How to use gRPC-web with React

For the past few months, my team has been working on a gRPC service. A few weeks back a new requirement came in: we needed a web portal to display some information. Since we already had a gRPC backend, the server side was sorted. But for the front-end, we had a few important choices to make.

1. Vue or React (We choose react)
2. REST or gRPC from the web portal

If you don’t know what gRPC is you can read about it here. Here are a few reasons that made us choose gRPC over REST.

One major factor for choosing gRPC was the fact that we already had protos that we used in our backend service. We could use the same protos to generate client-side code in javascript**.**
Using gRPC would mean that we would not have to write any code for creating the client. Adding new endpoints would mean making changes to the proto and generating client-side code.
We needed server-side streaming which is supported by gRPC-web.
We already had a setup of envoy for loading balancing our backend service (more on this later).

Caveats

gRPC web-client won’t send HTTP2 requests. Instead, you need a proxy between your web-client and gRPC backend service for converting that HTTP1 request to HTTP2. gRPC web client has built-in support for Envoy as a proxy. You can find more information about this here.
The teams at Google and Improbable both went on to implement the spec in two different repositories. We will be using gRPC web client provided by Google. You can find the implementation by Google here and by Improbable here.
As of now, client-side streaming is not supported.

Credits: https://grpc.io/blog/state-of-grpc-web

Now that we have some idea about gRPC web, below is a diagram depicting how the entire communication will take place. We are going to make a react web application that will send a Ping request and get a Pong response for it.

Front-end + Proxy + Back-end

Before starting make sure you have the following installed:

1. npm (Node package manager) - For generating react project
2. Docker - For running envoy locally
3. protoc - For generating code using protos

There are 3 pieces to this puzzle. We are going to tackle each of them one by one.

1. User Interface — Website using react

For creating a react project, we will use the create-react-app command.

create-react-app learn-react-grpc

Now that we have a sample project in place, let’s create a proto. This is what a ping pong proto looks like.

syntax = "proto3";
	

	package pingpong;
	

	message PingRequest {
	    string ping = 1;
	}
	

	message PongResponse {
	    string pong = 1;
	}
	

	service PingPongService {
	    rpc pingPong(PingRequest) returns (PongResponse);
	}

For subsequent commands to run, make sure that the proto is inside the src/ folder of the react project. For generating client-side code in javascript, run the following command:

protoc -I=. src/ping_pong.proto --js_out=import_style=commonjs:. --grpc-web_out=import_style=commonjs,mode=grpcwebtext:.

This will generate two new files: ping_pong_pb.js andping_pong_grpc_web_pb.js, with all the generated code in it. We will use this code to make requests to our gRPC service.

First, let’s update our package.json with a few gRPC and protobuf related dependencies and then run npm install*.*

{
	  "name": "learn-react-grpc",
	  "version": "0.1.0",
	  "private": true,
	  "dependencies": {
	    "react": "^16.8.6",
	    "react-dom": "^16.8.6",
	    "react-scripts": "2.1.8",
	    "@grpc/grpc-js": "^0.3.6",
	    "google-protobuf": "^3.7.1",
	    "grpc": "^1.19.0",
	    "grpc-web": "^1.0.4"
	  },
	  "scripts": {
	    "start": "react-scripts start",
	    "build": "react-scripts build",
	    "test": "react-scripts test",
	    "eject": "react-scripts eject"
	  },
	  "eslintConfig": {
	    "extends": "react-app"
	  },
	  "browserslist": [
	    ">0.2%",
	    "not dead",
	    "not ie <= 11",
	    "not op_mini all"
	  ]
	}

Below is the entire logic for building our website. You can use this code in your App.js file. It is a really simple website which contains a button, clicking on which creates a ping pong request and gets a response.

import React, { Component } from 'react';
	import logo from './logo.svg';
	import './App.css';
	

	const { PingPongServiceClient } = require('./ping_pong_grpc_web_pb');
	const { PingRequest, PongResponse } = require('./ping_pong_pb.js');
	

	var client = new PingPongServiceClient('http://localhost:9090', null, null);
	

	class App extends Component {
	  
	  callGrpcService = () => {
	    const request = new PingRequest();
	    request.setPing('Ping');
	

	    client.pingPong(request, {}, (err, response) => {
	      if (response == null) {
	        console.log(err)
	      }else {
	        console.log(response.getPong())
	      }
	    });
	  }
	

	  render() {
	    return (
	      <div className="App">
	        <header className="App-header">
	          <img src={logo} className="App-logo" alt="logo" />
	          <button style={{padding:10}} onClick={this.callGrpcService}>Click for grpc request</button>
	        </header>
	      </div>
	    );
	  }
	}
	

	export default App;

Now if you run the node server using **npm start, **you are likely to face this compilation issue. This is apparently an issue when using gRPC-web with a project created using create-react-app command line interface.

