Create subdomains on the fly with .htaccess (PHP)

Question 1

I am looking to create a system which on signup will create a subdomain on my website for the users account area.

e.g. johndoe.website.com

I think it would be something to do with the .htaccess file and possibly redirecting to another location on the website? I don't actually know. But any information to start me off would be greatly appreciated.

Creating a sign up area is not the problem - I have done this many a time. I am just unsure where to start with the subdomain.

Question 2

The quick rundown

You need to create a wildcard domain on your DNS server *.website.com
Then in your vhost container you will need to specify the wildcard as well *.website.com - This is done in the ServerAlias ^DOCs
Then extract and verify the subdomain in PHP and display the appropriate data

The long version

1. Create a wildcard DNS entry

In your DNS settings you need to create a wildcard domain entry such as *.example.org. A wildcard entry looks like this:

*.example.org.   3600  A  127.0.0.1

2. Include the wildcard in vhost

Next up in the Apache configuration you need to set up a vhost container that specifies the wildcard in the ServerAlias ^DOCs directive. An example vhost container:

<VirtualHost *:80>
  ServerName server.example.org
  ServerAlias *.example.org
  UseCanonicalName Off
</VirtualHost>

3. Work out which subdomain you are on in PHP

Then in your PHP scripts you can find out the domain by looking in the $_SERVER super global variable. Here is an example of grabbing the subdomain in PHP:

preg_match('/([^.]+).example.org/', $_SERVER['SERVER_NAME'], $matches);
if(isset($matches[1])) {
    $subdomain = $matches[1];
}

I have used regex here to to allow for people hitting your site via www.subdomain.example.org or subdomain.example.org.

If you never anticipate having to deal with www. (or other subdomains) then you could simply use a substring like so:

$subdomain = substr(
                 $_SERVER['SERVER_NAME'], 0,
                 strpos($_SERVER['SERVER_NAME'], '.')
             );

Mass Virtual Hosting

Mass virtual hosting is a slightly different scheme to the above in that you would usually use it to host many distinct websites rather than attempting to use it power an application as the question proposes.

I have documented my mod_rewrite based mass virtual hosting environment before in a post on my blog, which you could look at if that is the route you wish to take. There is also, of course, the respective Apache manual page.

Apache also has an internal way of dealing with mass virtual hosting that is slightly less flexible than the mod_rewrite method I have used. This is all described on the Apache Dynamically Configured Mass Virtual Hosting manual page.

Question 3

Save thumbnails to disk. Image processing takes a lot of resources and, depending on the size of the image, might exceed the default allowed memory limit for php. It is less of a concern if you have your own server with only your application running but it still takes a lot of cpu power and memory to resize images. If you're considering creating thumbnails on the fly anyway, you don't have to change much - upon the first request, create the thumbnail from the source file, save it to disk and upon subsequent requests just read it off the disk.

Question 4

The htaccess file should look something like this:

RewriteCond %{HTTP_HOST} !^(www.)?domain.co.uk$ [NC]
RewriteCond %{HTTP_HOST} ^([^.]+).
RewriteCond %{REQUEST_URI}::%1 !^/([^/]*)/?(.*)::1
RewriteRule ^(.*)$ /%1/$1 [L]

Question 5

Using mod_rewrite, you can try:

RewriteEngine On

# the request URI doesn't already start with /users/
RewriteCond %{REQUEST_URI} !^/users/

# host doesn't start with www
RewriteCond %{HTTP_HOST} !^www.  [NC]

# host starts with something else
RewriteCond %{HTTP_HOST} ^([^.]+).mywebsite.com$  [NC]

# rewrite
RewriteRule ^(.*)$ /users/%1/$1  [L]

This will make it so when someone enters http://joe.mywebsite.com/some/page.html they will be served the file in /users/joe/some/page.html

Question 6

You should definitely use GraphAdapterBuilder.

As you said in the comment under @Braj 's answer,

workshift is set transient for a reason so that it won't serialize this object when serializing visit object. If its not marked as transient then the serialization falls into exception - by creating an unstoppable loop

This has a simple solution.

