Julie  Donnelly

Julie Donnelly

1597741764

Configure Amazon EC2 to Run PostgreSQL, Anaconda and Jupyter Notebook

In this tutorial, we are creating a new _ Amazon EC2_ instance and installing AnacondaPythonPostgreSQL, and Jupyter notebook to run our python scripts from our local machine(windows 10) on _EC2 _ instance throw SSH.

1- Lunch EC2 Instance:

  • From AWS Management Console we chose EC2 service then we start by launching our new EC2 instance with an Ubuntu Server AMI.
  • For the sake of this tutorial, we will stay at the free tier of _AWS _ by selecting instance type t2.micro which is free tier eligible.
  • We will leave the configuration details as it is, raise the volume size(optional step max 30GiB), we will proceed with no tags and finally, we will open our instance to SSH on _port 22, PostgreSQL _ on _ port 5432, Jupiter notebook _ on _ port 8888, HTTP _ on _ port 80, _ and _ HTTPS _ on _ port 443 _ to our local machine IP only.

Image for post

  • After verifying our configurations we attach a new key-pair to the instance or chose an existing one.

2- Configure SSH on Your Local Machine:

  • Since our local machine’s OS is probably windows 10🙏 SSH is provided with the **_CMD _**by default otherwise we will be needing to use **_puTTY _**to connect to the instance using throw SSH.
  • On our local machine, we navigate to **_C:\Users\our-local-user **then .\ssh we add a new text file named **‘config’ _**then we fill it as shown in the picturebelow.

(note: to save the file with no extension we File → Save as → Write the file name inside double quotes, everything after the ## sympol is only for domenstrations )

Image for post

#aws #jupyter-notebook #python #ec2 #postgres #postgresql

What is GEEK

Buddha Community

Configure Amazon EC2 to Run PostgreSQL, Anaconda and Jupyter Notebook
Julie  Donnelly

Julie Donnelly

1597741764

Configure Amazon EC2 to Run PostgreSQL, Anaconda and Jupyter Notebook

In this tutorial, we are creating a new _ Amazon EC2_ instance and installing AnacondaPythonPostgreSQL, and Jupyter notebook to run our python scripts from our local machine(windows 10) on _EC2 _ instance throw SSH.

1- Lunch EC2 Instance:

  • From AWS Management Console we chose EC2 service then we start by launching our new EC2 instance with an Ubuntu Server AMI.
  • For the sake of this tutorial, we will stay at the free tier of _AWS _ by selecting instance type t2.micro which is free tier eligible.
  • We will leave the configuration details as it is, raise the volume size(optional step max 30GiB), we will proceed with no tags and finally, we will open our instance to SSH on _port 22, PostgreSQL _ on _ port 5432, Jupiter notebook _ on _ port 8888, HTTP _ on _ port 80, _ and _ HTTPS _ on _ port 443 _ to our local machine IP only.

Image for post

  • After verifying our configurations we attach a new key-pair to the instance or chose an existing one.

2- Configure SSH on Your Local Machine:

  • Since our local machine’s OS is probably windows 10🙏 SSH is provided with the **_CMD _**by default otherwise we will be needing to use **_puTTY _**to connect to the instance using throw SSH.
  • On our local machine, we navigate to **_C:\Users\our-local-user **then .\ssh we add a new text file named **‘config’ _**then we fill it as shown in the picturebelow.

(note: to save the file with no extension we File → Save as → Write the file name inside double quotes, everything after the ## sympol is only for domenstrations )

Image for post

#aws #jupyter-notebook #python #ec2 #postgres #postgresql

Rodrigo Senra - Jupyter Notebooks

Nosso convidado de hoje é diretor técnico na Work & Co, PhD em Ciências da Computação, já contribuiu com inúmeros projetos open source em Python, ajudou a fundar a Associação Python Brasil e já foi premiado com o Prêmio Dorneles Tremea por contribuições para a comunidade Python Brasil.

#alexandre oliva #anaconda #apache zeppelin #associação python brasil #azure notebooks #beakerx #binder #c++ #closure #colaboratory #donald knuth #fernando pérez #fortran #graphql #guido van rossum #ipython #java #javascript #json #jupyter kenels #jupyter notebooks #jupyterhub #jupyterlab #latex #lisp #literate programming #lua #matlab #perl #cinerdia #prêmio dorneles tremea #python #r #rodrigo senra #scala #spark notebook #tcl #typescript #zope

Background Fetch for React Native Apps

react-native-background-fetch

Background Fetch is a very simple plugin which attempts to awaken an app in the background about every 15 minutes, providing a short period of background running-time. This plugin will execute your provided callbackFn whenever a background-fetch event occurs.

