Abstract:
An agent system which can be loaded onto a computer in a network is adjusted based on the hardware and/or software of the computer. This makes it possible to incorporate even small mobile computers, in particular simple process computers, into a network in which agent systems are installed on the individual computers, without the power of the agent system needing to be significantly restricted in principle and without needing to dispense with the fundamental applicability of agent systems for small computers.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is based on and hereby claims priority to PCT Application No. PCT/DE00/02705 filed on Aug. 11, 2000, German Patent Application No. 199 39 058.4 filed on Aug. 18, 1999, the contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   The invention relates to an agent system, in particular an agent system for mobile agents, to a computer network having a plurality of computers networked by data lines and to a method for loading an agent system from a host computer onto a client computer. 
   Agents are autonomous, cooperative software units comprising code and data. They are independently operating software units which require no continual interaction with the user. There are both static and mobile agents. 
   Mobile agents are known, by way of example, from U.S. Pat. No. 5,603,031 and from the book Software Agents, Bradshaw Jeffrey, Menlo Park, Calif.: AAAI Press/The MIT Press, 1996. The chapter on mobile agents in this book can be retrieved in a slightly modified version on the Internet at the address http://www.generalmagic.com/technology/techwhitepaper.html. 
   Mobile agents are programs which can be active at various stations in a computer network and can change their location in the computer network. Conventionally, programs in a network are loaded from one computer onto another computer while they are not active. By contrast, mobile agents are first activated and automatically change their position in the network while they are active. 
   This small but fundamental difference with respect to conventional programs has considerable effects on the type of applications on the mobile agents in the network. The agents are created at a particular station in the network, which involves stipulating the functions needing to be performed by the agent, so that the agent, having been transmitted to another station in the network, represents the previous station in the network and performs the appropriate functions. This means that functions can be stipulated at one station in the network which are performed at another station in the network. In principle, this is also possible with conventional systems, with this requiring a permanent exchange of information in the network between the two stations so that the station at which the appropriate control operations are stipulated transmits them to the station at which they are performed. 
   By contrast, the mobile agents require no such control operations, since their functions are stipulated once in advance and are then performed automatically. This significantly reduces the data throughput in the network, with any desired operations being able to be performed at the stations remote from the task issuer. 
   However, the agents do not always need to operate fully detached from their initiator, but rather can set up communication channels thereto or also to other stations in the network. 
   When moving from one station in a network to another station in the network, the mobile agents execute a migration command (e.g. “go”). Such a command requires a destination description containing the name, address or type of the station to which the agent is intended to move, or a combination of these. Different stations do not always need to be arranged at different computers in the network. It is also possible for agents to be active at different stations within one computer. 
   Mobile agents can also multiply, so that they perform their functions independently of one another at different stations. 
   Mobile agents are frequently used for collecting predetermined data, some of which are evaluated in situ, so that an already preprocessed result is sent to the original task issuer. 
   One possible application for such mobile agents arises, by way of example, when a purchaser of a particular object receives a low price guarantee from the vendor. The purchaser can then send out one or more mobile agents which independently obtain corresponding offers from other suppliers, possibly monitor them over a certain period of time and send them to the purchaser, so that he can compare them with the price offered by the vendor. 
   Other, known mobile agents and agent systems are marketed under the names Aglets, Voyager and Concordia and can generally be obtained over the Internet. 
   So that the mobile agents on the individual computers in the network can be active, these computers need to have a respective “agent system”. An agent system is a collection of service programs which need the respective agents for their tasks. These service programs generally comprise an agent manager connected to other service programs, so that the active mobile agents can fall back on the respective computer resources and can migrate from one agent system in the network to another agent system in the network via network interfaces. Generally, an agent system controller is provided which regulates the execution of the agent system on the respective computer. 
   These agent systems form the stations in the network at which the agents can become active. 
   Such agent systems are generally written in a platform-independent computer language, such as JAVA, so that they can run on any computer systems. 
   The transfer of the agents in the network while they are active creates a new programming paradigm according to which the program code itself is moved to the data needing to be processed instead of data being transported to the processing code or the processing code needing to be loaded in the inactive state onto the respective computer. 
   Agents are generally relatively small programs which are sent out and exploit the intelligence available in situ. Since mobile agents can also perform their tasks when there is no permanent network connection between the individual computers, they are ideally suited to use on mobile computers, which are generally not permanently connected to a network. 
   However, the agent systems known to date are too extensive for them to be able to be installed on arbitrary simple mobile computers. 
   Within the context of the present patent application, the term computer also covers simple process computers equipped merely with a minimal hardware configuration (processor, memory and display). Such simple process computers are integrated on a single chip, for example. 
