Method and apparatus for coordination of client/server processes

Abstract

The invention provides for the coordination of client / server processes. One or more embodiments provide a completion object comprised of various states of completion of a client request. The completion object may be manipulated to transition from one state to another by both the client and server. The following states of completion may be provided: idle, ready, active, completing, completed, and acknowledged. In the idle state, the completion object is obtained by the client (by constructing a new object or retrieving an existing object that has been recycled). In the ready state, the request has been initialized but not yet issued to the server or I / O device. In the active state, the server processes the I / O request. In the completing state, the server has completed the I / O operations requested but has not yet stored the results. In the completed state, the server stores the results to be returned to the client and notifies the client. At the acknowledged state, the client examines the results, performs additional operations and frees up the completion object for use by another client request. Depending on the state of the completion object, a request to cancel the I / O operations may require varying actions. The completion object provides the ability to easily and quickly determine where in the completion process an I / O request is. Further, when a client request is canceled, the completion object provides the ability to easily identify the actions necessary to properly cancel the request.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 157,764 filed May 28, 2002, now U.S. Pat. No. 7,233,972 issued Jun. 19, 2007; which is a continuation of U.S. patent application Ser. No. 09 / 161,112 filed Sep. 28, 1998, now U.S. Pat. No. 6,418,464 issued Jul. 9, 2002, which is incorporated herein by reference as if fully set forth herein, under 35 U.S.C. §120.FIELD OF THE INVENTION [0002] This invention relates to the field of computer software, and, more specifically, to completing input / output transactions. [0003] Portions of the disclosure of this patent document contain material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office file or records, but otherwise reserves all copyright rights whatsoever. Apple, Macintosh, AppleTalk, AppleScript, and all...

AI Technical Summary

Benefits of technology

"The invention provides a way to coordinate the work of different processes in a computer system. It ensures that requests to perform operations are only acted on once, and that clients can stop requests after they have been initiated. The system also allows multiple clients and servers to work independently, without causing conflicts. The invention introduces a concept called a \"completion object\" that can be manipulated to represent different stages of a request, such as \"idle,\" \"ready,\" \"active,\" \"completing,\" and \"acknowledged.\" This object helps to easily determine where a request is in the process and what actions need to be taken to cancel it. Overall, the invention improves the efficiency and reliability of computer systems."

Problems solved by technology

For example, a request may complete normally or it may complete abnormally due to user action, a hardware failure, or a time-out (i.e., the specified time limit for the server to respond to the client request expired).

Prior art methods do not precisely track client I / O requests resulting in two process paths of completion, one path from the client, and one path for the server.

Thus, when a request is initiated by a client, the client waits for the completion of the request and is not informed and cannot obtain the status of the request.

In the prior art, the client is unable to pick and choose which processes to complete or wait for subsequent to initiating the request.

Consequently, there is no defense against a process that is initiated and never completes (e.g., due to a hardware failure, time-out, etc.).

Images