How to Use SODA for REST with OAuth Client Credentials in your Node.js/Web App to CRUD Oracle Autonomous Database?

Use SODA for REST with OAuth Client Credentials in your Node.js or Web application to CRUD Oracle Autonomous Database

How to Create ads.txt for your Ghost blog website

How to Internationalizing your Flutter apps ?

First Reading:

https://flutter.dev/docs/development/accessibility-and-localization/internationalization

Steps:

1. add flutter_localizations dependencies into pubspec.yaml

dependencies:

flutter:

sdk: flutter

flutter_localizations:

sdk: flutter

2. add localizationsDelegates and supportedLocales into MaterialApp

Applocalizations.delegate is your app-specific localization delegate.

will be introduced in next step.

Widget build(BuildContext context) {

return MaterialApp(

localizationsDelegates: [

AppLocalizations.delegate,

GlobalMaterialLocalizations.delegate,

GlobalWidgetsLocalizations.delegate,

GlobalCupertinoLocalizations.delegate,

],

supportedLocales: [

const Locale.fromSubtags(languageCode: 'zh'), // generic Chinese 'zh'

const Locale.fromSubtags(

languageCode: 'zh',

scriptCode: 'Hans'), // generic simplified Chinese 'zh_Hans'

const Locale.fromSubtags(

languageCode: 'zh',

scriptCode: 'Hant'), // generic traditional Chinese 'zh_Hant'

const Locale.fromSubtags(

languageCode: 'zh',

scriptCode: 'Hans',

countryCode: 'CN'), // 'zh_Hans_CN'

const Locale.fromSubtags(

languageCode: 'zh',

scriptCode: 'Hant',

countryCode: 'TW'), // 'zh_Hant_TW'

const Locale.fromSubtags(

languageCode: 'zh',

scriptCode: 'Hant',

countryCode: 'HK'), // 'zh_Hant_HK'

const Locale('en', ''),

],

3. Defining your own class for the app's localized resources

import 'package:flutter/material.dart';

import 'app_localizations_delegate.dart';

class AppLocalizations {

AppLocalizations(this.locale);

final Locale locale;

static AppLocalizations of(BuildContext context) {

return Localizations.of<AppLocalizations>(context, AppLocalizations);

}

static Map<String, Map<String, String>> _localizedValues = {

'zh': {

'appTitle': '海德堡要理问答',

},

'en': {

'appTitle': 'The Heidelberg Catechism',

},

};

String get appTitle {

return _localizedValues[locale.languageCode]['appTitle'];

}

static const LocalizationsDelegate<AppLocalizations> delegate =

AppLocalizationsDelegate();

}

import 'package:TheHeidelbergCatechism/i18n/app_localizations.dart';

import 'package:flutter/foundation.dart';

import 'package:flutter/material.dart';

class AppLocalizationsDelegate extends LocalizationsDelegate<AppLocalizations> {

const AppLocalizationsDelegate();

@override

bool isSupported(Locale locale) => ['en', 'zh'].contains(locale.languageCode);

@override

Future<AppLocalizations> load(Locale locale) {

print(locale.languageCode);

return SynchronousFuture<AppLocalizations>(AppLocalizations(locale));

}

@override

bool shouldReload(AppLocalizationsDelegate old) => false;

}

4. Use AppLocalizations

@override

Widget build(BuildContext context) {

// This method is rerun every time setState is called, for instance as done

// by the _incrementCounter method above.

//

// The Flutter framework has been optimized to make rerunning build methods

// fast, so that you can just rebuild anything that needs updating rather

// than having to individually change instances of widgets.

return Scaffold(

appBar: AppBar(

// Here we take the value from the MyHomePage object that was created by

// the App.build method, and use it to set our appbar title.

title: Text(AppLocalizations.of(context).appTitle),

),

Demo:

How to measure the maximum throughput (TPS - Transactions per Second) that a single website instance(host) can handle via curl tool ?

tps.py, a python script using curl to measure the time per transaction requested to your website

curl --connect-timeout 10 --max-time 10 -o /dev/null -s -w "%{http_code},%{size_download},%{time_appconnect},%{time_connect},%{time_namelookup},%{time_pretransfer},%{time_starttransfer},%{time_total}" -k

