Don't Worry About Performance!

There was a statement made a number of years ago in an ISWG (Integration Services Working Group) meeting which, to summarize, said "Don't worry about performance, we'll take care of that".  While that is probably going to be the epitaph of at least one person, I think it is time to set the record straight.

Worry about performance.

OK, now that we've gone 180 degrees it's time to put some parameters around this.

• Don't worry about things over which you have no control.  The speed of a DCOM call is something you have no control over, neither is the time required to create a connection for a connection pool, the time required to retrieve session state, nor the time required to process an HTTP request.
• Do worry about things over which you do have control.  While you can't do anything about the speed of a DCOM call, you can control, to an extent, the number of DCOM calls that you make.  Less chattiness is better.  While you do not have control over the speed of the resources, you have control over how effectively you use those resources.

The UAT and Production environments into which your application will eventually move has a myriad of interconnected pieces that, together, create the environment in which your application will exist.  While you cannot control those resources you control how you use them.  <Al Gore>  Ineffective use of resources and our unwavering dependency on technologies that produce greenhouse gases is threatening our livelihood and our very planet.</Al Gore>  Ineffective use of resources in any ecosystem is bad, whether that ecosystem is our planet, or our clustered production environment.  Infinite resources are not available and never will be, but effective use can be made of existing technology:

• Up until the late 1990's the computers on board the Space Shuttle flight deck were Intel 8086 chips.
• The original Xbox had a 733MHz CPU with 64MB of memory and yet it could (still can) outperform peoples desktops.
• Mission critical systems have been designed with, when compared to modern technology, primitive means.
• The first spreadsheet I used, Visicalc, ran on a 1 MHz processor.

All of these examples show that you can make something run well in limited circumstance, but you have to want to.

Identity Theft

I guess I can say that I am now a statistic.  You know, one of those millions of people who have been the victims of identity theft.  Let me tell you the story.

When I got home from work on Monday I noticed that I had supposedly been sending out emails from eBay account at lunch.  Within 15 minutes of the start of the emails I received an "A26 TKO Notice: Restored Account" from eBay UK stating that:

It appears your account was accessed by an unauthorized third party and used to send unsolicited emails to other community members, including email offers to sell items outside of eBay. It does not appear that your account was used to list or bid on any items.

The first thing I tried to do was log into my account.  Well, something either eBay UK did or something the hacker did was change my password.  I tried to enter in my answer to the Secret Question, but that didn't work either as the information on my account had been changed.  Following the various prompts on the eBay site I ended up sending them an email telling them what had happened and what the next step should be.

A couple of hours later I got another email that I apparently sent out eight hours after the first round.  Not content to sit by and wait for the email process to work its way through the system I then started scouring the eBay site for a phone number to call.  You know, that is one of the hardest things I had to do!!!!  I followed all the usual routes and ended up with forms to fill out.  I never did get a phone number, so I had to use their "Live Help" facility.  (My reluctance to go with this approach was due in part to a 45 minute wait on the weekend for "live help" from another company, which never even connected with a human being.)  In the case of eBay, however, the wait was less than two minutes, they told me my position in the queue (started at number 5) and the approximate wait time. 

The person who was on the other end of the chat could have been anyone, anywhere in the world.  The fact of the matter is, they looked at the information on my account, the notes they had sent to me and knew that I needed to talk to the Account Security division.  Within 30 seconds I was "chatting" with someone else who had the power to help.  Two minutes later things were fixed and that included changing the password on my account to a "stronger" password.

Was it brute force hacking of my account and password?  Not if this article is correct.

This particular episode was rather benign in that all that really happened was that some emails got sent and I had to change my password.  It could have been worse.  Much worse.  Think of that the next time you sign up for a web site.  Or, more importantly, think of that the next time you are building an externally facing application.  What are you doing to safeguard the information that you keep on your clients?  What are you doing to protect their safety?  Can you honestly say that you've done your best?

