Java – REST API with Spring Security

Securing REST API with Spring Security.

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Java – Recording Java Flight Recording in Java 9

Command line to enable Java Flight Recording feature in Java9 for measure JVM performance.

$ java -XX:+UnlockCommercialFeatures -XX:StartFlightRecording=filename=recording.jfr AppName
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Java – JDK9 tool jdeps and jdeprscan to inspect any illegal usage

The following jdeps command will inspect any illegal usage in My.class and provide alternative way to fix problems.
This tool exists in JDK9.

$ jdeps -jdkinternals My.class

Static analysis tool detect the usage of deprecated APIs.

$ jdeprscan -cp My
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Java – Guidance of using wildcard in generic

The basic guidance of using wildcard in Java generic

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C++11 – Monoid, Functor, Applicative Functor and Monad

How CPP express Monoid, Functor, Applicative Functor and Monad.

The below documentation shows a good explanation.

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Python – HTTP send a JSON object and decoding example

import http.client
import ssl
import json
import base64
from collections import namedtuple
from optparse import OptionParser

def load_input_data(input_path):
    with open(input_path) as inputFile:

def string_to_base64(s):
    return base64.b64encode(s.encode('utf-8')).decode('utf-8')

def create_json_data(s, protocol):
    class CustomRequestData(object):
        def __init__(self):
            self.version = "0.1"
            self.description = "test"
            self.enableDebug = True
            self.protocol = protocol
            self.requestPayload = string_to_base64(s)

    request = CustomRequestData()
    return json.dumps(request.__dict__)

def create_http_header():
    password = string_to_base64("user:password")
    headers = {
        'content-type': "application/json",
        'authorization': "Basic " + password

    return headers

def base64_to_string(b):
    return base64.b64decode(b).decode('utf-8')

def _json_object_hook(d):
    return namedtuple('X', d.keys())(*d.values())

def json_to_obj(data):
    return json.loads(data, object_hook=_json_object_hook)

def connect_https_server(host_name):
    port_number = 9992
    host_end_point_address = host_name + ":" + str(port_number)
    return http.client.HTTPSConnection(host_end_point_address, timeout = 5, context = ssl._create_unverified_context())

def send_request_save_response(host_name, protocol, input_edifact_path, output_file_path):
    json_data = create_json_data(load_input_data(input_edifact_path), protocol)
    conn = connect_https_server(host_name)
    conn.request("POST", "/endpoint_data", json_data, create_http_header())

    res = conn.getresponse()
    data =

    result = json_to_obj(data.decode('utf-8'))

    file = open(output_file_path, 'w')

def main():
    parser = OptionParser()
    parser.add_option("-s", "--server",
                      help="server name of service")
    parser.add_option("-p", "--protocol",
                      help="protocol type")

    parser.add_option("-i", "--input_path",
                      help="input file path")

    parser.add_option("-o", "--output_path",
                      help="output file path")

    (options, args) = parser.parse_args()

if __name__ == "__main__":

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Scala – ~> [Tilde arrow] explanation

“~>” is a place holder for type.
Main reason to use “~>” is to make readable on type A goes to type B. This is possible because Scala allow to express in in-fix notation for pre-fix expression.

trait Order[~>[_,_]] {
   def sort[A,B](f: A ~> B): B

is equivalent to

trait Order[M[_,_]] {
   def sort[A,B](f: M[A, B]): B

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