Limited-Resource Systems Testing with Microagent Societies

Transcription

1 Limited-Resource Systems Testing with Microagent Societies Liviu Miclea, Enyedi Szilárd, Lucian Buoniu, Mihai Abrudean, Ioan Stoian*, Andrei Vancea Technical University of Cluj-Napoca, Cluj-Napoca, Romania * IPA Cluj-Napoca, Romania Paper submission to European Test Symposium 2004 Preliminary paper Contact information: Liviu Miclea Technical University of Cluj-Napoca Department of Automation Baritiu Str., RO , Cluj-Napoca, Romania Tel.: Liviu.Miclea@aut.utcluj.ro Webpage: Designated presenter: Liviu Miclea Abstract This paper presents a novel approach to distributed systems testing and its management, involving the use of multiagent societies running under Java 2 Micro Edition on embedded, low-resources computational devices. Tester microagents within the society perform the actual testing, aided by certain utility agents. We impose a set of specifications such a society should adhere to, and then present two experimental implementations proving the availability of the proposed solution. Keywords: system testing, microagent, multiagent system, distributed testing management. 1. Introduction Industrial applications make use of large numbers of embedded computational devices. These naturally have limited resources, in terms of memory, processing power and I/O capability, while also being diversified to meet a broad range of demands. Therefore, in-field testing of these devices and the equipment controlled by them usually implies developing heterogeneous test routines, the management and centralization of whose results is highly susceptible of becoming complex and cumbersome. Assuming the devices are connected to a network, two major approaches may be adopted for testing such a heterogeneous, distributed group of related devices. The first of them is remote testing, which is centralized and can solve the testing problem with limited efficiency and important drawbacks, such as communicational overhead. A much better solution is decentralized, distributed testing. The decentralization greatly reduces the communicational overhead and increases the flexibility and reliability of the testing system itself. Being natively decentralized, distributed and heterogeneous, we chose a multiagent society as a natural solution to the distributed testing management problem. Before continuing, we shall specify some terminology used throughout this paper. An agent is a piece of software capable of independent

2 Miclea, Enyedi, Buoniu, Abrudean, Stoian, Vancea 2 of 6 existence within an environment provided for it, able to communicate with similar entities situated locally or remotely, to unaidedly accomplish the work assigned to it, learn from its experience, and possibly even travel between geographically separated locations within its environment (capability hereafter named agent mobility). A testing society shall be a multiagent society whose main actors are tester agents. Due to the diversity of the software that runs and hardware it runs on at the various locations under test, the most fit implementation language for the agents is the platform-independent, highly network-enabled Java programming language. Multiagent testing societies have been designed and employed under Java 2 Standard Edition ([2], [3]). However, due to the large memory and processing power requirements of such implementations, they are not feasible for running on the limitedresource devices subjects of this paper. Therefore, we propose the usage of the Java Micro-Edition platform for our multiagent testing society. In this approach, the agents are able to run on embedded or mobile devices with memory spans starting at 128 KB, processors on 16 or 32 bits starting at 25 MHz clocks, and low power resources. An agent running under Java2ME will hereafter be called a microagent, the society that contains such agents becoming a microagent society. The microagents will be able to test both the embedded devices they run on and other devices connected to these, which lack the capability of running the agent code. BIST 1 in the latter will be supported by the microagents. 2. Specifications In this section we summarize the requirements the designed microagent societies must meet. First, the society must be standards-compliant, and the standards it will obey are the widely accepted FIPA 2 specifications. The structure of the society is depicted in figure 1 and is derived from the testing society designed in [1]. Different locations under test are represented as ellipses, and agents as colored labeled rectangles. Figure 1. Society structure An agent management system [6] is assumed as part of the agent platform utilized in development. We do not need to reinvent the wheel, as there are freely available agent platforms that support Java2ME. The Directory Facilitator (or DF) microagent implements the Directory service specified in [5]. Its role is to maintain a list of services the agents can supply ( things they know how to do), list that can be queried and updated by other agents. For example, if an agent knows how to test the V6366C- J Yamaha VLSI IC, it should register with the DF as supplier of a service named something like 1 BIST Built-In Self Testing 2 FIPA The Foundation for Intelligent Physical Agents,

