This post explains how various aspects of the new FixMyStreet maps work, including how we supply our own OS StreetView tile server and how the maps work without JavaScript.

Progressive enhancement

During our work on FiksGataMi (the Norwegian version of FixMyStreet) with NUUG, we factored out the map code (for the Perlmongers among you, it’s now using Module::Pluggable to pick the required map) as FiksGataMi was going to be using OpenStreetMap, and we had plans to improve our own mapping too. Moving to OpenLayers rather than continuing to use our own slippy map JavaScript dating from 2006 was an obvious decision for FiksGataMi (and then FixMyStreet), but FixMyStreet maps have always been usable without JavaScript, utilising the ancient HTML technology of image maps to provide the same functionality, and we wanted to maintain that level of universality with OpenLayers. Thankfully, this isn’t hard to do – simply outputting the relevant tiles and pins as part of the HTML, allowing latitude/longitude/zoom to be passed as query parameters, and a bit of maths to convert image map tile clicks to the actual latitude/longitude selected. So if you’re on a slow connection, or for whatever reason don’t get the OpenLayers JavaScript in some way, the maps on FixMyStreet should still work fine. I’m not really aware of many people who use OpenLayers that do this (or indeed any JavaScript mapping API), and I hope to encourage more to do so by this example.

Zooming

We investigated many different maps, and as I wrote in my previous blog post, we decided upon a combination of OS StreetView and Bing Maps’ OS layer as the best solution for the site. The specific OpenLayers code for this (which you can see in map-bing-ol.js is not complicated (as long as you don’t leave in superfluous commas breaking the site in IE6!) – overriding the getURL function and returning appropriate tile URLs based upon the zoom level. OpenLayers 2.11 (due out soon) will make using Bing tiles even easier, with its own seamless handling of them, as opposed to my slight bodge with regard to attribution (I’m displaying all the relevant copyright statements, rather than just the one for the appropriate location and zoom level which the new OpenLayers will do for you). I also had to tweak bits of the OpenLayers map initialisation so that I could restrict the zoom levels of the reporting map, something which again I believe is made easier in 2.11.

OpenStreetMap

Having pluggable maps makes it easy to change them if necessary – and it also means that for those who wish to use it, we can provide an OpenStreetMap version of FixMyStreet. This works by noticing the hostname and overriding the map class being asked for; everything necessary to the map handling is contained within the module, so the rest of the site can just carry on without realising anything is different.

OS StreetView tile server

Things started to get a bit tricky when it came to being ready for production. In development, I had been using http://os.openstreetmap.org/ (a service hosted on OpenStreetMap’s development server) as my StreetView tile server, but I did not feel that I could use it for the live site – OpenStreetMap rightly make no reliability claims for it, it has a few rendering issues, and we would probably be having quite a bit of traffic which was not really fair to pass on to the service. I wanted my own version that I had control over, but then had a sinking feeling that I’d have to wait a month for something to process all the OS TIFF files (each one a 5km square) into millions and millions of PNG tiles. But after many diversions and dead ends, and with thanks to a variety of helpful web pages and people (Andrew Larcombe’s guide [dead link removed] to his similar install was helpful), I came up with the following working on-demand set-up, with no pre-seeding necessary, which I’m documenting in case it might be useful to someone else.

Requests come in to our tile server at tilma.mysociety.org, in standard OSM/Google tile URL format (e.g. http://tilma.mysociety.org/sv/16/32422/21504.png. Apache passes them on to TileCache, which is set up to cache as GoogleDisk (ie. in the same format as the URLs) and to pass on queries as WMS internally to MapServer using this layer:

[sv]
type=WMS
url=path/to/mapserv.fcgi?map=os.map&
layers=streetview
tms_type=google
spherical_mercator=true

MapServer is set up with a Shapefile (generated by gdaltindex) pointing at the OS source TIFF and TFW files, meaning it can map tile requests to the relevant bits of the TIFF files quickly and return the correct tile (view MapServer’s configuration* – our tileserver is so old, this is still in CVS). The OUTPUTFORMAT section at the top is to make sure the tiles returned are anti-aliased (at one point, I thought I had a choice between waiting for tiles to be prerendered anti-aliased, or going live with working but jaggedy tiles – thankfully I persevered until it all worked 🙂 ).