   SUMMARY OF THE INVENTION 
   One possible object of the invention is to provide an agent system which is able to offer the scope of functions of known agent systems and is nevertheless also suitable for small computers, such as small process computers. 
   Another possible object of the invention is to provide an appropriate computer network and a method for loading an agent system from a host computer onto a client computer in a computer network. 
   The agent system, which can be installed on computers connected in a computer network, has an agent platform and an agent system controller. The agent platform comprises service programs required by a mobile agent in order to be able to be executed on the respective computer. The agent system controller contains an agent system launcher which can be loaded onto a client computer independently of the rest of the agent system and is used for loading the agent system from a host computer. 
   The agent system is distinguished in that the agent system launcher is designed such that, before an agent system is loaded from a host computer onto the client computer on which at least the agent system launcher is installed, an identifier describing the hardware and/or software of the client computer is sent to the host computer, and a server system, the agent system update program, installed on the host computer is designed such that it takes the identifier describing the hardware and/or the software of the client computer as a basis for compiling an agent system adjusted to the hardware and/or software of the client computer and loads this agent system onto the client computer. 
   Within the context of the present invention, a host computer is any computer in the network from which it is possible to load an agent system onto another computer, which is referred to as a client computer. It is thus possible for any computer in the network to be a host computer and a client computer, irrespective of its function otherwise in the network. 
   The agent system launcher, which sends an identifier identifying the client computer to the host computer, and the agent system which is installed on the host computer and takes this identifier as a basis for compiling an adjusted agent system and makes this adjusted agent system available to the client computer make it possible for even small, in particular mobile, computers, for example comprising a simple process computer or a personal digital assistant, to be incorporated into a computer network and to be provided with the agent system, since this agent system is automatically adjusted to the respective client computer and its power. 
   Typical criteria for adjustment are, by way of example, the display (e.g. color picture tube, color LCD screen, b/w LCD screen, small alphanumeric LCD display or small numeric only display), the available memory space and the available memory medium (RAM, hard disk or the like) or the system software available on the computer (JAVA and derivatives thereof, Windows, Windows-CE, etc.). 
   The individual adjustment of the agent systems installed on the respective computer means that high powered computers can have agent systems with a correspondingly high scope of performance installed on them, and lower powered computers can have simplified agent systems installed on them which are specifically tailored to the available software and hardware, including any peripheral units which are available. 
   Another advantage of the agent system is automatically adjusted to the respective environment or the computer and its installed software, so that nobody need worry about the correct configurations of the agent systems on the various computers in a network, even if it is not yet known from the outset which terminals are present on the network. This means that an environment can automatically develop in a network. The individual computers in the network need merely have agent system launchers installed on them. 
   In a network in which a full agent system has been installed on a single computer, it is sufficient, in principle, for only the agent system launcher to be installed on other computers onto which such an agent system is intended to be loaded, said agent system launcher then requesting, loading and starting an agent system adjusted to its environment. 
   Another advantage of the agent system is that the agent system launcher can be provided with an update function which tests whether a host computer is able to request a more recent version of the agent system and, if this is possible, the more up to date version of the agent system is requested, loaded on the client computer and started. Since such updates can generally rarely be performed, it is expedient for a full new agent system to be loaded in each case during an update. With very extensive agent systems which are regularly modified, it can be useful to use the update function to test whether individual parts of the agent system on the host computer are more up to date than those on the client computer, in which case possibly only individual parts of the agent system are then loaded from the host computer onto the client computer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention will become more apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  shows a network by which a plurality of computers are connected together and on which a respective agent system has been installed, 
       FIG. 2  shows a block diagram of the design of an agent system, and 
       FIG. 3  shows a flowchart for the method for loading an agent system from a host computer onto a client computer in a computer network. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     FIG. 1  is a simplified schematic illustration of a network having a plurality of computers  1  which are connected to one another by data lines  2 . The computers  1  have different scopes of performance, that is to say that they can have different processor powers, storage capacities and/or system programs. The power of the individual computers  1  is shown symbolically by the size of the rectangle representing the respective computer  1 . The computers  1  are numbered from I. to IV., where the computer I. can be the most powerful and the computer IV. is a mobile terminal. The data line  2  from the computer IV. to the other computers is a mobile radio link which is not maintained permanently. It is therefore shown using a dashed line in  FIG. 1 . 
   The individual computers  1  have a respective agent system AS-I. to AS-IV. installed on them. The network contains a few mobile agents AG-I. to AG-IV., which are either arranged on one of the computers  1  or move from one computer to another (III.→II.). 