#!/usr/bin/python
#-*- coding: UTF-8 -*-

import commands
import getopt
import os
import re
import sys
import thread
import threading
import time

def help(code):
    print 'tps.py -A "useragent" -C "cookies" -H "header" -P "period" -T "tps" -U "url" -O "outputdir"'
    print 'examples:'
    print 'tps.py -U https://www.amazon.com -T 20 -P PT5M'
    print 'tps.py -U https://www.amazon.com -T 20 -P PT1H'
    sys.exit(code)

def check_args(a, c, h, p, t, u, o):
    if u == '':
        print 'no URL specified!'
        help(2)
    if t == '':
        print 'no TPS specified!'
        help(2)
    if p == '':
        print 'no PERIOD specified!'
        help(2)
    cmd = 'curl --connect-timeout 10 --max-time 10 -o /dev/null -s -w "%{http_code},%{size_download},%{time_appconnect},%{time_connect},%{time_namelookup},%{time_pretransfer},%{time_starttransfer},%{time_total}" -k'
    if not a == '':
        cmd = cmd + " -A \"" + a + "\""
    if not c == '':
        cmd = cmd + " -b \"" + c + "\""
    if not h == '':
        cmd = cmd + " -H \"" + h + "\""
    cmd = cmd + " " + u
    fp = os.getcwd() + '/tps.csv'
    if not o == '':
        fp = o + "/tps.csv"
    tpspt(cmd, t, p, fp)

def tpspt(cmd, t, p, fp):
    f = open(fp, 'w+')
    if not f:
        print "fail to create tps.csv under ", os.getcwd()
        sys.exit(1)

    m = re.match('^PT(\d+)[MH]$', p)
    if not m:
        print ' wrong PERIOD pattern!', p , 'not match "PT\d+[MH]"'
        help(2)
    m = int(m.group(1))
    if p[-1] == 'H':
        m = m * 60 * 60
    else:
        m = m * 60
    t = float(t)
    print "-tps", t, "-period", p, ",", int(m * t), "transactions will be executed!"
    print cmd
    start = time.time()
    wq = []
    ths = []
    maxm = m
    if t < 1:
        maxm = int(m*t)
    for x in range(0, maxm):
        if t < 1:
            thargs = [cmd, t, wq, int(x/t) + 1]
            th = threading.Timer(int(x/t) + 1, tps, thargs)
        else:
            thargs = [cmd, t, wq, x + 1]
            th = threading.Timer(x + 1, tps, thargs)
        th.start()
        ths.append(th)
    for th in ths:
        th.join()
    end = time.time()
    print "Finish ", int(m * t), "transactions in", int(end - start), "seconds!"
    print "Writing results to tps.csv ......"
    f.write("id,http_code,size_download,time_appconnect,time_connect,time_namelookup,time_pretransfer,time_starttransfer,time_total")
    f.write('\n')
    for line in wq:
        f.write(line)
    f.close()
    print "Done! Please check results in", fp

def tps(cmd, t, wq, x):
    print "execute", t, "transactions at the ", x, "seconds"
    while t > 0:
        starttime = time.strftime('%Y-%m-%d %H:%M:%S',time.localtime(time.time()))
        status, output = commands.getstatusoutput(cmd)
        # sample output
        # http_code,size_download,time_appconnect,time_connect,time_namelookup,time_pretransfer,time_starttransfer,time_total
        # 200,79059,0.011196,0.000273,0.000214,0.011224,1.091032,5.055447
        cells = output.split(",")
        if len(cells) < 8:
            print "ERROR!!!", output
            continue;
        cell0 = cells[0]
        if not cell0 == '200':
            print "WARNING!!!", cell0, "is not wanted response code!!!"
        cell1 = cells[1]
        cells = map(lambda x: float(x) * 1000, cells[2:])
        cells.insert(0, float(cell1)/1024)
        cells.insert(0, int(cell0))
        cells = map(lambda x: str(x), cells)
        cells.insert(0, starttime)
        wq.append(','.join(cells))
        wq.append('\n')
        t = t - 1;

def main(argv):
    useragent = ''
    cookie = ''
    header = ''
    period = ''
    tps = ''
    url = ''
    outputdir = ''

