Computer system having agent retracting method and agent returning method

• US 6,065,040 A
• Filed: 12/03/1997
• Issued: 05/16/2000
• Est. Priority Date: 07/07/1997
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Mima, Yoshiaki, Yamamoto, Gaku, Kosaka, Kazuya
• Primary Examiner(s): Asta, Frank J.
• Assistant Examiner(s): PIERCE, IVAN
• Application Number:
  US08/984,154
• Time in Patent Office: 895 Days
• Field of Search: 709/202, 709/217, 709/206, 395/200.32, 395/200.47, 395/200.36, 707/100-103
• US Class Current: 709/202
• CPC Class Codes: H04L 63/029 Firewall traversal, e.g. tunnelling or, creating pinholes
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation

Abstract

An apparatus and method retracts a mobile agent from a second execution environment back to a first execution environment, the retraction being performed by the first environment sending a retraction request, and the second execution environment establishing a connection to the first execution environment in response. The second execution environment searches for an agent under its control corresponding to an agent identity in the retraction request, and converts the corresponding agent, if located, to a bit sequence and returns the bit sequence to the first execution environment via the connection. Sending the bit sequence through the established connection safely alleviates firewall issues because a connection is established from the inside of the firewall to the outside.

Claims

1. A computer for active and inactive mobile agents having an identity data ID, comprising:

computer means for establishing a first execution environment for the active and inactive mobile agents;

computer means for establishing a second execution environment for the active and inactive mobile agents;

a connection module associated with said first execution environment for establishing a connection from said first execution environment through a network to said second execution environment;

a retraction module associated with said first execution environment for transmitting a retraction request having an ID of an agent under management of the second execution environment, via the connection established by the connection module;

a module associated with said second execution environment for searching for an agent within said second execution environment corresponding to said ID and, based on a result of said search, transmitting a bit sequence representation of an agent corresponding to said ID;

notification means for notifying the mobile agent to be retracted if it is in the active state, otherwise forwarding means for forwarding the corresponding pointer of the mobile agent to be retracted to the communication module; and

a module associated with said first execution environment for receiving the bit sequence via the established connection.

2. A computer system according to claim 1, wherein the second execution environment further comprises a conversion module for converting an agent being executed on the second execution environment into the bit sequence representation.

3. A computer system according to claim 2, wherein the conversion module converts the bit sequence into a form executable on the second execution environment.

4. A computer system for active and inactive mobile agents having an identity data ID, comprising:

a computer means for establishing a first execution environment for the active and inactive mobile agents, said first execution environment having a module for generating a first connection request and having a module for generating a first agent retraction request over a connection between the first and a second execution environments, the first agent retraction request having an agent ID;

a computer means for establishing the second execution environment for the active and inactive mobile agents;

a network connecting said first computer means to said second computer means, wherein said second execution environment includes;

a connection establishing module for establishing the connection through the network with the first execution environment in response to receiving the first connection request from the first agent execution environment;

a search module for performing a search of the agents under management of the second agent execution environment in response to reception of the first agent retraction request, and said retraction request being transmitted from the second agent execution environment via the established connection, and for generating a search result data representing a result of the search;

a conversion module for converting, in response to the search result data, an agent having an ID the same as the ID of the first retraction request into a bit sequence of said agent;

notification means for notifying the mobile agent to be retracted if it is in the active state, otherwise forwarding means for forwarding the corresponding pointer of the mobile agent to be retracted to the communication module; and

a module for transmitting the bit sequence to the first execution environment via the established connection.

5. A computer system according to claim 4, wherein the search module of the second execution environment comprises:

a module for searching among agents being executed on the second execution environment for an agent having an ID corresponding to the ID of the first retraction request and for generating a first search result in response; and

a module for notifying, based on the first search result, the agent being executed having an ID corresponding to the ID in the first retraction request of reception of the first retraction request.

6. A computer system according to claim 4,

wherein the second computer means comprises a storage means for storing agents in an inactive form, and

wherein the conversion module for the second execution environment converts agents into an inactive form, stores the inactive form agents in the storage means, retrieves the inactive form agents from the storage means, and converts the retrieved inactive form into an active form for execution in the second execution environment;

an agent status table for storing a plurality of agent status entries representing a status and a record of agents with the second execution environment, said agent status entries each including an ID of an agent, an active/inactive status data for said agent, and a storage location in the storage means for an inactive form of the agent;

a module for maintaining the active/inactive status data and storage location entries in the agent status table, the entries corresponding to the conversion module'"'"'s converting, storage, retrieving and and reconverting operations;

a module for searching the agent status table based on the first retraction request and for generating the search result data based on said searching; and

a module for notifying the transmitting module, based on the search result data, of the storage location of an agent indicated by the agent status table as having an inactive form stored in the storage medium at said location, and wherein the transmitting module has provision for transmitting the bit sequence from said location to the first execution environment.

7. A computer system according to claim 4, further comprising a computer means for establishing at least one other execution environment for the mobile agents, and

wherein the second computer means has an agent movement status table for storing a plurality of agent movement entries, each entry having an ID of an agent moved from the second execution environment to a destination execution environment among said another execution environments, and each entry having a destination data identifying the destination execution environment, and

wherein the second execution environment further comprises:

a module for maintaining the movement entries in the movement status table according to movement of agents from said second execution environment;

a module for searching the movement status table based on the first retraction request and for generating a location search result data based on said searching, the location search result data identifying any entry in the movement status table having an ID corresponding to an ID of the first retraction request and the destination data of said entry;

a second connection establishing module for establishing a connection through the network with a destination execution environment corresponding to the destination data of said entry identified by the location search result data; and

a module for generating a second retraction request, having an ID corresponding to the first retraction request and for transmitting said second retraction request to said destination execution environment via the connection established by the second connection establishment module.