However, this issue can be fixed by adding *eslint-disable *to all of the proto generated files. Make sure that you do this for all the files. Now if you start the server, everything should be working.

2. Backend — gRPC server in Node

Let’s create a simple node server. We will be using the same proto that we used in our react app. Let’s create a node js application node-ping-pong-server. Here is our sample server.js file.

var grpc = require('grpc');
	var pingPongProto = grpc.load('ping_pong.proto');
	var server = new grpc.Server();
	

	server.addService(pingPongProto.pingpong.PingPongService.service, {
	  pingPong: function(call,callback) {
	    console.log("Request")
	    return callback(null,{pong:"Pong"})
	  }
	});
	

	server.bind('localhost:8080',grpc.ServerCredentials.createInsecure());
	server.start();

We can run the node server using the following command:

node server.js

3. Proxy — Envoy

As mentioned above, we will be using Docker for setting up envoy. Here is the docker file. As of writing, the latest tag points to Envoy* version 1.11. *Create a Dockerfile inside src/ folder of your react app.

FROM envoyproxy/envoy-dev:latest
	

	COPY ./envoy.yaml /etc/envoy/envoy.yaml
	

	CMD /usr/local/bin/envoy -c /etc/envoy/envoy.yaml -l trace --log-path /tmp/envoy_info.log

Before running the Docker container, we need to make sure that we have a config file for envoy. Add this envoy.yml inside the src/ folder of your react app.

admin:
	  access_log_path: /tmp/admin_access.log
	  address:
	    socket_address: { address: 0.0.0.0, port_value: 9901 }
	

	static_resources:
	  listeners:
	  - name: listener_0
	    address:
	      socket_address: { address: 0.0.0.0, port_value: 9090 }
	    filter_chains:
	    - filters:
	      - name: envoy.http_connection_manager
	        config:
	          codec_type: auto
	          stat_prefix: ingress_http
	          route_config:
	            name: local_route
	            virtual_hosts:
	            - name: local_service
	              domains: ["*"]
	              routes:
	              - match: { prefix: "/" }
	                route:
	                  cluster: ping_pong_service
	                  max_grpc_timeout: 0s
	              cors:
	                allow_origin:
	                - "*"
	                allow_headers: keep-alive,user-agent,cache-control,content-type,content-transfer-encoding,x-accept-content-transfer-encoding,x-accept-response-streaming,x-user-agent,x-grpc-web,grpc-timeout
	                expose_headers: grpc-status,grpc-message
	          http_filters:
	          - name: envoy.grpc_web
	          - name: envoy.cors
	          - name: envoy.router
	  clusters:
	  - name: ping_pong_service
	    connect_timeout: 0.25s
	    type: logical_dns
	    http2_protocol_options: {}
	    lb_policy: round_robin
	    hosts: [{ socket_address: { address: host.docker.internal, port_value: 8080 }}]

Let’s understand what this envoy configuration file does:

admin:
	  access_log_path: /tmp/admin_access.log
	  address:
	    socket_address: { address: 0.0.0.0, port_value: 9901 }

9901 is the port where envoy admin portal is running. You can use this portal to check envoy routes, health checks and a lot more.

listeners:
	  - name: listener_0
	    address:
	      socket_address: { address: 0.0.0.0, port_value: 9090 }

9090 is the port where envoy is listening for incoming requests. Our website will make a request to envoy on this port.

virtual_hosts:
	  - name: local_service
	    domains: ["*"]
	    routes:
	    - match: { prefix: "/" }
	      route:
	        cluster: ping_pong_service
	        max_grpc_timeout: 0s
	    cors:
	      allow_origin:
	      - "*"
	      allow_headers: keep-alive,user-agent,cache-control,content-type,content-transfer-encoding,x-accept-content-transfer-encoding,x-accept-response-streaming,x-user-agent,x-grpc-web,grpc-timeout
	      expose_headers: grpc-status,grpc-message
	  http_filters:
	  - name: envoy.grpc_web
	  - name: envoy.cors
	  - name: envoy.router

clusters:
	  - name: ping_pong_service
	    connect_timeout: 0.25s
	    type: logical_dns
	    http2_protocol_options: {}
	    lb_policy: round_robin
	    hosts: [{ socket_address: { address: host.docker.internal, port_value: 8080 }}]

Any request that matches the above prefix is routed to the ping_pong_service cluster. Since our node server (aka cluster) is running on the host machine (your laptop) and not the docker container, we need to route those request out of the container to the host. host.docker.internal does exactly this.

