What does ajax GET data look like at the lowest level? - http

Question

GET requests can be used to retrieve images and text and other things I'm guessing. There is no need to specify Content-type.
What does this data look like at the bit level? If you are looking at the 1s and 0s in the HTTP packet, what specification governs what can be put here.
Using the client, when I send / receive data via ajax GET, is the data directly transferred into 1s and 0s in the packet or is there some sort of transformation?
For example:
xhr = new win.XMLHttpRequest();
xhr.open('GET', config_ajax.url, true);
xhr.onload = function () {
if (this.status === 200) {
config_ajax.callback(xhr.responseText);
}
};
xhr.send(send);
// example data
send = "0xFF";
xhr.responseText = "0x0A"
Would one see 11111111 being sent and 00001010 being received if they were analyzing the bit stream?

Answer 1

I guess there is no need to specify Content-type. What does this data look like at the bit level? If you are looking at the 1s and 0s in the HTTP packet, what specification governs what can be put here.
You're looking for the HTTP specification itself, section 7. Indeed it works quite like you assumed:
7 Entity
Request and Response messages MAY transfer an entity if not otherwise
restricted by the request method or response status code. An
entity consists of entity-header fields and an entity-body, although
some responses will only include the entity-headers.
In this section, both sender and recipient refer to either the client
or the server, depending on who sends and who receives the entity.
In this section, both sender and recipient refer to either the
client or the server, depending on who sends and who receives the
entity.
7.1 Entity Header Fields
Entity-header fields define metainformation about the entity-body
or, if no body is present, about the resource identified by the
request. Some of this metainformation is OPTIONAL; some might be
REQUIRED by portions of this specification.
entity-header = Allow ; Section 14.7
| Content-Encoding ; Section 14.11
| Content-Language ; Section 14.12
| Content-Length ; Section 14.13
| Content-Location ; Section 14.14
| Content-MD5 ; Section 14.15
| Content-Range ; Section 14.16
| Content-Type ; Section 14.17
| Expires ; Section 14.21
| Last-Modified ; Section 14.29
| extension-header
extension-header = message-header
The extension-header mechanism allows additional entity-header
fields to be defined without changing the protocol, but these
fields cannot be assumed to be recognizable by the recipient.
Unrecognized header fields SHOULD be ignored by the recipient and
MUST be forwarded by transparent proxies.
7.2 Entity Body
The entity-body (if any) sent with an HTTP request or response is
in a format and encoding defined by the entity-header fields.
entity-body = *OCTET
An entity-body is only present in a message when a message-body is
present, as described in section 4.3. The entity-body is obtained
from the message-body by decoding any Transfer-Encoding that might
have been applied to ensure safe and proper transfer of the message.
7.2.1 Type
When an entity-body is included with a message, the data type of
that body is determined via the header fields Content-Type and
Content- Encoding. These define a two-layer, ordered encoding
model:
entity-body := Content-Encoding( Content-Type( data ) )
Content-Type specifies the media type of the underlying data.
Content-Encoding may be used to indicate any additional content
codings applied to the data, usually for the purpose of data
compression, that are a property of the requested resource. There is
no default encoding.
Any HTTP/1.1 message containing an entity-body SHOULD include a
Content-Type header field defining the media type of that body. If
and only if the media type is not given by a Content-Type field, the
recipient MAY attempt to guess the media type via inspection of its
content and/or the name extension(s) of the URI used to identify the
resource. If the media type remains unknown, the recipient SHOULD
treat it as type "application/octet-stream".
7.2.2 Entity Length
The entity-length of a message is the length of the message-body
before any transfer-codings have been applied. Section 4.4 defines
how the transfer-length of a message-body is determined.