Aztec UI Display Server
You could see that Pierre did truly love the mademoiselle.
- Chuck Berry
Aztec UI Display Server
The Aztec UI Display Server is a subsystem within the Aztec Engine. It runs in its own OS thread, and operates as a UI message server for the Aztec UI Class Framework. The system responsible for actually displaying the local user windows (UI Display Server) is completely independent from the UI Class Framework code that is driving the creation and management of the UI windows, even though they may exist in the same physical executable. This independence provided the opportunity to completely remove the UI Display task from the same machine that is running the Aztec Script and associated UI framework, and locate the UI Display server on a remote machine. Add some support from the Aztec Sockets subsystem, and the network ready Aztec UI Display Server is born.
The UI Display Server can be used in two different ways.
♦ With Aztec Engine running in Execute mode, the UI Class Framework uses the LOCAL instance of the UI Display server for all UI services to the local display/machine.
♦ This happens automatically with nothing required from the script.
♦ With Aztec Engine running in UI Display Server mode, the Engine provides UI services for one or more Aztec Script instances, which can be running on other machines across a network or the internet.
♦ The UI Display Server is launched using the "Aztec -display XXXX" command, where XXXX is the TCP/IP port number associated with the communication (e.g. 1080 or 1081).
♦ The remote Aztec Script creates a new Display object and connects to the UI Display server using Display.Connect().
♦ When a "top level" frame or dialog window is created in the Aztec Script, simply pass the remote Display object instead of the local Display object, and remote UI services are handled automatically and seamlessly from there.
When the Aztec Engine is running in "UI Display Server" mode, a connection statistics dialog is provided on the Aztec Engine system menu, as shown in the picture below.
Any number of Aztec Script instances can connect to the same UI Display Server, from any number of separate remote machines. The remote UI Display server works across any standard TCP/IP network, including local area networks and the internet.
UI Display Server Communication
The following diagram shows the UI message communication path from Aztec UI Framework through the Virtual Machine. From there, it goes to the Display Communication Manager for local UI services, and to the Socket Communication Manager for remote UI services.
♦ "Requests" originate with the UI framework to perform a task (create new button, add a menu item, display a dialog), and "Events" originate with the UI Display Server (ButtonClickEvent, WindowCloseEvent).
♦ UI Display Server underlying C++ code is implemented in two tiers, platform independent code and platform dependent code.
Aztec Display Class
The Display class is an important part of the simplicity associated with remote UI Display server processing. The script/application simply creates a new Display object, connects it to the UI Display server, and then uses it when creating a top level frame or dialog window. Everything else happens automatically. The script provides the necessary UI event handlers, and the remote UI system sends the events back to the script for processing.
The same Display class is used to represent the local UI Display and remote UI Display Servers. There is a method in the 'Script' class and a global method to get the 'Display' object associated with the LOCAL UI Display server were the script/application is running.
Script Method
♦ public method<Display> Display()
Global Method
♦ public method<Display> GetDisplay()
The following table shows the key members of the Display class. The Name() method for the local Display returns "Local".