Now let’s build our docker image using the following command:

docker build -t mohak1712/learn-grpc-web .

Now let’s run the docker image:

docker run -d -p 9090:9090 mohak1712/learn-grpc-web

We need to forward host port 9090 to the containers port 9090 so that any request on port 9090 is forwarded to the docker container where envoy is running.

Final Output

Now that everything is set up, make sure that the website, node server and envoy container are running. You can run the following set of commands in case you still haven’t.

npm start -> start web server
node server.js -> start node server
docker run -d -p 9090:9090 mohak1712/learn-grpc-web -> start envoy

Now when you click on the button, it sends a Ping request and gets a Pong response for it!

That’s about it! Thank you for reading, and I hope you enjoyed the article.

#reactjs #web-development

What is GEEK

Buddha Community

Nilesh Patil

1567423891

I am unable to set proxy. I have

windows8 machine and docker

2)D:\My Projects\KOS\KOS-gRPC_UI\my-app\src>docker -v

Docker version 18.03.0-ce, build 0520e24302

 I tried to run docker build and run command but permissin error over there . Could you please explain how to use envey proxy to run the project.

Autumn Blick

1598839687

How native is React Native? | React Native vs Native App Development

If you are undertaking a mobile app development for your start-up or enterprise, you are likely wondering whether to use React Native. As a popular development framework, React Native helps you to develop near-native mobile apps. However, you are probably also wondering how close you can get to a native app by using React Native. How native is React Native?

In the article, we discuss the similarities between native mobile development and development using React Native. We also touch upon where they differ and how to bridge the gaps. Read on.

A brief introduction to React Native

Let’s briefly set the context first. We will briefly touch upon what React Native is and how it differs from earlier hybrid frameworks.

React Native is a popular JavaScript framework that Facebook has created. You can use this open-source framework to code natively rendering Android and iOS mobile apps. You can use it to develop web apps too.

Facebook has developed React Native based on React, its JavaScript library. The first release of React Native came in March 2015. At the time of writing this article, the latest stable release of React Native is 0.62.0, and it was released in March 2020.

Although relatively new, React Native has acquired a high degree of popularity. The “Stack Overflow Developer Survey 2019” report identifies it as the 8th most loved framework. Facebook, Walmart, and Bloomberg are some of the top companies that use React Native.

The popularity of React Native comes from its advantages. Some of its advantages are as follows:

Performance: It delivers optimal performance.
Cross-platform development: You can develop both Android and iOS apps with it. The reuse of code expedites development and reduces costs.
UI design: React Native enables you to design simple and responsive UI for your mobile app.
3rd party plugins: This framework supports 3rd party plugins.
Developer community: A vibrant community of developers support React Native.

Why React Native is fundamentally different from earlier hybrid frameworks

Are you wondering whether React Native is just another of those hybrid frameworks like Ionic or Cordova? It’s not! React Native is fundamentally different from these earlier hybrid frameworks.

React Native is very close to native. Consider the following aspects as described on the React Native website:

Access to many native platforms features: The primitives of React Native render to native platform UI. This means that your React Native app will use many native platform APIs as native apps would do.
Near-native user experience: React Native provides several native components, and these are platform agnostic.
The ease of accessing native APIs: React Native uses a declarative UI paradigm. This enables React Native to interact easily with native platform APIs since React Native wraps existing native code.

Due to these factors, React Native offers many more advantages compared to those earlier hybrid frameworks. We now review them.

