These are a modern version of the old storefront crank-up awnings of the last century. Tension arms and a roller bar are supported by a torsion bar. The torsion bar a/k/a square bar fits into wall or soffit or fascia or roof mounted brackets that spread the load to the wall or roof truss. Hand-cranked awnings are still available, but motorized awnings are now most common. The motor is inside the roller tube that the fabric rolls around and therefore is not visible. Many motors now have a built-in receiver and are operated by remote control, smartphone, tablet or home automation.
Retractable awnings are now becoming very popular with homeowners in the United States. They have been popular in Europe for many years, due to higher energy costs and lack of air conditioning.
Awnings were first used by the ancient Egyptian and Syrian civilizations. They are described as "woven mats" that shaded market stalls and homes. A Roman poet Lucretius, in 50 BC, said "Linen-awning, stretched, over mighty theatres, gives forth at times, a cracking roar, when much 'tis beaten about, betwixt the poles and cross-beams".
The other (projecting) end of the canvas was draped over or laced to a front bar with the edge often hanging down to form a valance. On ornate examples, metal posts were adorned with filigree and the tops decorated with spear ends, balls or other embellishments. On overcast days or when rain did not threaten, the covering was often rolled up against the building facade; during the winter months proper maintenance called for the removal and storage of awnings. Photographs from the mid-19th century often show the bare framework, suggesting that the covering was extended only when necessary. Canvas duck was the predominant awning fabric, a strong, closely woven cotton cloth used for centuries to make tents and sails.