Young-Il Choi

Generating test cases for web services using extended finite state machine

Web services utilize a standard communication infrastructure such as XML and SOAP to communicate through the Internet. Even though Web services are becoming more and more widespread as an emerging technology, it is hard to test Web services because they are distributed applications with numerous aspects of runtime behavior that are different from typical applications. This paper presents a new approach to testing Web services based on EFSM (Extended Finite State Machine). WSDL (Web Services Description Language) file alone does not provide dynamic behavior information. This problem can be overcome by augmenting it with a behavior specification of the service. Rather than domain partitioning or perturbation techniques, we choose EFSM because Web services have control flow as well as data flow like communication protocols. By appending this formal model of EFSM to standard WSDL, we can generate a set of test cases which has a better test coverage than other methods. Moreover, a procedure for deriving an EFSM model from WSDL specification is provided to help a service provider augment the EFSM model describing dynamic behaviors of the Web service. To show the efficacy of our approach, we applied our approach to Parlay-X Web services. In this way, we can test Web services with greater confidence in potential fault detection.

An Integrated Data Model and a Query Language for Content-Based Retrieval of Video

As video data have been used in multimedia information systems, the need for the database support that provides an efficient way for users to retrieve video data is growing. In this paper, we propose a video data model that integrates feature based model and annotation based model for the purpose of improving content-based retrieval of video data. The proposed video data can act as a generic video data model for multimedia applications, and support free annotations, image features, and structure information of video data within the same framework. The proposed video query language provides semantics to access arbitrary segments in the video data. It can formalize various kinds of queries based on the video contents.

Third Party Call Control in IMS using Parlay Web Service Gateway

One of the key factors of next generation networks (NGN) is opening up the capabilities of the network. Parlay Group leads the standard, so called Parlay/OSA API, to open up the networks by defining, establishing, and supporting a common industry-standard APIs. Parlay Group also specifies the Parlay Web services API, also known as Parlay X API, which is much simpler than Parlay/OSA API to enable IT developers to use it without network expertise. One of Parlay X API is third party call (TPC) API which provides simple API for the purpose of creating and managing the call by the third party. IMS was devised originally by 3GPP for mobile networks, but currently it is accepted widely as a reference model of NGN even in fixed network domains. IMS has an interface called ISC to open the network capabilities. This paper overviews how Parlay X Web services can be supported in IMS in an architectural perspective, and discusses how the third party call can be implemented in IMS using Parlay X TPC APIs

An Efficient Context Model for Fast Responsiveness of Context-Aware Services in Mobile Networks

In order to provide context-aware services, context modeling is one of the most important tasks. Ontology has been widely accepted for the context modeling but it brings some overheads in the process of reasoning large-scale and dynamic information. In mobile networks, especially, ontology should be verified to be applicable for Context-aware Services since real-time responsiveness for large scale moving users is highly required to be guaranteed. This paper proposes an efficient context model to overcome the limitation of ontology. For the purpose, we design a conceptual context model and compare the processing time of the context-aware mobile service system implying the three different context modeling approaches - ontology, database, and proposed hybrid modeling. As the result of performance evaluations, the proposed hybrid model shows faster processing time among them and lesser affected by the major metrics of mobile services - changeability and number of users - than the two existing models. Based on the experimental results, we expect that the proposed hybrid model is very useful and efficient for fast responsiveness to support Context-aware Services for large scale users in mobile networks.

Presence-based call reservation service using open API on the Web-service architecture in broadband converged network

Open API in telecommunication is a service control technologies and is a set of abstract standard operations which can provide capabilities to access telecom network for the 3rd party service provider in a secure manner. This paper describes presence-based call reservation service which is a case study of converged service with open API on the Web-service architecture in broadband converged network. The presence-based call reservation service could provide the enterprise with combining capabilities of accessing network resources and manipulating enterprise data resources. We also propose a simple control mechanism for realization of this service with open API on the Web-service architecture

Context-aware user model for personalized services

With the advent of ubiquitous computing environments, a significant amount of work has been devoted to context-aware. We proposed the context-aware user model, which is aware of its userpsilas situation and recommends personalized services based on this information. This paper focuses on how our algorithms can be applied to a variety of environment easily and evolve user model without previously known information since the concerns of privacy. The proposed user model consists of context and action pairs. Using context-aware user model, we learn user behavior pattern in the situation, which is captured by union of contexts according to current environments. In order that our user model applies to new environment, only context profiles are required to be defined without any modification to model. Moreover we evolved user model through interactions between users and mobile devices using learning mechanism. Finally, we evaluate the precision of proposed approach using simulation with data sets of UCI depository.

Event detection in composite context aware-service

Recent computing paradigm will advance in a form of more user-centric services spurred by smart phone where smart phone users enjoy a large variety of contextual information. Under the context-aware domain, contexts are forming more complicated and thus the concept of composite context has been proposed. While providing a useable context to users is important, it is also essential to reserve such a composite context even if it is not available. Once the context is available to user, there should be a methodology maintained to alarm the user of its existence. In this paper, we propose new event detection architecture for new composite system. In the later part of the paper, we provide two case studies using the proposed event detection architecture: video streaming service and office automation service.

Revolutionary direction for 5G mobile core network architecture

It is expected that the emergence of new service scenarios driven by user needs beyond 2020 will be different from today. But current 4G LTE (Long Term Evolution) network is not enough to fulfill arising new requirements because of fundamental problems in Evolved Packet Core (EPC), including centralized routing mechanism. In this regard, 5G mobile network architecture needs to be redesigned to solve the problems of EPC. In this paper, we present revolutionary direction for the architecture of 5G mobile core network to meet the requirements of the new services which are described in IMT (International Mobile Telecommunications) 2020 vision. In addition we propose a reference model and key mechanisms to implement those proposed directions for 5G mobile core network.

An Interworking Mechanism between SCFs and Protocols in the Open Service Gateway

One of the important key aspects of NGN is the separation of service control and provision from the underlying network. Considering the evolution of customer requirements for converged services, opening up the network capabilities is inevitable. Open interfaces such as Parlay/OSA and Parlay X API enable third party service providers to develop communication services without specific knowledge of the underlying network. Open service gateway provides open APIs which abstract network capabilities such as call control, presence, terminal location, multimedia messaging, and etc for application developers. Each interface is implemented in the form of SCF (service feature capability) in the gateway. Since open service gateway interacts with NGN which is broadband convergence network, it should process more than one network protocol. During processing a protocol message in the gateway, it is necessary to find the target SCF which is supposed to receive that message. In this paper, a mechanism including appropriate data structure to find and dispatch protocol messages, especially SS no.7 protocol messages, from the underlying network in the open service gateway is proposed

Slice architecture for 5G core network

The emergence of new service scenarios driven by user needs beyond 2020 generates new mobile network requirements. Current 4G LTE (Long Term Evolution) network is not enough to fulfill arising new requirements because of fundamental problems in Evolved Packet Core (EPC), including centralized routing mechanism. In this regard, 5G mobile network architecture needs to be redesigned for emerging use cases. In this paper, we present network slice architecture for 5G core network and provide working mechanisms for slice selection, NAS routing, and slice reselection to support multiple logical networks over a single physical network.