Service matchmaking among heterogeneous software agents in the Internet is usually done dynamically and must be efficient. There is an obvious trade-off between the quality and efficiency of matchmaking on the Internet. We define a language called Larks for agent advertisements and requests, and present a flexible and efficient matchmaking process that uses Larks. The Larks matchmaking process performs both syntactic and semantic matching, and in addition allows the specification of concepts (local ontologies) via ITL, a concept language. The matching process uses five different filters: context matching, profile comparison, similarity matching, signature matching and constraint matching. Different degrees of partial matching can result from utilizing different combinations of these filters. We briefly report on our implementation of Larks and the matchmaking process in Java. Fielded applications of matchmaking using Larks in several application domains for systems of information agents are ongoing efforts.

The amount of services and deployed software agents in the most famous offspring of the Internet, the World Wide Web, is exponentially increasing. In addition, the Internet is an open environment, where information sources, communication links and agents themselves may appear and disappear unpredictably. Thus, an effective, automated search and selection of relevant services or agents is essential for human users and agents as well. We distinguish three general agent categories in the Cyberspace, service providers, service requester, and middle agents. Service providers provide some type of service, such as finding information, or performing some particular domain specific problem solving. Requester agents need provider agents to perform some service for them. Agents that help locate others are called middle agents[2]. Matchmaking is the process of finding an appropriate provider for a requester through a middle agent, and has the following general form: (1) Provider agents advertise their capabilities to middle agents, (2) middle agents store these advertisements, (3) a requester asks some middle agent whether it knows of providers with desired capabilities, and (4) the middle agent matches the request against the stored advertisements and returns the result, a subset of the stored advertisements. While this process at first glance seems very simple, it is complicated by the fact that not only local information sources but even providers and requesters in the Cyberspace are usually heterogeneous and incapable of understanding each other. This gives rise to the need for a common language for describing the capabilities and requests of software agents in a conve-

The Internet not only provides data for users to browse, but also databases to query, and software agents to run. Due to the exponential increase of deployed agents on the Internet, automating the search and selection of relevant agents is essential for both users and collaboration among different software agents. This paper first describes the agent capability description language LARKS. Then we will discuss the matchmaking process using LARKS and give a complete working scenario. The paper concludes with comparing our language and the matchmaking process with related works. We have implemented LARKS and the associated powerful matchmaking process, and are currently incorporating it within our RETSINA multiagent framework (Sycara et al. 1996).

The Java programming language has gained substantial popularity in the past two years. Java's networking features, along with the growing number of Web browsers that execute Java applets, facilitate Internet programming. Despite the popularity of Java, however, there are many concerns about its efficiency. In particular, networking and computation performance are key concerns when considering the use of Java to develop performance-sensitive distributed applications.

The Java programming language has gained substantial popularity in the past two years. Java’s networking features, along with the growing number of Web browsers that execute Java applets, facilitate Internet programming. Despite the popularity of Java, however, there are many concerns about its efficiency. In particular, networking and computation performance are key concerns when considering the use of Java to develop performance-sensitive distributed applications. This paper makes three contributions to the study of Java for performance-sensitive distributed applications. First, we describe an architecture using Java and the Web to develop MedJava, which is a distributed electronic medical imaging system with stringent networking and computation requirements. Second, we present benchmarks of MedJava image processing and compare the results to the performance of xv, which is an equivalent image processing application written in C. Finally, we present performance benchmarks using Java as a transport interface to exchange large medical images over high-speed ATM networks. For computationally intensive algorithms, such as image filters, hand-optimized Java code, coupled with use of a JIT compiler, can sometimes compensate for the lack of compiletime optimization and yield performance commensurate with identical compiled C code. With rigorous compile-time optimizations employed, C compilers still tend to generate more efficient code. However, with the advent of highly optimizing Java compilers, it should be feasible to use Java for the This research is supported in part by a grant from Siemens Medical Engineering, Erlangen, Germany. performance-sensitive distributed applications where C and C++ are currently used.

The Java programming language has gained substantial popularity in the past two years. Java's networking features, along with the growing number of Web browsers that execute Java applets, facilitate Internet programming. Despite the popularity of Java, however, there are many concerns about its efficiency. In particular, networking and computation performance are key concerns when considering the use of Java to develop performance- sensitive distributed applications. This paper makes three contributions to the study of Java for performance-sensitive distributed applications. First, we describe an architecture using Java and the Web to develop MedJava, which is a distributed electronic medical imaging system with stringent networking and computation requirements. Second, we present benchmarks of MedJava image processing and compare the results to the performance of xv, which is an equivalent image processing application written in C. Finally, we present performance benchmarks using Java as a transport interface to exchange large medical images over high-speed ATM networks. For computationally-intensive algorithms like image filtering, Java code that is optimized both manually and with JIT compilers can sometimes compensate for the lack of compile- time optimizations and yield performance commensurate with equivalent compiled C code. With rigorous compile-time optimizations, however, C compilers still generally generate more efficient code. The advent of highly optimizing Java compilers should make it feasible to use Java for performance-sensitive distributed applications where C and C++ are used currently.