Машинальное масло

Analyst defines purpose of the system. Analyst says about system what it is for. The job of analyst is done when there is sufficient details given to Architect to complete his job and there is enough details given to Tester to complete his job too.

Architect defines functional elements of the system, their relations with system purpose and each other. Architect says what needs to be done. The job of an architect is done when there is sufficient details given to Engineer to complete his work.

Engineer eliminates "somehows" from what he is given by an architect. Engineer says how exactly elements of the system defined by an architect will be made and how they will interact with both - outside of the system and each other. Engineer has done his job when there is sufficient details given to Implementor to complete his job.

Implementor is making what is defined by an architect the way defined by an engineer. Implementor is the one who is actually producing the candidate on the role of Product. Implementors job is done when Tester has confirmed that there are no more differences between what was defined by Analyst and what there is at actual presence in the Product.

Tester compares what is given to him as a Product to what it is expected to be. Tester says what is different between one and the other. The job of Tester is done when each significant element of system purpose either confirmed to be matching with an actual Product or there is description of the difference provided.

So who the hell is the Developer?

Developer is the person who is nominated to play some parts of all of the above roles without recognising their boundaries nor providing products of each.

"Developer" is the substitute for "vaguely defined process" and nothing more than that.