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iPhoto Beaming: Under the hood
Earlier today, Steve Sande showed you how to beam photos using the new iPhoto app. Now it's my turn, and I'll briefly discuss what's actually happening when you use this new feature. Beaming relies on two devices sharing the same Wi-Fi network. That's because the communication channel seems to be built on Zero Configuration (Bonjour) networking. Bonjour, Apple's branding for zeroconf/mDNS device discovery, allows computers and mobile devices to advertise services on a shared network. This lets Macs, PCs and iOS devices easily connect to printers, AirPlay servers, and so forth. iPhoto Beaming uses a UDP service called _mobileiphoto._udp. Devices that are ready to receive beams announce themselves in an easily discoverable way. A service appears on-network as soon as you enable Wireless Beaming. To beam, a source device searches for possible recipients. Once detected, iPhoto offers to connect to them. It negotiates a handshake, asks for permission at the far end to send data, and then transfers photos. The Bonjour device name seems to be made up of a hash filed by a local file name. This is quite similar to what goes on with GameKit peer-to-peer connectivity. Only properly hashed identifiers are recognized as valid destinations. To spoof iPhoto, a Mac client would need to provide a valid hash in this way. And, no, I was unable to get my GameKit hashing to match the iPhoto beaming hash in my initial attempts. Possibly operator error on my part, possibly they just used a different approach. What's more, the executable seems to be built using GKSession objects, so there's apparently some common genetic background between the two approaches. I didn't find other GameKit classes, so not all that much commonality. Before jumping into iPhoto, I had been hoping this would be some kind of AirDrop implementation that might later open up to other apps -- but from what my quick dive indicates, it looks like this is proprietary to iPhoto and not going to become a general solution yet. To summarize, the iPhoto beaming looks, at least from my initial scans, to be a jury-rigged solution proprietary to this one title rather than a general iOS file-sharing solution. The app-specific Bonjour name (mobileiphoto) and lack of custom framework classes suggest this isn't the future, it's just iPhoto. Pity.
How-to: Beam your photos with iPhoto for iOS
One of the quick points touched upon during yesterday's iPad event was that iPhoto for iOS can be used to "beam" photos between iOS devices. While that comment was enough to send our intrepid and beleaguered blogger Dave Caolo into a "Newtongasm" (Apple's groundbreaking PDA was happily beaming information via infrared back in the day), there was no word on how to actually use this capability. Here, in a few short steps, is the lowdown on how to beam images from one iOS device to another. First, you'll need to have iPhoto for iOS (US$4.99) installed on both devices. Launch iPhoto, then tap on the gear icon in the upper right corner of the iPad app (lower right on the iPhone app) to show Settings. The top item is Wireless Beaming -- make sure that is set to On on both devices. Next, make sure that both devices are on the same Wi-Fi network, and then tap on an image that you wish to send to the other device. At the top of iPhoto is the common iOS share button -- a box with a right-pointing arrow coming out of it. Tap on that to bring up the share pane seen below. This pane displays a number of ways to share your images, including creating a web-based journal, sending an edited image to your camera roll, emailing, printing, beaming and more. Tapping the Beam icon brings up a dialog (below) showing any images you have selected or flagged, or you can select any of the images in your photo library. You can select up to 100 thumbnails from your photo library to beam, and then tap Next. The next screen (below, left) shows a list of all iOS devices running iPhoto that are on the same network. Tap on the name of the one you wish to beam the image(s) to in order to select it, and then tap the Beam Photos button. You'll be asked on the receiving device if you wish to accept photos from the sending device. Tap the Yes button, and the images are beamed almost immediately (below, right). It took about four seconds on an 802.11n network for two images to transfer. Beaming is an easy and fun way to share images between devices, and would be well worth the $5 investment in iPhoto for iOS even if it didn't have all of the other editing and enhancing features. Give it a try!
