| |
| |
Screen scraping software for TN3270, TN5250 and VT420 |
| | |
Screen scraping of legacy applications
"Screen scraping" is used here to mean procedures that allow an application program to extract data from the display output by another program. So when writing a Windows-based application that simplifies the interface to a legacy application (PC to host integration) this is done by copying or “scraping” the values of the fields output by the host application and displayed within a terminal emulator like IntelliTerm. Using this kind of screen scraping within an application allows Windows application integration with legacy applications when the legacy applications do not provide any other access (like an API) to these fields.
In brief, by using screen scraping, the output of an application running on an IBM mainframe or AS/400 midrange system (i.e. any field contents that is displayed within IntelliTerm on a PC), can be used as input to another application running on the PC. This allows the PC application to automate data collection and analysis while using the power of the larger system to generate the data. For example, instead of porting a legacy database to a PC, you can integrate it into PC applications by using IntelliTerm to connect to the legacy host transparently, retrieve the necessary data from the database and represent the data to the user with a more modern look and feel.
The screen scraping feature is available to different extents for all the emulation types in IntelliTerm, specifically for TN3270 on the mainframes, TN5250 on the AS/400 and VT100,VT220 or VT420 on UNIX based systems. So wherever your data is being processed you can still have a user-friendly front end application to it residing on a Windows-based PC.
The Developer Edition of IntelliTerm contains
samples illustrating how to programmatically (i.e. without any user interaction) connect to a 3270/5250
or Unix host, login automatically and "navigate" the legacy application's screens, recognizing them by specific text strings and
sending emulated keystrokes to move from one screen to another.
Screen scraping using IntelliTerm
IntelliTerm provides the following host integration interfaces:
- OLE Automation Interface, which can be utilized within any environment capable of instantiating ActiveX objects.
- WinHLLAPI/EHLLAPI, which is a standard Terminal Emulation API interface
- Macro Language, which provides the same object model as the OLE Automation Interface but from within a built-in
VBA-like environment
Host integration developers can use these interfaces to connect to a remote server, send keyboard input, copy and paste data to
and from the remote application fields, retrieve the whole screen contents, position the cursor, etc.
HLLAPI interface provides a few
unique features not available in OLE Automation Interface, such as intercepting keystrokes or preventing the user from closing the terminal
window.
The OLE Automation Interface, on the other hand, is easier to use in such environments as VBA or WSH (Windows Scripting Host).
For example, a system administrator
can quickly write a simple WSH script in notepad to automate some tasks using IntelliTerm's OLE Automation interface
without having to write a C++ or .NET application in order to be able to import HLLAPI dll.
|
|
|