#android app #frontend #ios app #mobile app development #benefits of react native #is react native good for mobile app development #native vs #pros and cons of react native #react mobile development #react native development #react native experience #react native framework #react native ios vs android #react native pros and cons #react native vs android #react native vs native #react native vs native performance #react vs native #why react native #why use react native

Chloe Butler

1667425440

Pdf2gerb: Perl Script Converts PDF Files to Gerber format

pdf2gerb

Perl script converts PDF files to Gerber format

Pdf2Gerb generates Gerber 274X photoplotting and Excellon drill files from PDFs of a PCB. Up to three PDFs are used: the top copper layer, the bottom copper layer (for 2-sided PCBs), and an optional silk screen layer. The PDFs can be created directly from any PDF drawing software, or a PDF print driver can be used to capture the Print output if the drawing software does not directly support output to PDF.

The general workflow is as follows:

Design the PCB using your favorite CAD or drawing software.
Print the top and bottom copper and top silk screen layers to a PDF file.
Run Pdf2Gerb on the PDFs to create Gerber and Excellon files.
Use a Gerber viewer to double-check the output against the original PCB design.
Make adjustments as needed.
Submit the files to a PCB manufacturer.

Please note that Pdf2Gerb does NOT perform DRC (Design Rule Checks), as these will vary according to individual PCB manufacturer conventions and capabilities. Also note that Pdf2Gerb is not perfect, so the output files must always be checked before submitting them. As of version 1.6, Pdf2Gerb supports most PCB elements, such as round and square pads, round holes, traces, SMD pads, ground planes, no-fill areas, and panelization. However, because it interprets the graphical output of a Print function, there are limitations in what it can recognize (or there may be bugs).

See docs/Pdf2Gerb.pdf for install/setup, config, usage, and other info.

pdf2gerb_cfg.pm

#Pdf2Gerb config settings:
#Put this file in same folder/directory as pdf2gerb.pl itself (global settings),
#or copy to another folder/directory with PDFs if you want PCB-specific settings.
#There is only one user of this file, so we don't need a custom package or namespace.
#NOTE: all constants defined in here will be added to main namespace.
#package pdf2gerb_cfg;

use strict; #trap undef vars (easier debug)
use warnings; #other useful info (easier debug)


##############################################################################################
#configurable settings:
#change values here instead of in main pfg2gerb.pl file

use constant WANT_COLORS => ($^O !~ m/Win/); #ANSI colors no worky on Windows? this must be set < first DebugPrint() call

#just a little warning; set realistic expectations:
#DebugPrint("${\(CYAN)}Pdf2Gerb.pl ${\(VERSION)}, $^O O/S\n${\(YELLOW)}${\(BOLD)}${\(ITALIC)}This is EXPERIMENTAL software.  \nGerber files MAY CONTAIN ERRORS.  Please CHECK them before fabrication!${\(RESET)}", 0); #if WANT_DEBUG

use constant METRIC => FALSE; #set to TRUE for metric units (only affect final numbers in output files, not internal arithmetic)
use constant APERTURE_LIMIT => 0; #34; #max #apertures to use; generate warnings if too many apertures are used (0 to not check)
use constant DRILL_FMT => '2.4'; #'2.3'; #'2.4' is the default for PCB fab; change to '2.3' for CNC

use constant WANT_DEBUG => 0; #10; #level of debug wanted; higher == more, lower == less, 0 == none
use constant GERBER_DEBUG => 0; #level of debug to include in Gerber file; DON'T USE FOR FABRICATION
use constant WANT_STREAMS => FALSE; #TRUE; #save decompressed streams to files (for debug)
use constant WANT_ALLINPUT => FALSE; #TRUE; #save entire input stream (for debug ONLY)

#DebugPrint(sprintf("${\(CYAN)}DEBUG: stdout %d, gerber %d, want streams? %d, all input? %d, O/S: $^O, Perl: $]${\(RESET)}\n", WANT_DEBUG, GERBER_DEBUG, WANT_STREAMS, WANT_ALLINPUT), 1);
#DebugPrint(sprintf("max int = %d, min int = %d\n", MAXINT, MININT), 1); 

