Lianne Bodenstaff

Monitoring Dependencies for SLAs: The MoDe4SLA Approach

In service oriented computing different techniques for monitoring service level agreements (SLAs) are available. Many of these monitoring approaches focus on bilateral agreements between partners. However, when monitoring composite services it is not only important to figure out whether SLAs are violated, but we also need to analyze why these violations have occurred. When offering a composite service a company depends on its content providers to meet the service level they agreed upon. Due to these dependencies a company should not only monitor the SLA of the composite service, but also the SLAs of the services it depends on. By analyzing and monitoring the composite service in this way, causes for SLA violations can be easier found. In this paper we demonstrate how to analyze SLAs during development phase and how to monitor these dependencies using event logs during runtime. We call our approach MoDe4SLA (monitoring dependencies for SLAs).

Analyzing Impact Factors on Composite Services

Although Web services are intended for short term, ad hoc collaborations, in practice many Web service compositions are offered longterm to customers. While the Web services making up the composition may vary, the structure of the composition is rather fixed. For companies managing such Web service compositions, however, challenges arise which go far beyond simple bilateral contract monitoring. It is not only important to determine whether or not a component(i.e., Web service) in a composition is performing properly, but also to understand what the impact of its performance is on the overall service composition. In this paper we show which challenges emerge and we provide an approach on determining the impact each Web service has on the composition at runtime.

Value-Driven Coordination Process Design Using Physical Delivery Models

Current e-business technology enables the execution of increasingly complex coordination processes that link IT services of different companies. Successful design of cross-organizational coordination processes requires the mutual alignment of the coordination process with a commercial business case. There is however a large conceptual gap between a commercial business case and a coordination process. The business case is stated in terms of commercial transactions, but the coordination process consists of sequences, choices and iterations of actions of people and machines that are absent from a business case model; also, the cardinality of the connections and the frequency and duration of activities are different in both models. This paper proposes a coordination process design method that focusses on the the shared physical world underlying the business case and coordination process. In this physical world, physical deliveries take place that realize commercial transactions and that must be coordinated by a coordination process. Physical delivery models allow us to identify the relevant cardinality, frequency and duration properties so that we can design the coordination process to respect these properties. In the case studies we have done so far, a physical delivery model is the greatest common denominator that we needed to verify consistency between a business case and a coordination process model.

MaDe4IC: an abstract method for managing model dependencies in inter-organizational cooperations

Inter-organizational cooperations are complex in terms of coordination, agreements, and value creation for involved partners. When managing complex cooperations, it is vital to maintain models describing them. Changing one model to regain consistency with the running system might result in new inconsistencies. As a consequence, this maintenance phase grows in complexity with increasing number of models. In this context, challenges are to ensure consistency at design time and to monitor the system at runtime, i.e., at design time, consistency between different models describing the cooperation needs to be ensured. At runtime, behavior of the software system needs to be compared with its underlying models. In this paper, we propose a structured and model-independent method that supports ensuring and maintaining consistency between running system and underlying models for inter-organizational cooperations.

Dynamic consistency between value and coordination models – research issues

Inter-organizational business cooperations can be described from different viewpoints each fulfilling a specific purpose Since all viewpoints describe the same system they must not contradict each other, thus, must be consistent Consistency can be checked based on common semantic concepts of the different viewpoints This is sufficient for equal concepts, while weakly related concepts, e.g related to runtime behavior of viewpoints, have to be considered explicitly In this paper we identify dynamic consistency issues correlated to the runtime behavior between value and coordination viewpoints on behalf of an example In particular, an issue class on occurrence estimations of execution options and an issue class on granularity differences in modelling are identified and illustrated.

Managing dependency relations in inter-organizational models

In various fields like software development, information systems development, and e-business development, model-based approaches allow specifying different models of which each emphasizes one specific aspect or part of the software system. In this thesis we consider particularly model-based approaches for defining inter-organizational cooperations. These cooperations are usually complex in terms of coordination, agreements, and value creation for involved partners. At design time one should ensure that the different models are consistent with each other, i.e., that they describe the same system. At runtime we additionally have to deal with the fact that behavior of the software system might be different from that agreed upon. Such deviant behavior can, for example, be caused by partners in the cooperation that do not behave according to the agreement. Therefore, the challenges are to ensure consistency at design time as well as to monitor the system at runtime in order to detect inconsistencies with the models it relies on. When managing complex cooperations, it is also vital to maintain the models describing them to keep an overview on the successfulness of the cooperation. Changing one model to regain consistency with the running system might result in new inconsistencies between the different models. As a consequence, this maintenance phase of the models is time consuming and grows in complexity with increasing number of models describing the system. This thesis proposes a method that supports ensuring and maintaining consistency between running system and underlying models for inter-organizational cooperations. We provide a structured and model-independent approach to check and maintain consistency. Thereby, we focus on identifying and maintaining these inter-model relations. We validate our method by conducting two case studies in two different fields of research. The first scenario deals with business and coordination models, while the second one addresses Web service compositions. Furthermore, we provide a prototypical implementation as proof-of-concept evaluation of both scenarios. We conclude with an empirical validation of the Web service composition scenario by an extensive and interactive survey conducted among 34 participants. This survey confirms the suitability of our proposed management solution provided for real life use.

MONITORING SERVICE COMPOSITIONS IN MoDe4SLA - Design of Validation

In previous research we introduced the MoDe4SLA approach for monitoring service compositions. MoDe4SLA identifies complex dependencies between Service Level Agreements (SLAs) in a service composition. By explicating these dependencies, causes of SLA violations of a service might be explained by malfunctioning of the services it depends on. MoDe4SLA assists managers in identifying such causes. In this paper we discuss how to evaluate our approach concerning usefulness for the user as well as effectiveness for the business. Usefulness is evaluated by experts who are asked to manage simulated runs of service compositions using MoDe4SLA. Their opinion on the approach is an indicator for its usefulness. Effectiveness is evaluated by comparing runtime results of SLA management using MoDe4SLA with runtime results of unsupported management. Criteria for effectiveness are cost reduction and increase in customer satisfaction.

An Approach for Maintaining Models of an E-commerce Collaboration

To keep an overview on complex e-commerce collaborations several models are used to describe them. When models overlap in describing a collaboration, the overlapping information should not contradict. Models are of different nature and maintained by different people. Therefore, keeping model-overlap contradiction-free is challenging. In this paper we propose a novel approach for maintaining models representing an E-Commerce collaboration. Applying this approach supports avoiding contradictions in models during evolution of E-Commerce collaborations.

Representing and Validating Digital Business Processes

Today, the term extended enterprise (EE) is typically meant to designate any collection of organizations sharing a common set of goals. In this broad sense, an enterprise can be a whole corporation, a government organization, or a network of geographically distributed entities. EE applications support digitalization of traditional business processes, adding new processes enabled by e-business technologies (e.g. large scale Customer Relationship Management).

Empirical Validation of MoDe4SLA; Approach for Managing Service Compositions

For companies managing complex Web service compositions, challenges arise which go far beyond simple bilateral contract monitoring. For example, it is not only important to determine whether or not a component (i.e., Web service) in a composition is performing properly, but also to understand what the impact of its performance is on the overall service composition. To tackle this challenge, in previous work we developed MoDe4SLA which allows managing and monitoring dependencies between services in a composition. This paper empirically validates MoDe4SLA through an extensive and interactive experiment among 34 participants.