Agent-based multimedia communications on Internet

The paper presents a prototype implementation of a Java-based mobile agent architecture. The main focus lies on service trading and easy access to various services for mobile agents. The mediator for both mobile and service agents is called Service Center which is a crucial constituent of each agent platform within the mobile agent infrastructure. It allows to independently program services and mobile agents based on the generic agent concept. Another advantage of the Service Center architecture is the exploitation of an already existing LDAP server that is used as the distributed service directory for mobile agents.

Network computing is changing rapidly these days. The mobile agent technology invented to overcome the complexity resulting due to the increasing size of network components rises new network management schemes. Many prototype applications providing mobile agent capability have been proposed for being used in network management. E-commerce and information retrieval are some of them. The motive behind the agent mobility is that, it addresses some limitations faced by traditional centralized client-server architecture, which are mainly, minimizing bandwidth consumption, supporting network load balancing, enhancing scalability as well as flexibility, increase fault tolerance and solve problems caused by unreliable network connections. However, despite its benefits, mobile agent systems still pose security threats. In this paper we propose a mobile agent architecture that supports flexible and reliable interaction of autonomous components in a distributive network environment. We present a management scheme in a hierarchical level that provides to a user with a reliable and flexible global access to Internet/network information services. We further describe a protection mechanism to both agents and their hosting sites of execution called agent servers

Nowadays, a lot of e-Learning systems are widely deployed in educational schools. Typical e-Learning systems are implemented as client-server model. In the client-server model, the number of clients affects on the load of the server. In order to reduce the load on the server, we developed a P2P-based distributed e-Learning system. The proposed system consists of a lot of mobile agents which manage study contents and some functions such as scoring, showing questions, and correct answers. When a learner requests content, a mobile agent who has its content comes to the learner's computer, and then he/she can start the study. Here, a mobile agent has to manage multimedia data, which may be a huge size of data. Thus, a mobile agent has to migrates to the learner's node with a huge size of data. Then, the learner cannot start the study until the mobile agent finished to migrate. In order to solve this problem, we divide multimedia data into fragments and prepare mobile agents which manages each fragments. Since each mobile agents become small, a learner can start the study soon without waiting for the migration of a mobile agent which has a huge size of multimedia data. We, however, have to search a mobile agent which manages their fragments. Therefore, a mobile agent which manages n-th fragments informs its location to the agent which manages (n+1)-th fragments, and vice versa. Since each agent knows the location of a mobile agent which manages next and previous fragment, and fragments are cached into learner's node, a learner can play multimedia data smoothly without finding the location of mobile agent which manages holding next fragment. Experiment results show the effectiveness of our method.

Mobile agent technology is used in modern information technology to facilitate interoperability between isolated information systems. In addition, mobile agents have many advantages that make them a viable and attractive option in health sector applications. We propose the development of a health architecture based on integrated mobile agent technology and a service-oriented architecture (SOA) with distributed health applications involving the interoperability of remote or local homogeneous and heterogeneous applications, besides the SOA, and providing support for mobile agents. Furthermore, the SOA can be tested on different platforms. The development of a mobile agent architecture using Health Level Seven, known as HL7, for data exchange in the health sector is an essential step in making it widely accepted by centers that use health records as their means of communication. Each health center’s local data format can be modified for data exchange with other health centers through a mapping process that transforms the data from its local format to HL7, and vice versa. This research introduces a mobile agent architecture that can be applied to distributed health information systems to achieve interoperability.

The virtual home environment (VHE) is a concept for service mobility. Several tool kits are under standardization for its realization. Beyond these tool kits, it is worth researching mobile agents. A few mobile agent based architectures have been proposed for VHE. In these architectures, mobile agents carry services and customized data and follow roaming end-users, by relocation or cloning. This paper focuses on how these agents and their clones are updated. It proposes two novel schemes for updating mobile service agents in VHE. The schemes rely on the agent's ability to notify a network entity of the changes made by end users to the customized data, and also on the agent's ability to update itself if requested. In the first scheme, the clones are updated remotely, whereas in the second scheme, an updating mobile agent tours all the clones to update them locally. We have derived requirements, articulated the schemes, built a prototype, and made measurements. The measurements indicate that the scheme where the network entity requests the updates directly performs better in most cases.

