Presentation engines

Presentation engines

A presentation engine object displays UI elements at runtime.

Native presentation engine

Use the Native presentation engine for typical HMI applications that run on targets with an operator panel. There can be only one Native presentation engine in a project.
When you run a project, an interactive session generates and authenticates with the starting user.
You can change the current user in an interactive session. Based on the user and logic created, the interface can change dynamically in the same session.

Web presentation engine

Use a Web presentation engine to make a web user interface available to multiple users who connect from different web browsers. Web presentation engines are compatible with HMI applications that run on target devices equipped with an operator panel and with devices that do not have a dedicated administration interface. There can be only one Web presentation engine in a project.
TIP:
Due to security reasons, to view websites with self-signed SSL certificates inside a WebBrowser object with the Web Presentation Engine, you must first open the website in another tab of the same browser and approve the certificate in that tab. You can then go to the WebUI tab and reload the page to display the self-signed SSL website. Only websites with a content security policy that allows embedding can open inside a WebBrowser on a WebUI session. See Certificate errors.
When a user connects to the web server, an interactive session is generated for the authenticated user. The same user can generate additional interactive sessions by accessing the project from multiple devices. Each session creates a start window. See Sessions and locales.
TIP: Use the
Aliases
{Session}
Session
UI Session
IP Address
 variable to get the IP address of the client. Create dynamic links to use the client IP address in the application logic. For example, display different graphic objects to clients connecting from specific IP addresses. For more information, see Dynamic links and Aliases.
TIP: Web presentation engine can only load files from the project directory (
%PROJECTDIR%
). This applies to any object in the project that can load files, including image, web browser, and PDF viewer objects.

SVGs in presentation engines

To use an SVG image that renders consistently between the WebPresentation Engine and the NativePresentation Engine, you must define a height and width attribute for the SVG element within the image file.
For example:
<svg xmlns:xlink="http://www.w3.org/1999/xlink" height="100" width="100" xmlns="http://www.w3.org/2000/svg">        
     <rect width="100" height="100" style="fill:rgb(0,0,255)"/> 
</svg>

Session

Both the native presentation engine and web presentation engine expose a session type pointer. To read or modify session nodes, use the
{Session}
 alias instead. For more information, see Built-in aliases.
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