Mechanism to load first version classes into a runtime environment running a second version of the class

• US 7,543,002 B2
• Filed: 01/18/2005
• Issued: 06/02/2009
• Est. Priority Date: 12/02/2004
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: BEA Systems Incorporated (Oracle Corporation)
• Inventors: Ghattu, Satya Srinivas, Simpson, Franklin Fulton
• Primary Examiner(s): Breene; John E
• Assistant Examiner(s): Sweeney; Patrick E
• Application Number:
  US11/037,482
• Publication Number:
  US 20060123067A1
• Time in Patent Office: 1,596 Days
• Field of Search: 707/203, 707/8
• US Class Current: 1/1
• CPC Class Codes: G06F 9/44552 Conflict resolution, i.e. enabling coexistence of conflicting executables
• CPC Class Codes: G06F 9/45504 Abstract machines for programme code execution, e.g. Java virtual machine [JVM], interpreters, emulators
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

Mechanisms and methods for loading a first version of a class into a second version runtime environment running a second version of the class. The runtime environment may be comprised of a Java Virtual Machine (JYM). These mechanisms and methods make it possible for applications to retrieve and convert legacy data into current versions of the runtime environment. The conversion of data may be done automatically and/or transparently to a user or calling process.

Claims

1. A method for loading a first version of a class into a second version of a runtime environment running a second version of the class, the method comprising the computer implemented steps of:

instantiating an object in a first version of a runtime environment wherein the object is an instance of a first version of a class loaded in a first version of a class loader;

serializing the object to create a serialized object and storing the serialized object on a storage medium;

allowing the first version of the class to be modified to create a second version of the class, wherein the second version of the class has a different definition from the first version of the class;

loading a second version of the class in a second version of a class loader for a second version of the runtime environment;

receiving the serialized object in the second version of the runtime environment, wherein the first version of the class is incompatible with the second version of the class loader for the second version of the runtime environment;

constructing a class file with a class file name for the class that represents the serialized object and a serial version identifier for the first version of the class;

loading, into the second version of the runtime environment, the serialized object using the class file as constructed in an auxiliary class loader compatible with the first version of the class; and

converting information from the serialized object into an intermediate storage format for use with the second version of the runtime environment.

2. The method of claim 1, wherein

the first version of the class is compatible with a first version of the runtime environment, wherein modifying the first version of the class to yieid the second version of the class renders the first version of the class incompatible with the second version of the class loader of the second version of the runtime environment.

3. The method of claim 2, wherein a first party controlling the second version of the class is blocked from changing the first version of the class by a second party'"'"'s control over the first version of the class.

4. The method of claim 3, wherein the first party creates the second version of the class by modifying the first version of the class prior to relinquishing control over the first version of the class to the second party.

5. The method of claim 3, wherein the second party creates the second version of the class by modifying the first version of the class after receiving control over the first version of the class from the first party.

6. The method of claim 2,

wherein the first version of the class is a serializable java class lacking a SerialVersion ID;

thereby causing the first version of the class to be barred from being loaded in the second version runtime environment by the second version class loader.

7. The method of claim 1, futher comprising:

defining the auxiliary class loader; and

adding the first version class to a classpath of the auxiliary class loader.

8. The method of claim 1, wherein converting information according to the first version of the class into an intermediate storage format further comprises:

converting information according to the first version class into at least one of a string, an XML object, a hashmap and a Java object.

9. The method of claim 1, further comprising:

providing the intermediate storage format data to a process or user requesting loading of the first version of the class.

10. The method of claim 1, further comprising:

loading a second version of the class using a second version of the class loader, the second version of the class loader being incompatible with the first version of the class.

11. The method of claim 1, wherein the second version of the runtime environment comprises a modified version of the first version of the runtime environment.

25. The computer-implemented method of claim 1, wherein the step of constructing a class file with a class file name for the class that represents the serialized object and a serial version identifier for the first version of the class comprises:

loading the serialized object into a first virtual machine that does not contain a version of the serializable class;

receiving a first message that contains the name of the serializable class;

constructing a first class file with the name of the serializable class;

loading the first class file in a second virtual machine that contains the second version of the serializable class;

receiving a second message listing an expected serial version identifier;

constructing a second class file with the name of the serializable class and the expected serial version identifier;

loading the second class file in the second virtual machine;

receiving a third message listing required data members; and

constructing a third class file with the name of the serializable class, the expected serial version identifier, and the required data members.

12. The method of claim l, wherein selecting an intermediate storage format for the information for use with the second version runtime environment comprises:

selecting a hashmap as intermediate storage format for the information if the first version class comprises name/value pairings;

selecting an eXtended Markup Language (XML) object as intermediate storage format for the information if the first version class comprises metadata; and

selecting a string object as intermediate storage format for the information if the first version class comprises a long string data.

