I have heard the story behind the development of "Booking.com" that conducts 1000 A / B tests a day [Part 2]

Accommodation reservation site "Booking.comIsIt has 1,000 A / B tests per day and has data totaling 15 petabytes in totalAnd that. I asked Mr. Brendan Bank, Chief Information Officer (CIO), how the organization including the server system supporting the service of Booking.com and the engineers who develop it are made.

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Brendan Bank (hereafter, bank):
Eight years ago when I came to Booking.com it was pretty bad and 30 developers were doing what they wanted to do. However, it is very interesting that it is functioning though it is doing apart from being tangled.


By the way, we call "Commercial awareness" "Craftsmanship (craftsmanship)" "Creativity (creativity)" here as "three C". For those with all three Cs, there is not much need to help as an engineer.


Techniques that you must have as a craftworker have various elements including coding. The important thing in that is to take communication. There are various differences between the digital world and the real world, so we have to explain to customers about incorporating real life into applications. I mentioned earlier that it was in a bad state at the start, but while working, nature and the group have solidified. This is because there were people who were good at three C from the beginning.

What I would like Booking.com is not an engineer who just works down and coding only everyday, but those who have these three C elements. Even during recruitment and bonus assessment, we always see these three points.

For example, when the company is expanding, he hired an Egyptian developer. When I hired him, I saw an Arabic site that was already there, he said "What is this terrible, is not it?" It seems that the way of selecting the date was completely different from the local one. At that time I realized that by incorporating native speakers, the people in the country, into the team, we can make more improvements.


Now, Booking.com is doing very good results in the Middle East is that the one Arabic speaking developer came in. So, in order to make a good product, it is important that you carry out "localization" in both China and Japan, people from the land there participate. He did not hire him to fix the Arabic site, but it was a translation that various ideas came out because it happened to be his mother tongue.

Also, it is very difficult for each engineer to work well with 1,200 people. So, in order to achieve results, Booking.com turned upside down the organization of the company.


In this way, by creating an organization that gives data directly to engineers, even if something does not work well, it can be solved well. It is because data is always flowing from the site and it is made possible to check on the dashboard that "Where changed" or "Where has the effect". It is creating a very workable environment for engineers. I mentioned earlier that "At first it was awful", but the current state is not terrible, but it is very solidly constructed. Engineers are not interfered, have a creative idea all the time, and are creating an environment that can continue to improve products.

At this time, the developer is sitting somewhere in the corner and not developing products by himself, but an autopilot-type "team" including designers etc. works in cooperation with communication. For example, in the case of a team building a search box, we will do with roughly 2 teams, but the team will be responsible for everything from the first idea to the completion of the product. The team is functioning like a micro enterprise as it is saying. And, as I mentioned earlier, it is always possible to see on the dashboard what the project is doing well and how it works.

Q:
One person in entrepreneurial culture of Booking.com that it is an entrepreneur "Entrepreneurial spiritIn that case, I think that opinions may collide. How are you making adjustments?


bank:
Although engineers are good at coding, engineers are often not good at communicating in many cases, so there is a coach to find out what "something is wrong" when a collision occurs. Because there are certainly reasons why engineers chose IT.

Q:
What is the specific scale and number of servers?

bank:
At the beginning there were only 10, but now there are around 20,000. Because every week the hardware comes in rapidly.

Q:
How has the server system of Booking.com, a server that manages websites and managing huge amounts of data, evolved?

bank:
When I came, there were about 100 to 200 servers, so that users logged in. Amazon and Google are not yet cloud services. So, I made a cloud-based platform by themselves. Now all is automated, the system is running the system. So, for example, if you think you want 50 databases, it may take 2 minutes or 2 hours, but you can do it.

Q:
Is there a large server center located in a specific place and operating in there?

bank:
There are data service centers in Amsterdam and Frankfurt, London and the size is small, but it is also in Hong Kong, Singapore and New York. But the speed of service is faster in Tokyo and slower going to Porto in Porto.

Q:
What is the intention of preparing a server on its own without using a server provided by another company?

bank:
The start was different. Since we started when there is no cloud, we made our own server system. From now on moving to the cloud would be like dismissing engineers so far, and that is the idea to make better ones and improve it if that is the case.

Q:
About the vast amount of accumulated data, we were told that about 20% of 15 petabytes has been used so far. How do you want to utilize that data?

bank:
I would like to have a doctorate data scientist etc. to analyze the difficult part. By doing so, we can further improve our services and we will be able to provide more information. Without new tools and systems, we can not yet see the black data.

Q:
Is data still increasing at a speed that can not catch up with the analysis?

bank:
That's right, I can not catch up with you. Besides, I think that is also a problem once it catches up.


Q:
I've heard about the A / B test a while ago, but I think that you have plenty of wind-like know-how that makes it easy for hotels to be selected. Is it that there are things that it is easy for hotels that paid a lot for advertising to be easy to choose?

bank:
Booking.com is a service for customers, so it's not like anything but money, and inevitably a good hotel comes up on top.

Q:
Does that mean that Booking.com does not have any intention to control it?

bank:
Like Google's algorithm, it is a specification that a good hotel goes up automatically.

Q:
relieved.