There are obviously many possible causes of the network problems you're
experiencing (including bugs in the framework or even faulty hardware). All
I can say is that I have not experienced problems like that, nor I believe,
have the users of my applications.
Tom.
2008/11/24 joshv <[EMAIL PROTECTED]>
>
> I don't have any sniffing capabilities. The "no route to host" error
> would suggest that the attempt never leaves the phone, as the other
> devices on my network have no issues accessing the internet at the
> same time. This is by the way replicable on my access point at work,
> as well as at home, so it's not something in my access point - unless
> perhaps it's an issue with WPA. But I also see the same behavior when
> I have a strong 3G connection as well. On 3G I might expect a little
> bit of flakiness, though again, not 100% failure for minutes on end.
>
> On Nov 24, 2:01 pm, "Dorn Hetzel" <[EMAIL PROTECTED]> wrote:
> > If you sniff the wire just past the wifi access point, how many
> > requests/responses do you see during this time?
> >
> > On Mon, Nov 24, 2008 at 2:59 PM, joshv <[EMAIL PROTECTED]> wrote:
> >
> > > My issues is that I am sitting 3 feet from a stable wi-fi access point
> > > and for minutes on end every single URLConnection attempt will fail.
> > > I could certainly understand if maybe the first attempt failed, or
> > > took longer, because I was waiting for the radio to turn on, but 100%
> > > failure for minutes on end is just weird. There is no good reason for
> > > it. It should be considered a bug. And even when it does work, it's
> > > still not 100%, the failure rate is still very high.
> >
> > > This makes for a really crappy application experience, as I simply
> > > cannot predict when my user will see their data update. I feel like
> > > there are reliable ways of communicating, as even when my application
> > > is experiencing errors, I get emails and IMs on the phone, and I can
> > > browse the internet - so somehow the google apps are able to
> > > communicate. That's why I am asking if I am doing something wrong or
> > > if there is some other API I should try. I can try out the Apache
> > > HTTPComponents, but I am assuming they just wrap the lower level java
> > > network APIs. I am not sure what benefit I would get.
> >
> > > On Nov 24, 1:44 pm, "Tom Gibara" <[EMAIL PROTECTED]> wrote:
> > >> I don't know if this is related to what you're experiencing, but it's
> my
> > >> understanding that the wifi connections shuts down when the phone
> sleeps. I
> > >> believe this is because, unlike the radio, it requires the CPU to be
> active
> > >> to maintain the connection.
> > >> Also, contrary to your view, I think it's not intrinsically a hardware
> or
> > >> software problem. It's simply that in the context of mobile phone
> software,
> > >> the probability of a connection failure is greater than that you may
> be used
> > >> to, and due to the necessary limitations in powering the device,
> simple
> > >> solutions (like constantly striving to maintain a wifi connection)
> aren't an
> > >> option.
> >
> > >> Perhaps a better perspective is to see the various data connections
> (wifi,
> > >> GPRS, EDGE, 3G etc.) as fallible primitives which you can combine to
> form a
> > >> more reliable transport suited to your application's needs.
> >
> > >> Tom.
> >
> > >> 2008/11/24 joshv <[EMAIL PROTECTED]>
> >
> > >> > As I pointed out in my previous post, the polling occurs only when
> the
> > >> > application is active and on screen. It starts/stops in onResume/
> > >> > onPause - so I am not sure how this is going to limit battery life
> > >> > unless the user forces the application to remain active for hours at
> a
> > >> > time.
> >
> > >> > Could you please explain to me why, with a solid wi-fi signal and
> > >> > connection to a local access point, my URLConnections would ever
> throw
> > >> > an exception unless there is a problem with the remote website? Are
> > >> > the implementations of these APIs that brittle? Is the hardware
> > >> > really that flaky?
> >
> > >> > Are there other APIs that bang on the hardware until it works,
> without
> > >> > throwing exceptions? Am I doing something wrong? Or is this level
> of
> > >> > unreliability, even over local wi-fi, to be expected?
> >
> > >> > On Nov 24, 10:58 am, Jean-Baptiste Queru <[EMAIL PROTECTED]> wrote:
> > >> > > Even with a 10-second pause between the end of a response and the
> next
> > >> > > request, you're likely to keep the radio (either cell or wifi)
> turned
> > >> > > on all the time, since they tend to stay up for about that long
> even
> > >> > > when there's no activity before powering back down. That could
> limit
> > >> > > the phone's battery life to as little as 3 or 4 hours (with the
> screen
> > >> > > constantly off and the CPU idle most of the time).
