1. A method of modifying behavior of a computing device, comprising: maintaining byte code corresponding to an application in the computing device; receiving at the computing device, a message transmitted by a server while the computing device is executing the application, wherein the computing device is exhibiting a first behavior while under control of the application; responsive to the message, changing a first implementation pointer related to the application by replacing a first address stored in the implementation pointer with a second address, wherein the second address corresponds to a code block maintained in a library of modules on the computing device, and wherein changing the first implementation pointer modifies the first behavior; and storing the first address in a second implementation pointer, wherein the first implementation pointer is identified in the byte code using a first function selector and the second implementation pointer is identified by a second function selector, wherein an address is stored in the implementation pointer during loading of the application, and the first address corresponds to a target function that is linked to the application, wherein invoking the first function selector after replacing the first address with the second address in the first implementation pointer causes the computing device to execute the code block, wherein executing the code block includes invoking the second function selector such that the computing device is caused to execute the target function after each execution of the code block.