Apple Airplay

One of the more appealing features of more recent Apple devices is the Airplay function. In a nutshell, this allows OSX (10.8 or later) and iOS devices to share their screens with a compatible display device. The two big targets we’re looking at the ADM school district are Apple TV’s, and the use of the Reflector App. The first will allow a simplified means of wireless connections from our Macbooks and iPads to projectors. Some of our projectors offer limited means to do this, but the results have been less than ideal. The second allows a computer running Reflector to display the screen from an Airplay compatible device. Airplay devices are detected automatically, and on an iPad you swipe from the bottom upwards and if a compatible device is available you will see an icon. Tapping it will show all the devices and tapping the device establishes a connection. 

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The biggest restriction we have regarding allowing Airplay is that it relies heavily on the Bonjour service. This was designed by Apple to allow devices to discover each other over a network, and share their capabilities so that, for example, a device storing songs could stream them to another device. You could have all your songs on a computer in your office, but could play them on your iPod in the kitchen. It is also used to share printers on Mac’s, but more on that later. Unfortunately, Bonjour was designed primarily around simple home networks where there wouldn’t be a likelihood of there being more than a dozen devices to discover, and only one network to discover them on. On larger networks, the method that Bonjour uses to discover other devices can cause significant amounts of traffic to flow, or it would not be able to discover devices on a different logical network, and on wireless networks it can quickly cause things to grind to a halt. Fortunately, one of the great features of the managed WiFi network we use, that came with a recent update, is that it can put controls in place to limit the amount of traffic that Bonjour transmits, and also can target it to only be seen in certain locations.

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Because we’re only in the testing phase, there are only three locations in the ADM district where this will work. These are the Adel Elementary Gym, the High School/Middle School Media Center, and the High School science classrooms. Each of these sections is restricted so that only devices in each section can see compatible devices in that section. By this, we can stop an iPad in the media center being able to use a display in the elementary school, and vice versa. This keeps the broader network traffic to a minimum, while allowing the devices to function as intended. There does exist a potential for students to abuse the functionality. For example, using a school issued iPad to connect to an Apple TV which is paired with another device. To counter this, we can specify access codes on the Apple TV’s which must be entered before it will display. 

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While we are still in the testing phase, all signs point to there being no detrimental effects on wireless services and we intend to make this functionality more widely available in the not too distant future. If any teachers reading this would like me to enable this functionality in your area, feel free to get in touch and I’ll do what I can to accommodate. 

Anyone who made it this far, and was paying attention earlier, will probably be asking about printing. One of our higher priority goals is to get iPad printing working reliably and the controls we can now place over Bonjour should allow us to do that since much of the way Apple devices handle printer discovery is identical to how AirPlay discovery works. The easiest solution is to get printers which are AirPrint compatible. These connect to our WiFi and we could use the wireless management to regulate which printers appear, and where. Unfortunately, none of the printers currently available which use AirPrint meet our requirements. Those which meet our needs for robustness and reliability are too expensive for us to consider, and those which could be justified on cost grounds wouldn’t stand up to our usage needs. Ideally, these problems will go away in the future and we’re looking forward to the possibility of using them but for the time being we’re taking a more circuitous route which will allow our current crop of cable-networked printers to be selectively advertised. What we shall do is use a printer management application that is already in use in the ADM district, Papercut. This acts as an intermediary between the iPads and our print server and looks to be the most practical solution for our needs. Before this comes in to use, we need to make some changes to our underlying network configuration. This would most likely require a few hours of interruptions to wireless network services so we’re looking for a good time to make the changes so that disruption is kept to a minimum. 

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