x3270is Introduction

The x3270is library is a simple interface between applications and the x3270 emulator family. It can be used in one of two ways:

• To form the glue between an interactive wx3270 or wc3270 session and a scripting process started by the Script() action.
• To start a copy of ws3270 to completely control a host session.

Script() Worker Process

wx3270 and wc3270 support a Script() action that allows running sophisticated scripts to control the emulator session. For example, a script could read the contents of a file and paste it into fields on the host display, it could take data from the host display and generate a report, or it could implement features not present in the emulator, such as the 5250 Field Exit key. (The key difference between the Script() and Source() actions is that Source() blindly reads a set of actions from a file and executes them one by one. Script() invokes a program that can perform different actions based on the state of the emulator and the result of previous actions, and it can access outside resources.)

The Script() action takes one or more arguments. The emulator will start up a copy of the program named by the first argument, and will pass the remaining arguments as command-line parameters to it. For example, to run a Powershell script, a typical invocation would be:

  Script(powershell.exe,-File,MyScript.ps1)

That would cause the emulator to start a copy of powershell.exe and pass it -File and MyScript.ps1 as parameters.

Before starting the program, the emulator sets up a socket to accept connections to process commands from the script. The port number is passed to the program in the environment variable X3270PORT. The socket communication protocol between the script and emulator is simple but quite strict. The WorkerConnection class in the x3270is library handles all of the details (setting up a socket, formatting and sending actions and decoding the results) so the script can focus on doing its work.

Pure Screen Scraping (New Host Session)

The x3270is library also supports pure screen scraping. A screen-scraping application starts a copy of ws3270 and uses it to connect to a host. It then controls all aspects of the session, such as logging in, entering data and interpreting the results. The NewEmulator class in the X3270is library handles the details of starting ws3270 and connecting to it, and uses the same methods as WorkerConnection to send actions and decode the results.

Supported Clients

x3270is is a DLL that can be used by any .NET application, such as PowerShell or user-generated C# or VB.NET code. It can also be registed with COM during installation of wx3270 or wc3270, so it can be used with VBScript and JScript.