime). The system applies a rule-based filtering mechanism to choose a topology that does not violate any data flow constraints. Each of the partitions belonging to the chosen topology is executed within the same domain as the corresponding web service it invokes, thus having the same access rights as the corresponding web service. The composite web service is orchestrated in a decentralized fashion using these partitions, thereby ensuring that no data flow constraints are violated.

Abstract: Disclosed are methods, apparatus and computer programs for improving performance and resource utilization of cluster-based data processing systems. The number of persistent connections between first and second data processing units of a system is adjusted according to monitored performance of communications between the nodes. The monitored performance measure is the queuing delay between the nodes, and the number of connections is increased and decreased as changing load conditions increase and decrease the queuing delay. A method of establishing and closing persistent connections in response to a monitored queuing-delay between a front-end gateway computer and each of a cluster of back-end servers is used to improve the performance of a cluster-based Web server or provision of Web services. Unwanted connections are closed to enable system resources to be allocated to other processes.

Abstract: In an ASP server farm, requests to use an application are directed to a particular executing instance of the application (or an appropriate component thereof) that is identified as being the least loaded of the available such instances of the application or its component. The number of such instances is dynamically increased or decreased in response to the number of requests for the application or components thereof. Requests may be directed (in accordance with the first aspect) or the instances adjusted (in accordance with a second aspect) on a per client-basis, in which instances of the application and/or components thereof are reserved for the use of a user or a particular group of users. Operation in this manner facilitates compliance with service agreements with respective users or groups of users.