How to send custom HTTP header in response?

The problem is that some of your $_GET variables aren't set, this will throw an error (the extra output text you have) and can be prevent by checking if they are empty first before using them.

$request = array(    'request' => !empty($_GET['request']) ? $_GET['request'] : '',    'device_id' => !empty($_GET['device_id']) ? $_GET['device_id'] : '',    'launch_date'=> !empty($_GET['launch_date']) ? $_GET['launch_date'] : '',    'allowed_hours'=> !empty($_GET['allowed_hours']) ? $_GET['allowed_hours'] : '',    'site_id'=> !empty($_GET['site_id']) ? $_GET['site_id'] : '',    'product'=> !empty($_GET['product']) ? $_GET['product'] : '',    'software_version'=> !empty($_GET['software_version']) ? $_GET['software_version'] : '',    'platform_os'=> !empty($_GET['platform_os']) ? $_GET['platform_os'] : '',    'platform'=> !empty($_GET['platform']) ? $_GET['platform'] : '',    'platform_model'=> !empty($_GET['platform_model']) ? $_GET['platform_model'] : '');$response = array(    'response_code' =>200 ,    'device_id'=> !empty($_GET['device_id']) ? $_GET['device_id'] : '',    'allowed_hours'=> !empty($_GET['allowed_hours']) ? $_GET['allowed_hours'] : '',    'product'=>'mlc',    'prov_ur'=>NULL );header('Content-Type: application/json');echo json_encode( $response );

Using the normal php get like below will sometimes throw some errors

$_GET['allowed_hours'];

I would recommend change to codeIgniter input class methods.

$this->input->get('allowed_hours');

Codeigniter Input Class will save you putting lot of code.

As said in user guide: With CodeIgniter’s built in methods you can simply do this:

Updated:

$request = array(   'request' => $this->input->get('request'),   'device_id' => $this->input->get('device_id'),   'launch_date'=> $this->input->get('launch_date'),   'allowed_hours'=> $this->input->get('allowed_hours'),   'site_id'=> $this->input->get('site_id'),   'product'=>$this->input->get('product'),   'software_version'=> $this->input->get('software_version'),   'platform_os'=> $this->input->get('platform_os'),   'platform'=> $this->input->get('platform'),   'platform_model'=> $this->input->get('platform_model'));

Codeigniter has own Output Class

And

$response = array(    'response_code' => 200,    'device_id'=> $this->input->get('device_id'),    'allowed_hours'=> $this->input->get('allowed_hours'),    'product'=> 'mlc',    'prov_ur'=> NULL );return $this->output      ->set_content_type('Content-Type: application/json')      ->set_output(json_encode($response));