You Know One Programming Language, You Know Them All…(sort of, don’t forget…. Time is Money)

I know that all two of my faithful readers out there (hi mom, hi dad), want to know how my job search has gone. Well… it has gone really well. I found myself a really good gig working for a product based company, that writes software for network tools. But make no mistake, the interviews I went on made me feel like I was back in college. All of a sudden, I was up all night studying the different algorithms to sort trees, explain TCP/IP, and making sure I can discuss the languages I know like the back of my hand, and at least show some understanding of the languages I don’t know.

The job who offered me the job had a pretty grueling, 5 hour interview. I guess I did pretty good considering that many of the questions revolved around Ruby, Perl, and the Rails framework. All of which are concepts I’ve only read about and briefly touched in my early days. During the last 2 weeks at my previous job, I got into some debate about the importance of Computer Science and Software Engineering fundamentals. My old job consisted of quite a few people who believed that if you are a pretty good programmer in one language, then you can easily move to another language. They believe this because, other then some syntax differences, all languages are the same… Right?  Well, sort of.

You see, some languages are compiled, some aren’t. Some languages are object oriented, some aren’t. Some languages are interpreted, and some aren’t. These are all important attributes of a language, and will affect how your code. Interpreted languages are more flexible, but can have some performance issues, so you need to keep that in mind if speed is a need. Object oriented languages are wonderful to design with, but tend to carry a lot of overhead. What if you are a Java programmer, taking a job writing C code? That’s when you realize that garbage collection has made you dependent. But that’s not all. Different software has a different purpose, which is important. Are you going to be writing client/server code? Client only code? Web based applications?  The concept of using HTTP is much different then writing a client side application. 

So, where am I going with this?  I managed to convince this company, which works in an area that I am unfamiliar with, with code that I rarely, if ever use, to hire me. It wasn’t only because I am a pretty good Java programmer, but I showed that I understand computers, networks, software, and the fundamentals of Computer Science and Software Engineering. I showed that I have the initiative to learn what I don’t know, and take the challenges head on.If I would have went into the interview with just my Java history, then I wouldn’t have gotten the job. What my old coworker didn’t understand is that time is money. If you cannot prove that you will be up to speed in a timely manner, then they have to make their decision based on that. Companies don’t want to waste time and money on someone who doesn’t understand fundamentals. Especially when there are others out there who want the job too. You only have a short time during the interview to prove why you are better then then next guy.

During my first couple week at the new job, I’ve been learning all I can and diving right into Ruby on Rails with ext JS. My oop and Java history has helped me pick it up pretty quickly, but I made sure going in that I already started learning. There was one mistake I made the other day, that I spent hours trying to figure out. It wasn’t until I asked the guy in the cube next to me what I was doing wrong, and he picked out a syntax mistake right away. I didn’t realize that back ticks ( ` ) actually meant something But it did show me that syntax is not as trivial as many believe. So my advice to you is to learn about the company that you are interested in. And learn their technologies. At least be able to discuss the concepts, but don’t be afraid to tell them you don’t know something. Just as long as you let them know that you will know it.

My Common Interview Questions… Technical and Introspective

With all this focus I’ve had on finding another job, I started to look at the questions, and standards I have when interviewing a candidate in my company.  My upper management doesn’t like my questions, because I tend to lean more towards the computer science/software engineering side of the candidates skill set. Where my management would rather me evaluate their ability to show up to work on time (not that I’m bitter or anything). You see, I work for a service based company. One that get’s paid for “warm bodies”. They don’t have a large amount of pride and discipline for the engineering craft. Which is one of the main reasons I am looking for another job.

Anyway, I digress, my focus on what I bring to an interview, has been improved by my own interview questions. I like to use these to determine if someone is as average a web geek as I am.  I've collected a bunch of questions that are technical, but also inquire about the candidate’s professional and technical personality.

