I'm looking for a project management tool with the following characteristics;
1) web based
2) collaborative. One person (the project manager) must be able to create tasks and assign them to co-workers. The co-workers must be able to edit them en resolve them, but they should not be able to close or reassign them. So if the project manager has given a task to someone, he can be sure that that task will stay with that person and will be reported back when it is finished.
3) ability to make a task dependent on something else. We find it unpleasant to have to do lists in which there are tasks that cannot be worked on for whatever reason. We want to be able indicate that a task is 'on hold', but that should only be possible when we indicate the on hold reason. This can be 'feedback from external person', 'feedback from other user', 'dependent on other task', 'postpone for x days' etcetera. These categories work differently; 'dependent on other task' will make the task active again when that other task is finished, 'postpone' should make the task active again when that time is elapsed, for 'feedback from external person' it should be possible to create a list of external persons and see the open feedback.
Is this kind of functionality available in any product you know of?