App requirements:
1. There should be at least two types of events the user can choose, which are Conference and Training
2. There should be at least 2 user types for the app, which are the Event Organizer and Event Attendee
3. You should use online database and online forms to allow users to do the necessary tasks such as event creation, invitation, registration, modification etc.
4. Assuming there is an AI engine for chatbot that you can readily use, incorporate the user interface on your web app to allow the user to chat with the chatbot engine.
I am good at website development especially in Java. I have 10 years Java back-end development experience, you can see my resume for detail, I think I am very proper for your project, can complete your requirement ASAP. Hope for more communication for the project detail.