Extend your H.323-based applications by using NON-STANDARD messages


Extend your H.323-based applications by using NON-STANDARD messages

Abstract

Comparing to SIP protocol or RTSP protocol, H.323 protocol is a strict one, which has its own working flow control, and every bits in it's protocol buf has its meaning. However H.323 provided a NON-STANDARD message machenism to allow users to extend your own bussiness rules. This document is discribing a example extended H.323 bussiness by using NON-STANDARD message of H.323. And also could be a guide of how to start your own NON-STANDARD message for your H.323-based applications.

Keywords: H.323, RAS, NON-STANDARD message

Key problems to be solved

H323 is a standard defined over ten years ago, the standard commands are no longer enough for some specified applications. In cases, we need to add some customized informations or command protocols for our featured implementations of our H.323-based products.

Solutions for the key problems

There is a machenism of NON-STANDARD message in H.323, which allow you to extend your own protocol/feature for your products.

And there are two ways to add your customized message to H.323 protocol:

  • Using an independent H.245 NSM command
  • Padding NSM data after a standard H.323 protocol(RAS, H.225, or H.245 message)

Both of them could be very helpful, if you want add some customized functions or integrate some value-added bussiness into your VoIP or H.323-base applications.
And its a really popular way to use NSM messages in H.323 protocol, I'm here providing you two examples both of them are claimed as patents, and both of them are Invention level of patents.

  • China Patent CN101119251B

Method for implementing video added value service in H.323 standard based network, invented by China Telecom.
You can download it here: http://docs.google.com/a/rg4.net/viewer?url=patentimages.storage.googleapis.com/pdfs/2b97ddd77940eba9f4f4/CN101119251B.pdf

  • US Patent US20060245419

Back-to back H.323 proxy gatekeeper, invented by Siddhartha Nag, Bo Shu, Rahul Gulati, Ilana Polyak
You can download it here: http://docs.google.com/a/rg4.net/viewer?url=patentimages.storage.googleapis.com/pdfs/US20060245419.pdf

Considering NSM's all-yours data format, by using it, you can do anything you want, integrate any bussiness you need to your H.323 applications. Don't you exciting?

Two ways to use NSM

Now I'll show you the codes of the two ways to send NON-STANDARD messages by using RV H.323 stack.

1. Independent H.245 NSM command

a. Packing and sending an independent H.245 NSM command

b. De-pack and parse out received independent NSM command

Code part 1: get the protocol type after received a H.245 message, if it is a NSM command, then call code part 2 to parse the NSM.

Code part 2: parse out the NSM message.

2. Padding NSM data after a standard H.323 protocol(RAS, H.225, or H.245 message)

a. Packing and sending a padding NSM data to the RRQ message(RAS)

b. De-pack and parse out received padding NSM data

Summary

As you can see, its really simple codes. By using it, you can do whatever functions you want, add any features you need for your applications. Furthermore, inventions are not far from you, if you want, you can have your own inventions.

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