    try:
        opts, args = getopt.getopt(argv,"hA:C:H:O:P:T:U:",["useragent=","cookie=", "header=", "outputdir=", "period=", "tps=", "url="])
    except getopt.GetoptError:
        help(1)
    for opt, arg in opts:
        if opt == '-h':
            help(0)
        elif opt in ("-A", "--useragent"):
            useragent = arg
        elif opt in ("-C", "--cookie"):
            cookie = arg
        elif opt in ("-H", "--header"):
            header = arg
        elif opt in ("-P", "--period"):
            period = arg
        elif opt in ("-T", "--tps"):
            tps = arg
        elif opt in ("-U", "--url"):
            url = arg
        elif opt in ("-O", "--outputdir"):
            outputdir = arg

    check_args(useragent, cookie, header, period, tps, url, outputdir)

if __name__ == "__main__":

    main(sys.argv[1:])

example usage:

./tps.py -T 10 -P "PT3M" -U https://errong.win 
-tps 10.0 -period PT3M , 1800 transactions will be executed!
curl --connect-timeout 10 --max-time 10 -o /dev/null -s -w "%{http_code},%{size_download},%{time_appconnect},%{time_connect},%{time_namelookup},%{time_pretransfer},%{time_starttransfer},%{time_total}" -k https://errong.win
.......
Finish  1800 transactions in 184 seconds!
Writing results to tps.csv ......
Done! Please check results in tps.csv

TPS Graph

As you can found, errong.win average responding time is about 420ms, not too bad.

curl -w manual

Make curl display information on stdout after a completed transfer. The format is a string that may contain plain text mixed with any number of variables. The format can be specified as a literal "string", or you can have curl read the format from a file with "@filename" and to tell curl to read the format from stdin you write "@-".
The variables present in the output format will be substituted by the value or text that curl thinks fit, as described below. All variables are specified as %{variable_name} and to output a normal % you just write them as %%. You can output a newline by using \n, a carriage return with \r and a tab space with \t.
NOTE: The %-symbol is a special symbol in the win32-environment, where all occurrences of % must be doubled when using this option.
The variables available are:

• content_type
  The Content-Type of the requested document, if there was any.
• filename_effective
  The ultimate filename that curl writes out to. This is only meaningful if curl is told to write to a file with the -O, --remote-name or -o, --output option. It's most useful in combination with the -J, --remote-header-name option.
• ftp_entry_path
  The initial path curl ended up in when logging on to the remote FTP server.
• http_code
  The numerical response code that was found in the last retrieved HTTP(S) or FTP(s) transfer.
• http_connect
  The numerical code that was found in the last response (from a proxy) to a curl CONNECT request. (Added in 7.12.4)
• http_version
  The http version that was effectively used.
• local_ip
  The IP address of the local end of the most recently done connection - can be either IPv4 or IPv6 (Added in 7.29.0)
• local_port
  The local port number of the most recently done connection (Added in 7.29.0)
• num_connects
  Number of new connects made in the recent transfer. (Added in 7.12.3)
• num_redirects
  Number of redirects that were followed in the request. (Added in 7.12.3)
• proxy_ssl_verify_result
  The result of the HTTPS proxy's SSL peer certificate verification that was requested. 0 means the verification was successful. (Added in 7.52.0)
• redirect_url
  When an HTTP request was made without -L to follow redirects, this variable will show the actual URL a redirect would take you to. (Added in 7.18.2)
• remote_ip
  The remote IP address of the most recently done connection - can be either IPv4 or IPv6 (Added in 7.29.0)
• remote_port
  The remote port number of the most recently done connection (Added in 7.29.0)
• scheme
  The URL scheme (sometimes called protocol) that was effectively used (Added in 7.52.0)
• size_download
  The total amount of bytes that were downloaded.
• size_header
  The total amount of bytes of the downloaded headers.
• size_request
  The total amount of bytes that were sent in the HTTP request.
• size_upload
  The total amount of bytes that were uploaded.
• speed_download
  The average download speed that curl measured for the complete download. Bytes per second.
• speed_upload
  The average upload speed that curl measured for the complete upload. Bytes per second.
• ssl_verify_result
  The result of the SSL peer certificate verification that was requested. 0 means the verification was successful. (Added in 7.19.0)
• time_appconnect
  The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed. (Added in 7.19.0)
• time_connect
  The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.
• time_namelookup
  The time, in seconds, it took from the start until the name resolving was completed.
• time_pretransfer
  The time, in seconds, it took from the start until the file transfer was just about to begin. This includes all pre-transfer commands and negotiations that are specific to the particular protocol(s) involved.
• time_redirect
  The time, in seconds, it took for all redirection steps including name lookup, connect, pretransfer and transfer before the final transaction was started. time_redirect shows the complete execution time for multiple redirections. (Added in 7.12.3)
• time_starttransfer
  The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pretransfer and also the time the server needed to calculate the result.
• time_total
  The total time, in seconds, that the full operation lasted.
• url_effective
  The URL that was fetched last. This is most meaningful if you've told curl to follow location

