Business Process Management

All enterprises’ operations require integrating information, and processing information with applications. This has been true for decades, if not centuries. Information and application integration has evolved from completely person centered verbal communication (blacksmith to apprentice), through paper documents-mail-fax, email and Web page interactions. The information and applications control the flow of goods and operations on them.

These are the business processes of the economy.

Coming from vastly different starting points, the evolutionary paths of business designs and IT architectures are converging, in a striking example of convergent evolution. In some cases, enterprises are almost purely information processing businesses, e.g. insurance. The past few years have seen explosive growth in direct program-program interaction for application integration, removing manual steps to yield tremendous improvements in reliability and efficiency. Controlling the sequence of program interactions and information flow, and knowing the status of the flows, are fundamental to an enterprise’s functions. Automating, monitoring and optimizing the flow is the field of business process management. The past two years have seen the emergence of several architectural and standards based innovations. This paper, with a focus on the end-to-end model, provides a technical overview of the standards, architecture, programming and runtime models that make modern BPM possible.

The release of BizTalk Server 2006 in March, and the upcoming releases of Windows Workflow Foundation and BizTalk Server 2006 R2 are milestones in Microsoft’s BPM strategy. This talk is about how BizTalk Server and Windows Workflow Foundation work together, how Microsoft thinks about and supports BPEL, how Microsoft partners can add and are adding value to this picture, and how all these pieces combine to deliver a BPM solution.

This paper addresses the problem of analyzing the interaction between BPEL processes. We present a technology chain that starts out with a BPEL process and transforms it into a Petri net model. On the model we decide

controllability

of the process (the existence of a partner process, such that both can interact properly) and compute its

operating guideline

(a characterization of all properly interacting partner processes). A case study demonstrates the value of this technology chain.

Workflow monitoring is a routine function of a workflow manag-ement system for tracking the progress of running workflow instances. To keep participating organisations as autonomous entities in an inter-organisational business collaboration environment, however, it brings challenges in generating workflow tracking structures and manipulating instance correspondences between different participating organisations. Aiming to tackle these problems, this paper proposed a matrix based framework on the basis of our relative workflow model. This framework enables a participating organisation to derive tracking structures over its relative workflows and the involved relevant workflows of its partner organisations, and to perform workflow tracking with the generated tracking structures.

In the domain of Business Process Management and Workflow Management Systems, the log of work transactions executed has been found to be a useful artifact. The ideas, work, and literature on workflow mining have been primarily concerned with examining the workflow event log to rediscover control flow. Workflow mining has generally been defined as “the process of extracting a workflow model from a log of executions of activities”. In fact, most of the literature specifically and narrowly is concerned with rediscovering the precedence relations amongst activities. It is generally a hidden assumption that all activities are known a priori because they are listed by label in the workflow event log. In this position paper, we explore the possibility of removing this assumption, and thus performing

workflow discovery

rather than precedence rediscovery. Workflow discovery does not assume that process structure or even activities are known a priori and is concerned with discovering a wholistic perspective of workflow.

Workflow management systems are

people systems

that must be designed, deployed, and understood within their social and organizational contexts. Thus, we argue in this document that there is a need to expand the concept of workflow mining beyond the behavioral perspective to encompass the social, organizational, and activity assignment perspectives; as well as other perspectives. To this end, we introduce a general framework and meta-model for workflow discovery, and show one approach to workflow discovery in a multidimensional perspective.

The proliferation of services on the web is leading to the formation of service ecosystems wherein services interact with one another in ways not necessarily foreseen during their development or deployment. A key challenge in this setting is service mediation: the act of retrofitting existing services by intercepting, storing, transforming, and (re-)routing messages going into and out of these services so they can interact in unforeseen manners. This paper addresses a sub-problem of service mediation, namely service interface adaptation, that arises when the interface that a service provides does not match the interface that it is expected to provide in a given interaction. The paper focuses on reconciling mismatches between behavioural interfaces, i.e. interfaces that capture ordering constraints between interactions. It presents a declarative approach to service interface adaptation based on: (i) an algebra over behavioural interfaces; and (ii) a visual language that allows pairs of provided-required interfaces to be linked through algebraic expressions. These expressions are fed into an execution engine that intercepts, buffers, transforms and forwards messages to enact the adaptation logic.

