#ebook #book #pdf #mongo #mongodb

Publish & Subscribe for dummies:

Open 2 different windows (pane) in terminal and go to redis console:

redis-cli

Now to subscribe into a specific channel:

127.0.0.1:6379> SUBSCRIBE first second
 Reading messages... (press Ctrl-C to quit)
 1) "subscribe"
 2) "first"
 3) (integer) 1
 1) "subscribe"
 2) "second"
 3) (integer) 2

As you can see we have subscribed to 2 channels called first and second. In another window open redis console again by redis-cli command and try to publish to those channels:

PUBLISH second Hello

Now you should see the output below in the first window where you have subscribed to channels:

1) "message"
 2) "second"
 3) "Hello"

If you want to know more about pub-sub scenario:
https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern

#redis #pub_sub #publish #subscribe #redis_cli

https://gist.github.com/pixelsonly/fabfa0245beccdf7d138

#git #zsh #oh_my_zsh #commands

Send free fax via faxplus chrome addon:

https://chrome.google.com/webstore/detail/faxplus-receive-send-fax/dhbnflghagkonoikejjbjinpbdcjjlbo

#fax #faxplus #chrome #addon

Hanlde basic authentication (username, password in header) via requests in python:

>>> from requests.auth import HTTPBasicAuth
 >>> requests.get('https://api.github.com/user', auth=HTTPBasicAuth('user', 'pass'))
 <Response [200]>

As you can see above you just need to provide username & password in auth parameter in order to have basic authentication.

#python #requests #authentication #basic #basic_authentication

https://qnimate.com/understanding-http-authentication-in-depth/

#authentication #basic

What is LPUSH in REDIS:

Insert all the specified values at the head of the list stored at key. If key does not exist, it is created as empty list before performing the push operations. When key holds a value that is not a list, an error is returned.

It is possible to push multiple elements using a single command call just specifying multiple arguments at the end of the command. Elements are inserted one after the other to the head of the list, from the leftmost element to the rightmost element. So for instance the command LPUSH mylist a b c will result into a list containing c as first element, b as second element and a as third element.

Return value:
Integer reply: the length of the list after the push operations.

For instance:

redis> LPUSH mylist "world"
 (integer) 1
 redis> LPUSH mylist "hello"
 (integer) 2
 redis> LRANGE mylist 0 -1
 1) "hello"
 2) "world"

NOTE1: time complexity of LPUSH command is O(1). So it is the best from performance point of view.

NOTE2: `LRANGE is used to get list members, if you use 0 to -1 it will return all list elements.

#redis #list #lpush #push

O(1) or O(n) access time?

O(1) means that it takes a constant time, like 14 nanoseconds, or three minutes no matter the amount of data in the set.

O(n) means it takes an amount of time linear with the size of the set, so a set twice the size will take twice the time. You probably don't want to put a million objects into one of these.

#time #complexity #time_complexity

The simplest way to generate hour, minute, seconds from seconds in python is divmod:

m, s = divmod(seconds, 60)
 h, m = divmod(m, 60)
 print "{}:{}:{}".format(h, m, s)

#python #divmod #format

Another way:

import datetime
 "{:0>8}".format(datetime.timedelta(seconds=66))

The output is:

00:01:06

#python #timedelta #datetime

Removing docker network in swarm mode gives error below:

Error response from daemon: network demo_net has active endpoints

In order to remove the network you need to remove dangling containers that are bound to the network, to see those containers:

docker network inspect demo_net

In Containers section you would see name of those containers. Grab the name of the container and use disconnect as below to remove it from the network:

docker network disconnect -f demo_net NAME_OF_YOUR_CONTAINER

#docker #network #disconnect #swarm

An in depth overview of flask framework. In this tutorial you would be able to create a fully functional website using flask. This tutorial aims on creating a club application that users can login, create questions, club, etc:

https://medium.freecodecamp.org/how-to-use-python-and-flask-to-build-a-web-app-an-in-depth-tutorial-437dbfe9f1c6

#python #flask #fullstacka #tutorial

flask base project that contains registration, login, email, redis for email queue management, etc:

https://github.com/hack4impact/flask-base

#python #flask #flask_base #github

How to replace multiple characters in a string using python?

As you may already know there is a method for string called replace that replaces 1 character with a new given character:

'+98 21 445 54 12'.replace('+', '')
 # output is 98 21 445 54 12

But what if you want to replace both + and [SPACE] inside of the string? The answer is simple just chain the methods:

'+98 21 445 54 12'.replace('+', '').replace(' ', '')

Here output would be 98214455412.

#python #string #replace #multiple_replacement

If the replacements are going to be more in number, you can do this in this generic way:

strs, replacements = "abc&def#ghi", {"&": "\&", "#": "\#"}
 print "".join([replacements.get(c, c) for c in strs])
 # abc\&def\#ghi

#python #join #replace

Fraud Detection on credit card using Apache Kafka KSQL:

CREATE TABLE possible_fraud AS
   SELECT card_number, count(*)
   FROM authorization_attempts
   WINDOW TUMBLING (SIZE 5 SECONDS)
   GROUP BY card_number
   HAVING count(*) > 3;

The above query creates a moving window in 5 seconds timeframe and check whether there are more than 3 authorization attempt on a
specific credit card, real time!

KSQL is a good fit for identifying patterns or anomalies on real-time data. By processing the stream as data arrives you can identify and properly surface out of the ordinary events with millisecond latency.

#apache #kafka #ksql #fraud_detection

How to check whether a socks server working or not?

Let's say you have run a socks server on port 8888. Now in order to test the server, you just need to use cURL! You need to provide --socks5 parameter to cURL as below:

curl --socks5 localhost:8888 binfalse.de

If you see some HTML stuff, your server is up & running, but if you see the below error it seems the server is not working properly:

curl: (7) Failed to connect to localhost port 8888: Connection refused

The above error says that port 8888 is not available, you may see different errors based on the server configuration stat. Hope it helps.

#socks5 #socks #socks_server #curl

#book #ebook #epub #angular

#programmer_jokes #fun