Creating a custom Workflow

Hello everyone,

For my project, I would like to create a workflow that would have 3 steps I think.

I need one of those step to involve a participant. This step would be the second and this participant does his job on a custome cq:page or a page or a form it doesn't matter as long as I can customize it like I want.

So the worklow would look like this :

1 - A Java Sling servlet would start the workflow

2 - The first Step would gather information around the JCR for the next step

3 - This is the participant step, the 2 step. the information collected in the previous step have been sent to my custom page. The participant received a notification in the inbox and goes to the custom page.

He does what he has to do on this page. To sum it up, he has to validate some stuff. Then by click "done", it advances the workflow to the last step sending information from the custom page to the last step

4 - Third and last step, information collected from the previous custom page are used by a java class to do som stuff

Here is my problem, how do I do this ? Especially the part where the workflow send information to a page, and this page send information back to the workflow so it can go on.

Thank you.