#define standard trace and pad sizes to reduce scaling or PDF rendering errors:
#This avoids weird aperture settings and replaces them with more standardized values.
#(I'm not sure how photoplotters handle strange sizes).
#Fewer choices here gives more accurate mapping in the final Gerber files.
#units are in inches
use constant TOOL_SIZES => #add more as desired
(
#round or square pads (> 0) and drills (< 0):
    .010, -.001,  #tiny pads for SMD; dummy drill size (too small for practical use, but needed so StandardTool will use this entry)
    .031, -.014,  #used for vias
    .041, -.020,  #smallest non-filled plated hole
    .051, -.025,
    .056, -.029,  #useful for IC pins
    .070, -.033,
    .075, -.040,  #heavier leads
#    .090, -.043,  #NOTE: 600 dpi is not high enough resolution to reliably distinguish between .043" and .046", so choose 1 of the 2 here
    .100, -.046,
    .115, -.052,
    .130, -.061,
    .140, -.067,
    .150, -.079,
    .175, -.088,
    .190, -.093,
    .200, -.100,
    .220, -.110,
    .160, -.125,  #useful for mounting holes
#some additional pad sizes without holes (repeat a previous hole size if you just want the pad size):
    .090, -.040,  #want a .090 pad option, but use dummy hole size
    .065, -.040, #.065 x .065 rect pad
    .035, -.040, #.035 x .065 rect pad
#traces:
    .001,  #too thin for real traces; use only for board outlines
    .006,  #minimum real trace width; mainly used for text
    .008,  #mainly used for mid-sized text, not traces
    .010,  #minimum recommended trace width for low-current signals
    .012,
    .015,  #moderate low-voltage current
    .020,  #heavier trace for power, ground (even if a lighter one is adequate)
    .025,
    .030,  #heavy-current traces; be careful with these ones!
    .040,
    .050,
    .060,
    .080,
    .100,
    .120,
);
#Areas larger than the values below will be filled with parallel lines:
#This cuts down on the number of aperture sizes used.
#Set to 0 to always use an aperture or drill, regardless of size.
use constant { MAX_APERTURE => max((TOOL_SIZES)) + .004, MAX_DRILL => -min((TOOL_SIZES)) + .004 }; #max aperture and drill sizes (plus a little tolerance)
#DebugPrint(sprintf("using %d standard tool sizes: %s, max aper %.3f, max drill %.3f\n", scalar((TOOL_SIZES)), join(", ", (TOOL_SIZES)), MAX_APERTURE, MAX_DRILL), 1);

#NOTE: Compare the PDF to the original CAD file to check the accuracy of the PDF rendering and parsing!
#for example, the CAD software I used generated the following circles for holes:
#CAD hole size:   parsed PDF diameter:      error:
#  .014                .016                +.002
#  .020                .02267              +.00267
#  .025                .026                +.001
#  .029                .03167              +.00267
#  .033                .036                +.003
#  .040                .04267              +.00267
#This was usually ~ .002" - .003" too big compared to the hole as displayed in the CAD software.
#To compensate for PDF rendering errors (either during CAD Print function or PDF parsing logic), adjust the values below as needed.
#units are pixels; for example, a value of 2.4 at 600 dpi = .0004 inch, 2 at 600 dpi = .0033"
use constant
{
    HOLE_ADJUST => -0.004 * 600, #-2.6, #holes seemed to be slightly oversized (by .002" - .004"), so shrink them a little
    RNDPAD_ADJUST => -0.003 * 600, #-2, #-2.4, #round pads seemed to be slightly oversized, so shrink them a little
    SQRPAD_ADJUST => +0.001 * 600, #+.5, #square pads are sometimes too small by .00067, so bump them up a little
    RECTPAD_ADJUST => 0, #(pixels) rectangular pads seem to be okay? (not tested much)
    TRACE_ADJUST => 0, #(pixels) traces seemed to be okay?
    REDUCE_TOLERANCE => .001, #(inches) allow this much variation when reducing circles and rects
};

#Also, my CAD's Print function or the PDF print driver I used was a little off for circles, so define some additional adjustment values here:
#Values are added to X/Y coordinates; units are pixels; for example, a value of 1 at 600 dpi would be ~= .002 inch
use constant
{
    CIRCLE_ADJUST_MINX => 0,
    CIRCLE_ADJUST_MINY => -0.001 * 600, #-1, #circles were a little too high, so nudge them a little lower
    CIRCLE_ADJUST_MAXX => +0.001 * 600, #+1, #circles were a little too far to the left, so nudge them a little to the right
    CIRCLE_ADJUST_MAXY => 0,
    SUBST_CIRCLE_CLIPRECT => FALSE, #generate circle and substitute for clip rects (to compensate for the way some CAD software draws circles)
    WANT_CLIPRECT => TRUE, #FALSE, #AI doesn't need clip rect at all? should be on normally?
    RECT_COMPLETION => FALSE, #TRUE, #fill in 4th side of rect when 3 sides found
};