General Questions:

• What sort of websites, blogs, and/or user forums do you follow? This is an open question, and there is no right answer. But anyone who is claiming to be technical should have a decent list of online resources for which they can learn, and stay on top of topics. For example, on a daily basis, I browse Slashdot, darknet, coding horror, DZone, Ben Nadel's ColdFusion blog, OWASP.org, and javablogs.com, among others.
• If you are developing an application, and you come across an error that you've never seen before, what would you do? The wrong answer in this case is to ask someone in the office right away. Even though I pride myself to being a good resource for my co-workers, many times, the answers to all problems could be as simple as a google search. There should be an amount of time spent in research before they ask others to take the time to supply help. The previous question is a good lead into this because, if a developer has a good set of online resources, then they can solve most of their problems fairly easily.
• How many web vulnerabilities are you aware of? And what can you do to prevent them? There are plenty to choose from, such as Reflected Cross Site Scripting, Persistent Cross Site Scripting, SQL Injection, Code Injection, Invalid Session management, Using default configurations, weak  encryption, improper error handling, poor input validation, weak authorization and authentication, and cross site request forgery, to name a few. The solutions to these problems include education, proper design, code review, testing, and common sense. A Good experienced programmer would recognize most, or more, of these. A mid-level programmer should know at least 4 or 5. A low level programmer would probably only recognize SQL Injection and cross site scripting.
• Follow up question, what is the difference between Reflected Cross Site Scripting and Persistent Cross Site Scripting? Reflected is a flaw in which the user's input is reflected back to the user, this can cause a problem by allowing JavaScript code to be run in the browser. Persistent is when a similar flaw is saved to some persistent storage. Being able to answer this shows that they are not just reading buzz words.
• Are you familiar with JavaScript? If so, how do you debug JavaScript? There are many tools out on the internet to help with JavaScript and CSS debugging. For example, I use FireBug, a plug-in for the Firefox browser to determine how JavaScript is running.

Advanced Programming:

• Explain the benefits of Object Oriented Programming, and describe some techniques that can be used with of OOP. The benefits include improved maintainability, design, portability, modularity, and extensibility. Some techniques include data abstraction, encapsulation, modularity, polymorphism, and inheritance. As a follow up, ask to explain examples of each.
• What are the differences between using stored procedures in a database vs writing the logic in a language like Java, and then calling the data with normal SQL queries. The DB stored procedures are compiled on the DB, so you can get better performance, but there is added complexity, since you may have different code based on different database’s.  This question shows that the candidate knows databases, and not just how to run SQL queries.
• How would you debug a performance problem?  For example, if you have a web page that takes a long time to load, how would you debug it? This is a pretty open question. The candidate should be wondering, is this a static or dynamic page? Is there a lot of data? Large Images? Media? Try to determine where the performance problem is. Is it the Database? Check the SQL queries, analyze the database connections when the page loads. Is it the Code? Review the code for intensive loops or data calculations, watch the resources on the server, when the page loads. Is it the Network? Run traceroute or a network sniffer to look at how the packets are being transferred. All of these are potential areas for a performance problem.
• Can you explain the differences between SOAP based web services and RESTful web services? SOAP is a standard, created by the W3C, that defines a request and response message for web services. REST is an architectural design which relies on XML, and HTTP request types. A follow up question would be to ask where you would use each.
• Are you familiar with Aspect Oriented Programming (AOP)? If so, what benefit does it provide? Most experience developers should at least understand the concept of AOP. AOP allows for separating redundant code from modules so the developer can focus on the task at hand of the module. This saves development time, and improves maintainability and modularity.