There is no way to increase the rate which a fetch-event occurs and this plugin sets the rate to the most frequent possible — you will never receive an event faster than 15 minutes. The operating-system will automatically throttle the rate the background-fetch events occur based upon usage patterns. Eg: if user hasn't turned on their phone for a long period of time, fetch events will occur less frequently or if an iOS user disables background refresh they may not happen at all.

:new: Background Fetch now provides a scheduleTask method for scheduling arbitrary "one-shot" or periodic tasks.

iOS

  • There is no way to increase the rate which a fetch-event occurs and this plugin sets the rate to the most frequent possible — you will never receive an event faster than 15 minutes. The operating-system will automatically throttle the rate the background-fetch events occur based upon usage patterns. Eg: if user hasn't turned on their phone for a long period of time, fetch events will occur less frequently.
  • scheduleTask seems only to fire when the device is plugged into power.
  • ⚠️ When your app is terminated, iOS no longer fires events — There is no such thing as stopOnTerminate: false for iOS.
  • iOS can take days before Apple's machine-learning algorithm settles in and begins regularly firing events. Do not sit staring at your logs waiting for an event to fire. If your simulated events work, that's all you need to know that everything is correctly configured.
  • If the user doesn't open your iOS app for long periods of time, iOS will stop firing events.

Android

Installing the plugin

⚠️ If you have a previous version of react-native-background-fetch < 2.7.0 installed into react-native >= 0.60, you should first unlink your previous version as react-native link is no longer required.

$ react-native unlink react-native-background-fetch

With yarn

$ yarn add react-native-background-fetch

With npm

$ npm install --save react-native-background-fetch

Setup Guides

iOS Setup

react-native >= 0.60

Android Setup

react-native >= 0.60

Example

ℹ️ This repo contains its own Example App. See /example

import React from 'react';
import {
  SafeAreaView,
  StyleSheet,
  ScrollView,
  View,
  Text,
  FlatList,
  StatusBar,
} from 'react-native';

import {
  Header,
  Colors
} from 'react-native/Libraries/NewAppScreen';

import BackgroundFetch from "react-native-background-fetch";

class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      events: []
    };
  }

  componentDidMount() {
    // Initialize BackgroundFetch ONLY ONCE when component mounts.
    this.initBackgroundFetch();
  }

  async initBackgroundFetch() {
    // BackgroundFetch event handler.
    const onEvent = async (taskId) => {
      console.log('[BackgroundFetch] task: ', taskId);
      // Do your background work...
      await this.addEvent(taskId);
      // IMPORTANT:  You must signal to the OS that your task is complete.
      BackgroundFetch.finish(taskId);
    }

    // Timeout callback is executed when your Task has exceeded its allowed running-time.
    // You must stop what you're doing immediately BackgroundFetch.finish(taskId)
    const onTimeout = async (taskId) => {
      console.warn('[BackgroundFetch] TIMEOUT task: ', taskId);
      BackgroundFetch.finish(taskId);
    }

    // Initialize BackgroundFetch only once when component mounts.
    let status = await BackgroundFetch.configure({minimumFetchInterval: 15}, onEvent, onTimeout);

    console.log('[BackgroundFetch] configure status: ', status);
  }

  // Add a BackgroundFetch event to <FlatList>
  addEvent(taskId) {
    // Simulate a possibly long-running asynchronous task with a Promise.
    return new Promise((resolve, reject) => {
      this.setState(state => ({
        events: [...state.events, {
          taskId: taskId,
          timestamp: (new Date()).toString()
        }]
      }));
      resolve();
    });
  }

  render() {
    return (
      <>
        <StatusBar barStyle="dark-content" />
        <SafeAreaView>
          <ScrollView
            contentInsetAdjustmentBehavior="automatic"
            style={styles.scrollView}>
            <Header />

            <View style={styles.body}>
              <View style={styles.sectionContainer}>
                <Text style={styles.sectionTitle}>BackgroundFetch Demo</Text>
              </View>
            </View>
          </ScrollView>
          <View style={styles.sectionContainer}>
            <FlatList
              data={this.state.events}
              renderItem={({item}) => (<Text>[{item.taskId}]: {item.timestamp}</Text>)}
              keyExtractor={item => item.timestamp}
            />
          </View>
        </SafeAreaView>
      </>
    );
  }
}

const styles = StyleSheet.create({
  scrollView: {
    backgroundColor: Colors.lighter,
  },
  body: {
    backgroundColor: Colors.white,
  },
  sectionContainer: {
    marginTop: 32,
    paddingHorizontal: 24,
  },
  sectionTitle: {
    fontSize: 24,
    fontWeight: '600',
    color: Colors.black,
  },
  sectionDescription: {
    marginTop: 8,
    fontSize: 18,
    fontWeight: '400',
    color: Colors.dark,
  },
});

export default App;

