1. A system comprising: a first machine hosting a server configured to provide a web service and a function call package associated with the web service, wherein the first machine is configured to communicate with a second machine hosting a web site, wherein the first machine is connected to the second machine over a network, and wherein the second machine is configured to receive a request for the web service from a user at a third machine; and a non-transitory computer-readable storage medium accessible by the first machine and storing the function call package, wherein the function call package includes a function call corresponding to the web service and information corresponding to one or more input parameters, output parameters, or return values defined for the function call, and wherein the server is operable to distribute the function call package to the second machine over the network, wherein the distributed function call package is configured to collect information from the user at the third machine visiting the web site hosted at the second machine and submit a transaction to the server on the first machine based on the collected information, and further configured to receive a response from the server and present the response to the user visiting the web site.