Problem statement: Most of the information retrieval systems used only client-server architectures. The client-server model though powerful, had some limitations. In mobile computing environment which has both wired network and wireless networks with limited communication capabilities, the performance of the system was very low. Approach: Mobile agents are considered a suitable technology to develop applications such as information retrieval system for mobile computing environment. Mobile agents are autonomous and dynamic entities that can migrate between various nodes in the network. They offer many advantages over traditional design methodologies like: reduction in network load, overcoming network latency and disconnected operations. Since the mobile agents do not need continuous communication with the mobile host, they are not affected by the sudden disconnection of wireless network and the situation of turning mobile host off for power saving. In order to get the complete benefit of mobile agent system, the system must be fault tolerant. In the context of mobile agents, fault-tolerance prevents a partial or complete loss of the agent. Results: Our system in mobile computing environment ensured that the agent arrived at its destination with result and performance of the system improved by the way of reduction in the response time. And also, the system allowed sending more requests by the way of creating many mobile agents without affecting the performance. Conclusion: Our research compared the performance of client-server architecture and fault tolerant mobile agent information retrieval system and proved that our system solved the limitations faced by the client server architecture. The system can also be extended to adhoc networks.

Autonomous Mobile agents can be extremely useful in dynamic environments that require a continuous network connection. Network bandwidth reduction, protocol encapsulation, software automation and intelligence gathering can significantly affect Web Services. Integrating mobile agents with Web Services enables software adaptation to cope with a dynamic environment, automated system configuration and application requirement changes that are frequent in today''s ever fast-evolving technology. In this paper, we use a lightweight and efficient composition for mobile agents based Web services complying with Representational State Transfer (REST) principles for agent creation, migration, and control. The paper presents the overall concept and architecture of RESTful agents for web services. A security scheme is proposed for mobile agent security based on an infrastructure-less Identity Based Encryption (IBE) scheme integrated with Broadcast based Secure Mobile Agent Protocol (BROSMAP). A proof- of-concept implementation is provided.

k-Anycast is a communication paradigm that is proposed to deliver a packet to any threshold k members of a set of communication group hosts. Most k-Anycast routing protocols are centralized and they are not suitable for high dynamic networks (such as wireless sensor networks and wireless ad hoc networks) because they assume that each routing node has global network information. A distributed k-Anycast routing protocol based on mobile agents is proposed in this paper. The protocol forms multiple components and each component has at least k members. Each component can be treated as a virtual server, so k-Anycast service is distributed to each component. In this protocol, mobile agents are applied to initiate or manage components and routing table, so each routing node needn't global network information, only needs to exchange routing information with its neighbors, so the protocol saves much communication cost and adapts to high dynamic networks. Compared to flooding method and centralized k-Anycast routing protocols, performances of the protocol are improved in terms of cost, time delay and scalability.

Developments toward ubiquitous and pervasive computing have lead to application scenarios where a large number of sensors and computing devices are connected to the network. These devices might constantly send status information via multicast to a number of applications or users. One big challenge in this environment is the amount of data traffic generated by such sensors, which depends on the size of the data, the transmission frequency, and the number of senders and receivers. However, for certain applications it is sufficient to receive less accurate, aggregated data from a group of sources. This leads to the possibility of using programmable routers to perform such data aggregation inside the network. While the basic algorithm for data merging has been described in literature, we address how a large number of sources can be organized in a hierarchical structure to allow multiple users to get a view of all sensors at different levels of aggregation. With the control information that is provided by an aggregating node, the user can traverse the aggregation tree by joining different multicast sessions that transmit different levels of detail. This provides a novel communication paradigm that reduces the network overhead from continuously transmitting sources and organizes data in a way that it is useful to receivers. We provide two detailed example scenarios: A battlefield information system, which aggregates geographic location data of units, and a conferencing application, which aggregates audio data. We describe the aggregation algorithm that is used and analyze its effect on delay and jitter of periodic transmissions by the sources. We describe the hierarchical control structure that provides multiple levels of aggregation and how real-time transport protocol (RTP) can be used to implement it. The performance of the proposed scheme is evaluated with measurements that were done on an implementation of the audio aggregation application.

The flexibility offered by mobile agents is quite noticeable in distributed computing environments. However, the greater flexibility of the mobile agent paradigm compared to the client/server computing paradigm comes at an additional threats since agent systems are prone to failures originating from bad communication, security attacks, agent server crashes, system resources unavailability, network congestion, or even deadlock situations. In such events, mobile agents either get lost or damaged (partially or totally) during execution. In this paper, we propose parallel checkpointing approach based on the use of antecedence graphs for providing fault tolerance in mobile agent systems. During normal computation message transmission, the dependency information among mobile agents is recorded in the form of antecedence graphs by participating mobile agents of mobile agent group. When a checkpointing procedure begins, the initiator concurrently informs relevant mobile agents, which minimizes the identifying time. The proposed scheme utilizes the checkpointed information for fault tolerance which is stored in form of antecedence graphs. In case of failures, using checkpointed information, the antecedence graphs and message logs are regenerated for recovery and then normal operation continued. Moreover, compared with the existing schemes, our algorithm involves the minimum number of mobile agents during the identifying and checkpoiting procedure, which leads to the improvement of the system performance. In addition, the proposed algorithm is a domino-free checkpointing algorithm, which is especially desirable for mobile agent systems. Quantitative analysis and experimental simulation show that our algorithm outperforms other coordinated checkpointing schemes in terms of the identifying time and the number of blocked mobile agents and then can provide a better system performance. The main contribution of the proposed checkpointing scheme is the enhancement of graph-based approach in terms of considerable improvement by reducing message overhead, execution, and recovery times.