Workshift.java

public class Workshift {
    private final transient Context context;
    private final Visit visit;
    //for testing
    private String workshift_description;

    public Workshift(Context context,String id) {
        this.workshift_description=id;
        this.context = context;
        this.visit = new Visit(this);

    }
    public String getId() {
        return workshift_description;
    }

    public void setId(String id) {
        this.workshift_description = id;
    }
    public String toString() {
        return "[Workshift element => { WD: "+this.workshift_description+", VD : "+this.visit.getVisit_description()+"}";
    }
}

Visit.java

public class Visit {

    private final /* transient  */ Workshift workshift;

    public Visit(Workshift ws) {
        this.workshift = ws;

    }
    public String getVisit_description() {
        return "visit containing  "+ workshift.getId();
    }

}

The trick resides here:

GsonBuilder gsonBuilder = new GsonBuilder();
        new GraphAdapterBuilder()
        .addType(Visit.class)
        .addType(Workshift.class)
        .registerOn(gsonBuilder);

Putting all together,

public static void main(String[] args) {

        Workshift[] workshifts = new Workshift[10];
        for (int i = 0; i < workshifts.length; i++) {
            //Replace Context(i) for the real one
            workshifts[i] = new Workshift(new Context(i), "Workshift#"
                    + i);
        }
        System.out.println("Original Workshifts array:");
        for (int i = 0; i < workshifts.length; i++) {
            System.out.println(workshifts[i]);
        }
        System.out.println("===================================");

        GsonBuilder gsonBuilder = new GsonBuilder();
        new GraphAdapterBuilder()
        .addType(Visit.class)
        .addType(Workshift.class)
        .registerOn(gsonBuilder);

        Gson gson = gsonBuilder.setPrettyPrinting().create();
        String serialized = gson.toJson(workshifts);
        // System.out.println(serialized);
        Workshift[] w_array = gson.fromJson(serialized, Workshift[].class);
        // System.out.println(gson.toJson(w_array));

        System.out.println("Des-serialized Workshifts array:");
        for (int i = 0; i < w_array.length; i++) {
            System.out.println(w_array[i]);
        }
        System.out.println("===================================");

Output:

Original Workshifts array:
[Workshift element => { WD: Workshift#0, VD : visit containing  Workshift#0}
[Workshift element => { WD: Workshift#1, VD : visit containing  Workshift#1}
[Workshift element => { WD: Workshift#2, VD : visit containing  Workshift#2}
[Workshift element => { WD: Workshift#3, VD : visit containing  Workshift#3}
[Workshift element => { WD: Workshift#4, VD : visit containing  Workshift#4}
[Workshift element => { WD: Workshift#5, VD : visit containing  Workshift#5}
[Workshift element => { WD: Workshift#6, VD : visit containing  Workshift#6}
[Workshift element => { WD: Workshift#7, VD : visit containing  Workshift#7}
[Workshift element => { WD: Workshift#8, VD : visit containing  Workshift#8}
[Workshift element => { WD: Workshift#9, VD : visit containing  Workshift#9}
===================================
Des-serialized Workshifts array:
[Workshift element => { WD: Workshift#0, VD : visit containing  Workshift#0}
[Workshift element => { WD: Workshift#1, VD : visit containing  Workshift#1}
[Workshift element => { WD: Workshift#2, VD : visit containing  Workshift#2}
[Workshift element => { WD: Workshift#3, VD : visit containing  Workshift#3}
[Workshift element => { WD: Workshift#4, VD : visit containing  Workshift#4}
[Workshift element => { WD: Workshift#5, VD : visit containing  Workshift#5}
[Workshift element => { WD: Workshift#6, VD : visit containing  Workshift#6}
[Workshift element => { WD: Workshift#7, VD : visit containing  Workshift#7}
[Workshift element => { WD: Workshift#8, VD : visit containing  Workshift#8}
[Workshift element => { WD: Workshift#9, VD : visit containing  Workshift#9}
===================================

There's no error.

if you un-comment the line

// System.out.println(serialized);

The output would be like this:

[
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#0"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#1"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#2"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#3"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#4"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#5"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#6"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#7"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#8"
    },
    "0x2": {
      "workshift": "0x1"
    }
  },
  {
    "0x1": {
      "visit": "0x2",
      "workshift_description": "Workshift#9"
    },
    "0x2": {
      "workshift": "0x1"
    }
  }

]

That's because Gson is replacing your references, in order to avoid that exception. It's like emulating pointers

Hope it helps.

Note: Remember to copy the files GraphAdapterBuilder.java and change the line

private final ConstructorConstructor constructorConstructor = new ConstructorConstructor();

with

private final ConstructorConstructor constructorConstructor = new ConstructorConstructor(instanceCreators);

It won't compile otherwise. Maybe it's fixed right now.