- he want to permit to his commercial partners to edit their own page (and only their page), with an access code for each one.
You could create separate user groups and link them to separate resource groups to only allow them to modify their own page(s). It may be easier to set up a front-end system for that though, as then you wont have to deal with ACLs and just make your custom FormIt hook get & save data to the right resource (hint: link it to a user ID).
- when a partner make a change on this own page, the modification have to be validated by the director of publication
This type of workflow solution is not yet available.. when you use the modx back-end you can refuse them publish permission, so they can’t actually publish anything.
- the director of publication should receive a notification when a modification of one of this partner’s page has to be validated
A simple plugin could do that - see my post here:
http://modxcms.com/forums/index.php/topic,64029.0.html