Dabr blog

People have been very excited to see some new functionality in Dabr – the mobile Twitter client I develop for. But what is it and how does it work?

@@ and geotag

Reply to All

The @@ symbol allows you to reply to all the people mentioned within the tweet.
It only shows up on tweets which mention other users – so you should only ever see it when it can be used.

Hitting @@ on the above tweet will pre-populate the text box with “@topgold @whatleydude @dabr”.

It should remove any duplicates and should also remove your username.

Geotagging

Twitter recently allowed the geotagging of tweets. This allows you to set the longitude and latitude of where you are when you wrote your message.
Clicking on the green globe (it just looks like a dot at that size!) takes you to a mobile mapping service.

Google Maps Mobile

It only shows up on tweets which are geotagged – so you should only ever see it when it can be used.

How Does It Work?

You can see all the code in the SVN, but here’s a quick rundown.

Geotagging is very simple.  Statuses now have a <geo> field.  If this is populated, it will contain a longitude and latitude.

We can take those values and pass them to Google Maps Mobile (or your favourite mobile mapping service).
if ($geo !== null)
{
   $latlong = $geo->coordinates;
   $lat = $latlong[0];
   $long = $latlong[1];
   $actions[] = theme('action_icon', "http://maps.google.co.uk/m?q={$lat},{$long}", 'images/map.png', 'MAP');
}

Reply to all is a little more involved.
Twitter provide an excellent set of Text Libraries. These provide officially sanctioned regular expressions to help your project find URLs, hashtags and usernames.

Using the Twitter Text Extractor class we can determine how many usernames are mentioned in a tweet. Any duplicates are removed – as is the user’s username.

Any questions – just ask!

 

 

This update comes from one of @Dabr's more prolific coders, Sir Terence of Eden - aka @edent..

Terence runs his own version of Dabr using the open-source code and has been playing and updating now for some time. With permission, David went through the main service and applied the awesome changes you can see above...

What do you think?
Do you - like @topgold - like these new features?

Cheers,
James

Some techy stuff about how I migrated Dabr to it's new home last month, cross posted from one of my other blogs:

After a recent purchase of VPS hosting from WebFusion, I wanted to move my high-traffic site dabr.co.uk onto it. With the site exceeding one million daily page views, I really had to be careful about how I’d move the site to it’s new home.

10%

Using the “Hostnames” report within Google Analytics, I was able to identify that 10% of users access the site via the m subdomain and 40% use www – the rest not using any subdomain at all. This was a real stroke of luck as it allowed me to test the new server with a controllable percentage of the total traffic, simply by updating the DNS records.

When given 10% load the VPS handled just fine, so after two days I moved on and tried it with 50%.

50%

A second report from Google Analytics also helped tremendously: hourly visits. With about 45% of hits coming from Indonesia (yes, really), I needed to know what time was the best window to try any drastic changes to the servers. The graph clearly shows that the longest quiet period I get is between 6pm and 9pm GMT – when most of Indonesia is asleep and web traffic drops in half:

On the first few occasions that I did try 50% of the load pointing at the new server – it buckled and almost completely fell over. A chat with Nick, a friend from Heavy Sumo, led me to explore the Apache configuration – and what a bizarre experience that was.

Here’s the settings that were used by default on the server, compared with the Apache defaults and the settings on the old server:

Setting	WebFusion VPS	Apache default	Old server
StartServers	1	5	8
MinSpareServers	1	5	5
MaxSpareServers	5	10	20
MaxClients	10	256	256
MaxRequestsPerChild	0	1000	4000

Notice the difference?

I have no idea why WebFusion would have their defaults so low. Changing these to match the settings of the old server had a significant boost on performance.

I left 50% traffic on the new server for a couple of weeks, and tried a couple of times to add a bit more, but users quickly complained about the site slowing down.  The slow down matched up to the Indonesian peak time around 2pm GMT, so I rolled back the DNS to point to the old server again.

90%

This stage required a little further exploration of Apache performance tuning articles. One interesting fact I discovered was that Apache has a hard-coded MaxClients limit of 256, which you can only raise by recompiling Apache – so that wasn’t particularly an ideal option.

The Apache Performance Tuning article from devside.net was the answer to my problems. It suggested a number of different solutions, two of which were to adjust Keep Alive and Timeout settings.

Setting	Webfusion VPS	Devside
Timeout	300	45
MaxKeepAliveRequests	100	80
KeepAliveTimeout	15	2

These changes, combined with the forking settings above, have made the server run much more smoothly. In fact, it’s now taking 100% of the traffic and people are noticing an improvement in speed.

100%

With the new server running well for a month, I then asked the previous host to delete the old server. Hopefully the new server should last a while before I need to consider load balancing to a second server.