English: A timezone indicator showing UTC+6 Ру...

I support a web application that is hosted on a virtual private server. The application architecture is JavaEE running under GlassFish on CentOS.

Like most ISP’s, my hosting provider builds vanilla Linux boxes that can be configured with various flavors of the OS.

Out of the box these images have their timezone set to UTC, and since my end users are in California, and I’m not doing anything on the client to handle timezone conversion, the times that come up in the application are off by 7 or 8 hours (depending on whether it’s Daylight Savings time or not. Continue reading

wordpress-logo-notext-rgbI was setting up a temporary WordPress site for a client as a placeholder for their business. All they wanted was their logo, a link to an existing product page, and a message about the site being under construction.

Since they were going to have some design ready shortly, I set them up with a WordPress site, and found a simple theme (Decode by Scott Smith) that their logo would work with.

The owner then told me she wanted to see the site running with SSL (aka HTTPS), so I grabbed a certificate and installed it.

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Recently after an upgrade of my Plesk panel, my web site was down.

In fact ALL of the domains I host on that particular cloud server were not working. A quick call to 1and1’s server guys and it appeared that there was some step in the upgrade process that failed.

They had it fixed in a moment, and then went the extra step to send me the command to fix this myself in the future:

/usr/local/psa/admin/bin/httpdmng –reconfigure-all

That simple command reset all the server config files and got all of the domains working again.

A huge thanks to the 1and1 Server Support guys and Khristian Byrd specifically !!!

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Screen Shot 2013-06-08 at 10.35.06 AMIf you read my previous post (WordPress Recovery), you know I’ve been writing some code to recover my old posts. It occurred to me I could take a small segment of what I’ve been doing with that code to demonstrate my approach to TDD.

Since I’m a hacker from way back, and also because I was in semi-panic mode about losing the content, I didn’t approach this task with testing in mind. Now that doesn’t always result in bad code: I’ve been doing this long enough that I can usually think through a fairly good model and code something that isn’t one long method full of inline code.

In this case however, once I had started coding, I realized again that this was an opportunity to practice coding the “right” way. I had already begun with a Maven project, and generated unit tests as I went through the process of starting to build the code, so I had at least some good functioning unit tests.

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Well, I have the basics of my blog recovered now, so almost all of my posts going back several years are once again available.

In my last post titled Lesson Re-learned: Backups !, I admitted that I had committed the cardinal sin of making changes to my web site without doing a backup first (walking the tightrope without a net).

Luckily for me I had installed the WP Super Cache plugin, so all of my content actually still existed as static files, and being a bit of a hacker, I was able to throw together some code to effectively recover my posts.

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Homer Simpson
Homer Simpson (Photo credit: Wikipedia)

I just shot my blog in the foot, or more accurately, I didn’t follow IT 101 and back things up before making a change.

I had moved my site to be completely WordPress based a while ago, and as a result I had a bit of a convoluted setup on my server.

When I first set up my WordPress blog it was as a sub-domain of accuweaver.com, and was housed at http://wordpress.accuweaver.com/ (also aliased to http://blog.accuweaver.com/). The http://www.accuweaver.com/ site just static pages that hadn’t changed for years.

So when I finally got my blog set up to host the few static pages I had, I just changed the directory on my server to have a symbolic link to the directory where wordpress.accuweaver.com had it’s content:

  1. Removed the directory httpdocs from /var/www/vhosts/accuweaver.com
  2. Added a link in that folder to /var/www/vhosts/accuweaver.com/subdomains/wordpress/httpdocs.

This actually worked really well, since the content was only in one place, and all I had to do was change the host name in WordPress. Continue reading

I was reminded a couple of days ago of the danger of using tools that help you to get things up and running quickly, by a question that I was asked in an interview. The question was pretty simple, but not something I’d thought about for a while, which was: “What are the verbs used in RESTful services?”.

 

Now intuitively I know that answer, but hadn’t really thought about it for a while, so I basically answered incorrectly (mostly because I suck at inteviews), only remembering that you do GET and POST in HTTP, so responding that GET is to query and POST is for inserts/updates.

Of course I know the reality (and one of the advantages) of RESTful services is that they behave by contract, so they can use the full complement of the HTTP verbs, and the convention is to use each one for a specific purpose:

  • GET – used to get or retrieve a resource (always returns the same resource for the same query).
  • POST – used to create a new resource (returns the location for the newly created resource).
  • PUT – used to replace a resource (typically an update).
  • DELETE – used to remove a resource
  • OPTIONS – sometimes used to describe information about what verbs a service can use for a specific URI (not normally implemented however).

But the last few times I’ve done RESTful services, I’ve simply let an IDE generate them for me, so I haven’t even thought about those last statements. In the IDE, all I had to do was say I wanted to add REST (using Jersey) to my session beans, and voila, I have a full fledged RESTful service.

And of course on the consuming side, all I have to do is call the right method, and under the covers the Jersey client stuff does the right thing about which verb to use. So I’m not actually thinking about what’s under the covers, and because of that wouldn’t be quick on my feet about how the service is constructed under the covers.

There are of course pros and cons to approaching code in this way. In the early days of writing code, we all had to know what the machine language underneath looked like. Modern languages hid that complexity from us, and reading assembly language became a lost art practiced by rocket scientists and performance gurus.

By hiding the complexity we have been able to develop insanely complex applications that would not have been possible without those building blocks. Freeing ourselves with increasingly general patterns in code, we are able to focus on solving the problem at hand, and stand on the shoulders of those that go before us in doing so.

I don’t expect to need to write a RESTful service from scratch any time soon, but it is a good reminder that when you rely on tools to build your code, you are risking living with a lack of understanding of the underlying mechanism, which could make it difficult to know about the pros and cons of a solution.

 

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