     FIG. 2  is a schematic illustration of the design of an agent system. The agent system has an agent platform  3  (also called platform) which comprises the service programs required by a mobile agent in order to be able to be executed on the respective computer  1 . The agent platform  3  has two central program parts, the agent manager  4  and the communication manager  5 . The communication manager  5  comprises a blackboard  6  and a plurality of protocol managers  7  providing the protocols for communication between agent systems and their applications, the agents  25 . In addition, the communication manager allows the agents to migrate. A network coupling  8  is used by the protocol managers  7  to allow the appropriate use of a connected network  9 . The blackboard  6  can be used to buffer store data for the platform local communication between agents. 
   The agent manager  4  has a monitoring module  10  which is used to monitor internal operations for applications  25  connected to the agent manager  4 . The monitoring information is processed by service programs, such as an agent software update program  11 , a user manager  12 , a security manager  13  and a resource manager  14 . The agent manager  4  is also connected to a read only memory  15 , for example represented by a hard disk. The read only memory  15  is used to store configuration data and important runtime information, such as agents, so that these are available again even after temporarily switching off. In small mobile computers IV, it is also customary for this read only memory  15  to be in the form of a semiconductor memory which can store data permanently, i.e. even after the computer has been switched off. 
   The agent manager  4  is provided with an administration interface  19  and an agent application interface  20 . The administration interface  19  is used to connect the agent manager  4  to an agent system controller  21  which has an administration program  22  and an agent system launcher  23   a  and also an agent system update program  23   b . The agent system launcher  23   a  is a service program which assists a user when starting and installing an agent system. The agent system update program  23   b  is a service program which can take particular presets as a basis for compiling an agent system and for sending it over the network  9 . The agent system update program  23   b  is generally part of an existing agent system. However, it can also be installed on a computer independently of an agent system. 
   The agent application interface  20  is used to connect the agent manager  4  to an area of application  24  containing agents  25  which can execute particular applications. The agents  25  can reach the area of application  24  via the network  9 , the communication manager  5  and the agent manager  4 . Alternatively, a user of the computer on which the available agent system has been installed can load them into the area of application  24  using an agent launcher  26 , and they can be activated in said area of application. The agent launcher  26  is a service program which assists a user in creating and activating agents  25 . 
   The administration program  22  of the agent system controller  21  assists users in configuring and diagnosing the agent system. 
   The agent system launcher  23   a  of the agent system controller  21  is used for starting and loading the agent system onto a computer in the network. The operations performed in this context are shown in the flowchart shown in  FIG. 3 . 
   In order for this method for loading an agent system onto a computer to be possible, the computer onto which the agent system is being loaded and which is referred to below as the client computer  28  needs to have the agent system launcher  23   a  loaded on it. The client computer  28  needs to be connected by a data line  2  to at least one computer on which an agent system update program  23   b  has been installed, so that this computer, which is referred to below as the host computer  29 , makes an adjusted or scaled copy of an agent system which is likewise available on it and can load it onto the client computer  28 . The data line  2  can be an electronic or optical cable or a radio link. 
   The method for loading and updating an agent system is carried out by the agent system launcher  23   a  and is started in a step S 1  ( FIG. 3 ). This is followed by a test to determine whether an agent system AS already exists on the computer (S 2 ). If this test reveals that no agent system exists on the present computer yet, program execution passes to step S 3 , which is part of a loading function  30  associated with the agent system launcher  23   a . In step S 3 , an identifier identifying the hardware and/or software of the client computer  28  is sent to the host computer  29 . This identifier contains statements relating to the power of the hardware and/or the software, such as the size of the available memory, the type of storage medium, the type of display and of the available system programs. 
   On the host computer, the identifier sent by the client computer  28  is assessed in a step S 4 , and an agent system is compiled in a step S 5  on the basis of the identifier. The agent system is adjusted by adding or omitting components which are suitable/required or not required and configuring and scaling the selected components for the hardware and software available on the client computer  28 . In addition, the components are configured in terms of their dynamic complexity, which is essentially based on the size of data structures. Besides the agent manager and the communication manager, the scalable service programs, such as the user manager  12 , the security manager  13  and the resource manager  14 , are adjusted, that is to say are scaled to the client computer  28 . Steps S 4  and S 5  are performed in the agent system update program  23   b  arranged in the agent system controller  21  on the host computer  29 . 
   When an agent system adjusted to the client computer  28  has been configured, this adjusted agent system is sent from the host computer  29  to the client computer in step S 6 . On the client computer  28 , the agent system is received and loaded onto the client computer  28  in step S 7 . Step S 7  is part of the loading function  30  of the agent system launcher  23 . When the agent system has been loaded from the client computer, it is started in step S 8 , and the method for loading the agent system is then terminated in the subsequent step S 9 . 
