Favourite Interview Process

Last month I resigned my post from daft.ie and am about to take up a development position with dotMobi, a leading mobile Internet services company. I had done interviews with several places, while reading plenty of articles on various other companies’ hiring practices. At the end of these couple of months, I came to the conclusion that in all my professional career, Daft had the best hiring process for a developer that I had ever both experienced and read about.

The process

Initial interview

First up, as with all jobs, you submit your resume/CV. This is then screened over by the development manager, who invites adequate candidates to a first-stage interview. This interview consists of him and another developer, basically going through the CV with the candidate, asking some general programming related questions, all just to try and get a better overview of the person, ensuring they pass the “no jerks” policy.

Programming Assignment

This is the main beauty of their hiring process, and is discussed in more details below. Candidates are given an assignment to work on in their own time at home, typically over a weekend. The assignment asks the user build a simple web form, with one text input to take free-text search strings that a user might enter when searching for property. They even give sample queries, such as “2 beds for sale in Dublin”. This string is to be submitted to a PHP script where all the necessary data is to be parsed from the string. Once parsed, a call is to be made to the Daft database via their API in order to get a list of results back. This result set is then displayed to the user. Finally, they need to write-up their code, explaining what’s going on in simple English.

Second Interview

Assuming you do a good job in the assignment, you’re then invited back for a more formal interview with senior management (company of about 60 people), to discuss career aspirations, salary requirements etc.

Why I think this is great

Skills it shows

As mentioned earlier, the key part of the process is the programming assignment. First up, the initial entry form and data submission. Here the user can show their knowledge of web security, CSS, (X)HTML standards and more. While none of these are actual requirements, it’s an easy place to show existing, fundamental web knowledge.

Once the data’s at the server, cleaned and verified, relevant data blocks (e.g. area, for sale/to let, number of bedrooms etc.) need to be parsed from the string. There are a number of different ways to do this and gives the developer plenty of scope for flair. A certain amount of analysis is required here also, mapping the domain of real estate to known keywords and looking for these in the string.

You also need to try and spot any relevant areas (e.g. County Dublin, Galway City etc.) the user may have entered. Without going into too much detail (in case potential candidates are reading this), there’s a key optimisation when doing this via the API and it’s a great way to spot those who have been programming seriously for a few years. Even if a programmer doesn’t implement this optimisation, they should still be aware of the problem it solves; this awareness can come across in their second interview, which is also accepted.

Once you know what the user is searching for, you then need to build a call to Daft’s SOAP API. This is good because it usually requires the candidate install PHP’s SOAP interface. While not overly complicated, it’s not trivial either and shows that the candidate is able to play around on a UNIX machine. Using the API also illustrates a candidates ability to follow documentation and quickly get to grips with a new system. Finally, by building a query from your parsed data that can be understood by the API, the candidate again has a chance to show some good, tidy code.

After pulling data from the API, the candidate again has a chance to show off XHTML/CSS skills to display the results set. Further ‘enhancements’ could be shown by doing all this over AJAX, without a page reload.

Finally, the candidate needs to document their code. This will illustrate communication skills, their attention to detail, writing skills (grammar, spelling) and more. Everyone in the software industry knows that communication is a large part of software development and it’s important to have good communicators on your team. Good code followed by an average write-up can often be less preferable than average code (which is generally easier to improve on) with a good write-up.

Why it’s better than others

While reading about other people’s interview experiences, one thing that stood out as annoying most developers is white-board coding, i.e. where you’re required to write some code on the fly, either on a white board or piece of paper. This a completely unrealistic situation and is asking a programmer to do something way outside their normal environment. Similar to this would be writing a program in the employer’s office in the space of an hour to 90 minutes; again this is wholly unrealistic as programmers are used to their own environment, have their own tools etc. The beauty of the Daft assignment is that it’s too tricky to do in less than two hours, plus they let you do it at home on your own machine. Yes, this does allow for potential plagiarism, but once you’re offered a job, you’re put on 6 months initial probation, so if you don’t code your assignment it’ll soon become obvious and they’ll have scope to not make you permanent.

Another great thing about it is that there’s no generic analytical questions such as “Why are man-holes round?” or “How many ties were sold in New York City last year?”. The value in asking these questions is surely waning these days, as they are easy enough to prepare for and people have learnt to expect them. Good programmers need to be good at analysis, but enough information about a candidates skills can be gleaned from how they approach the assignment.

Finally, there’s no over-bloated 7 round interview process. From the 2 interviews a candidate does, coupled with the assignment, it’s very easy to see what a person is like and that they’ve a decent level of programming competency.

One flaw

Not everything’s perfect and after chatting to my manager about the interview process, in preparation for this blog post, he pointed out that it’s poor at highlighting any “rockstar” programmers, as well as any existing systems administration skills. So, if you have 2 people competing against each other, one a decent programmer, the other amazing, it can be hard to differentiate between the 2; what’ll happen more often than not is that the ‘nicer’ one will be offered the job first.

Conclusion

From the above, it should be easy to see that current interview processes are far too complicated. 2 interviews will always be the least that’s required, but when you throw in a slightly complicated programming assignment, there shouldn’t be need for much more. The assignment’s a good way to test programming competency while the interviews are good to test a person’s likeability and career aspirations.