Python : How to run a function "foo" per second and last a few minutes or hours

Scenario

I tried to run a function "foo" every second. I have to do this for a few minutes (say 5).

The function foo () sends 100 HTTP requests (including JSON objects) to the server and prints the JSON response.

In short, I have to issue 100 HTTP requests per second for 5 minutes.

Using threading.Timer

 #!/usr/bin/python import time import thread import threading  def foo():     print time.strftime('%Y-%m-%d %H:%M:%S',time.localtime(time.time())), threading.active_count()  #5 minutes = 5 * 60 = 300 seconds for x in range(0, 300):     t = threading.Timer(x + 1, foo)     t.start() 

Expected output

function foo was executed per second and last about 5 minutes

2020-05-14 00:54:49 301 2020-05-14 00:54:50 300 2020-05-14 00:54:51 299 2020-05-14 00:54:52 298 2020-05-14 00:54:53 297 2020-05-14 00:54:54 296 2020-05-14 00:54:55 295 ....... 2020-05-14 00:59:44 6 2020-05-14 00:59:45 5 2020-05-14 00:59:46 4 2020-05-14 00:59:47 3 2020-05-14 00:59:48 2 

How to kill a bunch of processes which executed with almost same command ?

Scenario

Sometimes we need to manually terminate the process. If not killing too many processes, it is easy to find the pid and kill it. But what if there are a bunch of processes that need to be terminated? Today I encountered such a problem, started a lot of python process, but the result can not stop.

gkill Solution

add below function to your bash profile, then source the profile

function gkill() {     ps -ef | grep ${1} | grep -v grep | awk '{print $2}' | xargs --no-run-if-empty kill -9 } 

Then you can kill all processes that matched your serach pattern via gkill command.

gkill <search content> 

Extended knowledge

The commands related to the termination process are:

• ps: report a snapshot of the current process
• kill: send a signal to a process
• killall: kill process by name
• pkill: View or issue process signals based on name and other attributes
• skill: send a signal or report the process status
• xkill: destroy a client program according to X resources
• xargs --no-run-if-empty, very useful if args from pipe are empty

pgrep

pgrep is a tool to query the process by the name of the program, generally used to determine whether the program is running. This tool is often used in server configuration and management. Usage: pgrep parameter option program name.

grep

grep (global search regular expression (RE) and print out the line, comprehensive search regular expression and print out the line) is a powerful text search tool, it can use regular expressions to search for text, and print the matching line come out. Unix's grep family includes grep, egrep, and fgrep.

In simple terms, pgrep is to query the running status of the program, and grep is to search for content.

Recommend GC log analyzer tool : GCPlot & GCeasy

GCPlot

Install

Docker Installation
You can run GCPlot in a Docker container.

In order to run GCPlot as-is without additional configuration, run next command:

docker run -d -p 8080:80 gcplot/gcplot

After that eventually the platform will be accessible from your host machine at http://127.0.0.1:8080 address.

Upload GC log

JVM arguments

-verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintTenuringDistribution -XX:+PrintGCCause -XX:+PrintHeapAtGC -XX:+PrintAdaptiveSizePolicy -XX:+UnlockDiagnosticVMOptions -XX:+G1SummarizeRSetStats -XX:G1SummarizeRSetStatsPeriod=1 -Xloggc:/var/output/logs/garbagecollector.log -XX:+UseG1GC 

Analysis Groups

Universal GC Log Analyzer

https://gceasy.io/
It is more powerful than GCPlot, but you have to upload you GC logs to their backend and pay to see the analysis report.

GCPlot is free and open source

Fork from github
https://it.gcplot.com/