   When the agent system is started in step S 8 , a starting and initialization routine (step S 9 ) is called and is used to start and initialize the agent system. A startup sequence S 10  is used to load stored agents (step S 11 ). “Normal” operation of the agent system can then be executed, which is denoted by S 12  in  FIG. 3 . If operation of the agent system needs to be terminated, the agents and runtime information for the agent system are first stored with a shutdown sequence (step S 13 ). The agents are then terminated and the agent system is terminated (step S 14 ). 
   If, on the other hand, step S 2  described above establishes that an agent system already exists on the client computer  28 , program execution passes to step S 15 , which tests whether updating of the agent system is permitted. If updating of the agent system is not permitted, program execution passes to step S 16 , which tests whether the agent system is in operation. If the agent system is not in operation, it is started in step S 8  and the agent system launcher  23   a  is terminated in step S 9 . If the agent system is already in operation, program execution passes directly to step S 9 , where the agent system launcher  23   a  is terminated. 
   If the test in step S 15  reveals that updating of the agent system is permitted, program execution passes to step S 17 , which tests whether the agent system is in operation. 
   If the agent system is in operation, step S 18  calls step S 13  (shutdown sequence) in order to terminate the operation of the agent system. A subsequent program loop (step S 19 ) is used to test whether operation of the agent system has already ended. Only if the operation of the agent system has ended is program execution transferred to a step S 20 . 
   If the test in step S 17  reveals that the agent system is not in operation, program execution can pass directly to step S 20 . 
   With step S 20 , a version identifier is sent to the host computer  29 . The version identifier contains the information relating to the versions of the agent system, and components thereof, installed on the client computer  28 . 
   On the host computer  29 , the version identifiers are evaluated in step S 21  and, in the next step S 22 , version information for the most recent agent system, and components thereof, which can be loaded from the host computer are sent to the client computer. In step S 23 , the client computer  28  then compares its own version identifiers with the version information and of the host and tests whether the respective version which can be loaded from the host computer is more up to date than the version of the agent system, and components thereof, which is on the client computer. If the test reveals that the version which can be loaded from the host computer  29  is more up to date, program execution is transferred to step S 3 , whereupon an identifier identifying the hardware and/or software of the client computer  28  is in turn sent to the host computer, and the latter then compiles an agent system adjusted thereto and sends it to the client computer  28 . If, on the other hand, the test in step S 23  reveals that the versions which can be loaded from the host computer are not more up to date than the versions of the agent system, and components thereof, which are on the client computer, program execution is transferred to step S 8 , where the agent system is started. Hence, it is possible to update (during operation) the entire agent system or, if required, merely parts thereof. 
   Steps S 20  and S 23  form an update function  31  which the agent system launcher  23   a  uses to update an existing agent system. 
   The method for loading an agent system is carried out by the agent system launcher  23   a . The agent system launcher can be started manually at any time, irrespective of whether or not an agent system is available or whether or not the agent system is in operation. The agent system launcher  23   a  can also be activated automatically when it is first loaded onto a computer or when a computer is started. If a full agent system already exists, then the agent system launcher  23   a  can be controlled directly by the user or by the administration program  22 , with the administration program  22  being able to call it repeatedly, thus ensuring that the agent system is updated regularly and according to requirements. 
   To manage the agent systems on a plurality of mobile client computers  28 , a host computer  29  permanently connected to a network can be provided. If, by way of example, a small mobile computer, the client computer  28 , having a black and white screen is to start an agent system, then the host computer  29  sends a request to the client computer  28  and in so doing also transfers the current data relating to its resources (e.g. b/w screen, 8 MB RAM, maximum number of windows which can be shown on the screen, Java Virtual Machine available, graphical display of characters, user management functionality in the agent system for one or more users, etc.). The host computer  29  uses this information to compile an agent system which contains, by way of example, a Java class for printing specifically on b/w appliances. The equivalent class for printing on appliances with a color screen or a screen which can show only ASCII characters would have a different appearance. Depending on a Java Virtual Machine (Persona Java, JDK1.x, 1.2, etc.) available on the client computer  28 , the appropriate classes are compiled automatically. If only one user needs to be managed, as compared with a plurality, the appropriate class providing the user management is also correspondingly smaller and has a smaller resource requirement on the client computer  28 . 
   The agent system can optionally be provided with a function which automatically tests the hardware and/or software of the respective computer and starts the launcher  23   a  if required. This means that the agent system can be adjusted dynamically to changes in the hardware and/or in the software. This function can be provided by step S 24  in  FIG. 3 , which follows step S 17 . Step S 24  tests whether the hardware and/or software has been changed since the agent system was last updated. If such a change is established, program execution passes directly to step S 3 , where an appropriate identifier is sent to the host computer  29 . If such a change is not established, the program passes to step S 20  and is executed in line with the description above. The programs on which the agent systems are based can be stored and sold on electronically readable data stores. 
   The invention has been described in detail with particular reference to preferred embodiments thereof and examples, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.