Among other things, at a client computer system in communication with a computer network, a request object is generated that includes logic to control the handling of requests. At least one of the requests depends on (for example, simply by being part of a sequence) a result of at least one of the other of the requests. The request object is sent to a server computer system that is in communication with the computer network. A response object is received that includes results of at least some of the requests.