# The default hello world app

In the terminal window, go to your folder of choice or create a new one, for example **c:\vibeprojects**. Inside that folder, type the command

**dub init hello --type=vibe.d**

or

**dub init hello -t vibe.d**

And press **Enter** at every prompt that follows to accept the defaults.

```
c:\vibeprojects>dub init hello -t vibe.d
Package recipe format (sdl/json) [json]:
Name [hello]:
Description [A simple vibe.d server application.]:
Author name [Owner]:
License [proprietary]:
Copyright string [Copyright © 2023, Owner]:
Add dependency (leave empty to skip) []:
     Success created empty project in c:\vibeprojects\hello
             Package successfully created in hello
```

Go inside the newly created hello project folder and explore it.

```
c:\vibeprojects>cd hello
c:\vibeprojects\hello>dir
 Volume in drive C has no label.
 Volume Serial Number is 4E0A-BFEF
 Directory of c:\vibeprojects\hello
2023-01-04  01:30 PM    <DIR>          .
2023-01-04  01:30 PM    <DIR>          ..
2023-01-04  01:30 PM               131 .gitignore
2023-01-04  01:30 PM               215 dub.json
2023-01-04  01:30 PM    <DIR>          public
2023-01-04  01:30 PM    <DIR>          source
2023-01-04  01:30 PM    <DIR>          views
               2 File(s)            346 bytes
               5 Dir(s)  134,991,044,608 bytes free
```

You are now inside the root directory of the hello application. To compile and run this application in one step (you haven’t done anything yet!), type

**dub**

Since this is the first time you will be running this command, this will download all the dependencies, then compile, then link, and then run the application.

*c:\vibeprojects\hello>***dub**

There will be a lot of messages before you see this at the tail end:

```
     Linking hello
             Copying files for vibe-d:tls...
     Running hello.exe
[main(----) INF] Listening for requests on http://[::1]:8080/
[main(----) INF] Listening for requests on http://127.0.0.1:8080/
[main(----) INF] Please open http://127.0.0.1:8080/ in your browser.
```

The last three lines indicate that the application has successfully compiled and the server is now running.

Open your browser and point it to localhost, port 8080.

[http://127.0.0.1:8080](https://www.google.com/url?q=http://127.0.0.1:8080/\&sa=D\&source=editors\&ust=1676218018092712\&usg=AOvVaw0Md_Ifsolo71nWwXe2RnQN)&#x20;

or

[http://localhost:8080](https://www.google.com/url?q=http://localhost:8080/\&sa=D\&source=editors\&ust=1676218018093592\&usg=AOvVaw1YnTEfdHOzE3T2BB_4X1iT)

and you will see the ‘Hello, World!’ message in your browser.

<figure><img src="https://3936448450-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjGPCKHCWMHsDLNzX2hV8%2Fuploads%2F6wUJnVgA0FpCS4jr9vJp%2Fimage118.png?alt=media&#x26;token=5e8e501e-5996-44cd-8713-a1b2e087826c" alt=""><figcaption></figcaption></figure>

To stop the running application, press **Ctrl-C** (Control-C) on the terminal window. Sometimes you have to do it twice.

```
[00000000(----) INF] Received signal 2. Shutting down.
[main(----) INF] Stopped to listen for HTTP requests on ::1:8080
[main(----) INF] Stopped to listen for HTTP requests on 127.0.0.1:8080
^C
c:\vibeprojects\hello>
```

The common command options for **dub** are

dub init         - create a new project

dub run        - build and run combined

dub                - same as dub run

dub build       - completely compile the whole project and its dependencies but don’t run

dub test        - runs the unit tests

Let us take a closer look at the default application.

Open VS Code and go to *File->Open folder…*&#x20;

<figure><img src="https://3936448450-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjGPCKHCWMHsDLNzX2hV8%2Fuploads%2FYs5bTtyT0TFzqkdVGDB1%2Fimage124.png?alt=media&#x26;token=34fc3e77-5b07-495b-848d-839272c4683f" alt=""><figcaption></figcaption></figure>

Then open the new application folder **hello**.

<figure><img src="https://3936448450-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjGPCKHCWMHsDLNzX2hV8%2Fuploads%2FZnfssoMGCLpXbpw7UJg0%2Fimage122.png?alt=media&#x26;token=e3487527-a8cc-425c-9d2e-08586120dd9a" alt=""><figcaption></figcaption></figure>

In the Explorer window of VS Code, open **source\app.d** and you will see the automatically generated code.

<figure><img src="https://3936448450-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FjGPCKHCWMHsDLNzX2hV8%2Fuploads%2FrTsHPlMLV6H1gMQBkxIQ%2Fimage.png?alt=media&#x26;token=319bd385-0e79-49eb-9983-51028442007d" alt=""><figcaption></figcaption></figure>

```d
import vibe.vibe;
void main()
{
  auto settings = new HTTPServerSettings;
  settings.port = 8080;
  settings.bindAddresses = ["::1", "127.0.0.1"];
  auto listener = listenHTTP(settings, &hello);
  scope (exit)
  {
    listener.stopListening();
  }
  logInfo("Please open http://127.0.0.1:8080/ in your browser.");
  runApplication();
}
void hello(HTTPServerRequest req, HTTPServerResponse res)
{
  res.writeBody("Hello, World!");
}
```

In the **main()** method of **source\app.d**:

* a new HTTPServerSettings object is created
* the HTTP port number is set to 8080 (which you can change)
* the IP the server listens to is set to localhost in both IPv6 (“::1”) and IPv4 (“127.0.0.1”) format
* the listenHTTP(settings, \&hello) call means ‘run the hello() function using these settings’
* the runApplication() call starts the ball rolling (starts the event loop)


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