Abstract:
One embodiment of the present invention provides a system that automatically configures a server to support different types of file accesses. During operation, the system determines whether a file should be accessed in multi-user mode, wherein multiple users can simultaneously access the file through the server. The system also determines whether the server is configured to support multi-user access to the file. If the file should be accessed in multi-user mode, and if the server is not configured to support multi-user access to the file, the system configures the server to support multi-user access to the file, thereby eliminating the need for the user to manually configure the server to support multi-user access to the file.

Description:
BACKGROUND 
   Field of the Invention 
   The present invention generally relates to the client-server computer systems. 
   Computer-based applications often access data which is stored in files. For example, a financial application typically operates on data which is stored in a “company file.” As such applications become increasingly more sophisticated, significant advantages can be gained by moving from a simple company file to a more-sophisticated database system, which is controlled by a database server. Using a more-sophisticated database system can provide improved performance and scalability, especially for larger company files and simultaneous users. 
   However, it is typically necessary to configure a database server to operate in specific modes depending upon what types of file accesses are desired. For example, it may be necessary to configure the database server to access a remote file, or to support multi-user accesses to a file. This can be a problem because application users are typically not very knowledgeable about the technical details involved in configuring a database server. Hence, it is can be very challenging for a typical application user to know what configuration is necessary and then to configure a database server appropriately. 
   SUMMARY 
   One embodiment of the present invention provides a system that automatically configures a server to support different types of file accesses. During operation, the system determines whether a file should be accessed in multi-user mode, wherein multiple users can simultaneously access the file through the server. The system also determines whether the server is configured to support multi-user access to the file. If the file should be accessed in multi-user mode, and if the server is not configured to support multi-user access to the file, the system configures the server to support multi-user access to the file, thereby eliminating the need for the user to manually configure the server to support multi-user access to the file. 
   In a variation on this embodiment, in order to determine whether the file should be accessed in multi-user mode, the system determines whether the file is open in multi-user mode. The system also determines whether a client application, which is attempting to access the file through the server, is in multi-user mode. If the file is open in multi-user mode or the client application is in multi-user mode, the system determines that the file should be accessed in multi-user mode. 
   In a variation on this embodiment, configuring the server to support multi-user access to the file involves automatically configuring the server to enter a “hosting mode,” which supports network connections to multiple clients, whereby the server can use the multiple network connections to facilitate multi-user access to the file. 
   In a variation on this embodiment, configuring the server to support multi-user access to the file involves automatically prompting the user to obtain permission from the user before configuring the server to support multi-user access to the file. 
   In a variation on this embodiment, the system also determines whether the file is a remote file (which is located on a different machine from the server), and whether the server is configured to access a remote file. If the file is a remote file and the server is not configured to access a remote file, the system configures the server to access a remote file. 
   In a further variation, configuring the server to access a remote file involves automatically configuring the server to run as a process which is able to access remote files. 
   In a further variation, configuring the server to access a remote file involves automatically prompting the user to obtain permission from the user before configuring the server to access a remote file. 
   In a variation on this embodiment, the server is a database server and the file is a database file. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  illustrates how client applications access files through a server in accordance with an embodiment of the present invention. 
       FIG. 2  illustrates hosting modes which are required to support different types of file accesses in accordance with an embodiment of the present invention. 
       FIG. 3  presents a flow chart illustrating how a server is configured when the server starts in not-hosting mode in accordance with an embodiment of the present invention. 
       FIG. 4  presents a flow chart illustrating how a server is configured when the server starts in hosting-local-files-only mode in accordance with an embodiment of the present invention. 
       FIG. 5  presents a flow chart illustrating how a server is configured when the server starts in hosting-local-and-remote-files mode in accordance with an embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims. 
   The data structures and code described in this detailed description are typically stored on a computer-readable storage medium, which may be any device or medium that can store code and/or data for use by a computer system. This includes, but is not limited to, magnetic and optical storage devices such as disk drives, magnetic tape, CDs (compact discs), DVDs (digital versatile discs or digital video discs), or any device capable of storing data usable by a computer system. 
   System 
     FIG. 1  illustrates how client applications access files through a server in accordance with an embodiment of the present invention.  FIG. 1  illustrates a number of computer systems  102 - 106 . Computer systems  102 - 106  can generally include any type of computer system, including, but not limited to, a computer system based on a microprocessor, a mainframe computer, a digital signal processor, a distributed computing system, a portable computing device, a personal organizer, a device controller, and a computational engine within an appliance. 
   Computer system  102  includes a server  107 , which includes a mechanism for servicing requests from clients for computational and/or data storage resources. 
   A number of client applications  112 - 114  communicate with server  107 . In general, client applications  112 - 114  contain computational capability and a mechanism for communicating with a server. More specifically, client application  112  is a local application, which resides on the same computer system as server  107 , whereas client applications  113  and  114  are remote applications, which reside on remote computer systems  105  and  106 , respectively, which are located remotely from server  107 . 
   Server  107  accesses a number of files  108 ,  115  and  116 . File  108  is a local file which resides on the same computer system as server  107 , whereas files  115  and  116  are remote files which reside on remote computer systems  103  and  104 , respectively. 
