Network Programming in .NET

BurnerSMS.com is a website, where you can send a text message to a phone number, and the text and sender will appear on the webpage – after you refresh. It could be used for those services that want to use your mobile phone to send authorisation codes to, but you don’t want to share your real phone number.

That’s the idea anyway – but it really was a way so I could learn a bit about NodeJS, on a practical project.

So, here’s the architecture. The mobile messages actually come in via CloudAnsweringMachine.com – which offer an API that allow you view calls and texts sent to a given number. The API returns in XML, but I’ve used xml2js to convert the XML to a JSON.

The project is hosted on a Windows server, where I installed the latest version of NodeJs, NPM and IISNode. I had to do an IISReset after the installation for it to work.

I used NPM init to create my package.json file, which keeps track of the NPM packages I installed during the development. I used the following packages;

• request – Making life sooo much easier for HTTP requests
• xml2js – Converting the XML returned from the API to JSON
• underscore – A collection of handy Javascript functions just as _.filter
• ejs – A HTML templating engine, so I can separate my NodeJS and HTML presentation
• moment – handles date formatting, so I can display dates in a pretty format

The whole back end is as follows;

var http = require(‘http’);
const request = require(‘request’);
var parseString = require(‘xml2js’).parseString;
const _ = require(‘underscore’);
const ejs = require(‘ejs’);
var moment = require(‘moment’);

http.createServer(function (req, res) {
res.writeHead(200, {‘Content-Type’: ‘text/html’});
request(‘https://www.cloudansweringmachine.com/api.asmx/GetMessages?email=xxxx@xxx.com&password=xxxx’, (err, response, body) => {
if (err) { res.end(err); return; };
parseString(body, function (err, result) {
// result.ArrayOfMessages.Messages
var TextMessages = _.filter(result.ArrayOfMessages.Messages, function(msg){
return msg.MessageUrl[0] == “”;
});
result.ArrayOfMessages.Messages.forEach(function(element){
element.prettyDate = moment(element.DateArrived[0],”YYYY-MM-DDTHH:mm:ss”).format(“MMMM Do YYYY, h:mm:ss a”);
});
ejs.renderFile(“burner.ejs”, { messages: TextMessages }, {}, function(err, str){
res.write(str);
res.end();
});
});
});
}).listen(process.env.PORT);

This file – which I called Burner.js; and I’ve ommitted the username/password for the API call, you can get one yourself!

It starts a server which listens on port 80, and immediately calls the API. If successful, it converts the XML to JSON. It then uses the underscore filter function to remove elements from the response that refer to phonecalls rather than text messages. Following that, it uses moment to parse the DateArrived property, which is in an ugly Year-Month-Day format to a more readable Month Day Year format.

Once all that is done, it uses EJS to load the file “Burner.ejs” from the same folder, and passes through the filtered object to the page. The resultant HTML is then output using res.write

You need to call res.end() once the operation is complete, since this will close the connection between server and client, otherwise the client may hang.

Burner.ejs, is effectively a HTML file, and I won’t include the entire HTML here, just the dynamic part:

<% messages.forEach(function(message){ %>
<tr>
<td>
<%= message.prettyDate %>
</td>
<td>
<%= message.Sender[0] %>
</td>
<td>
<%= message.MessageText[0] %>
</td>
<td></td>
</tr>
<% }); %>

It looks almost like Classic ASP … but you can see how it iterates through each message in the messages array, and puts the output between the td’s

Now, that’s almost a wrapped up, just to say that you also need a web.config document in that folder to tell IIS that burner.js is to be handled by the server, not a javascript file to be sent verbatim to the client. – and that burner.js is the default document.

<configuration>
<system.webServer>
<handlers>
<add name=”iisnode” path=”burner.js” verb=”*” modules=”iisnode” />
</handlers>
<defaultDocument>
<files>
<add value=”burner.js” />
</files>
</defaultDocument>
</system.webServer>
</configuration>