3 Limited-Resource Systems Testing with MicroAgent Societies 3 of 6 V6366C-J-ic-tester. One DF resides at each location. The DFs are able to federate over the network, so that services may be also looked up remotely. The Connector is the link of the microagent society with a central database. The reason for which this database exists is that the tester agents cannot be equipped with knowledge about all devices that exist or might exist in the future in the network. Rather, the agents are initialized with a reasonable quantity of knowledge, and afterwards, if they encounter a device they do not know how to test, they query the society about it. The happiest case is when another agent knows about the given device it responds with the knowledge to the querying agent. If no tester has ever encountered such a device, the tester at a pinch will resort as a last solution to the database which should contain information about all the devices in the network at a given moment. The connector may be either a microagent or a full-blown Java2SE agent residing on a machine close to the database and communicating with the tester microagents. This is the reason why the connector was represented at a different location in figure 1. The connector may perform other tasks as well, e.g. storing the test results into the database. The Visualizer offers the human operator control over the distributed testing process and presents her/him with the test outcomes. This may also be either a microagent or a full-blown one, making use of the extensive GUI facilities offered by Java2SE. Typically, this agent also resides at a separate network location (such as in a control room). The Tester microagents are the main members of the microagent society. They are the ones that manage and perform the actual tests, learn about the devices, and handle the test results. One or more testers reside at each location under test. There may be locations without tester agents, as seen in figure 1, but not where devices that should be tested reside. All communication between agents complies with the FIPA Agents Communication Language (FIPA ACL) standard [7], and shall follow the interaction patterns described in [8]. The society shall be dynamic and fully scalable: new locations may be added, new testers and visualizers may be created at any moment, provided that a DF is present at each newly added location. 3. Experimental results 3.1. JADE-LEAP The first implementation of the specifications above originates in the extension of the work presented in [3] so that the testing society holds tester microagents. The original society was implemented in JADE (Java Agent Development Platform), a powerful agent framework, fully compliant with FIPA standards. The designed tester microagent runs on the JADE-LEAP extension of JADE. JADE-LEAP (Lightweight Extensible Agent Platform) is capable of running under Java2ME, thus enabling an agent to exist on an embedded system. The implemented agent community contains agents running both on Java2SE and Java2ME systems, communicating transparently with each other via the middleware provided by JADE-LEAP. Thus, tester agents capable of performing, storing and searching different test procedures for various devices can reside either on PCs, mobile phones or other embedded devices. The demonstrative scenario tests the display of the mobile phone the tester agent resides on. The following simple set of tests was devised: basic graphical elements tests (labels, tickers etc.) required by the Java2ME specification. base color tests (red, green, blue) for color displays. black and white patterns (such as a dot/blank/dot grid) for monochrome displays.

4 Miclea, Enyedi, Buoniu, Abrudean, Stoian, Vancea 4 of 6 Figure 2. JADE-LEAP microagent backend The resources of the microdevice being limited, storage of all the data related to the agent on the mobile phone is not feasible. JADE-LEAP allows the split of the agent s data between a container running in a PC environment and the device under test. A backend of the agent will be stored in the PC environment, as seen in the screenshot presented in figure 2. This backend is an interface between the agent society container and the microdevice. Each microagent has a name unique in the society, chosen by the operator prior to agent deployment. Figure 3, left shows a screenshot of the connection screen, running in a simulated mobile environment. Figure 3. JADE-LEAP tester microagent screenshots Microagents store data about testing procedures in special structures called record stores. A record store consists of a collection of data which will remain persistent across multiple invocations of the agent. Each testing procedure is identified by name. The operator issues a test by entering the name of the test (figure 3, right). The microagent searches the required testing procedure in the local record stores. If the test procedure is not found locally, the agent asks the agent society for it, and if no other agent knows it, the database is queried. Finally, the agent will store the procedure persistently in a record store. The procedure exemplified in figure 4 tests a mobile phones implementation of the Java2ME specification related to the user interface. A testing procedure consists of a list of display items (labels, gauges, tickers etc.) and questions to be asked for each one. The microagent reads the testing procedure, displays one by one the items contained therein and asks the questions. A test is considered passed if the user answers affirmatively to all questions. The instance showed in the figure tests a ticker (or marquee) which is a piece of text that runs continuously along the display.

