petertc hrchu

In 30mins, I will address crucial parts of implementing Solid in Python, so attendees can understand how to build a decentralized web application with Python and get the benefits of this promising architecture.

Overview: why we need decentralized web architecture and what does it look like in a Solid way?

In classical web architecture, application and data are bundled together, hence user data are naturally owned by service providers. This causes security, privacy, interoperability, and many other well-known issues for both users and service providers.

Service providers need to pay additional responsibility to protect user data in the scenario. Moreover, users cannot fully control and migrate their data without additional mechanisms provided by the service providers (GDPR tries to address this in a nontechnical way.)

With Solid, all personal data is stored in a data repository named Pod controlled by users. That could be set up on a user's server at home, or provided by a data storage supplier chos

TRY IT

sudo apt-get install heirloom-mail
config your email address and MTA server in send-mail.sh
sudo cp send-mail.sh /opt/send-mail.sh
sudo cp dummy.* /etc/systemd/system/
execute sudo systemctl start dummy.service to confirm it works.
sudo systemctl start dummy.timer
Check the schedule via systemctl list-timers

How to get a stack trace for each thread in a running python script

Sometimes a python script will simply hang forever with no indication of where things went wrong. Perhaps it's polling a service that will never return a value that allows the program to move forward. Here's a way to see where the program is currently stuck.

Install gdb and pyrasite

Install gdb.

# Redhat, CentOS, etc

	import logging
	from typing import Iterable, Dict, BinaryIO

	import boto3
	from boto3.s3.transfer import TransferConfig
	from botocore.config import Config
	from botocore.exceptions import ClientError

	KB = 1024
	MB = KB * KB

	// https://github.com/rdfjs/N3.js/

	import {Parser, StreamParser, Writer} from "n3";
	import * as fs from "fs";
	import {DataFactory} from 'n3';
	import {Writable} from 'stream';

	function fromQualsToAString() {
	const writer = new Writer({prefixes: {c: 'http://example.org/cartoons#'}});
	const {namedNode, literal, defaultGraph, quad} = DataFactory;

	def gen():
	a = range(5)
	for x in a:
	yield x

	x = gen() # instanlize

	x.__next__() # get next
	Out[36]: 0
	next(x) # alternative way

	18.04
	apt install python3-pip

	16.04
	sudo apt-get install vim htop nmon ngrep iftop tmux dnsmasq curl ifstat iperf httpie python-virtualenv build-essential

	# replace /sys/class/leds/led0/trigger with /sys/class/leds/led0 while on Raspberry Pi 2 model B


	def read_trigger() -> str:
	with open('/sys/class/leds/led0/trigger', 'r') as trigger:
	return trigger.read()

	org_trigger = read_trigger()
	def disable_trigger():
	with open('/sys/class/leds/led0/trigger', 'w') as trigger:

	#include <Python.h>
	#include <unistd.h>
	#include <fcntl.h>
	#include <sys/ioctl.h>
	#include <sys/mtio.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <linux/input.h>

	char* getDeviceName(char* device, char* name, size_t len)

	alist = [[1,1],[1,1]]

	assert([1, 1] == [x for x, y in alist]) # OK

	for x, y in alist: # OK
	assert x == 1

	assert([1, 1] == list(map(lambda x, y: x, alist))) # TypeError: <lambda>() missing 1 required positional argument: 'y'