# http

The `http` statement initiates an HTTP session using any settings previously configured using the [set](https://olddocs.exivity.io/3.5.4/data-pipelines/extract/language/set) statement. It can also be used for querying response headers.

## Syntax

**`http`***`method url`*

**`http dump_headers`**

**`http get_header`***`headerName`***`as`***`varName`*

## Details

### Executing an HTTP request

The `http` statement performs an HTTP request against the server and resource specified in the *url* paramater. Any http-related settings previously configured using [set](https://olddocs.exivity.io/3.5.4/data-pipelines/extract/language/set) will be applied to the request.

The *method* argument determines the HTTP method to use for the request and must be one of `GET`, `PUT`, `POST` or `DELETE`.

The *url* argument must start with either `http:` or `https:`. If `https:` is used then SSL will be used for the request.

The *url* argument must also contain a valid IP address or hostname. Optionally, it may also contain a port number (preceded by a colon and appended to the IP address or hostname) and a resource.

The following defaults apply if no port or resource is specified:

| Field      | Default                                     |
| ---------- | ------------------------------------------- |
| *port*     | `80` if using `http` `443` if using `https` |
| *resource* | `/`                                         |

The format of the `http` statement is identical when used in conjunction with the [buffer](https://olddocs.exivity.io/3.5.4/data-pipelines/extract/language/buffer) statement.

### Querying response headers

To dump a list of all the response headers returned by the server in the most recent session use the statement:

**`http dump_headers`**

This will render a list of the headers to standard output, and is useful when implementing and debugging USE scripts. The intention of this statement is to provide a tool to assist in script development, and as such it would normally be removed or suppressed with a debug mode switch in production environments.

To retrieve the value of a specific header, use the statement:

**`http get_header`***`headerName`***`as`***`varName`*

This will set the variable *varName* to be the value of the header *headerName*.

{% hint style="info" %}
If *headerName* was not found in the response, then a warning will be written to the log-file. In this case *varName* will not be created but if it already exists then its original value will be unmodified.
{% endhint %}

## Examples

### Example 1

```
# A simple request using the default port and no SSL
set http_savefile "/extracted/http/customers.json"
http GET "http://localhost/v1/customers"

# A more complex request requiring setup and a custom port
clear http_headers
set http_header "Accept: application/json"
set http_header "Authorization: FFDC-4567-AE53-1234"    
set http_savefile "extracted/http/customers.json"
buffer customers = http GET "https://demo.server.com:4444/v1/customers"
```

### Example 2

The following shows the process of retrieving a header. The output of:

```
buffer temp = http GET https://www.google.com
http dump_headers
http get_header Date as responseDate
print The Date header from google.com was: ${responseDate}
```

Takes the following form:

```
Last response headers:
HTTP/1.1 200 OK
Cache-Control: private, max-age=0
Date: Mon, 26 Mar 2018 13:50:39 GMT
Transfer-Encoding: chunked
Content-Type: text/html; charset=ISO-8859-1
Expires: -1
Accept-Ranges: none
P3P: CP="This is not a P3P policy! See g.co/p3phelp for more info."
Server: gws
Set-Cookie: 1P_JAR=2018-03-26-13; expires=Wed, 25-Apr-2018 13:50:39 GMT; path=/; domain=.google.co.uk
Set-Cookie: [redacted]; expires=Tue, 25-Sep-2018 13:50:39 GMT; path=/; domain=.google.co.uk; HttpOnly
Vary: Accept-Encoding
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Alt-Svc: hq=":443"; ma=2592000; quic=51303432; quic=51303431; quic=51303339; quic=51303335,quic=":443"; ma=2592000; v="42,41,39,35"

The Date header from google.com was: Mon, 26 Mar 2018 13:50:39 GMT
```