Does HTTP response "200 OK" give a guarantee that the document has been received by the machine who generated the HTTP request?
Solution 1:
Does the HTTP 200 code also work as an acknowledgment that document has been received?
No. Not at all.
It is not even a guarantee that the document was completely transmitted.
The response code is in the first line of the response stream. The server could fail, or be disconnected from the client anywhere between sending the first line and the last byte of the response. The server may not even know this has happened.
In fact, there is no way that the server can know if the client received a complete (or partial) HTTP response. There is no provision for an acknowledgment in the HTTP protocol.
Now you could implement an application protocol over the top of HTTP in which the client is required to send a second HTTP request to the server to say "yes, I got the document". But this would involve some "application logic" implemented in the user's browser; e.g. in Javascript.
Solution 2:
Absolutely not. HTTP 200 is generated by the server, and only means that it understood the request and thinks it is able to fulfill it (e.g. the file is actually there). All sorts of errors may occur during the transmission of the full response document (network connection breaking, packet loss, etc) which will not show up in the HTTP response, but need to be detected separately.
Solution 3:
A pretty good guide to the HTTP protocol is found here: http://blog.catchpoint.com/2010/09/17/anatomyhttp/
You should make a distinction between the HTTP protocol and the underlying stream transport protocol, which should be reliable for HTTP purposes. The stream transport protocol will ACKnowledge all data transmission, including the response, so that both ends of exchange will affirm that the data is transmitted correctly. If the transport stream fails, then you will get a 'network failure' or similar error. When this happens, the HTTP protocol cannot continue; the data is no longer reliable or even complete.
What a 200 OK message means, at the HTTP level, is that the server has the document you're after and is about to transmit it to you. Normally you will get a content-length header as well, so you will be able to ascertain if/when the body is complete as an additional check on top of the stream protocol. From the HTTP protocol perspective, a response receives no acknowledgement, so once a response has been sent there is no verification.
However, as the stream transport is reliable, the act of sending the response will either be successful or result in an error. This does verify whether the document has been received by the network target (as noted by TripeHound, in the case of non-direct connection, e.g. a proxy, this is not a guarantee of delivery to the final target).