5 Limited-Resource Systems Testing with MicroAgent Societies 5 of AgentLight Figure 4. JADE-LEAP tester microagent running a test A more evolved implementation is being developed using the AgentLight software platform. AgentLight is fully FIPA-compliant, and was written in Java 2 Micro Edition specifically for limitedresource systems. The microagents developed under this platform are autonomous, goal-driven, rulebased and capable of learning and sharing their knowledge in a word, intelligent. AgentLight provides an inference mechanism based on Prolog-like first-order logic, but is extensible over Java functionality by internal non-logical rules i.e. Java code sequences, essential for the actual device testing. Each device has a unique identification code, which may be queried by the microagent which is testing it. Using this ID, the tester microagent searches for knowledge that could enable it to determine if the device is functioning correctly. The actual testing of the device is done by raw Java code that adheres to a uniform tests implementation mechanism. The test scenario includes two National Semiconductor SCAN channel, 10:1 serializers with at-speed BIST capabilities, an Epson Electronics S1L35043 LSI CMOS gate array, and a National Semiconductor DP83840A VLSI physical layer device for 10-Base-T and 10-Base-X Ethernet. The visualizer runs in the current stage of the application under Java2SE, and communicates with the tester microagents by FIPA ACL. A screenshot of the GUI of this agent is shown in figure 5. To the left the visualizer outputs a table of known devices at the given location. The devices discovered faulty are visually differentiated. To the right, a history of all operations performed by the testers present at the given location is maintained. Figure 5. A screenshot of the Visualizer agent

6 Miclea, Enyedi, Buoniu, Abrudean, Stoian, Vancea 6 of 6 4. Conclusions and future work Being a natural approach to distributed testing and its management, the multiagent solution, combined with its realization in the Java2MicroEdition environment, offers the possibility of deploying an intelligent, distributed and decentralized testing system at the locations under test. This leads to a number of significant advantages, among which we can count: an increase in the flexibility and scalability of the testing system, which allows for the same qualities of the system under test; the testing software ability of reaching deep into the lower levels of the system under test; greater speed due to parallelism and tasks distribution; a decrease of the communicational overhead, due to decentralized management; easy maintenance and further development of the application, enabled by its high level of modularity. The area future efforts will target is the AgentLight version of the application, specifically behavioral aspects of the microagents, and the increase of testable devices coverage, including a broader variety of embedded devices supporting Java2ME. Tester microagents mobility is also considered, a society of mobile testers being much more adaptable to dynamic systems under test. References 1. L. Miclea, Sz. Enyedi, G. Toderean, A. Benso, P. Prinetto, Agent Based DBIST/DBISR and its Web/Wireless Management, International Test Conference 2003, Charlotte, NC, USA, September 30th - October 2nd, Lucian Busoniu, Multiagent Systems in DBIST and Distributed Testing, eng. diploma thesis, Technical University of Cluj-Napoca, Department of Automation, Sorin Serban, The Use of Multiagent Systems in Testing with ATE 3 s, eng. diploma thesis, Technical University of Cluj-Napoca, Department of Automation, L. Miclea, Sz. Enyedi, G. Toderean, I. Stoian, Web Based / Wireless BIST Management for Distributed Systems, European Test Workshop 2003, Maastricht, The Netherlands, 25th 28th May *** FIPA SC00001, Abstract Architecture Specification, 6. *** FIPA Agent Management Specification, 7. *** FIPA Agent Communication Specifications, 8. *** FIPA XXX Interaction Protocol Specification, ATE Automatic Test Equipment