ATLANTA — The relentless rise of online shopping is causing major changes in how companies like UPS get packages delivered to doorsteps. More people are using apps to buy everyday goods online, causing major changes in retailing. The flood of packages and expectations of quick delivery, meanwhile, are also shaking up the shipping business. For UPS, the trend means restructuring operations and deploying new technology to adjust to the greater demand. The effort is visible in the middle of a UPS sorting facility in Roswell, Ga., where packages move down a conveyor belt while a machine spits out a shipping label onto each.