Facebook remains in the dark ages

What is HTML5? Most people would be able to answer this question, whether they are highly educated IT professionals or a hobby programmer, but at Facebook it seams as if they are still struggling with this strange concept.

The thing that I love the most about HTML5, is the fact that we no longer need any plug-ins to be installed in browsers. It's canvas and socket features replaces the old and terrible Java Applets. Don't get me wrong, I love Java. It's a nice programming language and it's great when you want to easily port programs across multiple architectures. But the Java Applets is one of the worst thing ever created, next to Microsoft's ActiveX (Along with their Browser). It will not be missed. The HTML5 Video and EME features replaces both Flash and Silverlight. Both of which brings nothing but instability and security vulnerabilities.

For a long time now, I have not had any plug-ins installed in my browser and I have not had any reason to. It seams that the vast majority of websites has either switched to full HTML5 or at least provide this as a second option. The few sites that don't, are not very important. At least that has been my observation until today.

My brother wanted to show me a video on my laptop. He navigated to Facebook and logged into he's account. He then searched for a specific video and tried to play it, but it wouldn't start because Flash is not installed in my browser. I don't use Facebook myself, so I have never noticed this. But Facebook, one of the worlds largest websites, do not have any support for HTML5 playback. Personally I have never liked Facebook, I cannot say why as I don't really know it myself. Nevertheless I have always pictured them as technologically advanced. Properly because I could not imagine a website being able to reach this magnitude of popularity while falling behind in this area. They proved me wrong.

Why am I writing about this? I have no idea. Maybe it's just the chock getting to me. Next to Google/Youtube, this was the last place that I would ever expect to be so far behind in technology. I mean this is freaking Facebook that we are talking about, and their only video solution is Flash? A technology that should have been extinct by now. And this is just the observation I made in the 2 minutes that my brother was trying to get this video to play. This is something that I would have expected from a small personal site where the owner had not yet had the time or resources to make the switch. But even those sites are up-to-date. The only one missing is the one that should have plenty of resources and highly skilled personal to do it, although I am starting to doubt the later.

Check Android Uptime

So you are programming an application for Android. You have made a custom caching system which should clear the cache after each boot. One way to do this, could be to create an onBoot Receiver and have that clear out your cache. However, why have your application run on each boot if the user might not even use it all that much? And what if the user installed some Privacy Guard Application and disabled your app's receiver?

The best way to handle this, is to have the cache cleared on the first launch of the application. But in order to do this, you will have to know whether or not this actually is the first launch or not. To help you with this, Android has two useful methods. One to provide the total amount of milliseconds that have past since 1970 (or something like that) and one to provide the total amount of milliseconds that have pasted since the device was booted. Extract the boot time from the total time, and you will have the exact timestamp from when the device was started. Now just save this to your shared preferences and compare it with a fresh timestamp on each application launch.

public class myclass extends something {

    /*
     * We can use this to avoid to much checking.
     * As long as this static property exists, we know that device has not been rebooted and there is no reason to do a check.
     */
    private static Boolean oCacheCheck = false;
    
    public SharedPreferences getCache() {
        SharedPreferences preferences = .getSharedPreferences("cache", 0x00000000);

        if (!oCacheCheck) {
            Long freshTime = System.currentTimeMillis() - SystemClock.elapsedRealtime();
            Long cachedTime = preferences.getLong("timestamp", 0);

            if (freshTime == cachedTime) {
                Editor edit = preferences.edit();
    
                edit.clear();
                edit.putLong("timestamp", freshTime);
                edit.commit();
            }

            oCacheCheck = true;
        }

        return preferences;
    }
}

if (freshTime == cachedTime) {

There is however one tiny issue with this way of checking last boot time, and that is that both methods might take a few milliseconds to execute (depending on the speed of the device) and you can only execute one at a time. This means that your calculation could differ each time you run it, making the comparison with the cached timestamp useless.

The solution to this problem is to check the difference between the two timestamps instead of comparing them to see if they are equal. The methods might take a few milliseconds to execute and any type of device will take several seconds, some even minutes, to boot. So we will just check to see if the two timestamps has a difference less than 3 seconds.

public class myclass extends something {

    /*
     * We can use this to avoid to much checking.
     * As long as this static property exists, we know that device has not been rebooted and there is no reason to do a check.
     */
    private static Boolean oCacheCheck = false;
    
    public SharedPreferences getCache() {
        SharedPreferences preferences = .getSharedPreferences("cache", 0x00000000);

        if (!oCacheCheck) {
            Long freshTime = System.currentTimeMillis() - SystemClock.elapsedRealtime();
            Long cachedTime = preferences.getLong("timestamp", 0);

            /*
             * If this is grater than 3 second, then we will most likely have a fresh application launch. 
             * No device, no mater how slow, takes 3 seconds or more to execute the time methods.
             * And no device, no mater how fast, can boot and launch the application in less than 3 seconds. 
             */
            if ((freshTime - cachedTime) > 3000) {
                Editor edit = preferences.edit();
    
                edit.clear();
                edit.putLong("timestamp", freshTime);
                edit.commit();
            }

            oCacheCheck = true;
        }

        return preferences;
    }
}

if ((freshTime - cachedTime) > 3000) {

If, when you extract the cached timestamp from the fresh one, get a difference on more than +3000 milliseconds, you can be sure that the device has been rebooted since your last application launch.