Understanding the Emulation Options

Understanding the Emulation Options

GDT Migration

GDT-WDT is a component based technology that provides a powerful interface to BULL GCOS via TNVip, IBM AS/400 via TN5250, Unix systems via Telnet and migrated GDT systems using TCP/IP.

“VIP” is the escape sequences used to draw a screen. The ‘TN’ part of TNVIP stands for telnet. The telnet protocol (which contains header information like packet size, etc) is used to send the VIP sequences to the client and back to the server. Everything together is “TNVIP”.

GDT-WDT supports the TNVIP protocol so it can communicate with gateways.

In working with the GDT system, this is slightly different.The protocol used for the GDT system may be called “GDTVIP”. The “GDT” part means we use our own GDT headers to communicate with the GDT Server(GDT Server, describing both TCS(transaction control server) and GDT together). So, in this solution the telnet protocol is not used and what has been created is what can be called a “GDT Protocol” to “ferry” the VIP sequences to the client and back to the server.

GDT-WDT provides the ability to access your GCOS and GDT applications via a web browser in anumber of different ways:

1. Dynamic HTML Emulation

2. Dynamic HTML Emulation with Templates

3. Active/X Emulation

4. Custom Web Development using ASP or ASP.Net

Both HTML and Active/X give browser access to the host and the choice as to which is best

suited depends on a number of factors such as

1. Do you want to customize the screens ?

2. Do your users rely on auto-tab features?

3. Can your “power users” accept the slower response for HTML?

4. Do you need to provide remote access through a Firewall?

DYNAMIC HTML EMULATION

Dynamic HTML Emulation is a server based solution whereby GDT-WDT runs on the web server

(Microsoft IIS) and dynamically converts existing GCOS/AS400/GDT screens into HTML that

is displayed by the client browser.

Dynamic HTML Emulation can also interface with GDT-WDT Web Templates that give you the

opportunity to change the HTML presentation on a screen by screen approach.

The HTML option works well for true remote users who need occasional access and maybe using

any type of web browser. Security is not an issue as the only thing that is sent to the browser is

pure HTML. The connection to the host application is managed on the web server.

The host connection is maintained on the web server and a conversion is performed turning the original host screen into pure HTML. The browser receives the result of the conversion and is not connected to the host. When the user updates the fields and clicks on the “Transmit” button, a request is sent back to the web server which in turn does the transmit and the process is repeated.

Here is a summary of the Plus/Minus points for the Dynamic HTML approach:

+ Works in almost all browsers

+ Can customize the look and feel and use Templates to enhance the display

- Not quite as fast as Active/X, each Transmit must be ‘posted’ back to web server

- Power users will often complain about certain keys not working the same

Active/X Emulation

Active/X Emulation is similar to using a regular desktop emulator except that the emulation still

runs within the client browser and can be auto-deployed from the web server. When a user

requests the emulation web page, if the GDT-WDT terminal emulation has not been installed or a

newer version is available, the browser will automatically download and install the emulator.

The Active/X option works well for more advanced users who are typically on the local network.

The emulation object is downloaded from the web server and runs in the browser, where a direct

connection to the host is established.

Active/X Emulation gives users the power of a desktop emulator that runs within their web

browser and is very close to what they are probably used to.

The GDT-WDT “NVT” Active/X object is downloaded into a web browser and actually executes

within the browser on the client PC. The object has a direct connection with the host and the web

server plays no further part. The result is that there are no round trips back to the server every

time that the user moves between screens. This results in a faster connection and is much closer

to running a standard terminal emulator on the desktop.

Here is a summary of the Plus/Minus points for the Active/X approach:

+ Very fast, just like a desktop emulator

+ Well suited to power users who rely on auto-tab etc

- Needs a browser that supports Active/X controls

- Subject to more security issues (users can disable Active/X)

Using WebEmulation from your own .asp application

If you have written your own web application and wish to combine your own pages with standard

emulation or templates, you can use the GDT-WDT.WebEmulation object to wrapper your createdNVS.Terminal object and use the supplied methods to control the presentation etc.

10/5/20181Infosol, Inc