Mid-level Questions:

• What are 4 different types of scope used in web based programming languages like Java? Application, request, session, and page.
• How would you loop through the GET and/or POST request parameters, when you don't know the names of the request parameters? This can be different depending on the server side language the candidate is being interviewed about, but they should all recognize the name-value pair characteristic of the request. In Java they can easily use request.getParameterNames() for an array of names. A followup question is to ask what sort of information is passed in the request. The candidate should be able to talk about the header information.
• How would you design a multi-tiered application to separate display from business logic? This can be answered in many ways, but using a framework, an object oriented design, and or a design pattern,  can accomplish this. The key focus it to try to try and keep the HTML from getting cluttered up with logic code.
• What software frameworks are you familiar with? Each language has their own frameworks. In Java there are quite a few, including Struts, Spring, Seam, and JavaServer Faces. A mid level programmer should be able to understand frameworks, at least on a high level.
• What are some of the differences between Oracle and SQL Server, in terms of how the SQL is written? Most of the differences are with the out of the box functions, like getting time stamps getDate() for SQL Server, and SYSDATE for Oracle. But the SQL queries themselves are slightly different, especially with joining tables. SQL Server uses LEFT and RIGHT OUTER/INNER Join Syntax and Oracle has a short hand notation of using (+) to represent an outer join.
• What are the benefits and disadvantages of Normalized vs. Non-normalized database design? Normalized database tables are easier to use, understand, and cuts back on redundant data. However, non-normalized table perform better.  Typical web applications use a normalized design, but reporting applications sometimes uses a non-normalized design to be able to run queries with a lot of data)

Low level programmer:

If the interviewee only answer a few of the questions above, then chances are, they are a low level programmer. If they are claiming more then 5 years experience, and cannot answer any of the above questions, that should be a red flag. However, someone with 2-4 years experience is still learning, and you could ask them how they keep up on the new technologies.

Overall, different organizations have different requirements for who they hire. Some have a strict budget to follow, others have a reputation to uphold. Regardless, the interviewer should have the knowledge of who they want on their team. If the person performing the interview cannot answer the questions they are asking, then it can be very easy to hire the wrong person.

Software Engineer Job Interviews

About 2 months ago, I was notified by a friend, about some job openings for Software Engineers, at her company.  I am pretty comfortable in my current position, but this other company looks pretty cool. Things like flex time, no dress code, high tech environment, and free coffee, makes me think that it could be the perfect job.

After a couple hours of research, it also looks like this company has high standards and employs really talented people. Not just a “Web Development” company, they expect you to understand Big O notation, and different design patterns. I consider myself an “Average Web Geek”, but I did receive a Masters in Computer Science, and my interests have always leaned more towards the engineering of software, compared to the assembly line culture that some IT companies represent.

I talked to the recruiter of this company, pretty standard stuff. She tells me that there are 4 phases to the interview process. There is first contact, that is that talk with the recruiting officer. Then there is a “homework” assignment, so the engineers can evaluate my initial coding skills. Then there is a phone interview with an engineer. Finally, there is a face-to-face. With the exception of the “homework” it is pretty standard.

Now, I should explain, I enjoy my job. But I am frustrated by the lack of a technical track. My company is looking for people to build web sites, then spend the rest of their professional lives as non-technical managers. I am also realizing there is a significant amount of co-workers who do not take as much pride as I do in engineering, and innovation. I consider myself the “Average” web geek, because I don’t see myself as anything special. Though, when I look around my office, I see a lot of people who are comfortable with their position, and the fact that they have no need to advance their knowledge, or experience. So, as happy as I am, I need to expand, and continue to advance my technical experience. This other company looks to have the direction I want to focus on.

The recruiter sends me the assignment. There are a couple questions about object oriented programming, and a Java interface for which I am required to supply an implementation. Question 1 is “What is an abstract class? Describe a common pattern that requires the use of abstract classes?” This is interesting. Normally I would use this as a question in a phone interview. It is a pretty basic question to test someone's basic object oriented knowledge. The other questions are specific to Java.

Based on the Job description, I know that they want an engineer with a large amount of Java experience, along with Spring, Hibernate, and JUnit. So, even though it isn’t required, I make sure that the code I send with the implementation class, contains these these concepts.

