Re: HTTP ping pong

Roedy Green wrote:

Over time I have been learning how browsers and servers talk to each
other.

It seems to work like this:

Hm, for a protocol as well-known as HTTP, there's no need to make
assumptions.

<http://en.wikipedia.org/wiki/HTTP>
<http://www.ietf.org/rfc/rfc2616.txt> HTTP/1.1
<http://www.w3.org/Protocols/HTTP/1.0/spec.html> HTTP/1.0

RFCs are *the* source of information on web technologies (protocols).

Your browsers sets a GET or POST.
The server responds with web page.
In the web page are a number of images.
This is the browser parsing the HTML, and downloading resources.

the browser then simultaneously sends some more get requests. I think
each one gets its own socket. data seems to flow back simultaneously
(interleaved packets).

Sometimes there is a redirect. I think it is normally up to the
browser to request the next leg and wait for the response. Other
times the server can handle the redirect itself and send something
with a note in the header where the new home is.

There are two flavours of redirect, temporary and permanent. Temporary
ones are used for load balancing, redirecting to a backup server etc.
Permanent ones the server wants to you note, and use the new URL
instead. Temporary redirects will likely soon point nowhere.

There are a couple of things I have not yet figured out.

1. If I login for example sometimes I see a page on the browser, then
that page is replaced by another page a few seconds like. I did not
touch the keyboard. What happened?

Like Mark said, it's a header line with a time out.

2. Does the sever ever send more than one response to the same
request?

3. How do popups work. How can a server send you something you did not
request?
You requested the HTML, which tells the browser to do a popup. Some
browsers allow the user to deny such actions.

4. At the Java HTTP level, does do you know when you have hit the end
of the data? an EOF exception or something else?

See the RFC linked above.

As you might guess, I am feeling an urge to write a little essay
called HTTP ping pong.

<http://www.jmarshall.com/easy/http/>

Also note the difference between HTTP headers and HTML headers.
.

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