Today we take a  break to discuss websockets
Websockets come in helpful where previously we were doing polling over HTTP. Here we maintain a connection different from HTTP and over TCP where both client and server can push events. Yes events is a good example of using web sockets because they are time series and are also numerous in nature. Websockets are full duplex connections so both sides can be producer and consumer.
Some examples of Client side libraries include :
socket.io and
web-socket-js
while python implementations include
Autobahn
and crossbar.io
Crossbar.io is particularly helpful in synchronous python stacks that want the latitude of near realtime behavior to Django applications.
it enables us to trigger notifications from our synchronous python web stack because it comes with a pusher service that can be configured in the json configuration file.
As an example use case, consider that we want to display real time monitoring of cpu, memory metrics on a dashboard using a python django server. the clients publish ata from each monitored machine to a central django server that in turn publishes to the frontend. the frontend updates on each new statistic because it listens for those events with say Autobahn. Here the difference is highlighted from the traditional model where the front-end pulls the information from a time series database by running a query every once in a while.
<pre>
<code>
#codingexercise
Print next greater palindrome of a given array with each element denoting a single digit of an integer
        static List<int> GetNextPalin(List<int> digits)
{
var current = digits.Select(x => x).ToList();
while (IsPalindrome(current, 0, current.Count -1) == false)
{
int start = 0;
int end = current.Count - 1;
while(start<end)
{
current[end] = current[start];
end--;
start++;
}
    if (compareTo(current, digits) == -1) // current < digits
{
if (start == end)
{
        if (current[start] + 1 >= 10){
            AddOne(ref current, start);
               continue;
        }
        current[start] = current[end] + 1;
}
if (start > end)
{
        if (current[start] + 1 >= 10){
            AddOne(ref current, start);
             continue;
        }
        current[start] = current[start] + 1;         
        current[end] = current[end] + 1;
        end++;
        start--;
}
}
}
return current;
}
</code>
</pre>
 Int = 123456, Palindrome = 124421
Int = 1, Palindrome = 1
Int = 12, Palindrome = 22
Int = 92, Palindrome = 99
Int = 31, Palindrome = 33
Int = 13, Palindrome = 22
Int = 83422469, Palindrome = 83433438
Int = 12921, Palindrome = 12921
Int = 125322, Palindrome = 125521
Int = 14587678322, Palindrome = 14587678541
Int = 94187978322, Palindrome = 94188088149

bool isPalindrome( List<int> digits, int start, int end)
{bool ret = true;
while(start < end)
{
if (digits[start] != digits[end]) return false;
start++;
end--;
}
return ret;

}