Executing Custom Tasks

In addition to the default background-fetch task defined by BackgroundFetch.configure, you may also execute your own arbitrary "oneshot" or periodic tasks (iOS requires additional Setup Instructions). However, all events will be fired into the Callback provided to BackgroundFetch#configure:

⚠️ iOS:

  • scheduleTask on iOS seems only to run when the device is plugged into power.
  • scheduleTask on iOS are designed for low-priority tasks, such as purging cache files — they tend to be unreliable for mission-critical tasks. scheduleTask will never run as frequently as you want.
  • The default fetch event is much more reliable and fires far more often.
  • scheduleTask on iOS stop when the user terminates the app. There is no such thing as stopOnTerminate: false for iOS.
// Step 1:  Configure BackgroundFetch as usual.
let status = await BackgroundFetch.configure({
  minimumFetchInterval: 15
}, async (taskId) => {  // <-- Event callback
  // This is the fetch-event callback.
  console.log("[BackgroundFetch] taskId: ", taskId);

  // Use a switch statement to route task-handling.
  switch (taskId) {
    case 'com.foo.customtask':
      print("Received custom task");
      break;
    default:
      print("Default fetch task");
  }
  // Finish, providing received taskId.
  BackgroundFetch.finish(taskId);
}, async (taskId) => {  // <-- Task timeout callback
  // This task has exceeded its allowed running-time.
  // You must stop what you're doing and immediately .finish(taskId)
  BackgroundFetch.finish(taskId);
});

// Step 2:  Schedule a custom "oneshot" task "com.foo.customtask" to execute 5000ms from now.
BackgroundFetch.scheduleTask({
  taskId: "com.foo.customtask",
  forceAlarmManager: true,
  delay: 5000  // <-- milliseconds
});

API Documentation

Config

Common Options

@param {Integer} minimumFetchInterval [15]

The minimum interval in minutes to execute background fetch events. Defaults to 15 minutes. Note: Background-fetch events will never occur at a frequency higher than every 15 minutes. Apple uses a secret algorithm to adjust the frequency of fetch events, presumably based upon usage patterns of the app. Fetch events can occur less often than your configured minimumFetchInterval.

@param {Integer} delay (milliseconds)

ℹ️ Valid only for BackgroundFetch.scheduleTask. The minimum number of milliseconds in future that task should execute.

@param {Boolean} periodic [false]

ℹ️ Valid only for BackgroundFetch.scheduleTask. Defaults to false. Set true to execute the task repeatedly. When false, the task will execute just once.

Android Options

@config {Boolean} stopOnTerminate [true]

Set false to continue background-fetch events after user terminates the app. Default to true.

@config {Boolean} startOnBoot [false]

Set true to initiate background-fetch events when the device is rebooted. Defaults to false.

NOTE: startOnBoot requires stopOnTerminate: false.

@config {Boolean} forceAlarmManager [false]

By default, the plugin will use Android's JobScheduler when possible. The JobScheduler API prioritizes for battery-life, throttling task-execution based upon device usage and battery level.

Configuring forceAlarmManager: true will bypass JobScheduler to use Android's older AlarmManager API, resulting in more accurate task-execution at the cost of higher battery usage.

let status = await BackgroundFetch.configure({
  minimumFetchInterval: 15,
  forceAlarmManager: true
}, async (taskId) => {  // <-- Event callback
  console.log("[BackgroundFetch] taskId: ", taskId);
  BackgroundFetch.finish(taskId);
}, async (taskId) => {  // <-- Task timeout callback
  // This task has exceeded its allowed running-time.
  // You must stop what you're doing and immediately .finish(taskId)
  BackgroundFetch.finish(taskId);
});
.
.
.
// And with with #scheduleTask
BackgroundFetch.scheduleTask({
  taskId: 'com.foo.customtask',
  delay: 5000,       // milliseconds
  forceAlarmManager: true,
  periodic: false
});

@config {Boolean} enableHeadless [false]

Set true to enable React Native's Headless JS mechanism, for handling fetch events after app termination.

