When is a Plugin an External Program?

[Sam_Zen]

A attempt to answer the thread question here :
- An application can be an embedded function assigned in some program.
- An app as plugin can stay an independent function, but of course the main program must give access to read plugins in the 1st place.
- A plugin can become part of the application, when the app is adapted to integrate the plugin, like it's done with IVPaint.

[luciansabo]

Please don't confuse things.

- An application can be an embedded function assigned in some program.

A program can call an external app to do certain things. This does not mean an app is an embeded function.

- An app as plugin can stay an independent function, but of course the main program must give access to read plugins in the 1st place.

An application can never be a plugin.
Taken from wikipedia:

A plugin (plug-in, addin, add-in, addon, add-on or snap-in; but see extension) is a computer program that interacts with a host application. Applications support plugins for many reasons. Some of the main reasons include: enabling third-party developers to create capabilities to extend an application, to support features yet unforeseen, reducing the size of an application, and separating source code from an application because of incompatible software licenses.
[...]
Mechanism
The host application provides services which the plug-in can use, including a way for plugins to register themselves with the host application and a protocol by which data is exchanged with plugins. Plugins are dependent on these services provided by the host application and do not usually work by themselves. Conversely, the host application is independent of the plugins, making it possible for plugins to be added and updated dynamically without changes to the host application.
[...]
Plugins and Extensions
Plugins are slightly different from extensions, which modify or add to existing functionality. The main difference is that plugins generally rely on the host application's user interface and have a well-defined boundary to their possible set of actions. Extensions generally have fewer restrictions on their actions, and may provide their own user interfaces

IV cannot be considered a real plugin host, because of the lack of plugin API.
RIOT can be considered finally as an extension. It communicates with the main program by receiving the DIB image from memory. Calling as external app will receive only the filename, not the image from memory.

[Sam_Zen]

Nice explanation.