Decentralizing execution of composite web services

Abstract

Distributed enterprise applications today are increasingly being built from services available over the web. A unit of functionality in this framework is a web service, a software application that exposes a set of "typed'' connections that can be accessed over the web using standard protocols. These units can then be composed into a <i>composite</i> web service. BPEL (Business Process Execution Language) is a high-level distributed programming language for creating composite web services. Although a BPEL program invokes services distributed over several servers, the <i>orchestration</i> of these services is typically under centralized control. Because performance and throughput are major concerns in enterprise applications, it is important to remove the inefficiencies introduced by the centralized control. In a distributed, or decentralized orchestration, the BPEL program is partitioned into independent sub-programs that interact with each other without any centralized control. Decentralization can increase parallelism and reduce the amount of network traffic required for an application. This paper presents a technique to partition a composite web service written as a single BPEL program into an equivalent set of decentralized processes. It gives a new code partitioning algorithm to partition a BPEL program represented as a program dependence graph, with the goal of minimizing communication costs and maximizing the <i>throughput</i> of multiple concurrent instances of the input program. In contrast, much of the past work on dependence-based partitioning and scheduling seeks to minimize the <i>completion time</i> of a single instance of a program running in isolation. The paper also gives a cost model to estimate the throughput of a given code partition.

A systematic literature review of service choreography adaptation

“…Service orchestration refers to a service composition paradigm in which services are controlled in a centralized manner [53]. A single entity known as the orchestrator is responsible for managing and coordinating the whole composition execution flow.…”

“…Since service choreographies do not rely on a single party to coordinate the business processes, some authors claim that they are more scalable than orchestrations [35,53,57,58]. Nanda et al [53], for example, presents an algorithm to automatically generate a set of distributed processes given a single BPEL process as input, and provides experimental results showing improvements on the throughput when services interact without the central coordinator.…”

Optimized decentralization of composite web services

“…Nanda et al [15][5] present an approach to partition BPEL processes using program partitioning techniques with the aim of reducing the communication costs between the partitions. However, they do not take into account distribution constraints (Collocate and Separate) so the designer cannot control the partitioning.…”

Reference Architectural Styles for Service-Oriented Computing

“…P2P composition can be classified into three substyles, namely (1) Static, (2) Mobile, (3) Hybrid. .In the Static Composition Style (P2PC-S) style [37] [38] [39], [40], the overall process specification (e.g. BPEL4WS 2 ) is, at design-time, partitioned into smaller pieces and deployed to involved service providers and during run-time each local engine only obtains the partial copy of the whole process, and finally executes it at the local site where the invoked service resides.…”