Answer by Goot for Creating own entity types in Jira - extending data model

You can use Active Objects (AO), which will allow you to create new entities and let you store them in your jira database.

https://developer.atlassian.com/server/framework/atlassian-sdk/best-practices-for-developing-with-active-objects/

This is fully supported by the atlassian-sdk. To read more about the atlassian sdk, click here: https://developer.atlassian.com/server/framework/atlassian-sdk/set-up-the-atlassian-plugin-sdk-and-build-a-project/

For the ui please look at atlassian AUI: https://docs.atlassian.com/aui/

Some extra docs: https://community.atlassian.com

http://www.j-tricks.com/tutorials/active-objects-injection

Have Fun :)