Creative Juices

One of the best things to do, in order to keep the brain alert and creative, is to read different things.  In the same vein, writing is a good therapeutic use of brain cells.  It keeps the neurons working and allows you to be more creative in your job.

To that end, I would like to introduce National Novel Writing Month.  In essence, you are being challenged to create a novel (50,000 words) in less than a month. That's 1500 words per day.  You are considered a "winner" if you actually succeed at getting in 50,000 words.  They don't have to be perfect, you just need to try.

In this case it is definitely the journey which is important, not the final product.  By pushing yourself to reach this goal you are going to be exercising a variety of different areas of your brain.  You will need to be creative to come up with a plot (and subplots), with characters that you empathize with and the words that tie all of this together.

So, how does this help you in the IT field?  I think you would be amazed at how much it will help.  People talk about "thinking outside the box" in order to get something done.  The problem isn't so much thinking outside of the box, it's understanding where the box is in the first place!!!  As you start writing the novel you will be able to see the box that you have created around your novel and this insight, this new vision that you've gained, can help you see the boxes that surround your problems.  Being able to see something is the first step in being able to avoid it or, in this case, think outside of it.

Are you suddenly going to see everything in a new light?  No, but by constantly stretching and pushing your own mind you will see the limitations (the box) that you have put around yourself.

The Dark Side of Objects

The Dark Side of Objects?  (Luke, I am your father.) 

Sometimes you need reins on developers and designers.  Not because they aren't doing a good job, but because if you don't you may end up in a quagmire of objects that no one can understand. Objects are good, but they can be overdone.  Not everything should be an object and not everything lends itself to being objectified.  Sometimes a developers goes too deep when trying to create objects.

When I was learning about objects I had a great mentor who understood the real world boundaries of objects:  when to use them, how to use them and far to decompose them into additional objects.  Shortly after having "seen the light" with regard to objects I was helping a young man (okay, at my age everyone is young) write an application which was actually the sequel to the data entry application I mentioned in the previous note.  He needed to do some funky calculations so he created his own numeric objects.  Instead of using the built in Integer types he decided that he would create his own Number object.  This number object would have a collection of digits  When any calculations needed to be done he would tell one of the digits the operation to be performed and let that digit tell the other digits what to do.  Well, this gave him a method whereby he could perform any simple numeric operation (+-/*) on a number with a precision of his own choosing.  He spent weeks on perfecting this so that his number scheme could handle integers and floating point numbers of any size.  It was truly a work of art. 

And weeks of wasted time.

What he needed to do was multiple two numbers together or add up a series of numbers.  Nothing ever went beyond two decimal points of precision and no amount was greater than one million.  These are all functions built into the darn language and didn't need to be enhanced or made better.  The developer got carried away with objects and objectified everything when it didn't or in this case, shouldn't have been done.

Knowing when to stop using objects is just as important as knowing when to use objects.

Long Running Web Services

OK, the world is moving to web services.  I know that.  You know that.  So what more is there to discuss?  PLENTY!! For instance, how long should it take for a web service to complete?

Well, that's kind of a tricky question.  It basically comes down to "what is the web service doing?"  Some things should come back quickly.  Darn quick, in fact.  For instance, if you ask a web service, "What is the name of the person associated with this identifier?" you should be getting a response back in milliseconds.  If you are asking a web service "What course marks did this student get in high school?" you should be getting a response back in milliseconds.  If you are asking a web service "What are the names of all of the people associated with this school district?" you should be getting a response back in milliseconds.

What?  Getting the names of hundreds, potentially thousands of people, in just milliseconds?  Are you nuts?

Read carefully what I wrote "... getting a response back in milliseconds."  A perfectly valid response is: "Thank you for your request.  It is being processed and the results will be made available at a later date."  Web services should not be long running processes.  If they are long running or have the potential to be long running, then you need to implement some sort of callback mechanism to indicate when processing has finished.  This callback mechanism may be an email, a call to another web service with the results, depositing the results in a queue to be picked up later or even a combination of these methods.  Indeed, there are literally dozens of ways to get the response back to the caller.  What is important to understand is that you do not create a web service that has the potential to run for a long period of time.  Ever.  I'm serious about this one.

