What technology does the video chat room use to develop?

Video chat rooms have a lot of different techniques to develop, here are a few columns for everyone:

One, can use pure C/s architecture to develop, the advantage is that the function will be more powerful, the disadvantage is that the development cost is very high, the period is longer. Generally not suitable for small and medium-sized enterprises webmaster use.
Second, through the development of plug-ins to achieve high-performance video chat room, but its shortcomings and pure C/s architecture is the development cost is too high, the current network Trojan prevalence, many developers of this kind of way is not too cold.
Third, the use of pure web-based means to develop video chat rooms, its advantages are: low development costs, high operational efficiency, can be developed through a simple tool to achieve.
To sum up, the best video chat room development technology is still recommended in the form of pure web, but also many small and medium-sized webmaster's first program.

What technology does the video chat room use to develop?