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Sending Text Messages with Red and Twilio

red-twilio.png

Red is a next-gen programming language, strongly inspired by REBOL. It is both an imperative and functional programming language.

Red is different from other languages. With Red we'll be able to cross-compile GUI applications into stand-alone executables about 1 MB in size. As Gregg Irwin (Red Community Manager) puts it, we will look like superheroes, but our sidekick is the one doing all the work.

What are we going to build

"A picture is worth a thousand words", our stand-alone GUI application will look something like this:

Red GUI

It contains an input field for the destination phone number, another input field for the body of the message and a "Send" button. Pretty simple. Let's build this! (Oh..., and let's do it in 50 lines of code or less, no Xcode, Visual Studio or things like that, Red has the "batteries included".)

Setting Up for Development

To get started we need:

Next, let's install the Red toolchain. It comes as a single one-megabyte executable file, and we'll download it from here: http://www.red-lang.org/p/download.html

The download is named red-[something], where [something] has to do with versioning, (on Windows, the file also has an .exe extension).

Installing Red on macOS

  • create a new folder named red on your Desktop
  • move or copy the downloaded red-[something] to the red folder
  • for convenience rename the file to just red
  • in your Terminal, go to the red folder with cd ~/Desktop/red/
  • do a chmod +x red to obtain executable rights
  • now run ./red command (when doing this for the first time the "Red console" will be built)
  • after a bit of time the "Red console" will show up, and we can close it for now by typing quit and then hitting enter

Installing Red on Windows

  • create a new folder named red on your Desktop
  • move or copy the downloaded red-[something].exe in the red folder
  • make a new file red.bat with the following content @"%~dp0red-[something].exe" %*, save
  • in your "Command Prompt" go to the red folder with cd c:\Users\[username]\Desktop\red\
  • now run red.bat command (when doing this for the first time the "Red console" will be built)
  • after a bit of time the "Red console" will show up, and we can close it for now with quit + Enter

The fun part, getting our hands dirty and actually write some Red code

In our red folder, we'll create a text file twilio-sms.red with the code of our application.

Red [
    title: "Sending Text messages with Red and Twilio"
    needs: 'view                          
]


; assign Twilio credentials to global variables
twilio-account-sid: "ACe92063f2ef7820a132d7ff5a5ec2666f"
twilio-auth-token: "9d80bb08fb99cf0c2d04dc40c1c824df"
twilio-phone-number: "+19997775555"


; Twilio’s API end-point
api-url: to url! rejoin ["https://api.twilio.com/2010-04-01/Accounts/" twilio-account-sid "/Messages.json"]
; build the authentication string
auth-string: rejoin ["Basic " enbase/base rejoin [twilio-account-sid ":" twilio-auth-token] 64]


; function used to send the message via a POST request
send-message: does [

    payload-data: rejoin ["From=" twilio-phone-number "&To=" to-number/text "&Body=" message-body/text]
    url: api-url

    response: write url compose/deep [
        post [
            Content-Type: "application/x-www-form-urlencoded"
            Authorization: (auth-string)
        ]
        (payload-data)
    ]

    out/text: response
]


; the GUI of the application
view [ 

    title "Sending Text messages with Red and Twilio"
    below 

    text "To (phone number):" 
    to-number: field 100x30

    text "Message:" 
    message-body: field 500x30 

    ; a button to call the [send-message] function when clicked
    button "Send" [send-message]

    out: text 600x150 ""                          
]

Let's examine the code.

needs: 'view tells the compiler that this is a GUI application

The following lines of code, assign our Twilio credentials as well as our Twilio number to variables. Replace the values with your Twilio credentials, these here are just mock values. You can find your Twilio credentials (ACCOUNT SID and AUTH TOKEN), once you are logged in, on your Twilio account (dashboard).

We then build the value for the api-url: variable by joining Twilio's API specific strings and the content of twilio-account-sid:, then casting the result to a url! data type.

The auth-string: is built by Base64 encoding of twilio-account-sid ":" twilio-auth-token.

Next, we define a function send-message: does, this function is executed when we press the "Send" button on the interface. The function contains code that makes a POST request to Twilio, sending the authentication values as well as values extracted from the "To (phone number):" and "Message:" fields.

The code inside view [...] builds the interface and really is self-explanatory.

The moment of truth: build, run and test

  • in your Terminal, from inside the red folder run ./red -r -t macOS twilio-sms.red
  • if you're on Windows run red.bat -r -t Windows twilio-sms.red

On macOS a twilio-sms.app will be created, on Windows a twilio-sms.exe will be created. Double-click on the executable to launch the application.

A nice thing about the Red compiler is that we can cross-compile. We can build the app for other operating systems if we change the argument of the -t (target) flag, like

  • ./red -r -t Windows twilio-sms.red to build for Windows on macOS and
  • red.bat -r -t macOS twilio-sms.red to build for macOS on Windows.

So, there you have it, we just built a cross-platform, portable, no dependencies small in size (~1MB), GUI application that we can use to send messages via Twilio.

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