Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to accessing files using a file interface.  
           [0002]    The Joint Tactical Radio System (JTRS) Software Component Architecture (SCA) defines a set of interfaces and protocols, often based on the Common Object Request Broker Architecture (CORBA), for implementing a Software Defined Radio (SDR). In part, JTRS and its SCA are used with a family of software re-programmable radios. As such, the SCA is a specific set of rules, methods, and design criteria for implementing software re-programmable digital radios.  
           [0003]    The JTRS SCA specification is published by the JTRS Joint Program Office (JPO). The JTRS SCA has been structured to provide for portability of applications software between different JTRS SCA implementations, leverage commercial standards to reduce development cost, reduce development time of new waveforms through the ability to reuse design modules, and build on evolving commercial frameworks and architectures.  
           [0004]    The JTRS SCA is not a system specification, as it is intended to be implementation independent, but a set of rules that constrain the design of systems to achieve desired JTRS objectives. The software framework of the JTRS SCA defines the Operating Environment (OE) and specifies the services and interfaces that applications use from that environment. The SCA OE comprises a Core Framework (CF), a CORBA middleware, and a POSIX-based Operating System (OS) with associated board support packages. The JTRS SCA also provides a building block structure (defined in the API Supplement) for defining application programming interfaces (APIs) between application software components.  
           [0005]    The JTRS SCA Core Framework (CF) is an architectural concept defining the essential, “core” set of open software Interfaces and Profiles that provide for the deployment, management, interconnection, and intercommunication of software application components in embedded, distributed-computing communication systems. Interfaces may be defined in the JTRS SCA Specification. However, developers may implement some of them; some may be implemented by non-core applications (i.e. waveforms, etc.); and some may be implemented by hardware device providers.  
           [0006]    The file interface provided by the JTRS SCA typically provides the ability to read and write a file residing within a CF-compliant, distributed file system. The JTRS SCA file system interface typically defines a non-optimized file interface comprising set of CORBA operations that enable remote access to a physical file system, e.g. one located at a distance from the JTRS device. The file system interface further typically provides traditional operations associated with file accesses (i.e. remove, copy, directory listing, etc.). Additionally, the file system should make the underlying physical file system at the remote location transparent to the JTRS device user. Accordingly, different file systems like FAT32, NTFS, and the Unix file system may be used with the same file interface.  
           [0007]    However, use of CORBA interfaces often slows access to files and adds overhead to the JTRS device. The JTRS system, e.g. the JTRS SCA, forces client file access into using a cumbersome process. Clients wishing to avoid that process may be forced into using non-compliant methods to access files.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a schematic overview of an exemplary system;  
         [0009]    [0009]FIG. 2 is a schematic overview of file system, file handler, and local file access  
         [0010]    [0010]FIG. 3 is a schematic overview of client file access classes;  
         [0011]    [0011]FIG. 4 is a flowchart of a first exemplary method; and  
         [0012]    [0012]FIG. 5 is a flowchart of a second exemplary method. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    In general, throughout this description, if an item is described as implemented in software, it can equally well be implemented as hardware.  
         [0014]    As used herein, “data” is either singular or plural, as the context requires.  
         [0015]    As further used herein, “class,” “class property,” “class event,” and “class method” are given their ordinary meanings as will be familiar to those of ordinary skill in the object oriented software programming arts. “Class method” is used herein to distinguish between a “method,” as that term is common to patent claims, and invocable software executing in a computer and associated with a class. A “class process” is equivalent, as used herein, to a “class.” 
         [0016]    Referring now to FIG. 1, in an exemplary embodiment, as will be familiar to those of ordinary skill in the computer arts, files may be distributed, e.g. file  4  and file  5 . First processor  10  may have access to one or more files, e.g. file  4 , resident on file storage  16 . Similarly, second processor  20  may have access to one or more files, e.g. file  5  resident on file storage  26 .  
         [0017]    Client  12 , client  22 , file system class  13 , file system class  23 , file handler class  14 , and file handler class  24  are all compliant with the Joint Tactical Radio System (JTRS) Software Component Architecture (SCA). Client  12 , client  22 , file system class  13 , file system class  23 , file handler class  14 , and file handler class  24 , in this example, may be either a class or a class method, as the context requires.  
         [0018]    A client method or client process executing in a processor, e.g. client  12  executing in first processor  10 , may desire access to a file, e.g. file  4  or file  5 . In an exemplary embodiment, client  12  may invoke a file server service of a JTRS SCA server of which client  12  is aware, e.g. file system class  13 . Client  12  may pass a reference or other identifier which identifies the file that client  12  is requesting, e.g. file  4 , to a JTRS SCA class method such as a class method of file system class  13 .  
