Tuesday, May 24, 2016

The secrets of Stack Overflow decrypted

The secrets of Stack Overflow decrypted

Despite its massive audience, the site Q Stack Overflow has maintained the quality of its content but should have mechanically erode. According to Quantcast, Stack Overflow moved up to 41st websites with most traffic in the United States and records worldwide no less than 47 million unique visitors per month. But while community sites often see the quality of their content be eroded As the traffic growth (almost mechanical trend), the US site Q knew him, maintain the relevance of its information. How is Stack Overflow managed to solve this delicate equation? JDN could ask its CEO, Joel Spolsky.

A clever system of moderation
"The quality of a site like Stack Overflow is based mainly on the editing and moderation. It is this second point that was the most complex to manage," says Joel Spolsky. "Given our initial objectives in terms of traffic, ambitious from the outset, it was not possible to rely on paid moderators. It was unrealistic, because of the amount of work that would have involved. We therefore decided from the outset to give the possibility to users to moderate themselves." Based on this premise, Stack Overflow has developed a clever incentive moderation system.

Stack Overflow has several hundred moderators
To become a moderator, a visitor must first be active on the site, posting questions and answers. A device then allows users to assign points to that content according to their level of interest. More items published by a developer will reap points, the more this developer will have privileges in terms of contribution and moderation. In total, the site has 26 privilege levels. 15 points possible for example to vote for questions, 100 points to create chat rooms or enrich a post 10 000 points to access full moderation tools" The highest level, corresponding to 25 000 points provides access to our Google Analytics to track the site's audience, "says Joel Spolsky (see the complete list of privileges).
In total, several hundred Stack Overflow moderators.

How to Stack Overflow to the emergence of new communities
To bring about a community around a new theme, Stack Overflow leans in particular to the system of privileges, mentioned above, assigned to visitors. A developer who is rated 1 500 points will have the opportunity to add new thematic tags on the site. "This level of reputation brings the pledges we consider necessary, it also allows contributors to federate a community quickly enough to sustain the new space," says one at Stack Overflow.

Once communities and content created, remains to promote content. On this point, Stack Overflow will take into account the votes allocated to the Q to put forward more or less content on its pages. This signal will play somehow the role of internal ranking system. How is the quality of this ranking managed? By the elite of the site moderators, that is to say by those accessing moderation tools (and have therefore opportunity, also, to suppress the votes on issues that have been mispriced or spammed).

A site optimized in terms of SEO with an internal ranking system
Always with the objective of generating traffic, Stack Overflow then made sure that its site is optimized for the best present in the Google results. On this point, Stack Overflow pays particular attention to the HTML structure of its pages, tag material <Title> in particular. "In connection with Google, we have also put in place a tag associated with the votes on issues that are considered by the search engine," says Joel Spolsky. "Given our rich content, it is in Google's interest to have a good relationship with us," he thinks. Stack Overflow and sends its own ranking signal to Google.

Microsoft techno under the hood but not only
Speaking to developers, Stack Overflow is had, also, to provide a level of technical excellence. To maintain performance at the state of the art, the site is equipped with its own hosting infrastructure spread across two data centers, one in New York, the other in Denver. Why did he not opted for the cloud? "Offers like Azure and AWS are not suited to our performance issues and speed of access," says Joel Spolsky. "We chose to build our own hardware to best optimize our infrastructure in terms of hard drive and flash storage."

Under the hood, Stack Overflow has chosen the Microsoft platform: IIS web server (with an application layer in C#) and SQL Server database. But the site has not prevented the use of third-bricks. The open source Redis cache server, for example, which is the buffer between Web servers and database. To optimize access performance, Stack Overflow is also calling on CloudFlare content delivery network. "We are considering moving to another CDN", however loose, finally, Joel Spolsky.

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