#allow .012 clearance around pads for solder mask:
#This value effectively adjusts pad sizes in the TOOL_SIZES list above (only for solder mask layers).
use constant SOLDER_MARGIN => +.012; #units are inches

#line join/cap styles:
use constant
{
    CAP_NONE => 0, #butt (none); line is exact length
    CAP_ROUND => 1, #round cap/join; line overhangs by a semi-circle at either end
    CAP_SQUARE => 2, #square cap/join; line overhangs by a half square on either end
    CAP_OVERRIDE => FALSE, #cap style overrides drawing logic
};
    
#number of elements in each shape type:
use constant
{
    RECT_SHAPELEN => 6, #x0, y0, x1, y1, count, "rect" (start, end corners)
    LINE_SHAPELEN => 6, #x0, y0, x1, y1, count, "line" (line seg)
    CURVE_SHAPELEN => 10, #xstart, ystart, x0, y0, x1, y1, xend, yend, count, "curve" (bezier 2 points)
    CIRCLE_SHAPELEN => 5, #x, y, 5, count, "circle" (center + radius)
};
#const my %SHAPELEN =
#Readonly my %SHAPELEN =>
our %SHAPELEN =
(
    rect => RECT_SHAPELEN,
    line => LINE_SHAPELEN,
    curve => CURVE_SHAPELEN,
    circle => CIRCLE_SHAPELEN,
);

#panelization:
#This will repeat the entire body the number of times indicated along the X or Y axes (files grow accordingly).
#Display elements that overhang PCB boundary can be squashed or left as-is (typically text or other silk screen markings).
#Set "overhangs" TRUE to allow overhangs, FALSE to truncate them.
#xpad and ypad allow margins to be added around outer edge of panelized PCB.
use constant PANELIZE => {'x' => 1, 'y' => 1, 'xpad' => 0, 'ypad' => 0, 'overhangs' => TRUE}; #number of times to repeat in X and Y directions

# Set this to 1 if you need TurboCAD support.
#$turboCAD = FALSE; #is this still needed as an option?

#CIRCAD pad generation uses an appropriate aperture, then moves it (stroke) "a little" - we use this to find pads and distinguish them from PCB holes. 
use constant PAD_STROKE => 0.3; #0.0005 * 600; #units are pixels
#convert very short traces to pads or holes:
use constant TRACE_MINLEN => .001; #units are inches
#use constant ALWAYS_XY => TRUE; #FALSE; #force XY even if X or Y doesn't change; NOTE: needs to be TRUE for all pads to show in FlatCAM and ViewPlot
use constant REMOVE_POLARITY => FALSE; #TRUE; #set to remove subtractive (negative) polarity; NOTE: must be FALSE for ground planes

#PDF uses "points", each point = 1/72 inch
#combined with a PDF scale factor of .12, this gives 600 dpi resolution (1/72 * .12 = 600 dpi)
use constant INCHES_PER_POINT => 1/72; #0.0138888889; #multiply point-size by this to get inches

# The precision used when computing a bezier curve. Higher numbers are more precise but slower (and generate larger files).
#$bezierPrecision = 100;
use constant BEZIER_PRECISION => 36; #100; #use const; reduced for faster rendering (mainly used for silk screen and thermal pads)

# Ground planes and silk screen or larger copper rectangles or circles are filled line-by-line using this resolution.
use constant FILL_WIDTH => .01; #fill at most 0.01 inch at a time

# The max number of characters to read into memory
use constant MAX_BYTES => 10 * M; #bumped up to 10 MB, use const

use constant DUP_DRILL1 => TRUE; #FALSE; #kludge: ViewPlot doesn't load drill files that are too small so duplicate first tool

my $runtime = time(); #Time::HiRes::gettimeofday(); #measure my execution time

print STDERR "Loaded config settings from '${\(__FILE__)}'.\n";
1; #last value must be truthful to indicate successful load


#############################################################################################
#junk/experiment:

#use Package::Constants;
#use Exporter qw(import); #https://perldoc.perl.org/Exporter.html

#my $caller = "pdf2gerb::";

#sub cfg
#{
#    my $proto = shift;
#    my $class = ref($proto) || $proto;
#    my $settings =
#    {
#        $WANT_DEBUG => 990, #10; #level of debug wanted; higher == more, lower == less, 0 == none
#    };
#    bless($settings, $class);
#    return $settings;
#}

