In a service-oriented architecture, adaptive and evolvable applications should be able to select, configure and compose different existing application services to deal with the changes which can arise from runtime contextual changes or the change of user requirements and preferences. To support this, hybrid service composition approaches have been proposed, in which the core of application logic, which is rather stable, is specified in terms of processes while rules are employed to specify the conditions and constraints to adapt the application behaviour. The rules are then exposed as a decision service which can be employed by the process to make adaptation decision with respect to runtime circumstances. The interaction between processes and decision services are generally performed in synchronous request-response manner. We argue that such an interaction is not efficient to support different types of adaptation at runtime and therefore asynchronous interaction should also be supported. In this paper, we present an adaptive service provisioning architecture and a decision service template allowing both synchronous request-response interaction and asynchronous notification. To motivate the proposed architecture and the decision service template, we use a blood pressure monitoring scenario from the homecare domain. We also explain the implementation of the proposed approach based on commercially available rule and process engines. Finally, we discuss: 1) what is the efficient way (synchronous request-response interaction vs. asynchronous notification) of calling decision service to execute different types of decision rules? and 2) to what extent the use of decision service facilitates dealing with the unforeseen changes?

The realization of homecare services is difficult because of dynamicity requirements and constraints that exist in this domain. These requirements call for a dynamic service provisioning, i.e., adaptivity and adaptability of the (composition of) homecare services in response to a) frequently occurring changes like change in the location or vital signs, or b) slowly developing changes like extent of impairments of a care-receiver. In this paper, we explain our understanding of a dynamic service provisioning platform, its requirements and constraints. As such, we design an architecture based on an existing hybrid service provisioning approach (a combination of process and rule) and related architectural patterns. Then, we implement this approach using the commercially available process and rule engines. We demonstrate how a homecare application can be deployed, executed and how the application can adapt itself to the frequently occurring changes at runtime. We also demonstrated how a care-giver can modify the behaviour of the application to adapt the slowly occurring changes. Finally, we discuss the pros and cons of the approach and explain our future plan.

Dynamicity is one of the main challenges in providing sustainable solutions for the homecare domain. The dynamicity of homecare systems, caused by external entities like care-receivers and care-givers, can be addressed through combining distributed and heterogenous services both in design and runtime. In general, several research fields such as dynamic service composition, context-aware service composition and dynamic configuration contribute to provide solutions to handle the dynamicity. However, the dynamicity requirements and constrains in homecare domain demands its own solutions. In this paper, we explain our understanding of a homecare provisioning platform and its external entities which interact with the platform. Based on our application scenario and literature study, we identify different types of changes which are imposed by the external entities. Moreover, the characteristics of the external entities, which need to be taken into account to address the dynamicity, are discussed. Then, we study the existing dynamic service composition approaches to see their feasibility for the homecare domain. Finally, we explain our motivation for choosing a hybrid service composition approach as our basis for the homecare provisioning platform with respect to the identified changes and characteristics coming from the external entities.

In this paper we consider service-oriented applications composed of component services provided by different, economically independent service providers. As in all composite applications, the component services are composed and configured to meet requirements for the composite application. However, in a field experiment of composite service-oriented applications wef found that, although the services as actually delivered by the service providers meet their requirements, there is still a mismatch across service providers due to unstated assumptions, and that this mismatch causes an incorrect composite application to be delivered to end-users. Identifying and analyzing these initially unstated assumptions turns requirements engineering for service-oriented applications into risk analysis.In this paper, we describe a field experiment with an experimental service-oriented homecare system, in which unexpected behavior of the system turned up unstated assumptions about the contributing service providers. We then present an assumptions-driven risk identification method that can help identifying these risks, and we show how we applied this method in the second iteration of the field experiment. The method adapts some techniques from problem frame diagrams to identify relevant assumptions on service providers. The method is informal, and takes the "view from nowhere" in that it does not result in a specification of the component services, but for every component service delivers a set of assumptions that the service must satisfy in order to contribute to the overall system requirements. We end the paper with a discussion of generalizability of this method.

In most of the industrialized countries, the aging of the population dramatically progress rapidly. This trend demands economically feasible solutions to provide care to elderly, preferably at their home. IT can play an important enabling role in such solutions. Previously, we proposed an approach for personalizing IT-based homecare services by introducing a tailoring process. The tailoring process allows to create personalized services for elderly with various needs. The outcome of a service tailoring process is a so called service plan, which represents a composite service tailored to the specific needs of a specific elderly (the 'care-receiver') as understood by the person responsible for deciding on the care activities (the 'care-giver'). The service plan is created based on a treatment pattern that corresponds to the homecare task for which automated support is needed. In this paper, we elaborate on the idea of pattern-based service tailoring. First, we briefly introduce the architecture of the tailoring platform and identified common homecare tasks via interview with the care-givers. Then, we zoom in on how we established two important aids for creating a service plan, namely the treatment patterns and the abstractions of devices and applications that can be deployed in the automated support. We give examples of both patterns and abstractions, and discuss how these can be used in creating a tailored service plan.