Other than the fact that you are probably going to hit the HTTP timeout, COM+ timeout, or cause an excessive number of locks to be held in the database, why other reasons could their be?  Well, imagine from a Denial of Service perspective.  If one call to this web service can generate so much synchronous work, what would 10, 100, or even a 1000 simultaneous calls to this web service due to the underlying server?  Crash it?  Cause it to perform so slowly that everyone gets timed out?  Bring down the back end database?  "But, Don, this is going to be an internal web service only.  What's the problem?"  Depending upon which survey you read, anywhere from 10% to 50% of all attacks on web sites are from insiders.  Imagine a disgruntled employee and what damage he could do to the system with just a little bit of knowledge.

While this topic is ostensibly about web services, we should not create any service (COM+, Web, WCF enabled) that takes a long time to execute.  If you are in the least bit confused about whether something should be synchronous or asynchronous in nature, the odds are it should be asynchronous.  Err on the side of caution.

Hubris

I mentioned a solution architect yesterday and how they needed to be the person with the vision, the person that led the team to final solution.  Well, there is one character trait that a lot of solution architects have that needs to be understood and managed.

Hubris.

Defined as "excessive pride", many solution architects are unwilling to admit they are wrong and will go to any lengths to avoid admitting that they made a mistake.  Sometimes these mistakes can be trivial and sometimes they can be the smallest of decisions that has the biggest of impacts.  Case in point: on a very large project I was working on the solution architect decided that the default order the client had been using for the past 75 years was not right.  So, in the system that we were using he decided that we should change the order of the day, month,and year in the fields that we displayed on the screen.   Yes, that's right, instead of YYMMDD or MMDDYY, he chose a new way of ordering the parts of the date.

This may seem trivial, but we were using a code generator to build the cod and another tool to help create the CICS screens (yes, it was a very old system).  As a result, we had to customize the tool to make it work properly.  OK, it was up to me to make it work properly.  Oh, yay.  Suffice to say that we spent significantly more time on making our dates work out than we would have if we had followed, not just what the client had previously used, but a format that was in use in North America.

No one could convince him he was wrong.  No one at all.  He was convinced that he was right and the rest of the world was wrong.  I know what you're thinking, Don, was he really wrong?  Wasn't this sort of decision part of his job?  I would agree with you, but for those of you old enough to remember, the Y2K scare in the IT field was a big thing.  Imagine a solution architect in the early 90's designing a system where you were unable to enter the century!!!!!  We (okay, me again) had to devise complex schemes that would accurately take a 2 digit year and add the correct century to it.

Solution architects are good, sometimes absolutely necessary, but they are also prone to making very silly mistakes.

The Good Old Days

Why is it that the good stories start with "When I was younger ..."?

Anyway, when I was younger I was working on project to replace an aging mainframe based system with a new web based application.  The web based system utilized the existing database and a new database to create a whole new system that greatly increased the functionality and usability of the entire product.  One of the response time requirements we had was not with regard to individual screens, nor with regard to specific business processes, but with the length of the transaction in the database.  In order to get as much throughput as possible and minimize the amount of locking the requirement was that the new system operate in much the same manner as the old system and provide an average database transaction length of no more than 0.4 seconds.

400 milliseconds.

That is not a lot of time no matter how you look at it.  This 400 millisecond period was the average length over the course of a business day, but did not include any batch or asynchronous processing that occurrred.  This helped us out considerably because we had a lot of short transactions which lowered the average and a smaller number of longer transactions that raised the average.

Man, did we suck when we went live.  Over 2000 milliseconds for the first week and this did not include any of the deadlocks or timeouts that occurred. It took months, actually 18 of them, before we had things down to not just 400 milliseconds, but an average of just over 300 milliseconds. New hardware on the mainframe helped, but so did the fact that we worked really hard at lowering that average and we understood that anything that was going to take a long time was immediately turned into an asynchronous process or even part of a batch run that night.

