# Log

All log objects generated by the inputs and entering the pipeline must be [immutable maps](https://facebook.github.io/immutable-js/) which follow this specification.

## Log object

| Attribute | Type | Required? | Description                |
| --------- | ---- | --------- | -------------------------- |
| request   | Map  | yes       | A request map (see below)  |
| response  | Map  | yes       | A response map (see below) |

## Request object

| Attribute        | Type   | Required? | Description                                                                                    |
| ---------------- | ------ | --------- | ---------------------------------------------------------------------------------------------- |
| time             | string | yes       | When the web server received the request ([ISO-8601](https://en.wikipedia.org/wiki/ISO_8601)). |
| address          | string | yes       | IPv4 or IPv6 address (dotted notation)                                                         |
| method           | string | yes       | HTTP Method in uppercase: `"HEAD"`, `"GET"`, `"POST"`, ...                                     |
| url              | string | yes       | The relative URL (path + query string)                                                         |
| headers          | Map    | yes       | A collection of HTTP headers (string -> string)                                                |
| scheme           | string | no        | `"http"` or `"https"`                                                                          |
| protocol         | string | no        | `"HTTP/1.0"`, `"HTTP/1.1"`, or `"HTTP/2"`                                                      |
| port             | int    | no        | Default to `80` for `"http"` scheme and `443` for `"https"` scheme                             |
| captured_headers | array  | no        | List of headers the input had access to.                                                       |

**Note on `captured_headers`**

Ideally, the log clients forward all the HTTP headers and `captured_headers` does not need to be used.

However, when not all the headers are available, like in an `access.log` file for example, the client should indicate the list of headers that it has access to by listing their names in `captured_headers`.

This is useful for the pipeline to know whether a header is missing because it was not sent by the website visitor or because it was not available in the logs.

For example:

```javascript
{
  request: {
    captured_headers: ['user-agent', 'referer'],
  }
}
```

**Note on `headers`**

The name of the header must be lower-cased.

## Response object

| Attribute | Type    | Required? | Description                           |
| --------- | ------- | --------- | ------------------------------------- |
| status    | integer | yes       | The HTTP status code for the response |