Automated service composition is an important approach to automatically aggregate existing functionality. While different planning algorithms are applied in this area, heuristic search is currently not used. Lacking features like the creation of compositions with parallel or alternative control flow are preventing its application. The prospect of using heuristic search for composition with quality of service properties motivated the extension of existing heuristic search algorithms.

In this paper we present a heuristic search algorithm for automated service composition. Based on the requirements for automated service composition, shortcomings of existing algorithms are identified, and solutions for them presented.

Composition languages like BPEL and many enactment tools only support structured process models, while most composition approaches only consider unstructured models. In this paper, we outline a semi-automatic approach for composing a set of services with data flow dependencies into a structured process model. These data flow dependencies can be automatically derived from the input and output messages of each service, but some additional user input is needed to annotate dependencies with specific branching types. Heart of the approach is a fully automatic composition algorithm that given an annotated dependency graph constructs a structured composition. We illustrate the approach by applying it to an example case study from the CrossWork project, which studies the dynamic formation of cross-organisational workflows.

Current workflow languages for web services suffer from poor support for separation of concerns. Aspect-oriented software development is a well-known approach to improve this. In this paper, we present an aspect-oriented extension for the WS-BPEL language that improves on current state-of-the-art by introducing an explicit deployment construct, a richer joinpoint model, and a higher-level pointcut language. In addition, the supporting technology is compatible with existing WS-BPEL engines.

Classification.

Business process modeling and analysis, processes and service composition.

In various application domains there is a desire to compare process models, e.g., to relate an organization-specific process model to a reference model, to find a web service matching some desired service description, or to compare some normative process model with a process model discovered using process mining techniques. Although many researchers have worked on different notions of equivalence (e.g., trace equivalence, bisimulation, branching bisimulation, etc.), most of the existing notions are not very useful in this context. First of all, most equivalence notions result in a binary answer (i.e., two processes are equivalent or not). This is not very helpful, because, in real-life applications, one needs to differentiate between slightly different models and completely different models. Second, not all parts of a process model are equally important. There may be parts of the process model that are rarely activated while other parts are executed for most process instances. Clearly, these should be considered differently. To address these problems, this paper proposes a completely new way of comparing process models. Rather than directly comparing two models, the process models are compared with respect to some typical behavior. This way we are able to avoid the two problems. Although the results are presented in the context of Petri nets, the approach can be applied to any process modeling language with executable semantics.

Current approaches for proving the correctness of business processes focus on either soundness, weak soundness, or relaxed soundness. Soundness states that each activity should be on a path from the initial to the final activity, that after the final activity has been reached no other activities should become active, and that there are no unreachable activities. Relaxed soundness softens soundness by stating that each activity should be able to participate in the business process, whereas weak soundness allows unreachable activities. However, all these kinds of soundness are not satisfactory for processes containing discriminator, n-out-of-m-join or multiple instances without synchronization patterns that can leave running (lazy) activities behind. As these patterns occur in interacting business processes, we propose a solution based on lazy soundness. We utilize the

π

-calculus to discuss and implement reasoning on lazy soundness.

In this paper we examine the suitability of the Business Process Modelling Notation (BPMN) for business process modelling, using the Workflow Patterns as an evaluation framework. The Workflow Patterns are a collection of patterns developed for assessing control-flow, data and resource capabilities in the area of Process Aware Information Systems (PAISs). In doing so, we provide a comprehensive evaluation of the capabilities of BPMN, and its strengths and weaknesses when utilised for business process modelling. The analysis provided for BPMN is part of a larger effort aiming at an unbiased and vendor-independent survey of the suitability and the expressive power of some mainstream process modelling languages. It is a sequel to previous work in which languages including BPEL and UML Activity Diagrams were evaluated.

Very often, e.g. in the context of inter-organizational Workflow or web services, it is necessary to merge existing business process descriptions. It is clear that correctness criteria valid for the single process descriptions should remain valid also for the combined model. However, looking at the popular soundness criterion this can not always be guaranteed. In this paper various composition alternatives are summarized and their ability to preserve relaxed soundness (in contrast to soundness) is investigated.

Adaptivity in Process Management Systems (PMS) is key to their successful applicability in pratice. Approaches have already been developed to ensure the system correctness after arbitrary process changes at the syntactical level. However, still errors may be caused at the semantical level. Therefore, the integration of application knowledge will flag a milestone in the development of process management technology. In this paper, we introduce a framework for defining semantic constraints over processes in such a way that they can express real-world application knowledge. On the other hand, these constraints are still manageable concerning the effort for maintenance and semantic process verification. This can be used, for example, to detect semantic conflicts when applying process changes (e.g., drug incompatibilities). In order to enable the PMS to deal with such semantic conflicts we also introduce a notion of semantic correctness and discuss how to (efficiently) verify semantic correctness in the context of process changes.

