FESC: Functionally Equivalent Service Composition

Abstract

In the last few decades, researchers have focused on developing smart environment applications. In a smart environment, different kinds of smart devices are continuously working to make the lives of the inhabitants more comfortable. Smart environments are dynamic with respect to the context of user and availability of devices and services. A challenging problem is to satisfy a user’s request in case a service is unavailable in such environments. In this paper, we develop a novel method that provides a functionally equivalent service corresponding to an unavailable service. A knowledge-based system using a meta-reasoner tree is used to obtain a functionally equivalent service. The proposed approach is validated using a smart cooking system.

Introduction

Recent technological advances in handheld devices, sensors, and communication networks have transformed the vision of pervasive systems (made in the early 1990s [1]) into a reality today. Pervasive systems are embedded with a context-aware component that automatically senses and adapts itself to the changes in the environment without user intervention. These systems assist the users by composing the services according to the context. There exist several state-of-the-art context-aware systems such as Anamika [2], Scooby [3], and AUTO [4].

“Context is any information that can be used to characterize the situation of an entity. An entity is a person, place, object, or environment that is considered relevant to the interaction between a user and an application, including the user and applications themselves [5] (pp. 3).” Context-awareness means that the system is able to use context information. “A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user’s task [5] (pp. 6).”

It has been marked in recent years that user requests have become complex. Due to the complexity of user’s request, a single service is not enough to satisfy the request. Therefore, a set of services are composed to meet the user’s request, and this process is called service composition [2], [3], [6], [7]. The service composition system takes a user’s request as input and provides a composed service as output. For instance, a travel planner system takes the customer’s request, i.e., get a package which includes the itinerary travel ticket to a destination location and hotel accommodation. To satisfy the request, different services such as transport service, hotel service, and bank service are composed.

In this paper we consider a context-aware setting where an unavailable service is replaced by an equivalent service. One way to replace a service by another is by considering the structure (input-output) of a service [8]. If a replacement cannot be found, a user request cannot be satisfied. One way to address this situation is to relax the user request and then come up with a composed service that satisfies the original user request partially [9]. We wish to give a complete satisfaction of a user request by identifying services that have similar function. The process of automatically deciding if two services have similar functions is a very challenging task, in general. Thus, we assume that there is a meta-reasoner that can decide if two services are equivalent or not. Equivalent services are referred to as functionally equivalent services in this paper; informally meaning that the function of the services are same.

According to the service paradigm, everything is modeled as a service, including hardware devices, network resources, a piece of computation, and even a human being [10]. In order to demonstrate the applicability of functionally equivalent services, a smart cooking system, SmartChef, is developed. which has the potential to recommend an alternative in case a required ingredient is unavailable. The system monitors the availability of the ingredients and suggests an alternative ingredient, from the available ingredients, in case a required ingredient becomes unavailable.

The contributions of the paper are summarized as:

• A context-aware functionally equivalent service composition approach.

• Validation of the proposed approach on a smart cooking system.

The rest of the paper is structured as follows: Section 2 presents the related work. Section 3 presents the proposed approach. The experimental results are given in Section 4. Section 5 provides some conclusions.