Creating a Portal Application
Any application onboarded on ONAP Portal is a standalone program that can be visually accessed via the GUI in the ONAP Portal.
Onboarding application on ONAP Portal as a simple third-party-app URL with out single-signon (choose this option, if this is temporary and POC only): How to add a New Application to Portal homepage
Onboarding application on ONAP Portal as an integrated app using single-signon (recommended/preferred method - if the application is already developed and trying to integrate with portal): Onboarding How-To: ONAP Portal SDK's Framework (FW) based Applications on ONAP Portal
Here is sample Portal SDK integration code snippet from RIC Dashboard app that is already onboarded on ONAP Portal: Sample code from RIC Dashboard app; Sample configuration;
Developing Portal SDK based application and onboarding onto Portal – deep integration to take advantages of out-of-box Portal SDK features (choose this as long-term option, with appropriate time and resources when building an application for the first time): Developing Portal SDK based UI App and the initial setup