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In today's Internet, which includes diverse and complex network technologies and services, it is difficult to achieve 'comfortable communication' that satisfies network users from the viewpoint of aspects such as communication usability, availability, quality and safety. To alleviate these problems and make communication a comfortable experience for users, we developed a middleware named Communication Service Concierge (CSC). CSC focuses on communication dataflow and coordinates various resources affecting the behavior of the flow such as network applications, protocols, network devices and computing equipment. These elements can be scattered throughout the end-to-end communication link of the dataflow. CSC provides a distributed communication control framework, which improves user satisfaction on the basis of agent computing using configurable and downloadable software components. This paper briefly describes the design concept and basic architecture of CSC, as well as two prototype applications for it that are associated with home networking and mobile computing. These are the most effective ways in which CSC helps users to achieve more comfortable communication.

It is reported that TCP does not perform well in highspeed and long-distance networks. This problem led to the proposal of HighSpeed TCP (HS-TCP). HS-TCP is designed to achieve a steady-state throughput of 10 Gbps with a packet loss rate of 10-7 when the packet size is 1500 bytes and the round trip time is 100 ms. However, HS-TCP has a problem in terms of convergence times. That is, it takes a long time for a new HS-TCP flow to achieve fair bandwidth allocation if the existing HS-TCP flows have large congestion windows. This paper proposes a new mechanism to improve the convergence time of HS-TCP. The basic idea of our mechanism is that if a flow has larger window than is fair its window is decreased more aggressively than usual. Simulations show that our mechanism significantly improves the convergence time of HS-TCP.

To make communication a comfortable experience for users, we have developed a middleware called Communication Service Concierge (CSC). This is a network middleware for distributed environments, and it consists of Communication Resource Management (CRM) and Communication Logic Management (CLM). Communication Service Concierge realizes comfortable communications by combining CRM and CLM. Communication Logic Management provides a framework to directly operate communication data. Communication Resource Management provides a framework on which downloadable software components can be executed on distributed platforms, and plays a primary role in controlling CSC's communication.Using Java, we implemented CRM on OSGi service platforms, which provide dynamic executions of the software components locally. In other words, CRM provides a distributed agent computing feature for OSGi. In this paper we describe the roles and implementations of CRM, especially for security functions, as well as describing how CRM's software components work cooperatively.