Abstract: A system and method are provided that allow for improved code sequence verification through the use of an abstract syntax tree. This is accomplished by first constructing an abstract syntax tree from the code sequence and then determining whether the abstract syntax tree satisfies a predefined set of conditions indicative of the code sequence being executable on the computer without generating a predefined class of execution errors. The abstract syntax tree is constructed by reassembling the code sequence into a plurality of instructions, combining the instructions into a plurality of blocks, examining the blocks to determine entry points of a plurality of loops, and tagging locations in the series of instructions where control is transferred at the end of each loop. The instructions, blocks, loops and tagged locations are then examined to generate a plurality of control structures (the coarse structure).

Abstract: An apparatus and method are provided for on-line code replacement of a program running in a process. The apparatus and method utilizes a variant of the exec system call, which will be referred to as a text-only exec. The present invention, utilizing a checkpoint methodology, allows the programmer maximum flexibility in addressing upgrade/replacement program issues and determines where, when and how the transition to a new version of a program should occur with least impact to the services.

Abstract: Apparatus and method are provided for accomplishing on-line replacement of a script running in a process. The apparatus and method utilize a script registry that keeps track of the most current script for a particular service. The request for service is presented to the script registry to identify the location of the most current script that provides the requested service. Because this script registry is an internal data structure, it is therefore lightly portable between different operating system machine types. A superscript is further utilized to transfer script state information between execution of the service-providing scripts. This ensures that data information (i.e., execution mode, environment information, and variable data) is passed from a terminating service script to an initializing service script.

Abstract: Apparatus and method are provided for transferring state data between computer software programs within the same software process. The apparatus and method does not require a special operating system, but instead only requires the use of a few standard operating system calls (i.e, fork and exec, etc.), so therefore is highly portable between different operating system machine types. The apparatus and method have complete flexibility to change arguments or return values and change calling order, function names, function code, and the like within the new version of the program.

Abstract: Apparatus and method are provided for on-line replacement of a program running in a process. The apparatus and method do not require a special operating system, but instead use a few standard operating system calls (i.e, fork and exec, etc.). Therefore, the apparatus is highly portable between different operating system machine types.