         [0019]    In a first exemplary scenario, client  12  may request access to file  5 . As file  5  is remote to client  12 , i.e. resident on data store  26  local to processor  20 , file  5  will need to be accessed through JTRS SCA file system class  23  and/or file handler class  24 , such as via operating CORBA methods accessed via the Internet  100 . Access to files using CORBA is indicated by dashed lines in FIG. 1.  
         [0020]    In a second exemplary scenario, client  12  may request access to file  4 . In this second scenario, file  4  is resident on data store  16  which is local to processor  10 . Accessing file  4  through JTRS SCA file system class  13  and/or file handler class  14  may add complexities and overhead not needed by client  12  as client  12  is executing in the same processor as file system class  13  and/or file handler class  14 , i.e. first processor  10 . In this second exemplary scenario, access to file  4  by client  12  may be faster and more efficient if client  12  is allowed to access file  4  more directly, such as by using file access system calls native to operating system  17  executing on first processor  10 . Access to files using native operating system calls is indicated by solid lines in FIG. 1.  
         [0021]    Referring now to FIG. 2, file system class  13  is an instance of a base JTRS SCA file access class. In an embodiment, when invoked, file system class  13  may create an instance of a JTRS SCA compliant file handler class, e.g. file handler class  14 . As will be familiar to those of ordinary skill in object oriented software programming arts, file system class  13  and file handler class  14  may each comprise properties, events, and methods (PEM), some of which may be exposed and some of which may be private. As file system class  13  and file handler class  14  are instances of a base JTRS SCA class, file system class  13  and file handler class  14  may each further present a JTRS SCA standard application programming interface (API) that is compliant with a JTRS SCA file access API for their class.  
         [0022]    Additionally, local file class  18  may be added to file handler class  14  as an extension to file handler class  14 . Local file class  18  may be added to file handler class  14  as a class method of a base file handler class  14  or may be a class instance based on file handler class  14  which has its own class methods and/or properties. As a class instance based on file handler class  14 , local file class  18  will inherit file handler class  14  properties, events, and methods, allowing local file class  18  to use those inherited properties, events, and methods as defaults. Local class  18  may further comprise determination class method  18 a operable to determine if a process such as client  12  which is invoking local class  18 , directly or indirectly, is on a same processor, e.g.  10 , as a file to which access has been requested, e.g. file  4 .  
         [0023]    Referring now to FIG. 3, client  12  may further comprise one or more class methods. In an exemplary embodiment, client  12  comprises local file access class method  420 , which may be usable, e.g. able to be invoked, to access a file local to processor  10  (FIG. 1) in which client  12  is resident, such as file  4  (FIG. 1) and a default class method  422  usable to access a file not local to processor  10 , e.g. file  5 , where default class method  422  may default to class method  45  of file access class  40 . Access to non-local files such as file  5  may be accomplished through a file server class on the remote processor where the non-local file resides, e.g. file system class  23  on processor  20 .  
         [0024]    As used herein, local file access class method  420  may comprise one or more individual class methods to provide functionality to access file  4  (FIG. 1). In an embodiment, functionality for local file access class method  420  resides in individual class methods such as file manipulation method  420   a,  file name manipulation method  420   b,  file pointer method  420   c,  content manipulation method  420   d,  file properties method  420   e,  exception handler  420   f,  or the like, or a combination thereof.  
         [0025]    File manipulation class method  420   a  may comprise one or more class methods to accomplish reading, writing, opening, closing, creating, or deleting functions, or the like, or a combination thereof.  
         [0026]    File name manipulation method  420   b  may comprise one or more class methods to accomplish file name retrieval, file name modification, or the like, or a combination thereof. File name retrieval may be invoked to return a file name associated with file  4  (FIG. 1) where the file name is obtained from an interface to operating system  17  executing in processor  10 .  
         [0027]    File pointer method  420   c  may comprise one or more class methods to accomplish file pointer retrieval or file pointer modification. In the JTRS SCA, a file interface comprises class  40  (FIG. 3) that provides the ability to read and write files residing within a JTRS CF-compliant, distributed file system wherein a file can be thought of conceptually as a sequence of octets with a current filePointer describing where the next read or write will occur. This filePointer points to the beginning of the file upon construction of the file object.  
         [0028]    Content manipulation method  420   d  may comprise one or more class methods to accomplish accessing content of file  4  (FIG. 1), e.g. reading content, writing content, or the like, or a combination thereof.  
