Network Programming in .NET

You may have all your code saved safely in Source control, but your data is not something that can easily be regenerated in the event of a hard drive failure, or simple fat fingered, update or delete statement without a where clause.

Backing up your databases to the same machine saves against typos, but it doesn’t save against a server outage, you really need to get your backups off the server. Amazon S3 is a good option, since it costs under 2p per GB (London datacenter)

Now, there are a million ways you could get your server backups to S3, you could use a batch file, a custom script, some c# … However, I tried our Tnt Drive, which maps a drive to your S3 bucket, and uploads your files asyncronously.

Then all you need to do, is to put your backup on the mapped drive (Z), with a script like

backup database db to disk = ‘Z:\db.bak’

In the past, selling your services internationally was a logistically difficult task, however, with many IT products, you could just as easily find customers in Azerbaijan as you would in the USA. However, nobody in their right mind would consider localising to Azerbaijani before English. But, is Japanese more important than Spanish? for example.

So, lets get some caveats out of the way. This article assumes there is zero logistical, legal or technical boundaries between selling your app or website in any country worldwide. An app that gambles with real money will require country-specific licenses. It also assumes that your App is not culturally biased, few people in Japan will be interested in a weather app for Sweden.

So, do you focus on the richest countries, and target your app at Luxembourg, or the most populous countries, and go for Nigeria?, neither is a good choice, since one is too small, and the other is too poor. So, by going by total GDP you get US, China, Japan, Germany – the full list is here: https://en.wikipedia.org/wiki/List_of_countries_by_GDP_(nominal)

Now, this does not take into account the idea that an App in Spanish not only is applicable to Spanish users, but is also usable by Mexicans, Argentinians, Colombians etc. So, to combine GDP by Language, you get the following:

This list was compiled by Unicode.org.

So, in short, English is the obvious first language – and if you’re reading this, then your app is probably already in English. Chinese and Japanese come second, but Spanish comes before German – Even though Germany has higher GDP than Spain.

The next issue, is that you may need to take into account disposable income when planning your expansion. You have to discount the part of the population who are living in poverty, and thus will not buy anything outside their immediate needs. In china, the rate of poverty (i.e. <$5.50 a day), is 31.5%, (https://en.wikipedia.org/wiki/List_of_countries_by_percentage_of_population_living_in_poverty), so its relative importance is 8.5% , still above Spanish.

Of course, if you’re reading this, and you’re a translator – please feel free to register on OutsourceTranslation.com

Our Cloud Answering Machine App, version 1.5, available via the iOS App store is now available in Spanish, German and French. It will automatically detect your phone language, and will switch the user interface to your preferred language.  Version 1.6, which is currently in review, will add support for Japanese, Korean and Portuguese

It also supports 32 new counties for provisioning phone numbers – which are :

The App is also available for android, windows phone, and the web at https://www.cloudansweringmachine.com/

We’re now offering our UK car valuation API for free, all you need is a valid account on our website. You can access this API via the following endpoint

https://www.regcheck.org.uk/api/bespokeapi.asmx?op=CheckPrice

Where you pass the vehicle reg number, mileage and your username, and it will return data in the format (Prices are in GBP);

<Valuationxmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance“xmlns:xsd=”http://www.w3.org/2001/XMLSchema“xmlns=”http://Regcheck.org.uk/“>

<Description>

Peugeot 208 (2015-) 5Dr Hatchback 1.2 PureTech SS 110 EU6 GT Line EAT Auto6

</Description>

<Price>9240</Price>

</Valuation>

Deploying a website with every check-in is quite a risky buisness, but it’s great for testing, so that your testers can be sure that they are looking at the very latest build of your website.

So, if you are using GitHub as your source control, then you can use Github’s Webhook system to trigger your website to download the latest version of itself from Github, effectively self-updating.

So, if you want to skip to the end, just check out our Github repo at https://github.com/infiniteloopltd/AutoBuild and the corresponding test website at http://autobuild.webtropy.com The website is set to automatically download content from Github on every push.

First, set up a webhook. Go to the repo, and click Settings > WebHooks > Add Webhook

Set up the payload url to point to your website, plus “github.aspx”, and keep the other settings as default.

