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From Matt Goodall <matt.good...@gmail.com>
Subject _changes line breaks (was Re: _changes resource)
Date Tue, 07 Jul 2009 13:12:02 GMT
Splitting the discussion of line breaks in the _changes document into
separate email thread ...

2009/7/6 Chris Anderson <jchris@apache.org>:
> On Mon, Jul 6, 2009 at 5:50 AM, Matt Goodall<matt.goodall@gmail.com> wrote:

>> == Line Breaks ==
>>
>> If each results item is sent with its ending newline (the "," is sent
>> with the next item) it would make clients much easier and correct to
>> write, i.e. buffer bytes until a newline is received, split the
>> buffer, process the row, repeat. You've still got to remove the ","
>> from all but the first line but it's in a predictable place. Actually,
>> I don't believe TCP provides any guarantees that bytes sent are
>> received in the same chunks so relying on anything other than the
>> newline is probably flawed.
>>
>> It's a trivial change, patch attached.
>
> There's a certain elegance to the current system. So far I've been
> testing in the browser and it works fine. If there's demonstrated
> problems for a client then we shouldn't hesitate to change it.

Agreed, a comma at the end of the line is much prettier.

The 'changes' tests are very unlikely to highlight any problem because
there's such a small amount of data being sent (well below the MTU of
the network device) and a sleep(100) is almost certainly enough to
allow the data to arrive in the browser. If the tests caused lots of
data to be sent and the browser was listening for data using a
onreadystatechange callback we may be lucky enough to hit the problem.
However, "almost" and "may" are not good words when it comes to
testing ;-).

Anyway, from experience I believe the only way to prove this is to
explicitly have the bytes arrive slowly so, when I get a couple of
minutes, I'll write something simple that will hopefully demonstrate
the value of the newline terminator.

- Matt

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