For as long as there have been services there has been a desire to have a convenient medium to expose and discover service offerings. Since early on, various efforts have attempted various approaches at the exchange of computational services, prompting the question of whether there is a market for Web services. We believe that a services marketplace should fulfill the promise of an electronic emporium where third party service providers are able to offer their services in a ubiquitous ecosystem, and where service consumers are able to acquire service solutions that are tailored to their requirements. This paper explores the landscape of cloud services marketplaces, where we are, what enablers are needed to realize the vision, and it presents a prospective architecture to that end.

Video transmission in multiparty video conferencing is challenging due to the demanding bandwidth usage and stringent latency requirement. In this paper, we systematically analyze the problem of collaborative stream routing using one-hop forwarding assistance in a bandwidth constraint environment. We model the problem as a multi-source degree-constrained multicast tree construction problem, and investigate heuristic algorithms to construct bandwidth-feasible shared multicast trees. The contribution of this work is primarily two-fold: (1) we study the solution space of finding a feasible bandwidth configuration for stream routing in a peer-to-peer (P2P) setting, and propose two heuristic algorithms that can quickly produce a bandwidth-feasible solution, making them suitable for large-scale conference sessions, (2) we conduct an empirical study using a realistic dataset and show the effectiveness of our heuristic algorithms. Various QoS metrics are taken into account to evaluate the performance of our algorithms. Finally, we discuss open issues for further exploration. The feasibility study presented in this paper will shed light on the design and implementation of practical P2P multiparty video conferencing applications.

Motivated by the problem of limited bandwidth in peer-to-peer (P2P) multi-party video conferencing systems, in this paper we propose a non-intrusive adaptive multi-media routing algorithm that effectively calculates stream routing to achieve a maximum number of receiving streams. The technique is non-intrusive in that it makes use of current streaming status to infer link bottlenecks rather than sending active probing packets, which would seriously interfere with the latency-sensitive video conferencing application and waste bandwidth. When link bottlenecks are detected, the method will adaptively calculate streaming routes, allowing bandwidth abundant peers to act as relays. To test the performance, we use real data from a world wide bandwidth distribution archive and investigate the algorithm convergence rate and distribution fairness through simulation. Results show that the technique works well to achieve effective multi-media routing for latency-sensitive video conferencing applications.

In this paper, we study distributed home theatre, a video service which allows distributed users to debate a film. We investigate the interplay between bandwidth reduction and program replication techniques. We evaluate the impact of user distribution, network topology and number of users per session on this interplay. Moreover, we state a bandwidth minimization principle which can be used in admission control policies.

We present the multimedia gateway solution which represents an evolutionary approach for providing a natural migration to digital switched video services. We also present some initial analysis reflecting performance issues for a multimedia gateway.

Asynchronous transfer mode (ATM) is a connection-oriented technology in which all communication is based on virtual connections established prior to the transfer of data. It is expected that the bulk of traffic carried by the ATM network will be data traffic, e.g., local area network (LAN) internetwork traffic. Hence, a major issue regarding ATM is the support for connectionless (datagram) traffic. A scheme for the efficient support for connectionless traffic in ATM LANs based on trees of virtual connections is proposed. In this scheme, a sink tree is built for every switch in the LAN. Each tree provides an efficient means of routing connectionless traffic from any switch in the network to the sink switch (root) of the tree. The sink tree solution may also be used to broadcast connectionless messages in the reverse direction. The trees can easily be updated to adapt to topological changes or congestion in the network. A protocol for refreshing the tree structure using the ATM switch routing tables is described. An adaptive rate control solution, in conjunction with fast back pressure at the ATM layer, is presented. It is shown that this scheme achieves high utilization of available bandwidth for connectionless traffic, has low cell loss probability, and small overhead.