Next, Add the following three Nuget packages to your project;

Install-Package Octokit

Install-Package SharpZipLib

Install-Package Newtonsoft.Json

and then the corresponding using statements;

using Octokit; // Install-Package Octokit
using System;
using System.Configuration;
using System.IO;
using ICSharpCode.SharpZipLib.GZip; // Install-Package SharpZipLib
using ICSharpCode.SharpZipLib.Tar; // Install-Package SharpZipLib
using System.Threading;
using Newtonsoft.Json.Linq; // Install-Package Newtonsoft.Json

Now, I’ve kept my settings in my web.config, as follows;

<add key=”GITHUB_USERNAME” value=”infiniteloopltd”/>
<add key=”GITHUB_PASSWORD” value=”xxxxxx”/>
<add key=”GITHUB_REPO” value=”AutoBuild”/>
<add key=”DEPLOY_PATH” value=”C:\temp\”/>

And, I’ve set up some public variables as follows

protected GitHubClient client = new GitHubClient(new ProductHeaderValue(“Autobuild”));
string username = ConfigurationManager.AppSettings[“GITHUB_USERNAME”];
string password = ConfigurationManager.AppSettings[“GITHUB_PASSWORD”];
string repository = ConfigurationManager.AppSettings[“GITHUB_REPO”];
string output = ConfigurationManager.AppSettings[“DEPLOY_PATH”];

The ProductHeaderValue seems arbirary, but I’ve called it AutoBuild.

Now, the magic happens when I start using Octokit;

private bool DownloadArchive(string expectedCommit)
{
var tDownload = client.Repository.Content.GetArchive(username, repository);
var bArchive = tDownload.Result;
var stream = new MemoryStream(bArchive);
Stream gzipStream = new GZipInputStream(stream);
Stream gzipStream2 = new GZipInputStream(stream);
TarInputStream tarIn = new TarInputStream(gzipStream);
TarEntry tarEntry;
var strRoot = “”;
while ((tarEntry = tarIn.GetNextEntry()) != null)
{
string name = tarEntry.Name.Replace(‘/’, Path.DirectorySeparatorChar);
if (strRoot == “”)
{
strRoot = name;
if (!strRoot.Contains(expectedCommit)) return false;
}
if (tarEntry.IsDirectory)
continue;
if (Path.IsPathRooted(name))
name = name.Substring(Path.GetPathRoot(name).Length);
name = name.Replace(strRoot, “”);
string outName = Path.Combine(output, name);
string directoryName = Path.GetDirectoryName(outName);
Directory.CreateDirectory(directoryName);
FileStream outStr = new FileStream(outName, System.IO.FileMode.Create);
tarIn.CopyEntryContents(outStr);
outStr.Close();
}
tarIn.Close();
gzipStream.Close();
stream.Close();
return true;
}

What happens here, is that I request the latest archive of my repo from GitHub, which is in TAR.GZ format. What that actually means is that it is a TAR container of files, that has been compressed into a GZip stream.

I unzip the byte array, and pass it into a TarInputStream from SharpZipLib. GitHub wraps all your files into a folder that’s named

infiniteloopltd-AutoBuild-51d1c48\

i.e. {username}-{repo}-{commit}, this means that each file needs to be extracted one by one, since this wrapper folder needs to be removed.

However, the wrapper folder comes in very handy later on.

Now, that’s where everything is nice and sensible, then it gets ugly….

Unfortunately, if you call GetArchive too soon after the webhook is called, then you get the previous commit, and that’s useless, your files don’t update.

So, therefore, I need to read the parameters sent to the webhook to ensure that the commit I am expecting matches the one in the Archive, luckily, there is plenty of data sent to the webhook by github in Json format as follows;

{
  "ref": "refs\/heads\/master",
  "before": "b75dcf060de3710bfd7c054e4869397cc75380ba",
  "after": "90d9567997f96203853e071500136a16b1335c3a",
  "created": false,
  ....

The first 7 chars of this commit guid match the code shown on the website

… and also match the code contained in the wrapper folder, which allows you match the archive with the code. And if it doesn’t match, I just wait 5 seconds and try again.

