1. A method performed on one or more servers, comprising: enabling a client to define a Web service dynamically; storing, in memory on the one or more servers, code for different versions of script corresponding to the Web service, the different versions including at least one earlier version of the script and at least one later version of the script; receiving a call to the Web service from a device, the call comprising a HyperText Transfer Protocol (HTTP) command, the HTTP command identifying the script in accordance with a convention defined by a proprietor of the script; identifying the script corresponding to the Web service based on the HTTP command, the script defining a context among multiple contexts in which the script is to run, the context defining a set of privileges and permissions, the set of privileges and permissions being either generic or specific to an entity that created the Web service; executing, on the one or more servers, code corresponding to a version of the script in the context to implement the Web service, the code producing an output; and sending the output to the device; wherein an argument is received from the device with the call, the argument being associated with an aspect of an entity being monitored by the device; and wherein the version of the script obtains information associated with the argument and uses the information to produce the output.