13. A computer-readable storage medium storing one or more sequences of instructions for loading a first version of a class into a second version of a runtime environment running a second version of the class, which instructions, when executed by one or more processors, cause the one or more processors to carry out the steps of:

instantiating an object in a first version of a runtime environment wherein the object is an instance of a first version of a class loaded in a first version of a class loader;

serializing the object to create a serialized object and storing the serialized object on a storage medium;

allowing the first version of the class to be modified to create a second version of the class, wherein the second version of the class has a different definition from the first version of the class;

loading a second version of the class in a second version of a class loader for a second version of the runtime environment;

receiving the serialized object in the second version of the runtime environment, wherein the first version of the class is incompatible with the second version of the class loader for the second version of the runtime environment;

constructing a class file with a class file name for the class that represents the serialized object and a serial version identifier for the first version of the class;

loading, into the second version of the runtime environment, the serialized object using the class file as constructed in an auxiliary class loader compatible with the first version of the class; and

converting information from the serialized object into an intermediate storage format for use with the second version of the runtime environment.

14. The computer-readable storage medium as recited in claim 13, wherein

the first version of the class being compatible with a first version runtime environment, wherein modification to the first version of the class to yield the second version of the class has rendered the first version class incompatible with the second version class loader of the second version runtime environment.

15. The computer-readable storage medium as recited in claim 14, wherein a first party controlling the second version of the class is blocked from changing the first version of the class by a second party'"'"'control over the first version of the class.

16. The computer-readable storage medium as recited in claim 15, wherein the first party creates the second version of the class by modifying the first version of the class prior to relinquishing control over the first version of the class to the second party.

17. The computer-readable storage medium as recited in claim 15, wherein the second party creates the second version of the class by modifying the first version of the class after receiving control over the first version of the class from the first party.

18. The computer-readable storage medium as recited in claim 14,

wherein the first version of the class is a serailizable java class lacking a Serial Version ID;

thereby causing the first version of the class to be barred from being loaded in the second version runtime environment by the second version class loader.

19. The computer-readable storage medium as recited in claim 13, wherein the instructions further comprise instructions for carrying out the steps of:

defining the first version class loader; and

adding the first version class to a classpath of the first version class loader.

20. The computer-readable storage medium as recited in claim 13, wherein the instructions for carrying out the step of converting information according to the first version of the class into an intermediate storage format further comprise instructions for carrying out the steps of:

converting information according to the first version of the class into at least one of a string, an X M L object, a hashmap and a Java object.

21. The computer-readable storage medium as recited in claim 13, further comprising instructions which, when executed by the one or more processors, cause the one or more processors to carry out the steps of:

providing the intermediate storage format data to a process or user requesting loading of the first version of the class.

22. The computer-readable storage medium as recited in claim 13, further comprising instructions which, when executed by the one or more processors, cause the one or more processors to carry out the steps of:

loading a second version of the class using a second version class loader, the second version class loader being incompatible with the first version class.

23. The computer-readable storage medium as recited in claim 13, wherein the second version of the runtime environment comprises a modified version of the first version of the runtime environment.

24. The computer-readable storage medium as recited in claim 13, wherein the instructions for selecting intermediate storage format for the information for use with the second version runtime environment comprise instructions for carrying out a least one of the steps of:

selecting a hashmap as intermediate storage format for the information if the first version class comprises name/value pairings;

selecting an eXtended Markup Language (XML) object as intermediate storage format for the information if the first version class comprises metadata; and

selecting a string object as intermediate storage format for the information if the first version class comprises a long string data.

26. A system to load data from a serialized object of a first version of a class in a run time environment including a second version of the class, comprising:

a processor;

a serialized object stored on a storage medium, wherein the serialized object is an instance of first version of a class, wherein the first version of the class does not have a serial version identifier;

a run time environment that includes;

one or more virtual machines;

an instance of a second version of the class;

a primary class loader for loading the second version of a class;

an auxiliary class loader for loading the first version of the class;

computer code for constructing a class file for the first version of the class which includes a file name, serial version identifier, and data members;

computer code for loading the class file as constructed in the auxiliary class loader, and

computer code for extracting information from the serialized object into an intermediate storage format, for use with the instance of the second version of the class.

27. The system of claim 26, wherein the auxiliary class loader constructs a class file for the previous version of the class with file name, serial version identifier, and data members by performing steps comprising:

loading the serialized object into a first virtual machine that does not contain a version of the serializable class;

receiving a first message that contains the name of the serializable class;

constructing a first class file with the name of the serializable class;

loading the first class file with the name of the serializable class in a second virtual machine that contains the second version of the serializable class;

receiving a second message listing an expected serial version identifier;

constructing a second class file with the name of the serializable class and the expected serial version identifier;

loading the second class file with die name of the serializable class and the expected serial version identifier in the second virtual machine;

receiving a third message listing required data members; and

constructing a third class file with the name of the serializable class, the expected serial version identifier, and the required data members.

28. The system of claim 26, wherein the intermediate storage format for use within an instance of the current version of the class in the runtime environment is an eXtended Markup Language (XML) object if information in the previous version class comprises metadata.

29. The system of claim 26, wherein the intermediate storage format for use with an instance of the current version of the class in the runtime environment is a hashmap if information in the previous version class comprises name/value pairings.