A new generation of open

Business Process Management

(BPM) systems based on the service-oriented architecture and Web service technologies has recently emerged. The general tendency for these systems should be governed by the integration of independent Web-service specifications. Web services requirements guide the description, execution and choreography of business process and the implementation of frameworks for supporting the coordination, synchronization and creation of business transactions. However, a wide variety of open research issues related to the lack of maturity of the involved specifications makes the development of standard-based BPM systems difficult. In this paper we propose an abstract architecture inspired by Web service specifications to overcome these difficulties. Also, a particular implementation based on the

Nets-within-Nets

paradigm and the Renew tool is presented. The result is an executable infrastructure able to run business processes (their workflows and coordination protocols) as well as the horizontal protocols that guarantee a coherent outcome of their whole execution, such as the

WS-Atomic Transaction

protocol.

In this paper we study the use of case history for control structures in workflow processes. In particular we introduce a history-dependent join. History dependent control offers much more modeling power than classical control structures and it solves several semantical problems of industrial modeling frameworks. We study the modeling power by means of workflow patterns. Since proper completion (i.e. the ability of any configuration reachable from the initial one to reach the final one) is always an important ”sanity check” of process modeling, we introduce a modeling method that guarantees this property for the new control structures. Finally we consider an implementation of the proposed control structures on top of an existing workflow engine.

In recent years adaptive process management technolgy has emerged in order to increase the flexibility of business process implementations and to support process changes at different levels. Usually, respective systems log comprehensive information about changes, which can then be used for different purposes including process traceability, change reuse and process recovery. Therefore the adequate and efficient representation of change logs is a crucial task for adaptive process management systems. In this paper we show which information has to be (minimally) captured in process change logs and how it should be represented in a generic and efficient way. We discuss different design alternatives and show how to deal with noise in process change logs. Finally, we present an elegant and efficient implementation approach, which we applied in the ADEPT2 process management system. Altogether the presented concepts provide an important pillar for adaptive process management technology and emerging fields (e.g., process change mining).

Web services composition is an emerging paradigm for enabling application integration within and across organizational boundaries. Current Web services composition proposals, such as BPML, WSBPEL, WSCI, and OWL-S, provide solutions for describing the control and data flows in Web service composition. However, such proposals remain at the descriptive level, without providing any kind of mechanisms or tool support for analysis and verification. Therefore, there is a growing interest for the verification techniques which enable designers to test and repair design errors even before actual running of the service, or allow designers to detect erroneous properties and formally verify whether the service process design does have certain desired properties.

In this paper, we propose to verify Web services composition using an event driven approach. We assume Web services that are coordinated by a composition process expressed in WSBPEL and we use Event Calculus to specify the properties and requirements to be monitored.

E-service/process composition requires allocating suitable resources to a set of services that constitute a composite service/process. The problem is complicated due to undetermined constraints of each component service and unpredictable solutions contributed by service providers. It needs the ability to rapidly identify the suitable solutions as well as effectively coordinate them under various constraints. In this paper, an agent-mediated coordination framework for e-service/process composition is proposed. Each agent works as a broker for each service type, posting service constraints, searching suitable solutions and refining the constraints for achieving coherence among the decisions of each service. Based on the framework, a prototype of multi-agent supported e-supply chain composition is implemented. The experimental results indicate the significant effectiveness of the approach.

Electronic contracts describe inter-organizational business processes in terms of supply and consumption of electronic services (commonly Web services). In a given contract domain, it is usually possible to identify a set of well-defined common and variation points. Feature modeling is an ontology-like technique that has been widely used for capturing and managing commonalities and variabilities of product families in the context of software product line. This paper proposes a feature-based approach in order to decrease the complexity in Web service e-contract establishment. The feasibility of the approach is shown by a case study carried out within the telecom context and based on experimental software engineering concepts.

