What is reactive marketing ? And why ?

We would begin with the basic concept, what is marketing ? 
Marketing is the methodology of communicating the value of a product or service to customers, for the purpose of selling that product or service.

Marketing techniques include choosing target markets through market analysis and market segmentation, as well as understanding consumer behavior and advertising a product's value to the customer. From a societal point of view, marketing is the link between a society's material requirements and its economic patterns of response. Marketing satisfies these needs and wants through exchange processes and building long term relationships. Marketing blends art and applied science (such as behavioural sciences) and makes use of information technology.

But how we can do "communicating the value of a product or service to customers" ?
We must understand customer, see the needs, feel the user experience and create something better, to satisfy them. The important step, you send the right message at right context (time, location, ..) to the right customer.

Some methods, such as market analysis, market segmentation and user experience research could be used.

So what is exactly reactive marketing ?
As we know, we live in the age of "fast data", it means we should react immediately when we find potential customers.
2 refer links here:
http://venturebeat.com/2014/06/25/the-next-big-disruption-in-big-data/
https://www.youtube.com/watch?v=TnLiEWglqHk

Reactive just as "showing a response to a stimulus".  We have data as event stream, analyzing as patterns and context (I call them "the Function X", the computing object that contains both data, context and behavioural functions ) and reactive to that pattern immediately.
The idea of Function X comes from http://en.wikipedia.org/wiki/Actor_model, and the framework implementation is Akka, http://akka.io/
Reactive Function X is my implementation for core ideas in practice. http://www.mc2ads.com/p/rfx-for-big-data-developer.html

This picture could be useful.

Why ?
The benefits are expected to include analyzing more data, faster—helping to find “insights that would otherwise have been missed,” as well as other improved efficiencies.
The sale team and marketing team should adopt new techs, react to sophisticated shopper insights, gain more customers and faster than competitors 

How we do it ? Some simple diagrams, here

Refer links:
http://www.emarketer.com/Article/Using-Big-Data-Still-Challenge-Marketers/1010710
http://en.wikipedia.org/wiki/Marketing
https://hbr.org/2013/03/advertising-analytics-20