# Hosting Only

For the purposes of the service, the client instructs Sirdata to modify the headers of incoming HTTP requests to add additional parameters, specifically : 

<table><thead><tr><th width="210">Header</th><th width="193">Definition</th><th width="247">Possible Values</th><th>Example</th></tr></thead><tbody><tr><td>X-Appengine-City</td><td>User's Connection City</td><td>string</td><td>Paris</td></tr><tr><td>X-Appengine-Country</td><td>User's Connection Country</td><td>ISO 3166-1 alpha-2 country code</td><td>FR</td></tr><tr><td>X-Appengine-Region</td><td>User's Connection Region</td><td>ISO 3166-2 region code</td><td>IDF</td></tr><tr><td>X-Appengine-User-Ip</td><td>User's Connection IP Address</td><td>Adresse IP</td><td>1.1.1.1</td></tr></tbody></table>

To support the service, the client instructs Sirdata to modify the headers of incoming HTTP requests to remove or replace HTTP request headers when necessary, particularly (an asterisk "\*" indicates any string starting with the preceding characters):

* **X-Forwarded-For** : a comma-separated list of IP addresses, including the IP address of the request's origin and those through which the HTTP request was routed
* **X-Forwarded-Proto** : displays "http" or "https" depending on the protocol used by the client to connect to your application
* **X-**\*
* **Bunny**\*
* **Via**
* **Accept-Encoding**
* **Connection**
* **Keep-Alive**
* **Proxy-Authorization**
* **TE**
* **Trailer**
* **Transfer-Encoding**

To support the service, the client instructs Sirdata to modify the response headers for HTTP requests to add, remove, or replace parameters when necessary, particularly :

* **Cache-Control, Pragma, Expires, and Vary (**&#x73;pecify caching strategies)
* **Connection**
* **Content-Encoding (**&#x63;ompression used for the response, if any)
* **Content-Length**
* **Keep-Alive**
* **Proxy-Authenticate**
* **Server**
* **Alt-Svc**
* **Via**
* **Trailer**
* **Transfer-Encoding**
* **Upgrade**
* **Etag**
* **Age**