#use constant HELLO => "hi there2"; #"main::HELLO" => "hi there";
#use constant GOODBYE => 14; #"main::GOODBYE" => 12;

#print STDERR "read cfg file\n";

#our @EXPORT_OK = Package::Constants->list(__PACKAGE__); #https://www.perlmonks.org/?node_id=1072691; NOTE: "_OK" skips short/common names

#print STDERR scalar(@EXPORT_OK) . " consts exported:\n";
#foreach(@EXPORT_OK) { print STDERR "$_\n"; }
#my $val = main::thing("xyz");
#print STDERR "caller gave me $val\n";
#foreach my $arg (@ARGV) { print STDERR "arg $arg\n"; }

Download Details:

Author: swannman
Source Code: https://github.com/swannman/pdf2gerb

License: GPL-3.0 license

#perl

Franz Becker

1651604400

React Starter Kit: Build Web Apps with React, Relay and GraphQL.

React Starter Kit — "isomorphic" web app boilerplate

React Starter Kit is an opinionated boilerplate for web development built on top of Node.js, Express, GraphQL and React, containing modern web development tools such as Webpack, Babel and Browsersync. Helping you to stay productive following the best practices. A solid starting point for both professionals and newcomers to the industry.

See getting started guide, demo, docs, roadmap | Join #react-starter-kit chat room on Gitter | Visit our sponsors:

Hiring

Getting Started

Follow the getting started guide to download and run the project (Node.js >= 8.16.2)
Check the code recipes used in this boilerplate, or share yours

Customization

The master branch of React Starter Kit doesn't include a Flux implementation or any other advanced integrations. Nevertheless, we have some integrations available to you in feature branches that you can use either as a reference or merge into your project:

feature/redux (PR) — isomorphic Redux by Pavel Lang (see how to integrate Redux) (based on master)
feature/apollo (PR) — isomorphic Apollo Client by Pavel Lang (see Tracking PR #1147) (based on feature/redux)
feature/react-intl (PR) — isomorphic Redux and React Intl by Pavel Lang (see how to integrate React Intl) (based on feature/apollo)
feature/apollo-pure (PR) — Apollo devtools and TypeScript integration by piglovesyou (based on master)

You can see status of most reasonable merge combination as PRs labeled as TRACKING

If you think that any of these features should be on master, or vice versa, some features should removed from the master branch, please let us know. We love your feedback!

Comparison

	React Starter Kit	React Static Boilerplate	ASP.NET Core Starter Kit
App type	Isomorphic (universal)	Single-page application	Single-page application
Frontend
Language	JavaScript (ES2015+, JSX)	JavaScript (ES2015+, JSX)	JavaScript (ES2015+, JSX)
Libraries	React, History, Universal Router	React, History, Redux	React, History, Redux
Routes	Imperative (functional)	Declarative	Declarative, cross-stack
Backend
Language	JavaScript (ES2015+, JSX)	n/a	C#, F#
Libraries	Node.js, Express, Sequelize, GraphQL	n/a	ASP.NET Core, EF Core, ASP.NET Identity
SSR	Yes	n/a	n/a
Data API	GraphQL	n/a	Web API

Backers

♥ React Starter Kit? Help us keep it alive by donating funds to cover project expenses via OpenCollective or Bountysource!

lehneres Tarkan Anlar Morten Olsen Adam David Ernst Zane Hitchcox

How to Contribute

Anyone and everyone is welcome to contribute to this project. The best way to start is by checking our open issues, submit a new issue or feature request, participate in discussions, upvote or downvote the issues you like or dislike, send pull requests.

Learn More

Related Projects

GraphQL Starter Kit — Boilerplate for building data APIs with Node.js, JavaScript (via Babel) and GraphQL
Membership Database — SQL schema boilerplate for user accounts, profiles, roles, and auth claims
Babel Starter Kit — Boilerplate for authoring JavaScript/React.js libraries

Support

#react-starter-kit on Stack Overflow — Questions and answers
#react-starter-kit on Gitter — Watch announcements, share ideas and feedback
GitHub issues, or Scrum board — File issues, send feature requests
appear.in/react — Open hours! Exchange ideas and experiences (React, GraphQL, startups and pet projects)
@koistya on Codementor, or Skype — Private consulting

License

Author: kriasoft
Source Code: https://github.com/kriasoft/react-starter-kit
License: MIT License

#graphql #react

Abhishek Jaiswal

1607768450

What are hooks in React JS? - INFO AT ONE

In this article, you will learn what are hooks in React JS? and when to use react hooks? React JS is developed by Facebook in the year 2013. There are many students and the new developers who have confusion between react and hooks in react. Well, it is not different, react is a programming language and hooks is a function which is used in react programming language.
Read More:- https://infoatone.com/what-are-hooks-in-react-js/

#react #hooks in react #react hooks example #react js projects for beginners #what are hooks in react js? #when to use react hooks

Mathew Rini

1615544450

How to Select and Hire the Best React JS and React Native Developers?