   In one embodiment of the present invention, server  107  is a database server and files  108 ,  115  and  116  are database files. 
   Hosting Modes 
     FIG. 2  illustrates hosting modes which are required to support different types of file accesses in accordance with an embodiment of the present invention. The grid which appears in  FIG. 2  contains two rows and two columns. The first row is associated with a “local file” and the second row is associated with a “remote file.” The first column is associated with “multi-user mode,” whereas the second column is associated with “single-user mode.” 
   Cells within the grid illustrate which hosting modes are used for various cases. More specifically, if a local file is to be accessed in multi-user mode, the server should ideally be in “hosting-local-files-only mode.” Similarly, if a remote file is to be accessed in multi-user mode, the server should ideally be in “hosting-local-and-remote-files mode.” On the other hand, if a local file or a remote file is to be accessed in single-user mode, the server should ideally be in “not-hosting mode.” 
   One embodiment of the present invention provides three different hosting modes, which are illustrated  FIG. 2 . These hosting modes include: (1) not-hosting mode, (2) hosting-local-files-only mode, and (3) hosting-local-and-remote-files mode. 
   In not-hosting mode the server runs as a normal process, and is able to access local and remote files. Not-hosting mode does not support multi-user access to files. In not-hosting mode, client applications communicate with the server through shared memory. Hence, only client applications running on the same machine as the server can communicate with the server. (Note that this is the default mode because most users operate solely in single-user mode and do not want to be bothered about hosting.) 
   In hosting-local-files-only mode, the server runs as a service. This mode supports multi-user access to files located on the same machine as the server. In this mode, the server can use TCP/IP to communicate with client applications. Hence, client applications running on remote machines can communicate with the server. 
   In hosting-local-and-remote-files mode, the server runs as a normal process, and is able to access local and remote files, because it runs as the logged-in user. This mode also supports multi-user access to files. In this mode, the server can use TCP/IP to communicate with client applications. Hence, client applications running on remote machines can communicate with the server. 
   Configuring the Server 
   In one embodiment of the present invention, the server is configured (or reconfigured) whenever certain events occur. For example, the server can be configured (or reconfigured) whenever: (1) a file is created; (2) a file is opened, or (3) a file is switched from single-user mode to multi-user mode. Note that the code within the client application (or alternatively code that works alongside the client application) configures the server. This frees the application user from having to manually perform configuration operations. The decisions involved in configuring the server are described in more detail below with reference to the flow charts which appear in  FIGS. 3-5 . 
   Starting in Not-Hosting Mode 
     FIG. 3  presents a flow chart illustrating how a server is configured when the server starts in not-hosting mode in accordance with an embodiment of the present invention. The system first determines whether the file should be accessed in multi-user mode (step  302 ). In one embodiment of the present invention, this involves determining whether the file is open in multi-user mode, or whether a client application, which is attempting to access the file through the server, is in multi-user mode. If the file is open in multi-user mode or the client application is in multi-user mode, the system determines that the file should be accessed in multi-user mode. 
   If the file is not to be accessed in multi-user mode, the system remains in not-hosting mode (step  304 ). Otherwise, if the file is to be accessed in multi-user mode, the system determines whether the file is a local file or a remote file (step  306 ). This can be determined by examining the reference (or handle) for the file. If the file is a remote file, the system enters hosting-local-and-remote-files mode (step  308 ). Before entering this mode, the system can prompt the user to obtain permission from the user before configuring the server to enter hosting-local-and-remote-files mode. 
   On the other hand, if the file is a local file the system enters hosting-local-files-only mode (step  310 ). Before entering this mode, the system can prompt the user to obtain permission from the user before configuring the server to enter hosting-local-files-only mode. 
   Starting in Hosting-Local-Files-Only Mode 
     FIG. 4  presents a flow chart illustrating how a server is configured when the server starts in hosting-local-files-only mode in accordance with an embodiment of the present invention. The system first determines whether the file is a local file or a remote file (step  402 ). If the file is a local file, the system remains in hosting-local-files-only mode (step  404 ). 
   Otherwise, if the file is a remote file, the system determines whether the file should be accessed in multi-user mode (step  406 ). If the file is to be accessed in multi-user mode, the system enters hosting-local-and-remote-files mode (step  408 ). Before entering this mode, the system can prompt the user to obtain permission from the user before configuring the server to enter hosting-local-and-remote-files mode. (Note that this prompt mentions multi-user mode.) 
   On the other hand, if the file is not to be accessed in multi-user mode, the system also enters hosting-local-and-remote-files mode (step  410 ), except in this case the prompt that is displayed to the user does not mention multi-user mode. 
   Starting in Hosting-Local-And-Remote-Files Mode 
     FIG. 5  presents a flow chart illustrating how a server is configured when the server starts in hosting-local-and-remote-files mode in accordance with an embodiment of the present invention. In this case, the system remains in hosting-local-and-remote-files mode and the configuration of the server is not changed (step  502 ). 
   The foregoing descriptions of embodiments of the present invention have been presented only for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the present invention. The scope of the present invention is defined by the appended claims.