Other benefits of OpenLayers

As you drag the map around, you want the pins to update – the original OpenLayers code I wrote used the Markers layer to display the pins, which has the benefit of being simple, but doesn’t fit in with the more advanced OpenLayers concepts. Once this was switched to a Vector layer, it now has access to the BBOX strategy, which just needs a URL that can take in a bounding box and return the relevant data. I created a subclass of OpenLayers.Format.JSON, so that the server can return data for the left hand text columns, as well as the relevant pins for the map itself.

Lastly, using OpenLayers made adding KML overlays for wards trivial and made those pages of the site much nicer. The code for displaying an area from MaPit is as follows:

    if ( fixmystreet.area ) {
        var area = new OpenLayers.Layer.Vector("KML", {
            strategies: [ new OpenLayers.Strategy.Fixed() ],
            protocol: new OpenLayers.Protocol.HTTP({
                url: "/mapit/area/" + fixmystreet.area + ".kml?simplify_tolerance=0.0001",
                format: new OpenLayers.Format.KML()
            })
        });
        fixmystreet.map.addLayer(area);
        area.events.register('loadend', null, function(a,b,c) {
            var bounds = area.getDataExtent();
            if (bounds) { fixmystreet.map.zoomToExtent( bounds ); }
        });
    }

Note that also shows a new feature of MaPit – being able to ask for a simplified KML file, which will be smaller and quicker (though of course less accurate) than the full boundary.

*Broken link removed, Nov 2014

At mySociety we love our site FixMyStreet – it’s the epitome of a web tool that gives simple tangible benefits whilst generating a little accountability at the same time. Reports through the site were up 40% last year, so it’s clear that users quite like it too.

FixMyStreet has been copied in many different countries, which makes everyone in mySociety very happy, too, even apparently appearing in a slide deck the White House uses to show innovative services. However, it turns out that the cheerfully minimalist, almost wantonly unfashionable user-interface has an unfortunate down side: most people who copy the site look at it, think “That looks easy!” and then cheerfully start coding their own clone.

Deceptive simplicity

Alas – the very simplicity that makes the site good hides the fact that making a site like FixMyStreet really work well is actually way harder than it looks. What will you do when a government email inbox fills up? What about when administrative boundaries change, due to an election or restructuring? How do you know you’re not scaring users away with careless wording? All the hard-won lessons from these questions have been baked into the FixMyStreet codebase, and we’re only too keen to talk to people about them.

We were therefore particularly pleased when the Nowegian Unix User’s Group (NUUG) came to us to ask if we could help improve FixMyStreet to make it easier for them to install. Over the last month mySociety Senior Developer Matthew Somerville has been working hard with Petter Reinholdtsen and Christer Gundersen of NUUG, and here’s what they’ve managed in just a handful of weeks.

• The launch of a Norwegian FixMyStreet called Fiksgatami, covering nearly every corner of Norway’s 300,000 square kilometers.
• Problems reported anywhere within Norway will be correctly directed to any of the 400+ responsible municipalities, thanks to Petter and Christer’s amazing data sourcing skills.
• As a necessary side-effect of developing this, Norway now has a free, public administrative web service gazeteer – http://mapit.nuug.no. If Norway is anything like the UK this will soon become an indispensable service for many other web sites and mobile tools.
• The standard mapping is now OpenStreetMap, pulled together by the brilliant Norwegian OpenStreetMap community*. We couldn’t take a technological step backward, and so whilst the site uses OpenLayers if you have JavaScript, the map continues to work just fine without as well.
• The open source FixMyStreet codebase has been upgraded to make it easier to translate into other languages, easier to use different mapping with, and easier to install. These efforts will continue, as we realise this has been one reason why others have made their own versions.
• All this has been done without forking, so various major upgrades we have planned for the UK version will be exportable later in the year.

NUUG’s Fiksgatami is the epitome of what makes civic open source at its best so unmatchably good. It was developed incredibly quickly: just a month to create what is effectively a fully fledged, best-of-breed nationwide e-government service – albeit an unofficial one. Thanks to the hard work of the public servants who fix problem reports, it will make small but meaningful improvements to the lives of a lot of people in Norway.  And it has made the free FixMyStreet codebase better and easier for other people to use to help them do the same thing in other countries.

I know that at mySociety we are all looking forward to working with NUUG again. And I hope that this story inspires others to look at our code, and to work with mySociety to make FixMyStreet a service that can help everyone who would benefit from it.

* We’ll be rolling out updated mapping (including OSM) and more in the UK, soon.