Messaging between components in graphical user interfaces for industrial control systems

A computer-readable non-transitory storage medium with encoded instructions that, when executed by a processor, cause the processor to accomplish steps of:

• accessing a project comprising components arranged in a hierarchical structure and displayed in a web browser, each component having one or more graphical features or one or more behavioral features of the component when displayed in the web browser;
• receiving first definition input to define a message handler associated with a first component in the project for receiving messages for the first component, the definition input comprising:
• a message type definition for the message handler identifying the message the message handler reads;
• a scope definition for the message handler indicating one or more levels in the hierarchical structure of the project at which the message handler receives messages;
• a script implementation describing a response by the message handler to receiving messages;
• receiving second definition input to define a messenger associated with a second component in the project for sending messages to one or more message handlers, the message input comprising:
• a message type argument;
• a scope argument indicating a level of the project at which to deliver the message;
• and
• a payload option;
• and
• wherein, in response to receiving a payload input via the messenger associated with the second component from a session of the project:
• identifying the first component having the associated message handler by matching the message type definition to the message type argument of the messenger and the scope definition to the scope argument of the messenger;
• and
• delivering the payload as an argument to the identified first component with the matching message handler;
• and
• executing the script of the message handler associated with the first component.