Browse Prior Art Database

AS/400 OS/2 PC Support SHARED FOLDERS

IP.com Disclosure Number: IPCOM000037296D
Original Publication Date: 1989-Dec-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 4 page(s) / 53K

Publishing Venue

IBM

Related People

Cook, CL: AUTHOR [+5]

Abstract

An OS/2* shared folders file system driver (FSD) is a product that allows OS/2 file system calls to be redirected to an AS/400*. The AS/400 acts as a file server to the OS/2 requester. The shared folders FSD is the first remote FSD written for OS/2.

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AS/400 OS/2 PC Support SHARED FOLDERS

An OS/2* shared folders file system driver (FSD) is a product that allows OS/2 file system calls to be redirected to an AS/400*. The AS/400 acts as a file server to the OS/2 requester. The shared folders FSD is the first remote FSD written for OS/2.

OVERVIEW. The shared folders FSD is a two-privilege level OS/2 file system driver which accepts file system requests from OS/2 utilities and applications via the OS/2 installable file system interface. These requests are translated into distributed data management (DDM) byte stream protocol requests and passed to host AS/400 systems using Advanced Program to Program Communication (APPC) facilities of the OS/2 Extended Edition Communications manager. The shared folders FSD comprises two parts:

1. An OS/2 file system driver executing at OS/2 privilege level 0. The OS/2 FSD interacts with an OS/2 installable file system and accepts file system requests.

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2. An OS/2 EXE file executing at privilege level 3. The EXE file interacts with an OS/2 Release 1.2 EE communications manager and passes service requests to AS/400 systems using the supported DDM protocols.

OS/2 Application Programming Interface (API) calls are passed to the OS/2 installable file system which directs the requests to the FSD that manages the media that can satisfy the request. Shared folders have implemented an FSD, so application API requests are handled the same whether the request is for local media or for a remote AS/400 server.

Shared folders support requests from both real and protect mode applications. The IFS translates both protect mode and real mode requests into protect mode requests and passes them to the FSD managing the media which can satisfy the request. An overview is illustrated in Fig. 1.

TWO PRIVILEGE LEVEL INTERFACE. The shared folders FSD meets two OS/2 interface architectures. To be an OS/2 FSD, a level 0 interface to the IFS is needed. To use the OS/2 communications manager, a level 3 interface is needed.

To satisfy the interface with the IFS, an OS/2 Dynamic Link Library (DLL) was developed for shared folders to service calls from the IFS. Routines in this DLL execute on the caller's (application's) thread at privilege level 0 via the IFS.

An OS/2 EXE file was developed for shared folders that execute at privilege level 3 to interface with the OS/2 communications manager (which only supports a level 3 API).

The two shared folders processes communicate via DosFsCtl calls. The level 3 process of shared folders makes a pair of DosFsCtl calls to the level 0

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process. One of the calls represents a request from the level 0 process, and the other call represents a reply from the level 3 process. The reply call is made in response to a request call. With the two calls being made on two execution threads, overlap is provided between one service request and the next.

SHARED FOLDERS FLOW. Fig. 2 provides a block diagram of shared folders flow....