[whatwg] Issues with Web Sockets API
michaeln at google.com
Fri Jun 26 13:52:44 PDT 2009
Does disconnect() attempt to flush pending messages or drop them?
There isn't a way to determine if the WebSocket is successfully sending the
postMessage data? For all the caller knows, its just backing up and not
Something that might add value is an onmessagesent event that fires after a
postMessage has put the bits on the wire.
postMessage() may want another exception condition... 'too much data pending
exception'... consider calling postMessage in a while(true) loop... at some
point the system is going to have to give up queing the data if its
not actually making its way out on the wire.
On Fri, Jun 26, 2009 at 1:19 PM, Kelly Norton <knorton at google.com> wrote:
> Oh and one more thing:
> Doesn't it seem strange that disconnect() causes an onclose event to be
> dispatched? Should the method not be close() to be consistent with open(),
> onopen, onclose?
> On Fri, Jun 26, 2009 at 4:14 PM, Kelly Norton <knorton at google.com> wrote:
>> One thing about postMessage that I'm curious about. Since it has to report
>> failure synchronously by throwing an INVALID_STATE_ERR, that seems to imply
>> that all data must be written to a socket before returning and cannot be
>> asynchronously delivered to an I/O thread without adding some risk of
>> silently dropping
>> messages. Seems like the right choice would be to allow outbound messages to drop, which would mean that developers would be forced to do their own handshaking.
>> I'm also not sure there is good coverage of error conditions in the spec.
>> The only methods of error notification are exceptions in postMessage and
>> onclose. I had assumed that a WebSocket that fails to connect would invoke
>> onclose asynchronously, but I didn't see that in the spec. Without that you
>> don't even have the ability to know if a socket failed to establish a
>> connection (short of readyState polling). The spec also doesn't indicate
>> that the readyState should transition to CLOSED on connection failure.
>> (Description of the disconnect() method is careful to mention that it closes
>> a connection or a connection attempt, but description of when onclose is
>> fired just mentions a connection closing). I definitely think there should
>> be a way to receive an event if a connection fails to establish; I would
>> hate to have to poll another readyState.
>> On Fri, Jun 26, 2009 at 1:34 PM, Drew Wilson <atwilson at google.com> wrote:
>>> Yes, but the "closed" state of a given WebSocket doesn't have to exactly
>>> match the state of the underlying TCP connection, in the same way that
>>> document.cookies doesn't exactly match the current set of cookies that the
>>> network stack may be tracking (they can differ when HTTP responses are
>>> received in the background while JS is executing).
>>> So if the remote server closes the TCP connection, it generates a "close"
>>> event which marks the WebSocket as closed. It means that you could have a
>>> situation where you post messages to a WebSocket which aren't received by
>>> the server because the connection is closed, but that's true regardless due
>>> to the asynchronous nature of the networking protocol.
>>> On Fri, Jun 26, 2009 at 9:52 AM, Darin Fisher <darin at chromium.org>wrote:
>>>> On Fri, Jun 26, 2009 at 9:46 AM, Drew Wilson <atwilson at google.com>wrote:
>>>>> On Fri, Jun 26, 2009 at 9:18 AM, James Robinson <jamesr at google.com>wrote:
>>>>>> However, users can't usefully check the readyState to see if the
>>>>>> WebSocket is still open because there are not and cannot be any
>>>>>> synchronization guarantees about when the WebSocket may close.
>>>>> Is this true? Based on our prior discussion surrounding cookies, it
>>>>> seems like as a general rule we try to keep state from changing dynamically
>>>>> while JS code is executing for exactly these reasons.
>>>> I think this is a very different beast. The state of a network
>>>> connection may change asynchronously whether we like it or not. Unlike
>>>> "who" may access cookies or local storage, the state of the network
>>>> connection is not something we solely control.
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> If you received this communication by mistake, you are entitled to one free
> ice cream cone on me. Simply print out this email including all relevant
> SMTP headers and present them at my desk to claim your creamy treat. We'll
> have a laugh at my emailing incompetence, and play a game of ping pong.
> (offer may not be valid in all States).
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