Dynamic class loading

• US 20020046304A1
• Filed: 10/03/2001
• Published: 04/18/2002
• Est. Priority Date: 10/06/2000
• Status: Abandoned Application

• Current Assignee: ABB Research Ltd. (ABB Limited)
• Original Assignee: ABB Research Ltd. (ABB Limited)
• Inventors: Holle, Jorg, OʼReilly, Cheryl, Auf der Maur, Dominik, Fabri, Andreas
• Application Number:
  US09/968,786
• Publication Number:
  US 20020046304A1
• Time in Patent Office: Days
• US Class Current: 719/331
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading

Abstract

In the inventive method for dynamic class loading, a first computer program unit is remotely invokable by a second program unit, and the first program unit is able to return a software object to the second program unit after being remotely invoked. For the case that a class of the returned object is not known to the second program unit, the inventive method comprises the steps of

a) a publisher of a Java Message System publishing a class file containing a class description of the returned object, and

b) the second program unit acting as a subscriber of the Java Message System and receiving the class file.

This makes it possible that the second program unit receives the class file without having to know from where the class file originates. Furthermore, since the method uses the Java Message System, no internet protocol (IP) addresses and internet communication means are required for communicating with the second program unit.

Claims

1. Method for dynamic class loading in an object oriented computing environment, in which a first computer program unit is executable by a first data processing unit and is remotely invokable by a second computer program unit that is executable by a second data processing unit, where the first program unit is able to return a software object to the second program unit after being remotely invoked, and where a class of the returned object is not known to the second program unit, characterized in that the method comprises the following steps of

a) a publisher of a Java Message System publishing a class file containing a class description of the returned object, and

b) the second program unit acting as a subscriber of the Java Message System and receiving the class file.

2. Method according to claim 1, characterized in that the first computer program unit acts as the publisher publishing the class file.

3. Method according to claim 1, characterized in that the steps according to the method take place prior to a step of transmitting the returned object that is described by the class file to the second program unit.

4. Method according to claim 1, characterized in that the steps according to the method are preceded by the following steps of

x) the first program unit transmitting the returned object that is described by the class file to the second program unit,

y) the second program unit determining that a class file describing the returned object is not known to the second program unit,

z) the second program unit requesting the class file by sending a message with a class request.

5. Method according to one of the preceding claims, characterized in that the transmission of class files, objects and requests is accomplished through the Java Message System.

6. Method according to claim 1, characterized in that the first and the second data processing unit are in separate locations.

7. Method according to claim 1, characterized in that the first and second computer program units are methods of objects that are executable on a first and second Java Virtual Machine, respectively.

8. Method for dynamic class loading in an object oriented computing environment, in which a first computer program unit is executable by a first data processing unit and is remotely invokable by a second computer program unit that is executable by a second data processing unit, where the first program unit is able to return a software object to the second program unit after being remotely invoked, and where a class of the returned object is not known to the second program unit, characterized in that the method comprises the following steps being performed by the second program unit:

a) subscribing to a Java Message System,

b) receiving a class file containing a class description of the returned object,

c) deserializing the class file and storing a representation of the corresponding class.

9. Computer program for dynamic class loading which is executable on a data processing unit and comprises a class loader program unit for deserializing and loading class files that describe a software object and which computer program is able to remotely invoke another program unit and to receive a returned software object from the other program unit, characterized in that the computer program, when being executed,

a) subscribes to at least one topic of a Java Message System,

b) is able to receive a class file through the Java Message System,

c) upon receiving the class file through the Java Message System, deserializes it and stores a representation of the corresponding class.

10. Computer program product with a machine readable medium on which a computer readable program code representing the computer program of claim 9 is stored.