An important shortcoming in the Business Process Redesign (BPR) literature is the lack of concrete guidance on how to improve an existing business process. Our earlier work has aimed at filling this gap by identifying a set of BPR

best practices

. This paper takes a further step by showing how a set of best practices can be used to derive a redesign framework for a specific domain, in this case for

call centers

. Such a framework identifies the various available design options and specifies the relevant performance characteristics. To evaluate concrete design configurations (i.e., coherent combinations of design choices) we use a formal modelling approach based on Petri nets and the simulation tool CPN-Tools. An industrial case study is used to gather relevant context data. We expect that this work helps researchers and practitioners to optimize the performance of actual call centers and to set up similar frameworks for other domains.

The Internet has turned to be one the most common platform for the development of applications. In addition, sometimes the specification of these applications is given to web developers in the form of Business Processes (BP), and from this specification they are asked to develop the corresponding Web Application. In this situation, Web Engineering Methods should provide a way in which these specifications could be taken and be transformed into a Web Application that gives support to the process execution. Furthermore, when we are talking about B2B applications, we have to take into account that these BP usually involve the use of distributed functionality where different partners collaborate to accomplish an agreed goal. Therefore, in this work we provide a method for the automatic generation of Web Applications that give support to BP specifications. For this purpose, we generate from a BP definition the Navigation (web pages) and the WS-BPEL executable description that implements the entire process.

SOA, Service Oriented Architecture, some people tightly couple this concept with some technologies, as some believes that SOA is about Web Services and its orchestrations. SOA, is the umbrella of “Business Services” and “Enterprise Architecture”, meanwhile the technology evolves in the direction of building and sustaining both concepts; at early days it was tight to Enterprise Application Integration and vendor specific solutions, then Web Services and its orchestrations, and now Business Process Management is in the front with the WS-BPEL, WfMC-XPDL, ebXML-BP business integration open standards. However, Open Standards communities have helped a lot in understanding SOA concepts and building the base open standards for implementing SOA in right approaches, it is not providing an open solution implementation framework for SOA. This article proposes an Open Solution Business Process Integration and Management Implementation Framework based on technology open standards that we believe in its value for today and future. By this initiative article we are looking for examining and verifying this framework through SOA communities.

The Business Process Execution Language for Web Services (BPEL) has become a de-facto standard for executable process specifications. The broad industry acceptance of BPEL forces workflow and BPM system vendors to consider respective import and export interfaces. Yet, several existing systems utilize graph-based BPM languages such as EPCs, Workflow Nets, UML Activity Diagrams, and BPMN in their modeling component while BPEL is rather a block-oriented language inspired by process calculi. In this paper we identify transformation strategies as reusable solutions for mapping control flow between graph-based BPM tools and BPEL. Furthermore, we present a case study in which we have applied these strategies in an industry project. This case study shows that transformation strategies are helpful for implementing import and export interfaces in a systematic way, and that they can easily be extended to address vendor-specific aspects of a graph-based BPM tool.

Workflow management systems are very adequate for supporting the flow of work through enterprises, but do not deliver coordination support to end-users

within

the work items they perform. In this paper, the concept of

case management

is introduced, which specifically targets this type of support. Its associated technology is intended to be used as a harmonious extension of workflow technology, instead of a competing system. A discussion in some depth is presented of the concept, methods, and technology of case management, as well as experiences with its application in industry.

Car development is based on long running, concurrently executed and highly dependent processes. The coordination and synchronization of these processes has become a complex and error-prone task due to the increasing number of functions and embedded systems in modern cars. These systems realize advanced features by embedded software and enable the distribution of functionality as required, for example, by safety equipment. Different life cycle times of mechanical, software and hardware components as well as different duration of their development processes require efficient coordination. Furthermore, product-driven process structures, dynamic adaptation of these structures, and handling real-world exceptions result in challenging demands for any IT system. In this paper we elaborate fundamental requirements for the IT support of car development processes, taking release management as characteristic example. We show to which extent current product data and process management technology meets these requirements, and discuss which essential limitations still exist. This results in a number of fundamental challenges requiring new paradigms for the product-driven design, enactment and adaptation of processes.

The Service Component Architecture (SCA) is a new technology aiming to simplify application development in a service-oriented architecture. Developing a SCA application basically consists of two major parts: The implementation or discovery of individual components, and the assembly of sets of components. Since each assembly itself might act as a component within a larger application, SCA obviously enables the construction of complex distributed systems that are hardly analyzable. Hence crucial questions like compatibility, consistency or soundness of components need to be answered early during the development process. This paper presents

Wombat

– an analysis tool that is integrated into IBM’s development environment to perform on demand verification tasks.

