Hi, I’m Matthew Clark, the Senior Abstruse Architect for BBC Online’s Olympic website and apps.
Alongside colleagues Mike Brown and David Holroyd, it’s been my albatross to actualize the abstruse action that has accustomed us to aftermath acknowledged online Olympic products.
We’ve focused on the architectonics and development to accomplish abiding the armpit and apps break reliable and can handle aerial cartage loads, whilst alms added agreeable than anytime before. In this abstruse blog column I’ll be attractive at some of the challenges we faced and how we overcame them.
We accepted the Olympics would drive far more traffic to our armpit than anytime before, and it did. Planning for this aggregate was not easy. There are over 60,000 dynamically generated pages, abounding with a cogent aggregate of agreeable on them, so able folio bearing is vital.
Content needs to be as ‘live’ as possible, so abiding caching is not an option. We use a ambit of caches (including Agreeable Delivery Networks, Varnish, and mod_cache) to offload the aggregate of the cartage from our Apache web servers. For agreeable that’s dynamic, accumulation lifespan (max-age) varies amid a few abnormal and a few minutes, depending on the context. This is decidedly accurate for the new video player, which needs the latest abstracts every few abnormal to acclaim the alive video stream.
Page bearing is done appliance PHP, which is stateless and receives all of its abstracts through calls to a RESTful API. This API is the Java appliance band that retrieves its abstracts from a ambit of abstracts food (including MySQL databases, amateur stores, and XML agreeable stores). It’s the best analytical band from a achievement point-of-view, as aggregate is high, calls can absorb cogent processing, potentially assorted abstracts abundance calls, and limitations on what can be parallelised. Caching (mod_cache and Memcached) is afresh acclimated to abode the aggregate of the traffic.
From abstracts food to screens, sites and apps
We spent ample time modelling how cartage creates aggregate on the accomplished stack. This was aboriginal done apparently (through modelling of user behaviour, aggregate balancing, and caching). We again did it for absolute – we acclimated abstracts centres about the apple to abode aggregate agnate to over a actor circumstantial users on the site, to affirm aggregate formed during active Games load.
A moment back all 24 streams were active at the aforementioned time. Can you analyze what they are?
There’s been affluence of altercation about the BBC’s 24 video streams, and the challenges of creating them at the International Broadcast Centre by the Olympic Park. This is the agnate to 24 new channels, offered over cable and accessory as able-bodied as via IP.
Once the channels are created, the claiming is to absolute admirers to the adapted agreeable at the adapted times.
Sport schedules accept a addiction of alteration – added time, delays due to rain, etc – and the sites and apps charge to appearance this. Back an accident starts, the accoutrement acclimated by (human) controllers to ascendancy the video additionally log the alpha in our XML agreeable store. This metadata is again best up by pages and apps (via an API) so that, aural a minute of the accident starting, there are links to the agreeable throughout the site, app, and red on. A agnate action happens back advantage finishes. Olympic sessions can be as abbreviate as 45 minutes, so the faster a video beck can be fabricated available, the better.
The BBC has a four awning action area we advance for PCs, tablets, mobiles, and internet affiliated TV. For the Games we’ve offered an aberrant aggregate of agreeable to all four. In addition, there are Olympic apps for iOS and Android smartphones, a Facebook app, adopted accent agreeable for Apple Account sites, and a red on account for accessory and cable TVs.
Our architectonics is the archetypal multi-tier access – blame as abundant argumentation as accessible into aggregate components, so that the aggregate of development for anniversary interface is as low as possible. This is DRY (Don’t Repeat Yourself) at a multi-platform level. For web pages, a distinct PHP codebase creates both the desktop and adaptable versions. This includes the iOS and Android apps, which use PhoneGap to ‘wrap’ the adaptable website for best of its functionality. It has adored us accepting to carbon functionality in built-in code. Certain added applications, such as the Olympic Facebook app, are altered abundant to accreditation their own codebase, but still accomplish the aforementioned API calls to the Java appliance layer, area best of the ‘business’ argumentation is held.
Video aside, there is a abundance of abstracts adapted to accomplish the Olympic site. The primary antecedent is the Olympic Abstracts Service, which blog posts from Oli Bartlett and Dave Rogers accept already covered in depth. In brief, Olympic Broadcasting Casework (OBS) accommodate a absolute abstracts augment that covers all sports, and provides a abundance of abstracts – from latest array to badge tables. This, accumulated with belief from journalists, and added sources such as Twitter, creates the agreeable for tens of bags of results, athletes, country, and accident pages.
The Activating Semantic Publishing (DSP) model, which understands relationships (triples) amid all agreeable and concepts, is the action that ensures aggregate automatically appears in the adapted place. All created content, including stories, medals, and apple records, are tagged (normally automatically) with the adapted athletes, sports and countries. This causes the agreeable to arise on the adapted folio after animal intervention.
In essence, it’s this automatic curation of pages that has accustomed us to action such a ample ambit of product. The automation has kept aliment to a minimum, absolution journalists to focus on autograph content. It’s accustomed assorted articles and bags of pages to break a after a ample operational overhead.
With all this content, data, video, and technology, comes a huge engineering challenge: how do you analysis it? All development areas chase Analysis Driven Development (TDD) so there is no curtailment of automatic assemblage and basic tests. But what happens back you bung aggregate together? How can you be abiding that the adapted medals go to the adapted country, or that video works on all devices, or that after-effects arise accurately for all 36 sports? Unlike, say, the football season, the Olympics alone appear already every four years, and alone aftermost a brace of weeks.
There are no additional chances.
We bare to be 100% abiding that on day one of the Games, aggregate would assignment as expected.
To accouterment this we set up an absolute team, as big as any development team, with the job of proving aggregate would assignment back the Games started. We took a three-pronged approach:
This testing action lasted several months and bent a cogent cardinal of bugs and achievement problems. Fortunately it paid off – I was a little afraid on the aboriginal day of the Games, but it passed after incident.
With the end of the Games fast approaching, absorption now turns to added areas of the Sport website.
Some appearance accept already been activated throughout – for example, best alive video advantage will be in HD from now on. Added casework that we’ve offered for Olympics aren’t yet accessible for use abroad (mobile apps and video affiliate credibility actuality two). Over the advancing months we’ll be alive on bringing abounding of these appearance to the blow of Sport, and conceivably added genitalia of BBC Online too.
If you’ve any questions about the technology we’ve acclimated during the Olympics, amuse get in blow appliance the comments below.
Matthew Clark is Senior Abstruse Architect, Knowledge & Learning, BBC Aing Media
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