K Griffin - C/C++, Win/Linux, VoIP, MySQL, QT, Python, Embedded & Java programmer - Freelance Programmer / Developer, Pakistan

Development of H.245 Stack (ITU T H.245) for use in a H.324M application. This application was designed and developed using sockets and multithreaded programming and an even driven approach.
Encoding/Decoding of PER messages using message syntax specified in Annex A of ITU T H.245 Recommendation and PER rules specified in X.691. 
Implemented Logging and component level tracing mechanism for logging incoming/outgoing message to stack and module level Tracing for normal stack operations.
Implemented Multiplex Entry Send (MES), Remote Multiplex Entry(RME), Round Trip Delay (RTD) signaling entities for H.245 stack.
Developed in ANSI C for Enterprise Level application (3G gateway)

Development of a billing system using OpneGK:
Developed a Billing system for a H323 based call system using OpenGK which included getting RAS messages and extracting useful information for billing and record.
Used mysql as the back end data base system to store call records

As part of a team developed automated scripts to test and verify MLME functionality as described in the 802.11 specs.
One testing suit was developed using Python .
Other module was developed using C.

Developed and designed an inventory system for a large multi national aid agency (Mediwerks)
Development of data base for storing medical supply record.
Development of middle-ware system using java servlets, jdbc for using and manipulating data base records.
Development of a User interface for adding supplies to ware house, removing supplies from ware house etc. using  jsp.

Maintained the SME for 802.11 stack developed by the company. The SME part interacted with user on one end and WiFi driver on the kernel side. It has two interfaces:
Graphical Interface : developed using QT (for portability on Linux and windows).
Command line interface: Through this interface a user could Start, Join, authenticate and associate a WiFi node.

A graphical user interface application for the development and testing of Firmware for company’s WiFi processor. This firmware was used on company proprietary processor:
Designed and Developed an IDE (Integrated Development Environment) which included an editor, linker, assembler and debugger . 
The firmware generated by this tool was loaded onto PCI card and used for wireless communication.
IDE was developed for Linux platform using QT(www.trolltech.com) and then ported to windows.
Developed a virtual driver for managing shared memory resource that was being shared between two processes.
The core part was developed in C

Implemented an event driven state machine architecture for the proxy server. 
Implemented the SIP Parser for parsing incoming SIP requests and handing them over to event handler, which then invokes the state machine.
Implementation of RFC 3263 for calculation of routes in SIP proxy servers.
Interfacing to PSTN by loading a shared library for managing connection to PSTN from IP also implementing features like Fail-Over and CDR generation, billing and call monitoring.
Integration of a mysql client in C in our SIP Proxy for recording billing information as well as an LCR module.
Doing R & D for establishing a complete IMS solution on top the current 3261 implementation.
The system is designed to be highly efficient due to efficient data structures and efficient memory usage algorithms.
Proxy server is developed on top of an Asynchronous Framework which reduces the cost of building highly scalable server class applications by using an event driven approach thus reducing the complexity of development by giving an alternative to Thread programming.
Used FIFO's for communication between different modules of proxy and the underlying Asynchronous Framework.
Design of an efficient memory manager and sip parser

Worked on development of GnuGK(open source gatekeeper for H323 traffic). Wrote a patch for gnugk which enabled it to run behind a Layer 4 Load balancer by rewriting the Layer 7 destination address to machines behind load balancer  instead of load balancer itself.
Part of a team for research and design of a SIP: H.323 gateway. Explored osip/eXosip in order to understand the working of SIP protocol. Experimented with open source rtp stacks like ortp and uclmm rtp library to know the real time traffic and its issues like congestion control, packet loss etc.

Maintenance and enhancement of a java based work flow system that was developed by the company as product