vB Easy Archive - Does the BlackBerry push or pull e-mails?

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Does the BlackBerry push or pull e-mails?
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Posted by: afiuw

A Bell sales rep was saying how the Treo 600 isn't as good as the Blackberry because the Treo needs to poll a POP3 server to check mail.

So...how *does* the Blackberry check e-mail? Does the Blackberry keep an "always-on" data connection to the server or does the server somehow call up the Blackberry?

If anyone could point me to a technical document on how this works, that would be most appreciated.

Posted by: NJBlackBerry

The first place to start looking is the BlackBerry web site - http://www.blackberry.com ; there are tons of white papers on everything from security and encryption to how the push technology works.

The BlackBerry does not poll for e-mail. There are several methods for getting e-mail to a BlackBerry:

1) The BlackBerry Enterprise Server (BES). A BES sits between yoru BlackBerry and your Exchange or Domino e-mail server. This is generally a corporate solution, but there are hosted solutions out there. The BlackBerry maintains a GPRS connection to the RIM data centers; the BES encrypts the e-mail, using a key unique to the specific BB, and sends it to the RIM data center, and out it goes.

2) The BWC - BlackBerry Web Client - the BWC allows you to set up POP3 e-mail accounts, which the BWC (not the BlackBerry) will poll and forward to the BB every 15 minutes. Since you assign a unique e-mail address to the BB, you can forward (or send) messages directly to the BlackBerry and they don't wait the 15 minutes.

3) The desktop redirector; used if you have an Exchange or Domino/Notes e-mail server, but not a BES. Requires that you leave a PC logged in and on a network with the redirector working.

The BlackBerry never polls. It sits there and gets mail pushed to it.

Hope that helps.

Posted by: afiuw

I've searched the RIM site before, but I haven't come across anything really technical.

Any idea if the handset keeps a TCP/IP connection (and hence a packet connection like GPRS or 1xRTT) alive at all times? I don't see how else this would work...

Posted by: NJBlackBerry

With the exception of the Nextel BBs, none of the BBs have a full IP stack; they use UDP for data transmission (if I remember correctly).

Posted by: Mark Rejhon

afiuw,

You are correct. Yes, Blackberry keeps a constant connection idling to a Blackberry Enterprise Server. It's just like Microsoft Outlook which can maintain a constant TCP/IP connection to an Exchange Server, for realtime immediate email that shows up immediately after somebody clicks SEND on the email-sending computer.

It's equally proprietary (Blackberry Enterprise Server is similiarly proprietary as a Microsoft Exchange Server, in that they use proprietary email protocols rather than SMTP/POP) since SMTP/POP are not capable of realtime always-on email for the recipient. SMTP/POP is supported, at the expense of the delay of a 15-minute poll frequency rather than realtime.

There is an occasional ping that seems to happen every 10 minutes or so, to make sure the connection is alive, according to the signal transmit/receive indicator on the Blackberry screen. However, emails show up in 4 seconds after I click SEND on the remote system. It's pager style.

Whenever the connection gets lost, it continually keeps trying to reestablish the connection to the Blackberry Email Server. And if you are out of reception, it will keep trying until reception is back, and then reconnection is initiated immediately, and then any pending emails are sent/received immediately. No error messages to nag you -- just look at the reception indicator and the email-successfully-transmitted indicator. (Which usually flags in 1 second after you select SEND on the Blackberry if there's any reception of any sort.) So it's very reliable, and very persistent, and you get your emails on a Blackberry sooner, even in low-reception areas, because the Blackberry is so persistent and insistent on staying connnected to the Blackberry Email Server.

To see this happening using UNIX or Windows, run the 'netstat' command on an Internet connection that's between the Blackberry Enterprise Server and the Internet connection itself; you'll see a continuous TCP/IP connection between the Blackberry Enterprise Server and the Blackberry itself. UDP may be involved too as an alternate signalling mechanism, but I haven't monitored for this.

The data traffic overhead of keeping the connection persistent consumes only about 10 kilobytes per day at the most. Much, much, much smaller than the GPRS traffic of polling POP/SMTP every 15 minutes. So this has negligible impact on your data plan because GPRS is always-connected; it cost nothing to just simply be connected 24/7.

Blackberry is truly the DSL/Cable "feel" of wireless "always-connectedness" (just not the speed of DSL/Cable....)

NJBlackberry is probably right in UDP, but my netstat command still shows a TCP/IP connection between the Blackberry Enterprise Server and the carrier's own Blackberry gateway. So it seems like TCP/IP is involved.