So my Page_Load is defined as (With some logging)

protected void Page_Load(object sender, EventArgs e)
{
var strLog = “Started at ” + DateTime.Now;
client.Credentials = new Credentials(username, password);
var strJsonPayload = Request.Form[“Payload”];
string strExpectedCommit = “”;
if (!string.IsNullOrEmpty(strJsonPayload))
{
strLog += “\nGitHub payload ” + strJsonPayload;
var jPayload = JObject.Parse(strJsonPayload);
strExpectedCommit = jPayload[“after”].ToString().Substring(0, 7);
strLog += “\nExpected Commit ” + strExpectedCommit;
}
for(int i=0;i<10;i++)
{
var blnOK = DownloadArchive(strExpectedCommit);
if (blnOK) break;
Thread.Sleep(TimeSpan.FromSeconds(5));
strLog += “\nRetry ” + i;
}
File.WriteAllText(output + “buildlog.txt”, strLog);
}

Et Voila … every time you push a code change to GitHub. github calls this webhook, which downloads a zip of the code, and deploys it ontop of itself, creating a self-updating website! 🙂

This perhaps is not the best way to internationalize (i.e. make available in multiple languages) an Angular web app, but it works well for me, both as a Web app, or as part of a Cordova / Phonegap app.

In App.js, I define the following “Constant”

angular.module(‘app’, [‘ionic’, …. ])

.constant(‘translations’, {

‘en’ :

{

‘Register’ : ‘Register’,

‘Login’ : ‘Login’,

},

‘es’ :

{

‘Register’ : ‘Registrar’,

‘Login’ : ‘Iniciar sesión’,

},

current : function()

{

lang = ‘en’;

if (navigator.languages != undefined) lang = navigator.languages[0]; else lang = navigator.language;

if (lang.indexOf(“es”) != -1 ) return this.es;

return this.en; // default en

}

})

Which effectively defines two languages “en” (English) and “es” (Spanish), and defines two variables, or strings within it “Login” and “Register”, you can see how the translation differs between English and Spanish. You can of course define more words, and more languages, this demo is just making a basic case.

Now, in order to use this in a controller, you pass it in as follows;

.controller(‘loginCtrl’, [‘translations’,‘$scope’, …..

function (translations, $scope, …) {

$scope.translations = translations.current();

Then you can refer to the translation in the template html as follows;

<a  class=“button” ng-click=“login()”>{{ translations.Login }}</a>

Or in code as follows;

alert($scope.translations.Login);

This, once again is going to be used in version 1.5 of our iOS app for CloudAnsweringMachine.com

The WhatsApp Business API is open for applications, which you can sign up for via https://www.facebook.com/business/m/whatsapp/business-api – and it looks like they are working with Twilio to create a webhook layer on top of this.

But, there are some simple things you can do today, for example, if you want to encourage your users to send you a WhatsApp message from your app or website, then you can add a link to;

https://api.whatsapp.com/send?phone=<your number>&text=hello

It’s important to remember that whatsapp is not typically used from the desktop, so if you want this to work, and your user is on a desktop browser, then it is better to show a QR code for the URL above – that they can scan with their phone, rather than sending them directly to this url.

Once this API is in general release, it’ll be a new feature that we’ll add to https://www.cloudansweringmachine.com

Cloudflare is a service that can help keep your website safe from DDOS attacks, by taking the load of the attack without affecting your underlying server too badly.

However, assuming that your website is being specifically targeted, then it is obvious for an attacker to spot that your website is behind cloudflare, by simply checking the NS records on your domain. – So an attacker will look to find your underlying webserver, and attack it directly, rather than a “front door” attack via Cloudflare.

So, the first step, as a domain owner, is to make sure that your underlying werserver is not published anywhere on the web. Since, if you can find it – you can bet an attacker will too.

A first search is here: http://www.crimeflare.org:82/cfs.html – Scroll to the foot of the page, and enter your domain – if it’s there, make sure you change your IP address of your server, or ask the owner of this website to remove your listing from his database.

Next, check for historic A records of your domain here; https://securitytrails.com/domain/<your domain>/history/a – and make sure the IP address of the server you used before you moved to cloudFlare is no longer your production IP address.

In short, the general tip is – that if you used the same server IP before moving to CloudFlare, as you do now, – change it. Otherwise an attacker can bypass your CloudFlare protection.

If you are looking to implement a system that can determine if a car is insured in Italy, and to find its current insurer, then here is an API that solves this for you;

You can also find the current insurer of a car in Italy, by calling the following API; CheckInsuranceStatusItaly at http://www.targa.co.it/api/bespokeapi.asmx , passing the number plate and your username from www.targa.co.it

The response is in XML as follows;

If you have an app on VSTS, which suddenly started returning the error
{“Error”:”unauthorized_client”,”ErrorDescription”:null} and InvalidScope in the query string, then it appears that the culprit is vso.codesearch, which needs to be removed from the scope.

Unfortunately, if you already have created an app with this in it’s scope, then a bug in VSTS prevents you from saving it again – so you may need to create a duplicate of the app.