Interface between programming languages and method therefor

• US 20030145011A1
• Filed: 01/31/2002
• Published: 07/31/2003
• Est. Priority Date: 01/31/2002
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Lynch, James, Rauch, Samuel J., Su, Paul Sheng-Chi
• Granted Patent: US 6,959,309 B2
• Time in Patent Office: Days
• US Class Current: 707/100
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 2209/508 Monitor
• CPC Class Codes: Y10S 707/99944 Object-oriented database structure

Abstract

An interface (20) implements a file system for supporting Java record and resource management between an operating system (28) using a first programming language other than Java and a suite (22) of Java applications. The interface provides a method for maintaining any number of files to be open in a manner transparent to the Java applications. Location information of a file is put in storage allocated for usage by Java code when a maximum number of open files is exceeded. A table (506) is used to translate between file names of differing length and to identify directories in a manner to provide a hierarchical file system. An identifier is associated with a shortened Java file name in the table to quickly identify an operating system file with a shortened file name.

Claims

1. In a device that uses a Java programming language and a second programming language, a method of emulating more simultaneously open files in the device than is permitted by an operating system of the device comprising:

while running a predetermined program in the Java programming language, attempting to access a file stored within the device;

determining whether the file is already open from prior execution;

if the file is open, access to the file proceeds;

if the file is not open, a determination is made by the device of a number of files the device permits to be simultaneously open;

if the number is not exceeded by opening the file, the file is opened;

if the number is exceeded by opening the file, the device emulates having more files open than the number allowed by;

(1) saving a file position for at least one open file, the file position designating where a next byte in the at least one open file would be accessed;

(2) closing the at least one open file; and

(3) opening the file;

wherein subsequent accesses to the at least one open file that has been closed are made transparently to the predetermined program in the Java programming language by closing at least one currently open file, retrieving the file position previously saved, and opening and restoring the file position for that file.

2. The method of claim 1 further comprising:

saving the file position in storage allocated for usage by Java code.

3. The method of claim 1 further comprising:

implementing the second programming language as C programming language.

4. The method of claim 1 further comprising:

providing a table;

storing arbitrarily long file names in a first format;

storing corresponding shortened names in a second format not exceeding a maximum number of characters; and

translating from the first format to the second format when a file is initially opened under control of the Java programming language, the translating being implemented transparent to any Java programming language application so that the Java programming language does not utilize the corresponding shortened names.

5. The method of claim 4 further comprising:

performing the translating only when the operating system does not permit file names having a length exceeding a predetermined maximum number of characters.

6. The method of claim 4 further comprising:

performing the translating only when the operating system does not support first format file names.

7. The method of claim 4 further comprising:

placing a unique identifier within predetermined positions of the shortened names to identify which file is being retrieved by the operating system.

8. The method of claim 7 further comprising:

using the unique identifier to bypass the translating of the first format to the second format when a predetermined file is reopened after being previously closed.

9. The method of claim 1 further comprising:

providing a table;

storing a directory in the table, the directory indicating a Java language application suite corresponding to a predetermined file; and

using the directory in the table to distinguish files of the same name belonging to different Java language application suites.

10. The method of claim 1 further comprising:

using storage allocated for use by Java code to contain variables such as file position needed by the second programming language.

11. The method of claim 10 further comprising:

using the variables to track the current position within an open file and to reopen and reposition the file if the file is temporarily closed.

12. The method of claim 10 further comprising:

using automatic memory management features of the Java programming language including garbage collection to reclaim storage when the file is no longer in use.

13. The method of claim 1 further comprising:

implementing the device as a portable, wireless device.

14. A method of interfacing a file system in a device that uses both a Java programming language and another programming language, comprising:

selecting a predetermined operating system;

overlying a Java virtual machine for executing programs within the operating system in the another programming language;

overlying the operating system with a file system interface layer;

overlying libraries to the Java virtual machine and the file system interface layer, the libraries running in the Java programming language;

using the file system interface to determine if a maximum number of open Java files has been exceeded, and if so, storing position information of at least one open Java file in a currently open Java application prior to closing the at least one open Java file; and

subsequently reopening the at least one open Java file by restoring the position information transparent to any Java application.

15. The method of claim 14 further comprising:

providing a table;

storing a directory in the table, the directory indicating a Java language application suite corresponding to a predetermined file; and

using the directory in the table to distinguish files of the same name belonging to different Java language application suites.

16. The method of claim 15 further comprising:

using storage allocated for use by Java code to store variables needed by the another programming language.

17. The method of claim 16 further comprising:

using the variables to track the current position within an open file and to reopen and reposition the file if the file is temporarily closed.

18. The method of claim 14 further comprising:

providing a table;

storing arbitrarily long file names in a first format;

storing corresponding shortened names in a second format not exceeding a maximum number of characters; and

translating from the first format to the second format when a file is initially opened under control of the Java programming language, the translating being implemented transparent to any Java programming language application so that the Java programming language does not utilize the corresponding shortened names.

19. The method of claim 18 further comprising:

placing a unique identifier within predetermined positions of the shortened names to identify which file is being retrieved by the operating system.

20. The method of claim 19 further comprising:

using the unique identifier to bypass the translating of the first format to the second format when a predetermined file is reopened after being previously closed.