8. A computer system according to claim 7, wherein the movement status table does not store entries for movement of agents moving from the second execution environment in response to a retraction request.

9. A computer system according to claim 5,

wherein the second execution request further comprises a module for generating a notification that the first retraction request has been received,

and further comprising an agent on the second execution environment having an ending operation module which receives said notification and, in response, executes an ending operation for a retraction of said agent to the first execution environment.

10. A computer system according to claim 9, wherein said agent further comprises a module for notifying the first agent execution environment that a process of the ending operation module has finished.

11. A storage medium for storing a bit sequence of active and inactive mobile agents, said agents comprising:

a predefined ending operation method for a retraction, said predefined ending operation invoked in response to a notification that is output from a first agent execution environment when the first agent execution environment receives a retraction request including an ID of an active or inactive mobile agent via a connection with a second agent execution environment.

12. An active or inactive mobile agent retracting method which is executed by a first agent execution environment in a first computer system connected to a network to retract an active or inactive mobile agent from a second agent execution environment in a second computer system connected to the network, the active or inactive mobile agent retracting method comprising the steps of:

establishing a connection with the second agent execution environment;

transmitting a retraction request including an ID of an agent under management of the second agent execution environment via the established connection;

notifying the mobile agent to be retracted if it is in the active state, otherwise forwarding the corresponding pointer of the mobile agent to be retracted to the communication module; and

receiving a bit sequence of the active or inactive mobile agent having the ID transmitted from the second agent execution environment via the established connection.

13. An active or inactive mobile agent returning method which is executed by a first agent execution environment in a first computer system connected to a network to return an active or inactive mobile agent to a second agent execution environment in a second computer system connected to the network, the active or inactive mobile agent returning method comprising the steps of:

establishing a connection with the second agent execution environment in response to a connection establishment request from the second agent execution environment;

searching among active and inactive mobile agents under management of the first agent execution environment in response to reception of a retraction request including an ID of an active or inactive agent, said retraction request transmitted from the second agent execution environment via the established connection;

transmitting a retraction request including an ID of an agent under management of the second agent execution environment via the established connection; and

notifying the mobile agent to be retracted if it is in the active state, otherwise forwarding the corresponding pointer of the mobile agent to be retracted to the communication module.

14. An agent returning method according to claim 13, wherein the searching step comprises the steps of:

searching among agents being executed; and

notifying the agent having the same ID as said ID in the retraction request of reception of the retraction request if the agent having the same ID is being executed.

15. An agent returning method according to claim 14, wherein the searching step comprises the steps of:

searching among agents not being executed; and

taking out and transmitting a bit sequence of the agent having the same ID as said ID in the retraction request if the agent having the same ID is not being executed.

16. An agent returning method according to claim 14, further comprising the steps of:

storing an ID of an agent and a destination address thereof in a storage area,

wherein the searching step comprises the steps of;

searching the storage area; and

establishing a connection with a third agent execution environment that is the destination of the agent having the same ID as said ID in the retraction request if the agent having the same ID has already moved.

17. An agent returning method according to claim 14, further comprising the steps of:

said agent having the same ID as said ID in the retraction request receiving a notification that the retraction request has been received; and

said agent performing an ending operation for the retraction.

18. A storage medium for storing a program to be executed in a computer system connected to a network, said storage medium including a program for providing a first agent execution environment, said program comprising the steps of:

causing the first computer system to establish a connection with a program for providing a second agent execution environment in a second computer system connected to the network;

causing the computer system to transmit, via the established connection, a retraction request including an ID of an active or inactive agent under management of the program for providing the second agent execution environment;

notifying the mobile agent to be retracted if it is in the active state, otherwise forwarding the corresponding pointer of the mobile agent to be retracted to the communication module; and

causing the computer system to receive a bit sequence of the active or inactive agent having the ID transmitted from the program for providing the second agent execution environment via the established connection.

19. A storage medium according to claim 18, said program further comprising the step of:

causing the computer system to convert an agent being executed on the first agent execution environment into a bit sequence.

20. A storage medium for storing a program to be executed in a computer system connected to a network, said storage medium including a program for providing a first agent execution environment, said program comprising the steps of:

causing the first computer system to establish a connection with a program for providing a second agent execution environment in a second computer system connected to the network in response to a connection establishment request from the program for providing the second agent execution environment;

causing the computer system to search among active or inactive agents under management of the program for providing the first agent execution environment in response to reception of a retraction request including an ID of an agent, said retraction request transmitted from the program for providing the second agent execution environment via the established connection;

notifying the mobile agent to be retracted if it is in the active state, otherwise forwarding the corresponding pointer of the mobile agent to be retracted to the communication module; and

causing the computer system to transmit a bit sequence of an active or inactive agent having the same ID as said ID in the retraction request via the established connection.

21. A storage medium according to claim 20, wherein the causing to search step comprises the steps of:

causing the computer system to search among agents being executed; and

causing the computer system to notify the agent having the same ID as said ID in the retraction request of reception of the retraction request if the agent having the same ID is being executed.

22. A storage medium according to claim 20, wherein the causing to search step comprises the steps of:

causing the computer system to search among agents not being executed; and

causing the computer system to take out and transmit a bit sequence of the agent having the same ID as said ID in the retraction request if the agent having the same ID is not being executed.

23. A storage medium according to claim 20, said program further comprising the step of:

causing the computer system to store an ID of an agent and a destination address thereof in a storage area,

wherein the causing to search step comprises the steps of;

causing the computer system to search the storage area; and

causing the computer system to establish a connection with a third agent execution environment that is the destination of the agent having the same ID as said ID in the retraction request if the agent having the same ID has already moved.