Interview Questions

[Alissa Horner]

Suppose you are being interviewed for a Java developer position and you are asked the following questions. How would you answer them?

You have a Java application that executes SQL queries and you find out that one of the SQL queries is taking a long time to execute. How would you go about finding out why that SQL query is taking a long time to execute?

Clients are trying to send XML messages to your Java Web service, but they are getting connection refused errors. The server on which your Java Web service is deployed is actually running. Your clients are using the correct IP address or URL to connect with your Web service. The IP addresses of your clients have the permission to access your Web service. How would you find out why the clients are getting connection refused errors?

[chris webster]

How would you answer them? The aim here is most likely to find out how you would approach problems like this. If you know the details of any potential solutions, great, but it's also about revealing how you approach problems generally.

For example, what kind of problems might cause your SQL query to respond slowly when executed from your Java application? What happens when you execute a SQL query via Java e.g. do you know how the process is broken up into stages in your Java app, on the app server (if any) and in the database? What else might be going on to impact your query's performance? How could you isolate and investigate these possible causes? What are the possible solutions that might fix these different problems?

[Sam Atkinson]

Yup, Chris has got this one. There's no right or wrong answer, it's simply gauging how you would react and your methods of problem solving.

For the XML one for example, my answer would be something like this: Check the logs. Search for "Exception" and "error", and have a poke around to see what's in there. Hopefully you've got some better support tooling (maybe splunk/geneos etc) which can show what's going on. Next, try the connection myself. If I can use a test client I can check to see if everything works as expected. If it does then it's probably a network/proxy issue assuming that I'm probably on the same network as the server at work. Depending on the demands of the application (are we losing millions of pounds?) I'd probably do a rolling restart, because as all developers know turning it off and on again normally works ;).

When actually answering this question though it would be an interactive discussion so this would probably get fleshed out a bit as we went through.

[Alissa Horner]

Sam Atkinson wrote:Yup, Chris has got this one. There's no right or wrong answer, it's simply gauging how you would react and your methods of problem solving.

For the XML one for example, my answer would be something like this: Check the logs. Search for "Exception" and "error", and have a poke around to see what's in there. Hopefully you've got some better support tooling (maybe splunk/geneos etc) which can show what's going on. Next, try the connection myself. If I can use a test client I can check to see if everything works as expected. If it does then it's probably a network/proxy issue assuming that I'm probably on the same network as the server at work. Depending on the demands of the application (are we losing millions of pounds?) I'd probably do a rolling restart, because as all developers know turning it off and on again normally works ;).

When actually answering this question though it would be an interactive discussion so this would probably get fleshed out a bit as we went through.

Thank you for your input. Is there a tool other than a test client that can check a network connection?

[Jude Niroshan]

Try this out