  • 📂 index.js (MUST BE IN index.js):
import BackgroundFetch from "react-native-background-fetch";

let MyHeadlessTask = async (event) => {
  // Get task id from event {}:
  let taskId = event.taskId;
  let isTimeout = event.timeout;  // <-- true when your background-time has expired.
  if (isTimeout) {
    // This task has exceeded its allowed running-time.
    // You must stop what you're doing immediately finish(taskId)
    console.log('[BackgroundFetch] Headless TIMEOUT:', taskId);
    BackgroundFetch.finish(taskId);
    return;
  }
  console.log('[BackgroundFetch HeadlessTask] start: ', taskId);

  // Perform an example HTTP request.
  // Important:  await asychronous tasks when using HeadlessJS.
  let response = await fetch('https://reactnative.dev/movies.json');
  let responseJson = await response.json();
  console.log('[BackgroundFetch HeadlessTask] response: ', responseJson);

  // Required:  Signal to native code that your task is complete.
  // If you don't do this, your app could be terminated and/or assigned
  // battery-blame for consuming too much time in background.
  BackgroundFetch.finish(taskId);
}

// Register your BackgroundFetch HeadlessTask
BackgroundFetch.registerHeadlessTask(MyHeadlessTask);

@config {integer} requiredNetworkType [BackgroundFetch.NETWORK_TYPE_NONE]

Set basic description of the kind of network your job requires.

If your job doesn't need a network connection, you don't need to use this option as the default value is BackgroundFetch.NETWORK_TYPE_NONE.

NetworkTypeDescription
BackgroundFetch.NETWORK_TYPE_NONEThis job doesn't care about network constraints, either any or none.
BackgroundFetch.NETWORK_TYPE_ANYThis job requires network connectivity.
BackgroundFetch.NETWORK_TYPE_CELLULARThis job requires network connectivity that is a cellular network.
BackgroundFetch.NETWORK_TYPE_UNMETEREDThis job requires network connectivity that is unmetered. Most WiFi networks are unmetered, as in "you can upload as much as you like".
BackgroundFetch.NETWORK_TYPE_NOT_ROAMINGThis job requires network connectivity that is not roaming (being outside the country of origin)

@config {Boolean} requiresBatteryNotLow [false]

Specify that to run this job, the device's battery level must not be low.

This defaults to false. If true, the job will only run when the battery level is not low, which is generally the point where the user is given a "low battery" warning.

@config {Boolean} requiresStorageNotLow [false]

Specify that to run this job, the device's available storage must not be low.

This defaults to false. If true, the job will only run when the device is not in a low storage state, which is generally the point where the user is given a "low storage" warning.

@config {Boolean} requiresCharging [false]

Specify that to run this job, the device must be charging (or be a non-battery-powered device connected to permanent power, such as Android TV devices). This defaults to false.

@config {Boolean} requiresDeviceIdle [false]

When set true, ensure that this job will not run if the device is in active use.

The default state is false: that is, the for the job to be runnable even when someone is interacting with the device.

This state is a loose definition provided by the system. In general, it means that the device is not currently being used interactively, and has not been in use for some time. As such, it is a good time to perform resource heavy jobs. Bear in mind that battery usage will still be attributed to your application, and shown to the user in battery stats.


Methods

Method NameArgumentsReturnsNotes
configure{FetchConfig}, callbackFn, timeoutFnPromise<BackgroundFetchStatus>Configures the plugin's callbackFn and timeoutFn. This callback will fire each time a background-fetch event occurs in addition to events from #scheduleTask. The timeoutFn will be called when the OS reports your task is nearing the end of its allowed background-time.
scheduleTask{TaskConfig}Promise<boolean>Executes a custom task. The task will be executed in the same Callback function provided to #configure.
statuscallbackFnPromise<BackgroundFetchStatus>Your callback will be executed with the current status (Integer) 0: Restricted, 1: Denied, 2: Available. These constants are defined as BackgroundFetch.STATUS_RESTRICTED, BackgroundFetch.STATUS_DENIED, BackgroundFetch.STATUS_AVAILABLE (NOTE: Android will always return STATUS_AVAILABLE)
finishString taskIdVoidYou MUST call this method in your callbackFn provided to #configure in order to signal to the OS that your task is complete. iOS provides only 30s of background-time for a fetch-event -- if you exceed this 30s, iOS will kill your app.
startnonePromise<BackgroundFetchStatus>Start the background-fetch API. Your callbackFn provided to #configure will be executed each time a background-fetch event occurs. NOTE the #configure method automatically calls #start. You do not have to call this method after you #configure the plugin
stop[taskId:String]Promise<boolean>Stop the background-fetch API and all #scheduleTask from firing events. Your callbackFn provided to #configure will no longer be executed. If you provide an optional taskId, only that #scheduleTask will be stopped.