         [0029]    File properties method  420   e  may be used to obtain a property of file  4  (FIG. 1), e.g. a read-only status of file  4 , a physical size of file  4 , a filename of file  4 , time of file creation, date of file creation, time of the last access to the file, date of the last access to the file, time of the last modification of the file, date of the last modification of the file, or the like, or a combination thereof.  
         [0030]    In the operation of an exemplary embodiment, referring now to FIG. 4 and FIG. 5, in a typical JTRS SCA system, file system class  13  (FIG. 1) is created and initialized and handles at least a portion of access to local files, e.g. file  4  (FIG. 1). File system class  13  may further export an object reference back to a client process, e.g.  12  (FIG. 1), for use in accessing files. Typically, file system class  13  will cause an instance of file handler class  14  (FIG. 1) to be created to handle at least a portion of access to a local file, e.g.  4 .  
         [0031]    An existing JTRS SCA system may be expanded by use of local file class  18  (FIG. 2). In an exemplary embodiment, file  4  (FIG. 1) may be accessed using a file access interface provided by file system class  13  and/or file handler class  14 . An invocable file access class such as local file class  18  may be added to an existing Joint Tactical Radio System (JTRS) Software Component Architecture (SCA) file handler class  14  (FIG. 2) such as by creating local file class  18  as a class based on file handler class  14  (step  200 ).  
         [0032]    A client process such as client  12  (FIG. 1) may request access to file  4  using the JTRS SCA file access API. (step  210 ) Accessing file  4  may comprise requesting a determination of a file name of file  4 , a determination of a file attribute of file  4 , manipulating content of file  4 , or the like. The file name may be a fully qualified, native operating system file name, e.g. one comprising a path to the file, the file name, and the file extension. As will be familiar to one of ordinary skill in the software arts, one or more methods in file system class  13  and/or file handler class  14  may be used to accomplish these functions.  
         [0033]    Once it receives a request or message from client  12 , 22 , local file class  18  may determine if file  4  is local to the same processor, e.g.  10  (FIG. 1), as client  12 , 22 . (Step  220 ) For example, clients  12 , 22  (FIG. 1) may issue a request by invoking an appropriate method in local file class  18  (FIG. 2) such as by passing a first identifier local to client  12 , 22 , e.g. a CPU ID, to local file class  18 . A class method in local file class  18  may then identify a second identifier where the second identifier is local to local file class  18 , e.g. a CPU ID. A class method in local file class  18  may then compare the first identifier to the second identifier. File  4  may be found to be local when the first identifier equals the second identifier.  
         [0034]    If file  4  (FIG. 1) is local to the same processor, e.g. as may occur if client  12  (FIG. 1) desires access to file  4  (FIG. 1), the requesting client  12 , upon determining that file  4  is local to the same processor,  10 , may then use operating system calls native to operating system  17  (FIG. 1) to effect further access to file  4 , bypassing file system class  13  and file handler class  14 . (step  230 )  
         [0035]    If file  4  is not local, such as if client  12  is the requesting client needing further access to file  5 , file access to file  5  may be accomplished by using JTRS SCA default class methods such as over the Internet  100  (FIG. 1), e.g. using file system class  23  and CORBA.  
         [0036]    In certain embodiments, client  12 , 22  may access a file object reference (step  300  in FIG. 5) and invoke a class method to obtain a current host name of a current host in which client  12 , 22  is executing (step  310  in FIG. 5). A class method such as in file handler  14 , 24  may be invoked to determine if a file, e.g.  4  or  5 , which is associated with the file object reference is a local file with respect to the current host name (step  320  in FIG. 5). In a currently envisioned embodiment, file handler  14 , 24  is closed after the determination is made.  
         [0037]    If the requested file is local, client  12 , 22  may use operating system calls native to the current host for accessing the file (step  330  in FIG. 5). Otherwise, client  12 , 22  may obtain a copy of a non-local file, e.g. file  5  requested by client  12 , such as by writing a copy of file  5  to data store  16  local to the current host  10  and then closing the copied, non-local file  5  (step  340  in FIG. 5). The copy may be obtained using file system class  23 , 24 . This may be advantageous when the file desired is an executable file, e.g. a dynamically linked library file. Once copied, client  12  may use operating system calls native to the current host for accessing the copy of file  5 . In a preferred embodiment, once access to file  5  is no longer required, client  12  may delete the copied, local file.  
         [0038]    It will be understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated above in order to explain the nature of this invention may be made by those skilled in the art without departing from the principle and scope of the invention as recited in the appended claims.

Technology Category: 4