Mobile agent systems provide new perspectives for distributed e-commerce applications. These applications may present specific restrictions, making mobile agent systems a feasible solution. Even so, mobile agents present some security related problems. An important one is resource access control. The ability for mobile agents to provide a simple, scalable, flexible, and secure access control system is a key point for the widespread adoption of mobile agents. In this paper we propose a mechanism to safely assign roles to mobile agents and an access control method based on Role-based Access Control (RBAC). The access control method provides a simple, lightweight and distributed model for mobile agent applications. It is proposed as an extension of the MARISM-A (An Architecture for Mobile Agents with Recursive Itineraries and Secure Migration) project, a secure mobile agent platform.

Security in wireless sensor networks is very crucial especially whenever they deployed in military applications. Cryptography is used to protect sensitive information from disclosure. Key management is important component in cryptography. Cryptography is not useful if keys are disclosed to attackers. Designing an efficient key management for WSN is a difficult task because of scarcity of computing, communication, and memory resources. An efficient key distribution approach is proposed by using mobile agent paradigm rather than client–server model. The proposed approach will use good features of both symmetric and asymmetric cryptography. Mobile agents are used to generate public and private key pairs, update keys, and revocation of keys. The proposed scheme in the first level will use mobile agents for key distribution and coordination for asymmetric keys, and in the second level, sensor nodes can involve in constructing symmetric keys for secure communication through mutual authentication and encryption with those keys. The proposed method is implemented using NS2 simulator, and results are compared with existing similar methods in terms of evaluation parameters like communication, computation overhead, memory overhead, and resiliency. The performance of proposed method is improved when it is compared with similar existing methods.

In this paper we analyze the two major transport protocols that are currently under discussion for IPTV and propose extensions to support convergence. On the one hand, the MPEG-2 transport stream (MPEG2-TS) is well established in the broadcast world, whereas the real-time transport protocol (RTP) is widely adopted in the Internet and mobile world. Our analysis focuses on the timing aspects such as synchronization and buffer management. It is shown that the system target decoder (STD) defined in MPEG2-TS provides a well defined decoder model that allows minimum buffering delay and predictable behavior. In contrast, an RTP receiver is intentionally defined less accurately to allow flexibility for multiple applications. However, this flexibility results in less clear receiver behavior which is a problem for the design and integration of IPTV systems. By comparing the main differences in the timing models of the two protocols we derive additional constraints and definitions for RTP that minimize the difference to MPEG2-TS. It is proposed to specify these changes as part of an RTP/IPTV profile which also defines an RTP system target decoder (RTP-STD). An example for the application of these extensions is a protocol gateway supporting the convergence of broadcast and the Internet world in IPTV.

Modern e-commerce is vigorously developing. It makes the resources and services on Internet more richly colorful. Every day these rich resources and services can produce many new mass data which contain a large number of important information. These data are often heterogeneous, uncertain and unstructured. Their complexity has far exceeded the analysis and understanding ability which the humanity has at present. In order to resolve the problem, related technologies of distributed data mining in e-commerce environment are studied. Web services technology and agent technology are introduced in the e-commerce data mining. The distributed data mining structure in e-commerce environment based on Web services and mobile agent is put forward.

Mobility management is a necessity in highly dynamic and large-scale Mobile Agent (MA) networks, especially in a multi-region environment, in order to control and communicate with agents after launching. In this paper, we have proposed a hierarchical mobile agent monitoring mechanism using Mobile Monitor Agents (MMA’s). The mobile agent system is implemented in XML. This XML based system provides a system independent, standardized, effective and customized solution for application development. Distributing MMA dynamically solves the scalability issue of Centralized monitoring mechanism, and still has the advantages of Hierarchical monitoring mechanism to decrease the information processing bottleneck issue at centralized server. The MMA takes care of a certain number of agent servers and it reduces the traffic in the centralized server by bypassing queries from the agent servers under its control. XML helps to decrease the amount of data transferred and the processing part with the Java parsers is not transferred in network. There is less transfer of data because only data representation is migrated.KeywordsAgent ServerMobile AgentsMobile Monitor Agent