> >
> > >> > > The APIs that you're using are built on top of a foundation that
> was
> > >> > > designed for environments where the conditions that trigger
> exceptions
> > >> > > were indeed more exceptional than what you're seeing on a device
> > >> > > indeed. Such is the cost of making Android compatible with APIs
> that
> > >> > > developers are likely to be familiar with.
> >
> > >> > > JBQ
> >
> > >> > > On Mon, Nov 24, 2008 at 8:51 AM, joshv <[EMAIL PROTECTED]>
> wrote:
> >
> > >> > > > The polling happens only while the apps is loaded and displayed
> on
> > >> > > > screen. The second the screen turns off or another app is
> loaded, the
> > >> > > > polling stops. It's pretty well behaved in that respect. Also,
> I
> > >> > > > don't hammer the connection 6 times a minute no matter what -
> each
> > >> > > > thread waits for the previous to finish, waits ten seconds, and
> then
> > >> > > > attempts to connect.
> >
> > >> > > > My issue is that URLConnections seem to be so unreliable that
> > >> > > > Exceptions seem to be the rule, not the exception. This might
> be
> > >> > > > something unique to my handset, I only have one, so I can't
> tell. It
> > >> > > > certainly doesn't happen in the emulator. I might expect it to
> happen
> > >> > > > if I have a marginal 3G or edge connection - but not when the
> handset
> > >> > > > is literally 3 feet away from the WiFi access point it's using
> for a
> > >> > > > connection.
> >
> > >> > > > On Nov 24, 10:00 am, "Andrew Stadler" <[EMAIL PROTECTED]>
> wrote:
> > >> > > >> If your code is going to access a site every 10 seconds, the
> radio is
> > >> > > >> going to, essentially, stay "on" continuously. This is going
> to have
> > >> > > >> a significant impact on your users' battery life. Is this
> definitely
> > >> > > >> what you want to do?
> >
> > >> > > >> On Mon, Nov 24, 2008 at 5:17 AM, joshv <[EMAIL PROTECTED]>
> wrote:
> >
> > >> > > >> > I am attempting to write an application that regularly polls
> data
> > >> > from
> > >> > > >> > a publicly available website using a URLConnection. The code
> is
> > >> > > >> > pretty basic (urlStr contains the URL...)
> >
> > >> > > >> > URL url = new URL(urlStr);
> > >> > > >> > URLConnection urlConn = url.openConnection();
> > >> > > >> > urlConn.setConnectTimeout(5000);
> > >> > > >> > BufferedReader in = new BufferedReader(new
> > >> > InputStreamReader
> > >> > > >> > (urlConn.getInputStream()));
> > >> > > >> > String line;
> > >> > > >> > while ((line = in.readLine())!=null) { ....
> >
> > >> > > >> > Anyway, even when the G1 is connected to the network
> (verified in
> > >> > > >> > browser) this block of code will regularly throw
> > >> > > >> > java.net.SocketException: No route to host,
> > >> > > >> > java.net.SocketTimeoutException: Socket is not connected
> (though
> > >> > this
> > >> > > >> > is probably because I added a timeout), and many times throw
> an
> > >> > > >> > Exception claiming that it could not resolve the hostname in
> urlStr
> > >> > -
> > >> > > >> > oddly the web browser has no such issues resolving the name.
> >
> > >> > > >> > The above block of code runs every 10 seconds (or longer if
> the
> > >> > > >> > previous request takes longer), and I'd guess succeeds
> approximately
> > >> > > >> > 25-50% of the time, though it tends to be a bit streaky.
> When the
> > >> > > >> > connection succeeds, it take less than a second to connect
> and
> > >> > > >> > download the data, it's a very small data set - so the
> timeout
> > >> > setting
> > >> > > >> > should not be an issue.
> >
> > >> > > >> > The periods of error do not correspond to a loss of
> connectivity, as
> > >> > I
> > >> > > >> > can browser the web at the same time the errors are
> happening. This
> > >> > > >> > happens whether connected to local wi-fi or 3G.
> >
> > >> > > >> > Am I doing something wrong, or is network connectivity on the
> G1
> > >> > just
> > >> > > >> > this flaky?
> >
>
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