Probably the BugzillaInt plugin is an interesting plugin to get an impression which component you could use in your plugin.
wiki:
https://www.dokuwiki.org/plugin:bugzillaint
code:
https://github.com/timostamm/BugzillaInt
A fast look reveals that it uses:
- syntax components for adding some syntaxes
- helper plugin for building queries to retrieve info from an online platform with RPC. This helper component is used at different places in the code of this plugin.
- action plugin which handles ajax requests from javascript. So some content of the elements that are included in a wiki page with a syntax are dynamically loaded via javascript.
I have no idea what kind of info you like to add to your portal and in which way you could communicate between the wiki software and the jira software. So that does not help for providing more concrete examples.
See here for pointers about coding of the components of a plugin:
https://www.dokuwiki.org/devel:plugins