[whatwg] Issues with Web Sockets API
knorton at google.com
Fri Jun 26 13:19:23 PDT 2009
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(),
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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