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I've read some articles on the web and some questions on StackOverFlow, but no one seems to have a definite answer over a) If google uses Long Lived TCP connections for Gmail, Mail etc, and b) If using it in a custom app will drain battery life , and if so roughly how much?

Faisal Abid
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  • .. a long lived connection isn't so much of a problem **if** there isn't lots of traffic on it... of course that's assuming the device is on at all. – jldupont Nov 18 '09 at 15:23
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    Are you asking if holding a TCP connection open will drain battery-life? Maybe I am WAY off here but, holding a connection open shouldn't waste battery life... If you think it will I would love to know where you got that information. It sounds SO strange to me. –  Nov 18 '09 at 15:24

3 Answers3

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The answer to your first question is that, yes, Google's GTalkService maintains a persistent XMPP connection to Google servers, on Android phones with the Google applications installed.

As for your second question, the answer to that is more complicated than some of the comments here would have you believe. In particular, additional connections' keepalive packets -- or any small but continually occurring data transfers -- can affect your 3G radio's power management state cycle, which will have a noticeable impact on battery life.

See this article for more information:

https://www.ericsson.com/research-blog/smartphone-traffic-impact-battery-networks/

If possible, you might consider using the new Cloud to Device Messaging API which piggybacks on top of GTalkService, allowing your application to receive notifications without maintaining its own TCP connection. The downsides, unfortunately, are that C2DM won't work on pure open source Android, it requires the user to be signed into his or her Google account, and it's only available on Froyo or above.

spaaarky21
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mshroyer
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    also have a look at this blog post: http://devtcg.blogspot.com/2009/01/push-services-implementing-persistent.html – Erdal Apr 09 '11 at 03:21
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Maintaining an open-connection can translate to less resource usage: a small "trickle" traffic can maintain the connection open.

Consider the opposite situation: the Client "polls" the server on a regular interval (assume the same "refresh" rate as for the long-lived connection "trickle") : each time a new connection is opened generates more traffic.

Connection setup/teardown is expensive (of course, everything is relative in this universe ;-).

Major drawbacks of maintaining an open connection:

  • the client side browser might be limited in the number of connections per window/tab etc.
  • intermediate devices (e.g. NAT, Firewalls) can't reuse the port as often to serve other requests
jldupont
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  • @jidupont - So If im reading this correctly, keeping the connection "persistent" will take up less resources then polling every n seconds (sounds reasonable to me). @Everyone-else - The traffic will be 0 for a long long time till the user does the action that starts the push from the server, (the action is done on the computer) however it will be a pain in the ass for the user if he has to enable "push" each time he wants to do this, thus I thought about just let it run if it really doesn't take a lot of resources. What do you guys think? – Faisal Abid Nov 18 '09 at 15:36
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  1. You can use a tool like tcpdump or wireshark on your router or other machine to determine how long the TCP connections are kept open by Google's applications. You will need to filter on the ports or addresses you are interested in.
  2. If you are using Android 1.6, the best way to determine the drain is to use the new battery usage indicator. Just install your custom app and see what the monitor says over time.
Adam Goode
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  • True that is a really good idea. I think i should just run a custom app that just leaves the connection open and nothing else for a while to see the battery usage. – Faisal Abid Nov 18 '09 at 15:37
  • If I look at the Email Client, and the Google Apps suite (Gmail and Calendar) they both take up roughly 5-6% of the battery life. – Faisal Abid Nov 18 '09 at 15:39