# Creating an appointment reminder app with Node SDK

## Set up your Node.js application

First, we'll create the project folder and add a simple directory structure.

1. Navigate to the directory in which you'd like to store your project.
2. Create a folder called `sinch-appointment-reminder`.
3. Create the following directory structure:

```shell
sinch-appointment-reminder
│   .env
│   app.js
│   routes.js
│
├───public
│   └───css
│           style.css
│
└───views
        patient_details.html
        success.html
```
You'll learn what each of the files and folders does as you progress through the tutorial.
4. Make sure you're at the top level of  `sinch-appointment-reminder`, open a terminal or command prompt, and run the following command:

```shell
npm init
```
This command creates the Node.js project and adds the `package.json` file. You will be prompted to provide values for the fields. For this tutorial, you can simply accept the default values and press enter at each stage.


### Dependencies

This application requires a number of node modules to function.

1. Open your project's `package.json` file.
2. Add the following:

```json
"dependencies": {
    "@sinch/sdk-core": "",
    "connect-flash": "",
    "dotenv": "",
    "ejs": "",
    "express": "",
    "express-session": "",
    "luxon": "",
    "sessionstorage-for-nodejs": ""
  },
  "devDependencies": {
    "nodemon": "^3.1.0"
      }
```
3. Install the dependencies with the command:

```shell
npm install
```


Let's look at how these modules will help our application.

- `@sinch/sdk-core` is the Node SDK itself. It enables the app to send an SMS when an appointment is entered.
- `dotenv` lets your app load configuration settings from environment variables so they don't have to be hardcoded.
- `ejs` and `connect-flash` control the appearence of your application, as well as giving it the ability to display error messages.
- The final dependency is called `nodemon`. This isn't essential to create the app, but will be very helpful for testing it. `nodemon` lets you make changes to your app while it's running, just as you would with React.


### Client information

When using the SDK, you must initialize the client.

Before initializing a client using this SDK, you'll need three pieces of information:

- Your Project ID
- An access key ID
- An access key Secret


These values can be found on the [<b>Access Keys</b>](https://dashboard.sinch.com/settings/access-keys) page of the Sinch Build Dashboard. You can also [create new access key IDs and Secrets](https://community.sinch.com/t5/Conversation-API/How-to-get-your-access-key-for-Conversation-API/ta-p/8120), if required.

Note
If you have trouble accessing the above link, ensure that you have gained access to the [Conversation API](https://dashboard.sinch.com/convapi/overview) by accepting the corresponding terms and conditions.

You'll add these values to the file described in the next section (along with others).

### Adding the environment variables

Your app stores information, such as your Sinch credentials, as environment variables in the `.env` file.  This is much more flexible and secure than simply hardcoding them.



1. Open the `.env` file.
2. Paste the following text into the `.env` file:

```.plaintext
KEY_ID='YOUR_key_id'
KEY_SECRET='YOUR_key_secret'
PROJECT_ID='YOUR_project_id'
DEBUG=True
COUNTRY_CODE_EU='YOUR_EU_country_code'
COUNTRY_CODE_US='+1'
FROM_NUMBER='YOUR_sinch_number'
SMS_REGION='YOUR_sms_region(us/eu)'
```
3. Populate the fields in the file with your own values. Refer to the table below for guidance:
| Field | Description |
|  --- | --- |
| `KEY_ID` | Your access key ID, used for authentication. Refer to the [Client information](#client-information) section for more information. |
| `KEY_SECRET` | Your access key secret, used for authentication. Refer to the [Client information](#client-information) section for more information. |
| `PROJECT_ID` | Your project ID. Refer to the [Client information](#client-information) section for more information. |
| `DEBUG` | Set to `True` to enable debugging. |
| `COUNTRY_CODE_EU` | If you live in the EU or UK, this is the country code of your home country. For example the UK country code is `+44`. |
| `COUNTRY_CODE_US` | If you live in the US, this is the country code of your home country. For the US, it's `+1`. |
| `FROM_NUMBER` | Any number you've assigned to your Sinch account. Find the number on your Customer [Dashboard](https://dashboard.sinch.com/sms/api/rest) by clicking the service plan ID link and scrolling to the bottom of the page. |
| `SMS_REGION` | The region in which you would like to send SMS messages. Either `us` or `eu`. |


### Setting up your application entry point

`app.js` defines the entry point for your application. This file is a keystone of all Node.js applications, playing a couple of important roles:

- It acts like a starter motor, starting up the server that runs your application on a given port.
- It tells your app which components it needs to use.


Open `app.js` and add the following code:


```javascript
const express = require("express");
const app = express();
const session = require("express-session");
const flash = require("connect-flash");
const routes = require("./routes");
app.use(express.static(__dirname + "/public"));
app.use(express.urlencoded({ extended: false }));
app.use(
  session({
    secret: "secret key",
    resave: false,
    saveUninitialized: false,
  })
);

app.use(flash());
app.use(routes);
app.set("port", process.env.PORT || 3000);
app.engine("html", require("ejs").renderFile);
app.set("view engine", "html");

app.listen(app.get("port"), function () {
  console.log("server started on port " + app.get("port"));
});
```

Imagine that your application is like a company. The view engine that displays the web pages, the routing that controls the user journey, and the business logic that defines core functionality are like internal departments that work together to produce the right outcome. `app.js` defines the agenda that calls on each component to play their part.