The Atlassian OAuth Validator can be used as express js middleware for a Node JS application. It serves the purpose to authenticate incoming requests from an Atlassian Application to the Node JS application.
The flow would be as follows:
To use the middleware you need to register the following in your app configuration:
In this case only URLs under /issue will be protected. A consumerStore needs to be passed in which will be used to lookup and approve consumers (see example/consumerStore.js for the API that this consumerStore needs to implement).
For a complete working example checkout: https://bitbucket.org/knecht_andreas/nodejs-plugins3-server/