Using Drupal 7 Rules, how to react to a file upload and change a node field?
Workflow 


  This module allows you to create arbitrary Workflows, and assign them
  to Entities.
  
  Workflows are made up of workflow states. Transitions between states
  can be allowed per role. For example, a workflow with the states
  Draft, Review, and Published could be assigned to the Story node type.
  Only users with role 'chief editor' can set Stories to the published
  state. You can set up the Workflow to alter states from form, page,
  comment and a special workflow tab.
  
  Transitions between workflow states can have actions assigned to them.
  In our example, we could assign an action so that when the story moves
  from the Draft state to the Review state an email is sent out. Another
  action could be assigned to the transition from Review to Published so
  that the node's status is set to Published (and becomes visible on
  your website).


How we use workflow module 

Creating a Workflow

Editorial workflow with Rules