Wombat

benefits from established formal methods for distributed systems. It tailors those methods to relevant use case and puts them into a context that directly supports the development of SCA applications.

When dealing with complex business processes (e.g., in the context of a workflow implementation or the configuration of some process-aware information system), it is important but sometimes difficult to determine whether a process contains any errors. The concepts such as cancellation and OR-joins occur naturally in business scenarios but the presence of these features in process models poses new challenges for verification. We take on the challenge of finding new verification techniques for workflows with cancellation regions and OR-joins. The proposed approach relies on reset nets and reachability analysis. We present these techniques in the context of workflow language YAWL that provides direct support for these features. We have extended the graphical editor of YAWL with these diagnostic features.

This paper presents a methodology for deriving business process descriptions based on terms in business contract. The aim is to assist process modellers in structuring collaborative interactions between parties, including their internal processes, to ensure contract-compliant behaviour. The methodology requires a formal model of contracts to facilitate process derivations and to form a basis for contract analysis tools and run-time process execution.

The current WS-BPEL specification is based on a textual description of the semantics of its constructs. This can raise some misunderstandings and difficults the development of tools for analysis and verification of WS-BPEL processes. To alleviate this lack, several groups have proposed formal models for WS-BPEL. Such models comprise more or less the full semantics in a tightly-coupled approach. We consider that WS-BPEL needs a more flexible fault handling model. This paper presents an executable model based on AsmL which allows to seamlessly add/modify behavior to implement new transaction models.

Exception handling is the process by which a failure in a process is mitigated. Depending on the specifics of an exception, exception handers – specifications of exception handling processes – may range from halting a process, through attempts of activity reactivation, to an identification of an alternative path to successful completion of a process. Designing efficient exception handlers is not a simple task. By their very nature, exceptions are rare events that may result in poor design of exception handlers in terms of cost and logic. In this work we aim at improving exception handling performance in workflow management systems (WfMSs), a task which has been recognized as a fundamental component of WfMSs that is critical to their successful deployment in real-world scenarios. Our approach is based on the observation that when designing a business process as a workflow, a designer has some degree of freedom in streamlining actions. Therefore, we propose process model restructuring as a main tool in reducing the cost of exception handling. We believe that restructuring of a process model, based on exception efficiency consideration, can increase the overall productivity of the business process. Although the rarity of exceptions allows amortizing their costs over time we cannot ignore exception costs altogether. Therefore, we propose a cost-based approach to prioritize their impact on the workflow design. Our main contribution is the provision of a methodology for exception handling optimization at the workflow design phase.

Cross-organizational business processes are gaining increased attention these days, especially with the service oriented architecture (SOA) as a realization for business process management (BPM). In SOA, interaction agreements between business partners are defined as choreographies containing common interaction patterns. However, complex interactions are difficult to specify, basically because a formal, common standard supporting all interaction patterns is missing. This paper motivates the use of the

π

-calculus for formally representing service interaction patterns.

Process-aware Information Systems typically log events (e.g., in transaction logs or audit trails) related to the actual business process executions. Proper analysis of these execution logs can yield important knowledge that can help organizations to improve the quality of their services. Starting from a process model, which can be discovered by conventional process mining algorithms, we analyze how data attributes influence the choices made in the process based on past process executions. Decision mining, also referred to as decision point analysis, aims at the detection of data dependencies that affect the routing of a case. In this paper we describe how machine learning techniques can be leveraged for this purpose, and we present a

Decision Miner

implemented within the ProM framework.

Many business solutions provide best practice process templates, both generic as well as for specific industry sectors. However, it is often the variance from template solutions that provide organizations with intellectual capital and competitive differentiation. In this paper, we present a modeling framework that is conducive to constrained variance, by supporting user driven process adaptations. The focus of the paper is on providing a means of utilizing the adaptations effectively for process improvement through effective management of the process variants repository (PVR). In particular, we will provide deliberations towards a facility to provide query functionality for PVR that is specifically targeted for effective search and retrieval of process variants.

We propose a meta framework architecture for supporting the behaviour based integration of two business processes. The meta level provides basic integration operators to the domain engineer to create integration options for specific domains. Based on semantic relationships between nodes of two business processes these integration options are executed and transform parts of the business processes. The outcome of the model transformation is an integrated business process. Because of the arbitrary combination of basic integration operators, a potentially infinite set of integration options may be applicable, and some of these may lead to an incorrect business process. We analyse our framework according to a set of consistency criteria and propose verification and validation mechanisms to keep the integrated model consistent.

