[IronPython] Silverlight and Catching HttpWebRequest Errors

[Michael Foord]

Michael Foord wrote:
> Michael Foord wrote:
>> On May 12, 9:17 am, Jimmy Schementi <Jimmy.Scheme... at microsoft.com>
>> wrote:
>>  
>>> The actual type returned by HttpWebRequest.Create() is a 
>>> BrowserHttpWebRequest, but it's internal (not sure why). Anyway, it 
>>> has a ProgressFailed event you can hook.
>>>     
>>
>> Hello Jimmy,
>>
>> As far as I can tell it *doesn't* have the 'ProgressFailed' event.
>>   
>
> The actual failure I see is:
>
> Exception: [Arg_COMException]
> Arguments:
> Debugging resource strings are unavailable. Often the key and 
> arguments provide sufficient information to diagnose the problem. See 
> http://go.microsoft.com/fwlink/?linkid=106663&Version=2.0.30226.1&File=mscorlib.dll&Key=Arg_COMException 
>
>
>

Sorry for the noise. This one is actually for the sake of google (and 
all who sail in her).

Exception
   at MS.Internal.XcpImports.GetDownloaderBytes(IntPtr element, IntPtr& 
outBytes, Int32& outSize)
   at MS.Internal.InternalWebRequest.GetResponseStream()
   at System.Net.BrowserHttpWebRequest.Completed(Object sender, EventArgs e)
   at System.Windows.CoreInvokeHandler.InvokeEventHandler(Int32 
typeIndex, Delegate handlerDelegate, Object sender, Object args)
   at MS.Internal.JoltHelper.FireEvent(IntPtr unmanagedObj, IntPtr 
unmanagedObjArgs, Int32 argsTypeIndex, String eventName)

Michael

> This is using Safari. As I'm developing on the Mac I can't use 
> debugging, nor can I test in Firefox because of the bug in Chiron.
>
> It looks like some people have similar errors:
>
>    http://silverlight.net/forums/p/12500/40967.aspx#40967
>
> and a guy in the comments here:
>
>    
> http://www.cameronalbert.com/post/2008/03/HttpWebRequest-Helper-for-Silverlight-2.aspx 
>
>
> All the best,
>
> Michael Foord
> http://www.ironpythoninaction.com/
>
>> I need to make cross-domain POST, and although the request gets made
>> successfully I'm getting a COM Arg Exception everytime (I think
>> because the server is slow to respond). This is screwing me at the
>> moment.
>>
>> FYI - when I execute the following code in Silverlight:
>>
>>   from System.Net import WebRequest
>>   from System import Uri
>>
>>   u = Uri('http://www.v.com')
>>   req = WebRequest.Create(u)
>>   print req.ProgressFailed
>>
>> I get the following exception:
>>
>> Traceback (most recent call last):
>>   File "None", line 6, in <undefined>
>> AttributeError: 'BrowserHttpWebRequest' object has no attribute
>> 'ProgressFailed'
>>
>> All the best,
>>
>> Michael Foord
>> http://www.ironpythoninaction.com/
>>
>>  
>>> PS. If you REALLY want synchronous downloading, just hack on 
>>> XMLHttpRequest
>>>
>>> def download(url):
>>>     request = HtmlPage.Window.CreateInstance("XMLHttpRequest")
>>>     request.Invoke("open", "GET", url, false) # false means synchronous
>>>     request.Invoke("send", "")
>>>     return request.GetProperty("responseText")
>>>
>>> :)
>>>
>>> ~js
>>> ________________________________________
>>> From: users-boun... at lists.ironpython.com 
>>> [users-boun... at lists.ironpython.com] On Behalf Of Michael Foord 
>>> [fuzzy... at voidspace.org.uk]
>>> Sent: Monday, May 12, 2008 12:58 AM
>>> To: Discussion of IronPython
>>> Subject: [IronPython] Silverlight and Catching HttpWebRequest Errors
>>>
>>> Hello guys,
>>>
>>> I have a problem with catching network errors raised by HttpWebRequest
>>> in Silverlight. (Not necessarily an IronPython specific question - but
>>> you guys are so intelligent you are always the first place I turn...)
>>>
>>> HttpWebRequest uses an async model for fetching resources. If there 
>>> is a
>>> problem (triggered usually by a slow response from the server), then it
>>> can happen *after* I have made the request - but before my callback is
>>> invoked. This gives me nowhere to catch the exception, as 
>>> effectively it
>>> happens 'inside Silverlight'. I wondered if there was a solution... ?
>>>
>>> def callback(asyncResult):
>>>     ...
>>>
>>> uri = Uri(some_url)
>>> req = HttpWebRequest.Create(uri)
>>>
>>> req.BeginGetResponse(AsyncCallback(callback), object())
>>>
>>> The error occurs after BeginGetResponse, but before calback. Any ideas
>>> for catching it?
>>>
>>> Michael Foordhttp://www.ironpythoninaction.com/
>>>
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>>>     
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