Method of file access in a distributed processing computer network

• US 4,825,354 A
• Filed: 11/12/1985
• Issued: 04/25/1989
• Est. Priority Date: 11/12/1985
• Status: Expired due to Term

• Current Assignee: NCR Corporation
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: Agrawal, Rakesh, Ezzat, Ahmed K.
• Primary Examiner(s): Clark, David L.
• Application Number:
  US06/796,863
• Time in Patent Office: 1,260 Days
• Field of Search: 364/200 MS File, 364/900 MS File
• US Class Current: 1/1
• CPC Class Codes: G06F 16/182 Distributed file systems
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation

Abstract

A method of performing remote process execution in a computer network. A remote process execution request, including an identification of a process to be executed, is transmitted from a requesting computer to a serving computer. At both the requesting and the serving computers, a file addressing structure is established, so that a file reference by the remote process at the serving computer addresses a file located at the requesting computer. The remote process is activated at the serving computer in response to the remote process execution request. In response to a file reference by the remote process, the file is automatically accessed from the requesting computer in accordance with the addressing structure. The method includes a technique by means of which files may be selectively and automatically accessed from either the requesting or the serving computer, as desired by a user. A computer administrator may selectively override the file accessing instructions, if desired, thereby providing the ability to maintain file security for certain files.

Claims

1. A method of performing remote process execution in a computer network having a plurality of computers each with separate file and separate file addressing systems, comprising the steps of

transmitting remote process execution request, including an identification of a process to be executed, from a requesting one of the computers to a serving one of the computers, and

establishing a temporary file addressing system extension at both the requesting and the serving computers for the duration of existence of the remote process in response to said request transmission for linking the file system of the requesting computer into the file system of the serving computer,

addressing, via the extension in response to a remote process file access, a file located at the requesting computer as an integral part of the file system of the serving computer and not a file at the serving computer.

2. The method of claim 1 wherein the step of establishing a file addressing system extension further comprises

establishing one or more communication channels at the requesting computer for direct file access by the serving computer,

including in the remote execution request message information identifying the one or more communication channels at the requesting computer,

at the serving computer, linking the file addressing system to the one or more communication channels extending to the requesting computer, and

activating the identified process at the serving computer.

3. The method of claim 2 further comprising the steps of

establishing at the requesting computer a completion communication channel for receiving a remote process completion signal from the serving computer, and

including in the remote execution request message information by which the serving computer may address the completion communication channel.

4. The method of claim 1 further comprising the steps of

establishing a user process at the requesting computer in response to a login by a user, and

generating the remote execution request message in response to a command from the user identifying the process to be remotely executed.

5. The method of claim 4 further comprising the steps of

including in the remote execution request message information stored at the requesting computer describing the operating environment of the user process, and

at the server computer, establishing a remote process in response to the remote execution request to service the request, and

establishing an operating environment for the remote process using the operating environment information in the remote execution request message.

6. The method of claim 5 wherein the operating environment of a process includes one or more stored environment variables describing prescribed operating conditions for the process and wherein the step of including operating environment information further comprises the steps of

reading the states of environment variables, and

including the environment variable states in the remote execution request message.

7. The method of claim 6 wherein the step of establishing the operating environment for the remote process further comprises the steps of

storing the environment variable states contained in remote process request message in the environment variables associated with the remote process.

8. The method of claim 7 wherein each computer has an individual status variable for each process active in the computer and which contains information describing prescribed states of the process, the method further comprising the steps of

at the requesting computer, setting the status variable for the user process to a state identifying the process as an agent for the remote process, and

placing the agent process in an inactive state awaiting completion of the remote process.

9. The method of claim 1 further comprising the steps of

including in the remote process execution request message file selection information selectively identifying for any file that might be accessed by the remote process whether to access the file on the requesting or the serving computer and,

linking the file selection information into the file addressing extension.

10. The method of claim 2 wherein the file systems of the requesting and serving computers are each hierarchically arranged into a tree structure of directories containing files, beginning with a root directory, and wherein each computer process has associated with it a default root directory pointer and an alternate root directory pointer, and wherein the method further comprises the steps of

at the serving computer, setting the state of the default root directory pointer associated with the remote process to point to the root directory of the requesting computer and setting the state of the alternate root directory pointer to point to the root directory of the serving computer in response to file information contained in the remote execution request message.

11. The method of claim 10 further comprising the step of

at the serving computer, selecting either the default or the alternate root directory pointer to search for a file referenced by the remote process, in accordance with the file information from the requesting computer.

12. The method of claim 11 wherein files are identified by path names comprising sequence of directories in the file system and ending with a name of a file located in the last named directory, wherein the file information from the requesting computer further comprises one or more directory path names, and wherein the step of selecting either the default or the alternate root directory pointer further comprises the steps of

comparing the path name of a referenced file to the one or more directory path names from the requesting computer, and

selecting in response to said comparison the alternate root directory pointer to search for the referenced file if any of the one or more directory path names in the file information from the requesting computer is a prefix of the reference file path name and otherwise selecting the default root directory pointer.

13. The method of claim 12 wherein each computer comprises a local DISALLOWED variable which may contain one or more directory path names and wherein the method further comprises the step of

at the serving computer, in response to the remote execution request message, comparing each of the one or more directory path names in the file information to each of the path names in the DISALLOWED variable, and

deleting from the file information any directory path name which has a directory path name as a prefix in the DISALLOWED variable.

14. The invention of claim 13 wherein one of a plurality of environmental variables of a process identifies a present directory in which the process resides, and wherein the method further comprises the steps of

at the requesting computer, establishing a completion communication channel for receiving a remote process completion signal from the server computer,

establishing root directory and present directory communication channels for access by the server computer for the requestor computer root directory and the present directory, respectively, and

including addressing information of each said communication channel in the remote execution request to the server computer.