Business Process Execution Language (BPEL), or Web Services BPEL (WS-BPEL), is the standard for specifying workflow process definition using web services. Research on formal modelling and verification of BPEL has largely concentrated on control flow and data flow, while security related properties have received little attention. In this work, we present a formal framework that integrates Role Based Access Control (RBAC) into BPEL and allows us to express authorisation constraints using temporal logic. Using this framework, we show how model-checking can be applied to verify that a given BPEL process satisfies the security constraints.

In grid workflow systems, existing representative checkpoint selection strategies, which are used to select checkpoints for verifying fixed-time constraints at run-time execution stage, often select some unnecessary checkpoints and ignore some necessary ones. Consequently, overall temporal verification efficiency and effectiveness can be severely impacted. In this paper, we propose a new strategy that selects only necessary and sufficient checkpoints dynamically along grid workflow execution. Specifically, we introduce a new concept of minimum time redundancy as a key reference value for checkpoint selection. We also investigate its relationships with fixed-time constraint consistency. Based on these relationships, we present our strategy which can improve overall temporal verification efficiency and effectiveness significantly.

Little is known about error probability in enterprise models as they are usually kept private. The

SAP reference model

is a publically available model that contains more than 600 non-trivial process models expressed in terms of

Event-driven Process Chains

(EPCs). We have automatically translated these EPCs into YAWL models and analyzed these models using WofYAWL, a verification tool based on Petri nets, in order to acquire knowledge about errors in large enterprise models. We discovered that

at least 34 of these EPCs contain errors

(i.e., at least 5.6% is flawed) and analyzed which parts of the SAP reference model contain most errors. This systematic analysis of the SAP reference model illustrates the need for verification tools such as WofYAWL.

The

Business Process Execution Language for Web Services

provides an technology to aggregate encapsulated functionalities for defining high-value Web services. For a distributed application in a B2B interaction, the partners simply need to expose their behavior as BPEL processes and compose them. Still, modeling and composing BPEL processes can be complex and error-prone. With formal methods like Petri nets, it is possible to analyze crucial properties (e.g. compatibility) effectively. In this paper, we present a method that automatically generates compatible partner BPEL processes for a given BPEL processes. Our hybrid approach makes use of formal methods, but also incorporates the structure of the original BPEL process model, such that the generated partner process is easier to understand and manage.

Dynamic assembly of complex software is possible through automated composition of web services. Coordination scripts identify and orchestrate a number of services to fulfil a user or business goal. There exists a need for expressing high level business requirements in such a way that is accessible by businesses. Current solutions fail to include specifications at the appropriate level of abstraction. Our approach defines a graphical notation to depict a business goal in terms of objectives, which are refined by tasks. The specifics of each task as well as overarching business constraints are expressed by policies.

This paper presents the concept of parameterized WS-flows and two extensions to the BPEL language for enabling it. Another major contribution is a prototypical infrastructure enacting the execution, monitoring and adaptation of parameterized BPEL processes. The advantages of parameterized BPEL processes are the improved flexibility and reusability.

This work is in line with the

CoopFlow

approach dedicated for workflow advertisement, interconnection, and cooperation in virtual organizations. In order to advertise workflows into a registry, we present in this paper a novel method to abstract behaviors of workflows into symbolic observation graphs (SOG). We present in addition an efficient algorithm for SOG matching, which is used for interconnecting workflows.

The paper entitled “Towards Formal Verification of Web Service Composition”, starting on page 257 of this publication, has been retracted. A significant part of the paper was copied from three pieces of work by the authors K. Mahbub and G. Spanoudakis. The pieces of work in question are:

A Framework for Requirements Monitoring of Service Based Systems

http://dx.doi.org/10.1145/1035167.1035181

Requirements Monitoring for Service-Based Systems: Towards a Framework Based on Event Calculus

http://dx.doi.org/10.1109/ASE.2004.1342769

A Scheme for Requirements Monitoring of Web Service Based Systems

http://www.soi.city.ac.uk/project/DOC_TechReport/TR_2004_DOC_02.pdf

Plagiarism was committed by the first author, Mohsen Rouached. The other authors were not aware of this.