Debugging

iOS

🆕 BGTaskScheduler API for iOS 13+

  • ⚠️ At the time of writing, the new task simulator does not yet work in Simulator; Only real devices.
  • See Apple docs Starting and Terminating Tasks During Development
  • After running your app in XCode, Click the [||] button to initiate a Breakpoint.
  • In the console (lldb), paste the following command (Note: use cursor up/down keys to cycle through previously run commands):
e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateLaunchForTaskWithIdentifier:@"com.transistorsoft.fetch"]
  • Click the [ > ] button to continue. The task will execute and the Callback function provided to BackgroundFetch.configure will receive the event.

Simulating task-timeout events

  • Only the new BGTaskScheduler api supports simulated task-timeout events. To simulate a task-timeout, your fetchCallback must not call BackgroundFetch.finish(taskId):
let status = await BackgroundFetch.configure({
  minimumFetchInterval: 15
}, async (taskId) => {  // <-- Event callback.
  // This is the task callback.
  console.log("[BackgroundFetch] taskId", taskId);
  //BackgroundFetch.finish(taskId); // <-- Disable .finish(taskId) when simulating an iOS task timeout
}, async (taskId) => {  // <-- Event timeout callback
  // This task has exceeded its allowed running-time.
  // You must stop what you're doing and immediately .finish(taskId)
  print("[BackgroundFetch] TIMEOUT taskId:", taskId);
  BackgroundFetch.finish(taskId);
});
  • Now simulate an iOS task timeout as follows, in the same manner as simulating an event above:
e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateExpirationForTaskWithIdentifier:@"com.transistorsoft.fetch"]

Old BackgroundFetch API

  • Simulate background fetch events in XCode using Debug->Simulate Background Fetch
  • iOS can take some hours or even days to start a consistently scheduling background-fetch events since iOS schedules fetch events based upon the user's patterns of activity. If Simulate Background Fetch works, your can be sure that everything is working fine. You just need to wait.

Android

  • Observe plugin logs in $ adb logcat:
$ adb logcat *:S ReactNative:V ReactNativeJS:V TSBackgroundFetch:V
  • Simulate a background-fetch event on a device (insert <your.application.id>) (only works for sdk 21+:
$ adb shell cmd jobscheduler run -f <your.application.id> 999
  • For devices with sdk <21, simulate a "Headless JS" event with (insert <your.application.id>)
$ adb shell am broadcast -a <your.application.id>.event.BACKGROUND_FETCH

Download Details:
Author: transistorsoft
Source Code: https://github.com/transistorsoft/react-native-background-fetch
License: MIT license

#react  #reactnative  #mobileapp  #javascript 

How to set up Anaconda and Jupyter Notebook the right way

If Anaconda (conda) and Jupyter Notebook (Jupyter Lab) are set up the right way the combination of them can become the perfect team, where you are able to easily switch between Deep Learning conda environments.

Some programs requiring Tensorflow 1.15, others Tensorflow 2.0? No problem! Just switch environments and Tensorflow versions with a simple click.

Also, did you ever install Jupyter Notebook extensions in each conda environment? Do not worry anymore, we are going to install the extensions once, and have them available in each environment!

How are we going to achieve that?

  1. Install Anaconda or Miniconda
  2. Install Jupyter Notebook / Lab in the base environment
  3. Install a new environment
  4. Activate the environment for Jupyter Notebook

#tensorflow #jupyter #jupyter-notebook #anaconda #conda

Marcus Anthony

1612355729

Amazon Pay Clone, Amazon Pay Clone Script, Recharge & Wallet App Solution

Mobile wallet applications have become the new trend in today’s world. Apps like Amazon Pay, Paytm, PayPal are some of the leading apps that are owned and used by millions. Be it paying bills, recharging, or money transactions, everything has turned easier because of these apps. There were days when people used to travel for hours to do these tasks have been totally transformed. Moreover, consumers can use these e-wallet apps while paying in a store, either for shopping or while eating out. Thus, as far as mobile wallets are concerned, they are a convenient way for handling all the tasks involving finance.

As an aspiring entrepreneur, if you wish to succeed in your business, without second thoughts, go for Amazon Pay clone app development. Let’s narrow down your thinking processes for a quicker stride forward by analyzing the types of apps first.

Types of e-wallet apps you could develop:

Retail application: An app like Amazon is considered the retail app because it has a mobile wallet in it. It has all the basic functionalities, which helps users to redeem coupons and reward points. All the payment modes are accessible through the app, including net banking.

Dedicated app: The app allows P2P money transactions by storing a variety of cards. You could also make international money transfers using this app. Example: PayPal, Apple Pay, and Amazon Pay.

PoS payments: The PoS payment wallet apps are found at the stores. It is exclusively used by the users to make contactless payments without having to stand in a long queue.

Wrapping up,
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