Category Archives: Programming

Out Of My Comfort Zone: Building a Web App

If you read Fundamentals of Storage Systems – Stripe Size, Block Size, and IO Patterns you know I built a little web tool to help you with sizing and estimating your RAID array’s performance. This is way out of my area of expertise. Luckily for me I like a challenge and had a guiding hand from some friends. I haven’t done any web programming since I wrote a photo album mod for Snitz! forum package in 2002, using classic ASP. I still get thank you emails from folks that have been running it for years. Needless to say my skills are a little rusty. My first instinct was to fire up Visual Studio 2008 and build an page tied to a back end SQL Server 2008 database. Well, is just different enough that I was struggling to do the most basic things. So, I thought it would be good to “get back to basics”. A very good friend of mine has been a professional web developer for the same company since about the time my photo album came out. He lives and breathes web technology. The problem was he doesn’t do at all. Everything he does is standards compliant HTML and JavaScript. I told him about my spread sheet of calculations and my desire to turn it into a web page. Joe quickly begged me to leave him alone. Once I calmed him down, he did a little sample page to get me on the right track. I took a look at it and thought it would be easy to goof around in this JavaScript stuff. I was wrong. What a convoluted world web developers live in.

I hacked on it the weekend before Christmas and was pretty happy with my handy work, right up until I showed it to some people. Comments like “Kill it with fire!” were common. I explained what it was and that took some of the hostility out of the feedback. The next Monday I asked the two lead web heads at work to look at it. Once Ben had washed his eyes out with bleach he told me under no certain terms could he fix it. My powers of persuasion, and a threat to never approve another schema change, helped bring him around. He explained several new technologies to me I wasn’t aware off, like CSS. Ben showed me quickly how to format the page so peoples heads wouldn’t burst into flames when they saw it. He also spoke of things like Ajax and JSON. Being the clueless data guy that I am I turned to my trusty friend yet again, Google.

Quick Definition List

JavaScript, the underpinning of the modern dynamic web 2.0 world.

Ajax (asynchronous JavaScript and XML, a group of interrelated web technologies that allow for dynamic web design.

JSON (JavaScript Notation), a lightweight data-interchange format, a way to structure data like XML implementing name/value pairs and ordered lists.

JQuery, a JavaScript library used to traverse HTML elements and build dynamic content easily.

JavaScript Implementation

What struck me was just how much had changed, yet stayed the same. One of the things I’ve always hated is no two browsers render the page the same way. If it worked in Firefox it didn’t work in IE. The other thing I didn’t realize for quite a while was any of the browsers would happily run the worlds worst code. I’m not talking poorly written code, I mean flat wrong. They will let any old JavaScript run. JavaScript is defined as a loosely typed language. The way it is implemented it goes from loosely to sloppy very quickly. Don’t get me wrong here. The language specification EMCAScript, is solid. The implementations are very poor in most browsers and that is where the problems developing for JavaScript really come in. I’m not saying JavaScript is slow, quite the opposite in fact. It is just difficult to make sure you are actually writing the correct code. Having worked with Visual Studio for quite some time, I’ve become spoiled with having my IDE tell me when the syntax is wrong before I hit the compile button. So, I was back to Google again looking for tools to help me out.

The Tools

I quickly settled on Aptana Studio 2.0 to do the actual code work. I also used Notepad ++, which is by far the best text editor in the world. with Aptana Studio allowing me to see errors in real time and use the preview function to look at page renders without having to have browser windows open. I did look at Microsoft’s new Expression Suite 3.0. It is nice. The designer is slick, but in typical Microsoft fashion it mangles some parts of the code that I then have to fix by hand. Aptana Studio also has a built in JavaScript minimizer that shrinks the size of your JavaScript files for quicker load times. Aptana Studio doesn’t enforce the use of line terminators and when I compacted my JavaScript it wouldn’t load. I did some additional digging and found an awesome Lint tool for validating JavaScript JSLint. My favorite thing about it is the quote and link on the front page “Warning: JSLint will hurt your feelings.” I knew I had found the right tool. After several passes I got my code to validate and minimize without any errors. I quickly looked for other Lint based tools and found one for JSON as well JSONLint.