However, I should make a minor correction to NJBlackberry -- all Blackberries (even non-Nextel) has a TCP/IP stack built in!!!!!! The CATCH: They can only be configured to connect through a Blackberry Enterprise Server which is required. My network tools shows this rather clearly -- I see a true TCP/IP connection between my NON-NEXTEL 7280 Blackberry and the BES. BlackChat ICQ and Idokorro MobileSSH does a true RFC-compliant plain jane TCP/IP connection, at least at the Blackberry Enterprise Server to the carrier's own gateway (the telco carrier server that's on the ping hop between your Blackberry Enterprise Server and the Blackberry itself).

On the other hand, NJBlackberry might be right if there's a TCP/IP-to-UDP translation layer at the carrier server, but I can tell you with all certainity, that true RFC-standards-compliant TCP/IP is being done at least one ping hop beyond the Blackberry Enterprise Server (towards the Blackberry itself). One way to view this is that this is simply standard TCP/IP done over a UDP tunnel (this is possible to do, kind of a VPN over UDP, using your own software-based error correction and retransmission algorithm). However, I do not know beyond the netstat/traceroute/ipconfig TCP/IP diagnostics I've done on the connection between the Blackberry Enterprise Server and the Internet.

According to these diagnostics, this is how TCP/IP works.

Blackberry -> Carrier Gateway -> Blackberry Enterprise Server -> Internet

All the hops between Blackberry -> Blackberry Enterprise Server is a secure encrypted connection, fully encrypted. Lots of companies like the security of the Blackberry Enterprise Server, for keeping everything encrypted between the Blackberry itself and the internal company network (that the Blackberry Enterprise Server runs within). It is definitely a VPN of sorts. It's quite possible NJBlackberry might just be right that another protocol is being done at a lower layer, such as UDP, but intrisinically, TCP/IP is being done at the software/sockets API layer.

Conclusions All Blackberries have a Java-standards comliant TCP/IP stack! (Just the Blackberry OS restricts this to a secure VPN connection with a Blackberry Enterprise Server on non-Nextel Blackberries. Whatever protocol the VPN uses is another matter entirely -- a proprietary VPN-style protocol using UDP is definitely possible, in order to do TCP/IP over a UDP tunnel. However, at the software layer, all Blackberries have a full TCP/IP stack, just one that can only be piped over a VPN directly to a Blackberry Enterprise Server)

Additional proof: J2ME based TCP/IP Internet applications that were NEVER designed for Blackberries WORKS on BES-enabled Blackberries like my 7280. For example, the VNC program here:
http://www.howardforums.com/showthr...threadid=418315
Was not designed to work on for Blackberry. But it just happens to work on a Blackberry that's BES/MDS equipped.

Any experienced Java programmer that's familiar with J2ME, can write an Internet app for Blackberry. (even unsigned applications! No need for RIM involvement here) Incidentially, we need a free or low-priced Telnet/SSH client. (hint, hint)

Posted by: jwineburgh

So the conclusion is that the blackberris' only connectivity happens through the service provider's gateway - No way to have just a gprs data connection ($5 on T-mo) to a pop/smtp email server without going through (and paying handsomely for) the SP's gateway?

What about writing your own app from scratch with some of the development tools on the developer sites? Will the bb do a gprs connection out to the internet without going through the bes / sp's bb gateway?

Gotta be a way...

#JOE

Posted by: NJBlackBerry

It's a great idea, except that RIM controls the APIs that deal with the radio... I'm not so sure the carriers would like the idea, and the carriers are RIMs primary customer - not you and me.

Posted by: Mark Rejhon

>>bb do a gprs connection out to the internet without going through the bes / sp's bb gateway?

Not possible. GPRS is handled by your service provider, and by definition, your Internet must go through the service provider. Yes, there can be a NON-Blackberry gateway, but a gateway of some kind is essential for GPRS Internet. You may see terms elsewhere such as "APN", "Internet.com", etc, which are related to this.

So just as you have to pay for voice, you have to pay for data even if it bypasses a Blackberry server, since all carrier Internet gateways (Blackberry and non-Blackberry) are monitored by the carrier. Just like it's impossible to make a cell phone call without your carrier knowing!

Because the call goes through their network. So the only way to get a free ride is to buy an Unlimited data plan.

It's also possible, however, a silly situation might arise, you have an Unlimited data plan, but a limited-data BES/BWC/email/web plan. This would be kind of silly, and yes, then there would be a legitimate reason to bypass the metered data plan. However this situation does arise with SMS: Some Blackberry users like to do email an unlimited email/data plan, to bypass a pay-per-message SMS plan.