A significant driver for the consumer use of high bandwidth in the near future will be interactive video on demand (IVOD). A range of service types can be deployed, based on a differing sophistication, which must be traded against the network costs (bandwidth) and component costs (switch complexity and memory). The potential aggregate bandwidth required is huge (O(1Pb/s)), and thus it is essential to properly engineer the network to reduce the bandwidth required. This paper describes a variety of IVOD scenarios, and introduces a cost function that captures the combined bandwidth and storage requirements of the network. This cost function is used to compare different network engineering alternatives, particularly program caching and stream sharing. The effects of nonlinear pricing and differing weights of bandwidth and storage are also reflected by the cost function. This cost function can be used by network designers to determine optimal topology, sharing, and caching strategies for desired bandwidth versus memory costs in a particular network deployment. In addition, a simulation model is used to evaluate caching of programs or windows within programs. We show that there are some results that are widely applicable. In particular, the level in the network at which caching should take place is at approximately 80% depth in the distribution tree, above the head end switch in the network hierarchy. We also observe that the bandwidth savings in sharing streams (actually buffered windows of program content) is fairly small for user behavior based on Zipfs law. The overall intent of this work is to evaluate the effects of various server, cache, and sharing strategies on the bandwidth and storage requirements of the network and their proper placement within the network.>

ATM is a connection-oriented technology in which all communication is based on virtual connections established prior to the transfer of data. Initially, it is expected that the bulk of traffic carried by the ATM network will be data traffic. Hence, a major issue regarding ATM is the support for connectionless (datagram) traffic. A scheme for the efficient support for connectionless traffic in ATM LANs based on trees of virtual connections is proposed. In this scheme a sink tree is built for every switch in the LAN. Each tree provides an efficient means of routing connectionless traffic from any switch in the network to the sink switch (root) of the tree. The sink tree solution may also be used to broadcast connectionless messages in the reverse direction. The trees can easily be updated to adapt to topological changes or congestion in the network. A protocol for refreshing the tree structure using the ATM switch routing tables is described.>

CATV networks are targeted to provide multimedia services to the home. This paper presents a simulation model aimed at evaluating the capacity of CATV networks. The model is based on the user profile, the service discipline and the CATV bandwidth. The issues addressed include the number of users supported by a single broadcast CATV-tree, the probability of accepting a request for multimedia service, and the number of users served over a period of time.>

The suitability of IEEE 802.5 token ring LANs for the transport of multimedia traffic is examined. The token ring priority mechanisms and end-station queuing policies are studied in order to understand their effect on the delay characteristics of multimedia traffic. The multimedia traffic is modeled as isochronous data streams. Simulation results are presented to illustrate the access and queuing delays under various load conditions and traffic mixes.

Three transport services are offered by FDDI: asynchronous, synchronous, and isochronous (FDDI-II). In order to support the stringent multimedia (e.g., real-time video and voice) delay and bandwidth requirements the asynchronous transfer service will not suffice. The isochronous and synchronous transport services differ considerably in their implementation, but the differences in the service provided can be made to appear transparent to many multimedia applications. It is shown that synchronous traffic can support a wide range of application requirements efficiently at moderate cost when the connection between source and destination are on the same physical ring. However, isochronous class traffic has advantages, particularly when the network traffic is well behaved (the peak data rate is close to the mean data rate) and when connections traverse multiple rings.>

A mechanism is required which prevents the initiation of the claim process and maintains a constant ring latency during the insertion and removal of stations into the ring. Such a mechanism, graceful insertion and removal, is described. The mechanism is designed to support the graceful insertion and removal of stations into the M-ports of concentrators and requires no hardware modification of the endstations.>

The advantages and disadvantages of isochronous and synchronous transport services of the fiber distributed data interface (FDDI) are summarized. A comparison of both services is made based on application requirements (e.g. real-time video and voice). These requirements include timing constraints, such as jitter and delay, bandwidth utilization, and end-station requirements. It is shown that synchronous traffic can support a wide range of application requirements efficiently at moderate cost when the connections between source and destination are on the same physical ring. However, isochronous traffic has advantages, particularly when the network traffic is well behaved (the peak data rate is close to the mean data rate) and when connections traverse multiple rings.>