Since March 2020 reached 556 million monthly downloads have increased, It shows that React JS has been steadily growing. React.js also provides a desirable amount of pliancy and efficiency for developing innovative solutions with interactive user interfaces. It’s no surprise that an increasing number of businesses are adopting this technology. How do you select and recruit React.js developers who will propel your project forward? How much does a React developer make? We’ll bring you here all the details you need.

What is React.js?

Facebook built and maintains React.js, an open-source JavaScript library for designing development tools. React.js is used to create single-page applications (SPAs) that can be used in conjunction with React Native to develop native cross-platform apps.

React vs React Native

React Native is a platform that uses a collection of mobile-specific components provided by the React kit, while React.js is a JavaScript-based library.
React.js and React Native have similar syntax and workflows, but their implementation is quite different.
React Native is designed to create native mobile apps that are distinct from those created in Objective-C or Java. React, on the other hand, can be used to develop web apps, hybrid and mobile & desktop applications.
React Native, in essence, takes the same conceptual UI cornerstones as standard iOS and Android apps and assembles them using React.js syntax to create a rich mobile experience.

What is the Average React Developer Salary?

In the United States, the average React developer salary is $94,205 a year, or $30-$48 per hour, This is one of the highest among JavaScript developers. The starting salary for junior React.js developers is $60,510 per year, rising to $112,480 for senior roles.

* React.js Developer Salary by Country

United States- $120,000
Canada - $110,000
United Kingdom - $71,820
The Netherlands $49,095
Spain - $35,423.00
France - $44,284
Ukraine - $28,990
India - $9,843
Sweden - $55,173
Singapore - $43,801

In context of software developer wage rates, the United States continues to lead. In high-tech cities like San Francisco and New York, average React developer salaries will hit $98K and $114per year, overall.

However, the need for React.js and React Native developer is outpacing local labour markets. As a result, many businesses have difficulty locating and recruiting them locally.

It’s no surprise that for US and European companies looking for professional and budget engineers, offshore regions like India are becoming especially interesting. This area has a large number of app development companies, a good rate with quality, and a good pool of React.js front-end developers.

As per Linkedin, the country’s IT industry employs over a million React specialists. Furthermore, for the same or less money than hiring a React.js programmer locally, you may recruit someone with much expertise and a broader technical stack.

How to Hire React.js Developers?

Conduct thorough candidate research, including portfolios and areas of expertise.
Before you sit down with your interviewing panel, do some homework.
Examine the final outcome and hire the ideal candidate.

Why is React.js Popular?

React is a very strong framework. React.js makes use of a powerful synchronization method known as Virtual DOM, which compares the current page architecture to the expected page architecture and updates the appropriate components as long as the user input.

React is scalable. it utilises a single language, For server-client side, and mobile platform.

React is steady.React.js is completely adaptable, which means it seldom, if ever, updates the user interface. This enables legacy projects to be updated to the most new edition of React.js without having to change the codebase or make a few small changes.

React is adaptable. It can be conveniently paired with various state administrators (e.g., Redux, Flux, Alt or Reflux) and can be used to implement a number of architectural patterns.

Is there a market for React.js programmers?
The need for React.js developers is rising at an unparalleled rate. React.js is currently used by over one million websites around the world. React is used by Fortune 400+ businesses and popular companies such as Facebook, Twitter, Glassdoor and Cloudflare.

Final thoughts:

As you’ve seen, locating and Hire React js Developer and Hire React Native developer is a difficult challenge. You will have less challenges selecting the correct fit for your projects if you identify growing offshore locations (e.g. India) and take into consideration the details above.

If you want to make this process easier, You can visit our website for more, or else to write a email, we’ll help you to finding top rated React.js and React Native developers easier and with strives to create this operation

#hire-react-js-developer #hire-react-native-developer #react #react-native #react-js #hire-react-js-programmer