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Chapter 1: Introduction

This chapter gives a brief overview of the facilities provided by Fileshare and also describes how Fileshare works.

1.1 Overview

Fileshare is best suited to applications that share data files, concurrently, between many users, across a network. It supports all of the functionality provided by the base COBOL file handling system and provides several additional features:

The ability of any one application to take advantage of these features depends on:

You do not need to make any program source code changes to use the basic Fileshare system. Source code changes are only needed to take advantage of some of the advanced features provided by Fileshare.

1.2 How Fileshare Works

Using the base COBOL file handling system, a typical COBOL I/O request to a shared data file causes the file handler to make several accesses to that data file across the network. See Figure 1-1.

Figure 1-1: Conventional Network

With Fileshare, a program that needs to access a data file has its request processed by the File Handling Redirector (FHRedir) module. The FHRedir module sends the request over the network to a Fileshare Server that performs the low-level I/O operations and then passes the result of the I/O operation, including the file status, back to FHRedir. FHRedir returns the result to the program. See Figure 1-2.

Figure 1-2: Fileshare Network

A Fileshare System is made up of:

Fileshare Clients A Fileshare Client comprises a user program, making data file I/O requests, via the FHRedir module. FHRedir redirects the I/O requests to a Fileshare Server.
Fileshare Servers A Fileshare Server runs on the same machine as the data files that you want to access. The Fileshare Server accepts requests across the network from the Fileshare Client, processes them by calling a local copy of the Micro Focus File Handler and then returns the result to the Fileshare Client.


Since a single Fileshare Server processes all the requests from several Fileshare Clients, it can use a single copy of the Micro Focus File Handler, regardless of how many users are accessing the Fileshare Server. This has several advantages:

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