After a couple weeks, I hear back from them. They want to to set up a phone interview with a Lead Engineer. At this point, I am pretty excited. They seem like a pretty high tech company, with some really smart employees. So, I agree with excitement. The call comes in a couple days later. I take the call in the parking lot of a Trader Joes. I was expecting the interviewer to ask about my Java experience, shoot me some questions about Spring and Hibernate. Maybe test my knowledge of Java core concepts. But no, he hits me with a question to evaluate how I think.

He says “Lets say you are designing a card game, and you need a method to shuffle the cards. Describe the algorithm to do it.”

This question is very familiar, since I had it as a test question in my algorithms class during my graduate studies.  Unfortunately, that was about 8 years ago.  Though it shouldn’t be too hard. So, my first answer is to use 2 arrays. 1 contains 52 Card objects, and the other is empty. Then, using a random number generator, I would grab cards at random, and store them in the other array. Now, my current job hardly requires me to consider algorithms which are really speedy. Our datasets are small, and the schedules are short. So, usually the first solution is fine.  So, I was expecting his next question… “What about the blank cells in the original array? Are you concerned about those?”

Yes, of course. So, without thinking about redesigning the algorithm, I tell him that each time we remove a Card object, we can recreate the array with the size decremented. As I am talking I am realizing how stupid, and inefficient this sounds.  So I say, “It will work, but it isn’t efficient.” He then asks me to describe the performance in Big O notation. So…. there are n Card objects in the array (n = 52) , looping through the array n times to remove the Card objects. Then I would recreate the array as n-1, for each card. That is n*(n-1). Making the performance O(n^2), aka quadratic. Not very good considering that there is a better way.

After a couple minutes, it comes to me. There is actually a much simpler solution. I don’t need 2 arrays. Using just the original array of Card objects, I can generate 2 random numbers, and swap the cards. The random number generator, and swap function, would run in constant time, O(1). That leave the number of iterations. Therefore, the performance is O(n), aka linear. Much better.

The following code represents this algorithm:

public static void shuffleCards(Card[] deck) {
  Random generator = new Random();
   // shuffle the cards
   for (int i = 0 ; i < deck.length ; i ++) {
       int x1 = generator.nextInt(n) + 1;
       int x2 = generator.nextInt(n) + 1;
       Card card1 = deck[x1];
       Card card2 = deck[x2];
       deck[x1] = card2;
       deck[x2] = card1;
   }
}

This was the answer he was looking for. At this point, I could have pointed out that the code could be simplified by using the java.util.Collections class, which has a shuffle(List<?> list) method, and runs in linear time.

The phone interview continues with me asking questions about companies, and him asking a couple more questions about my experience. I guess I made an impression, since the recruiter schedules a series of face-to-face interviews. That will happen in the next week. So we would see what happens.

The moral of the story is, that there is a difference between being a average web coder, and a software engineer. I want to see what else is out there, so I have to break out of my IT shell and focus on the foundations which I learned in those Computer Science courses. It is very easy to grow comfortable and content in a stable position. But time keeps moving, and if you don’t keep learning, you can find yourself stuck. I hope one day I’ll consider myself to be more then just an Average Web Geek.

News About Programmer Jobs

I read in the October 16, 2006th copy of Information Week, that jobs for coders is starting to stabilize. The article has a dark view on this news, mainly because the amount of jobs is not going up. However, I see it differently. Overall, since 2000, the number of employed programmers has dropped about 200,000. While the number of people who considered themselves programmers, has dropped as well. I started my professional career in 1998 as a Java developer for an IT consulting firm. We got torn to shreds when the dot com crash of 2000/2001 hit. I was one of the lucky ones who managed to stay employed. I saw a lot of friends out of work. Every year it seemed like things were getting worse.

So, now, with the programming jobs becoming more stable, things look much better. I would rather that the jobs remain stable, then go down hill. The article lists updating legacy systems, customizing apps, and writing new apps as positions where developers are in high demand. One thing is certain though, technological progress will continue, therefore, programmers, and software engineers, will always be needed.