The Work

Over the course of a few weeks I tinkered with the page, adding features, correcting mistakes and cleaning up the layout. The biggest thing that I learned is just how fast JavaScript can be. Even after I did the initial page I had no doubt a database would be involved at some point. I had compiled a small database of hard drives and their characteristics and wanted to add that to the page. The problem was I would basically have to redo the page again in or some other dynamic language to pull the data from the database. So, I cheated. As a proof of concept I built a JSON structure with a sample of the data to load the drop down list box and all the variables dynamically. I was stunned at just how fast the page was to respond. I hacked together some T-SQL that would generate the JSON object from my database, all 1200 entries. I cleaned it up a bit made sure that JSONLint validated it ran the minimizer on it and plugged it in. Holy cow, it worked! It was also still very vast. I just couldn’t believe it. The only drawback is having to update the JSON if I add new drives to the database.


What I’ve Learned

The main takeaways for me on this project are simple, web development stinks. Now I know why web folks have a hard time with T-SQL, they already have to be experts in five or six different technologies across two or more platforms. I use to introduce Joe as “My friend who does JavaScript”, now I know is is a hard core developer! What I build is simple and works. I think the layout is tolerable. If you have any suggestions or feed back just drop me a note.

Understanding File System IO, Lessons Learned From SQL Server

I do more than just SQL Server. I enjoy programming. In my former life I have worked with C/C++ and Assembler. As I spent more and more time with SQL Server my programming took a back seat career wise. Having that background though really helps me day in and day out understanding why SQL Server does some of the things it does at the system level.

Fast forward several years and I’ve moved away from C/C++ and spent the last few years learning C#.

Now that I work mostly in C# I do look up solutions for my C# dilemmas on sites like and I love the internet for this very reason, hit a road block do a search and let the collective knowledge of others speed you on your way. But, it can be a trap if you don’t do your own homework.

I write mostly command line or service based tools these days not having any real talent for GUI’s to speak of. Being a person obsessed with performance I build these things to be multi-threaded, especially with today’s computers having multiple cores and hyper threading it just makes since to take advantage of the processing power. This is all fine and dandy until you want to have multiple threads access a single file and all your threads hang out waiting for access.

So, I do what I always do, ask by best friend Google what the heck is going on. As usual, he gave me several quality links and everything pointed to the underlying file not being set in asynchronous mode. Now having done a lot of C++ I knew about asynchronous IO, buffered and un-buffered. I could have made unmanaged code calls to open or create the file and pass the safe handle back, but just like it sounds it is kind of a pain to setup and if you are going down that path you might as well code it all up in C++ anyway.

Doing a little reading on MSDN I found all the little bits I needed to set everything to rights. I set up everything to do asynchronous IO and I started my test run again. It ran just like it had before slow and painful. Again, I had Mr. Google go out and look for a solution for me, sometimes being lazy is a bad thing, and he came back with several hits where people had also had similar issues. I knew I wasn’t the only one! The general solution? Something I consider very, very .Net, use a background thread and a delegate to keep the file access from halting your main thread, so your app “feels” responsive. It is still doing synchronous IO. Your main thread goes along but all file access is still bottle-necked on a single reader/writer thread. Sure, it solves the issue of program “freezing” up on file access but doesn’t really solve the problem of slow file access that I am really trying to fix.

I know that SQL Server uses asynchronous un-buffered IO to get performance from the file system. I did some refresh reading on the MSDN site again and struck gold. Writes to the file system may OR may not be asynchronous depending on several factors. One of which is, if the file must be extended everything goes back to synchronous IO while it extends the file. Well, since I was working with a filestream and a newly created file every time I was pretty much guaranteeing that I would be synchronous no matter what. At this point I dropped back to C++. I started to code it up when I realized I was doing things differently in my C++ version.

I was manually creating the file and doing an initial allocation growing it out to the size the file buffer and the file length on close if need be.

I started up my C++ version of the code and watched all the IO calls using Sysinternal’s Process Monitor. I watched my C++ version, and lo, it was doing asynchronous IO in the very beginning then switching to synchronous IO as the file started growing. I fired up my instance of SQL Server and watched as the asynchronous IO trucked right along…. until a file growth happened and everything went synchronous for the duration of the growth.


So, taking that little extra knowledge I manually created my file in C# set an initial default size and wouldn’t you know asynchronous IO kicked right in until it had to grow the file. I had to do a little extra coding watching for how much free space was in the file when I get close I now pause any IO,  manually the file by some amount and then start up the writes again keeping things from going into a synchronous mode without me knowing.

So, there you go my little adventure and how my old skills combined with knowing how  SQL Server works helped me solve this problem. Never assume that your new skills and old skills won’t overlap.