Mobile Cloud Computing for Providing Complex Mobile Web Services Feda AlShahwan College of Technological Studies, Public Authority for Applied Education, Kuwait fa.alShahwan@paaet.edu.kw Maha Faisal Faculty of Computer Engineering Department, Kuwait University, Kuwait maha.faisal@ku.edu.kw Abstract— Simple Web services can be provided directly from one mobile device acting as a server. However, complex services need a mobile cloud to provide computing resources and infrastructure to support seamless provision of its Web services in a light weight manner. Our approach focuses on the architecture of this mobile cloud, which consists of a set of collaborative mobile devices that relies on an Extended Mobile Host Complex Web service Framework (EMHCWF). The main building blocks of EMHCWF with their associated distributed mechanisms are defined and tested experimentally. Furthermore, the safety properties of mobile cloud infrastructure have been validated using formal methods that are based on process algebra. Keywords- decomposing mobile Web services; distributed mobile Web service provision; mobile cloud computing; orchestrating mobile Web services; RESTful-based mobile Web services; I. INTRODUCTION Mobile Web services (MWS) are self-contained modular applications that are defined, published and accessed across the Internet, in a mobile communications environment using standard protocols. This technology has evolved from advances in the mobile device technology, rapid growth of Web services development and progression of wireless communication in parallel with widespread use of Internet applications. Hosting Web services from mobile devices has a range of useful applications in most aspects of real life. For example, embedding Mobile Hosts (MHs) with Global Positioning System (GPS) receivers allows the tracking of the current location of a fleet, or on high value goods and their delivery. Another application area for mobile Web services is in the health care domain[10, 18]. Some of these location-based services require non-interrupted reliable provision from mobile devices to allow providing latest instant information before it becomes obsolete. For instance, providing the latest updated news and scene snapshots for a specific location in a predefined format requires portable devices with built-in GPS and cameras that are capable to move to the actual place of the event. Furthermore, it requires mobile hosts that are aware of their location to publish the event as a live feed and take latest information gathered at the current location. Mobile hosts allow processing of the gathered information and photos, and then make them available, instantly, to clients. Moreover, some of these services are more complex and demands heavy- weight process. Thus, a compensation for the limited resources of mobile hosts is needed in order to free some these resources for the mobile devices to perform its core functionality and enhance its performance. The aim of this approach is to allow using mobile cloud infrastructure to provide non-interrupted complex context- dependent mobile Web services in a light-weight processing manner. The main idea is to decompose complex services into several simple services and to distribute the simple services to different nodes in the cloud. The Mobile cloud consists of a set of collaborated mobile devices that share their resources and apply distributed mechanisms to facilitate providing compound services as a homogenous. The mobile cloud applies a workflow to manage the collaboration, which is described by a reduced Business Process Execution Language (BPEL) dialect. The structure of this mobile cloud and the associated workflow are defined in this paper. In addition the set of distributed mechanisms are investigated. The paper is organized as follows. First, a short introduction to the current state of the art for hosting Web services from mobile devices is presented. Also, some of the proposed solutions to compensate the limitations of mobile resources are highlighted. Then, a preface of mobile cloud computing with its associated applications is illustrated. After that a description of the mobile cloud architecture that allows the light-weight provision of complex context-based services is presented. The distributed mechanisms adopted with this system are also explored with the corresponding workflow. The proposed mobile cloud infrastructure is evaluated experimentally using a small test-bed prototype. Furthermore, the correct behavior of the proposed framework is verified by analytical study. Finally, conclusions on the findings of this work are presented. II. BACKGROUND AND RELATED WORK There has been extensive research into the development of frameworks for hosting simple mobile Web services. Most of the frameworks implemented are based on the Simple Object Access Protocol (SOAP) using either a centralized [4, 5, 15] or a non-centralized approach [7, 23]. Some research has focused on applying mechanisms that allow adaptation and compensation. Compensation is needed to counter the lack of mobile resources such as processing power, battery resources, etc. For example [4] and [3] propose a partitioning technique to execute complex mobile Web services. This partitioning mechanism allows the compensation for the lack of mobile processing