Markus Hillenbrand

A single sign-on framework for web-services-based distributed applications

The basic specifications of Web services com- pletely ignore the need for secure services that are based on a solid authentication and authorization infrastructure. An enhancement of the basic specifications is in progress, but takes time to complete. A large-scale application built today is still in need of an authentication and authorization infrastructure to offer its services to the customers of the service provider and only to the customers. In the following such an infrastructure is described that is able to empower Web services to properly handle authentication and authorization. This infrastructure is designed as services that can be used by any Web service needing authentication and authorization.

Facilitating the interoperability among different VoIP protocols with VoIP Web services

With the development of the Internet the VoIP technology is becoming a popular service on the Internet platform. Several VoIP protocols have been suggested to realize the VoIP communication. But different VoIP protocol clients cannot interoperate directly. This paper suggests a VoIP Web service infrastructure to facilitate the interoperability among different VoIP protocols. With this infrastructure all VoIP protocols signaling handling details are hidden through the corresponding Web service abstraction. Therefore different VoIP protocols can utilize the common Web service interfaces to achieve the interoperability.

Voice over IP - considerations for a next generation architecture

Voice over IP is on its way to becoming an alternative to the classical telephony system because more and more Voice over IP providers offer their solutions on the Internet and try to increase their clientele. But current voice over IP technology is still in its commercial and technological infancy and has not yet proven to be worldwide accessible, usable and scalable as the classical telephony system has proven in the past 100 years. In this paper, architecture for a next generation Voice over IP model will be outlined and discussed. The main focus lies on interoperability between different Voice over IP providers as well as dependability and robustness.

Developing Web applications for mobile devices

Today, even small mobile devices access the Internet. Therewith, mobility issues have become an important technical and economic topic - not only in new but in proven and successful Web applications as well. The main problem derives from a growing development of heterogeneity in hardware and software of mobile devices. To overcome this problem, this paper presents a framework to develop Web applications for mobile devices. This framework issues important points when developing web application that also focuses on mobile users. This includes completely new developments, as well as development that issue an upgrade of existing Web applications to mobile devices. An important element in this framework is the employment of the fairly new CC/PP standard.

A Web services based framework for voice over IP

Currently, more and more enterprises adopt the voice-over-IP (VoIP) technology to replace their traditional circuit switching infrastructure in order to reduce the cost of their telephony services. The most frequently used VoIP solutions are made up of stand-alone software - usually complex and requiring extra hardware in a local area network. Some VoIP service providers offer Web site based or plug-in based solutions, which are, however, difficult to integrate with other applications by the end user. Web services provide functionality over the Internet using various standards like XML and HTTP, independently of the operating system and programming language. In this paper, we propose a framework for voice-over-IP based on Web services. Service providers using this framework can offer their customers a protocol-neutral Web service interface, thus enabling the deployment of a general and integrated VoIP solution. Because of the simplified logic, a client in this system is easy to implement and can communicate with clients in other systems without additional local hardware for VoIP.

A Lightweight Service Grid Based on Web Services and Peer-to-Peer

What is The Grid? This question has been asked by many people and has been answered by many more. On our way to the One Grid, it is currently only possible to distinguish between several Computational, Data and Service Grids. This paper introduces Venice, a lightweight Service Grid that allows for easy service deployment, easy maintenance and easy service usage. It contains management services, information services and application services that can be used to build distributed applications upon. Its main focus in on providing a flexible and dependable infrastructure for deploying services that do not require special knowledge and expertise in Grid computing.

Implementing SIP and H.323 signalling as Web services

Nowadays, existing voice-over-IP (VoIP) clients are signalling protocol dependant. This means that they can only support one signalling protocol. One disadvantage of these VoIP clients is that they are rich clients, and the other is that the problem of interoperability between two clients supporting different signalling protocols must be solved by a signalling protocol translator. We propose a VoIP Web services architecture, taking advantage of the Web services technology to solve the above problems. This work explores the design and implementation of a VoIP Web services system architecture. We first propose a VoIP Web service architecture, and then we focus mainly on designing the signalling protocol Web services, and illustrate the call procedures between the simple client and the normal H.323/SIP client under this architecture. We also present the experience in implementing the prototype for the H.323/SIP Web services, and finally give some considerations about the implementation.

Web Services Directory Based on Peer-to-Peer Technology

Service-oriented architectures foster the interaction of a multitude of different services. In order to ensure flawless service interaction, a directory service is needed that can be used to find suitable services for a desired task. A centralized solution for local services might be suitable for small systems, but on a larger scale - when systems start to interact via federations of trust - the need for a highly available and easily maintainable directory service arises

14. Web Services and Peer-to-Peer

Peer-to-Peer and Web services both address decentralized computing. They can be considered as rather distinct from each other, but a closer look at the Web services technology reveals a great potential for a combination of both Peer-to-Peer and Web services.

DANCE: dynamic application oriented network services

The explicit usage of protocols in applications is common practice, but restricts the provided communication service. The dynamic utilization of more suitable protocols or taking into account specific user requirements is either hard to realize or even impossible. This work introduces a model which provides a service oriented view to a communication sub system. Its goal is to find the most suitable service provider. Therefore, service providers are selected dynamically at run time. This enables to take into account the requirements of both the application and the user as well as information about the current platform and network environment. Thus applications are able to benefit from uncommon protocols wherever such protocols make sense and are available. Otherwise standard protocols would be used.