One major challenge in self-adaptive systems is to assure the required quality properties. Formal methods provide the means to rigorously specify and reason about the behaviors of self-adaptive systems, both at design time and runtime. To the best of our knowledge, no systematic study has been performed on the use of formal methods in self-adaptive systems. As a result, there is no clear view on what methods have been used to verify self-adaptive systems, and what support these methods offer to software developers. As such insight is important for researchers and engineers, we performed a systematic literature review covering 12 main software engineering venues and 4 journals, resulting in 75 papers used for data collection. The study shows that the attention for self-adaptive software systems is gradually increasing, but the number of studies that employ formal methods remains low. The main focus of formalization is on modeling and reasoning. Model checking and theorem proving have gained limited attention. The main concerns of interest in formalization of self-adaptation are efficiency/performance and reliability. Important adaptation concerns, such as security and scalability, are hardly considered. To verify the concerns of interest, a set of new properties are defined, such as interference freedom, responsiveness, mismatch, and loss-tolerance. A relevant part of the studies use formal methods at runtime, but the use is limited to modeling and analysis. Formal methods can be applied to other runtime activities of self-adaptation, and there is a need for light-weight tools to support runtime verification.

/pdf/a-survey-of-formal-methods-in-self-adaptive-systems-4fvozdq7zn.pdf

A survey of formal methods in self-adaptive systems

https://wiki.epfl.ch/edicpublic/documents/Candidacy%20exam/1-s2.0-S0306437908000525-main.pdf

Multimedia group and inter-stream synchronization techniques: A comparative study

Applications of agent technology in communications: a review

Systems and methods are disclosed for obtaining and presenting information to a user playing a media item identifying playback positions of a number of other users also playing the media item. In one embodiment, a first user begins playback of a media item. Information identifying playback positions of a number of second users also playing the media item is obtained from a playback information broker and presented to the first user. The first user may then provide user input identifying a desired action to take with respect to one or more of the second users. In response, the desired action is effected.

System And Method For Playback Positioning Of Distributed Media Co-Viewers

Most multimedia group and inter-stream synchronization techniques define or use proprietary protocols with new control messages. Many multimedia applications have been developed using RTP/RTCP as the standard for transmission of multimedia streams over IP networks. Instead of defining a new protocol, we propose the use of RTP/RTCP to provide synchronization. We take advantage of the feedback capabilities provided by RTCP and the ability to extend the protocol by extending and creating RTCP messages containing synchronization information. We have implemented our proposal and tested it in our University WAN. Our experiments have shown that network load resulting from synchronization is minimized and that asynchronies are within acceptable limits for multimedia applications.

An RTP/RTCP based approach for multimedia group and inter-stream synchronization

An agent based synchronization scheme for multimedia applications

We propose a mobile agent based QoS management system to satisfy the five functional principles of QoS architecture, i.e., integration, separation, transparency, asynchronous resource management and performance. The mobile agent paradigm is a unique paradigm in contrast to the traditional client/server paradigm in a problem inherently distributed and complex, such as QoS management. This paradigm saves a considerable amount of bandwidth and reduces network traffic. We present analytical and simulation models of a mobile agent based bandwidth negotiation and management system for multimedia communication. Response time of the mobile agent is computed with different number of retransmissions and the intermediate "hops" for both the models. It is observed that the response time of the agent increases with the increase in the number of retransmissions and the hops. We also show that the increase in the arrival of mobile agents would affect the admission of new multimedia applications.

/pdf/qos-management-by-mobile-agents-in-multimedia-communication-3ktsupry6e.pdf

QoS management by mobile agents in multimedia communication

The allocation of bandwidth for multimedia traffic poses a technical challenge due to bursty and isochronous nature of applications. We propose a mobile agent based approach for bandwidth allocation in multimedia communication. It is based on the the network congestion monitored by the agents at the clients. The mobile agent hosted by the server will allocate bandwidth online to the applications within the requested range at regular intervals. Also, it keeps the aggregated bandwidth below the link bandwidth of server and clients. The approach reduces the network control traffic used in traditional online bandwidth allocation policies. The scheme is simulated and its performance is evaluated in terms of several parameters, like, bandwidth utilization, application rejection, agent response time, and agent migrations. The simulation results show that the use of agents increase flexibility and efficiency in end-to-end bandwidth allocation and operate asynchronously. The flexibility in using this technology is that, the allocation policies can be changed, customized and implemented easily.

S. S. Manvi

Papers

An agent based synchronization scheme for multimedia applications

QoS management by mobile agents in multimedia communication

Mobile agent based online bandwidth allocation scheme for multimedia communication

An agent based adaptive bandwidth allocation scheme for multimedia applications