Is Friday and congregational prayer obligatory upon the traveler, and if it is not obligatory, does the ruling differ if the duration of travel extends for months or years?

Travel is one of the excuses that permit missing Friday and congregational prayers. If a Muslim's journey is prolonged and he intends to reside [in a place], he is not permitted to avail himself of the concessions of travel, and Friday and congregational prayers become obligatory upon him. However, if he does not intend to reside for four days and remains undecided, or if he is continuously on the move, then he may avail himself of the concessions of travel, even if this continues for years.