Hello ！Does openfire belong to a bundle service?
What do you mean exactly? Openfire can be obtained as a stand-alone project. It works well with all kind of XMPP software, if you seek for interoperability.
Does its architecture belong to OSGi?
What service does the hot-plug mode belong to?
openfire is a hot-pluggable service! What architecture does this service belong to?
Are you referring to the plugin API that Openfire provides? That is a custom implementation.
I wanted to write the same emoji when i have read the thread…