Tracy Steven Brown

C-Based Multithreaded Webserver & Learning Management System (LMS)

Software Development: C and Java

The development of a C-based multithreaded webserver with native MySQL

database support was a multi-year project supporting a massively parallel

globally deployable 100% SCORM 1.2 compliant learning management

system (LMS) delivering standards-based learning materials to metallurgical

plant operators in remote areas of the world. SCORM is a specification of

the Advanced Distributed Learning (ADL) Initiative from the Office of the

United States Secretary of Defense. The software solution was written

entirely by Tracy Steven Brown while employed at Performance Associates

International (PAI), Inc. The source code is several hundred thousand lines

and highly complex; the screen shots provided here only show an

exceedingly small fraction of the project and serve to highlight Tracy’s C

programming style. Both C development and Java development were

performed on Oracle/Sun Solaris-10 UNIX using the NetBeans IDE.

The Webserver and server-side LMS logic was written in C and the web-

based front-end was developed in XHTML and Adobe Flash via the Adobe

Flex development framework. LMS specific communication was performed asynchronously via a custom Java applet

delivering SCORM compliant callback requests to the server. The server-side component supported both XML and JSON

formatted requests and was capable of sending XHTML, XML, and JSON structured responses. MySQL was embedded into

the webserver allowing native support for integrating structured storage – this was an architectural decision to allow tier-

1 support for database caching. Subsequent database layer logic was supported for non-cached data using standard

external API hooks.

The image above highlights the software engineering patterns used within the project. One of the more salient objectives

for Tracy was abstracting logic written in C into reusable patterns

common to C++ software architects. While inheritance and

encapsulation styled patterns could not be directly

implemented, several other patterns did lend themselves to

abstraction. Note that the AVL tree pattern in the example was

adapted from the Open Solaris Kernel.

The image to the left shows the initial code for creating a UNIX

daemon – equivalent to a Windows Service. The next source

code image follows up with UNIX TCP socket configuration for

listening and responding to TCP socket communication. The

source code displayed is a small subset of the full daemon and

socket configuration base; however, it does showcase Tracy’s C

programming style. Note that there are extensive preprocessing

statements used throughout the project for tracking the code

execution stack. Other preprocessing statements include return

value error condition checking; for example, ec_cmp() is a

preprocessing comparison statement for checking return values.