The users understood this change in philosophy.  In order to get good online processing for everyone involved there was a need to do things asynchronously or in batch.  Processing something in the middle of the day, when everyone is using the system, is not always necessary.  Even if a short turn around is desired, asynchronous processing can be a valuable alternative.

Funny, but this seems remarkably similar to yesterday's note about web services and performance.  See, everything old is new again.  The problem isn't new, but the technology is.  The solution isn't new either, but the will to implement it might be.

When not to choose the default

I talked recently about how you should leave the defaults the way they are in many cases because, well, for most circumstances they are probably the best values to use.  Sometimes, however, the default doesn't work that well and you need to understand the reasons why changing the default is a good thing.

Suppose you went to a web site and it asked you to fill in 10 fields.  You then hit submit and it came back and told you that field number 1 is suppose to be numeric, not alphanumeric.  You make the change and then submit.  It then comes back and tells you that filed number 4 is suppose to be less than field number 3.  You keep doing this for a number of changes until you finally say "Forget it" and you leave that site forever.  It's happened to me, so I can honestly speak from experience.

My biggest problem with the process wasn't so much the one error message at a time, but rather the fact that there was a round trip to the server for every error.  I had over half a dozen interactions with the server to fill out a darn form!!!  By default .NET sets the controls you place on an ASP.NET page to process interactions at the server (runat="server").  If you provide complete error checking for each page, then this may be a suitable method of operating.  However, if you only respond to the user one error message at a time, this is sure fired way of getting  someone annoyed with you.  And quickly.

To be brutally honest, some error checking should be done at the client side.  If you have a popular application, or even if it is not that popular, there is still a certain amount of overhead involved in getting IIS to receive the request, process the header information, pass the information along to the application pool and then have the application do what it needs to do in order to tell you that the field is only supposed to contain numbers.  Then the whole thread has to go backward, towards the user, in order to give them the message.  It is faster, more efficient, and less costly from an infrastructure point of view if you let the client take care of this sort of data validation.  Your application will also check when it gets the data from the client (don't ever assume the client is sending you perfect data), but many checks can be performed at the client end, decreasing turn around time for error processing, distributing the work load, and, more importantly, providing a better user experience.

Remember, when you're designing your application think in terms of what provides the best user experience.  Think about your experiences, what you've liked or, more importantly, what you've disliked, and go from there.  The default, while usually good, does not have to remain if there is a good reason to change.

Validity vs. Reasonableness

While most of our applications do validity checks on data, not all of them do reasonableness checks.  Let me explain the difference.

Data Validation.  Let us suppose you have a number of fields on the screen:  name, address, birth date, phone number, and spouse's name, spouse's address, spouse's birth date, spouse's phone number and a marriage date.  Data validation would ensure that if there is a birth date, it is a valid date.  So in this case it would check to ensure that all of the date fields are valid.  It would also check to ensure that the phone number follows any one of a number of different standards, but predominantly the fact that it is numeric in nature.  You can also extend data validation to more complex tasks such as determining if the postal code is correct.   In general terms, data validation serves to ensure that a single piece of data is a valid for that data type.

Data Reasonableness.  OK, now that we've gotten the basics out of the way, there are still a number of checks that we can perform.  If there is a marriage date, then the date must be a certain time period after the birth date of both parties.  This is not just a simple "if marriageDate > spouseBirthDate then Happiness()".  We need some additional logic to ensure that even if the data is valid, it also must make sense.  Having data make sense is as important as ensuring that it is valid.

While there are many schools of thought on this, most post secondary training lumps both data validation and data reasonableness together under the "validation" banner.  This, unfortunately, has had the effect, in most cases, of putting data reasonableness checks in the background or has the checks embedded deep within the business logic of the application.  In most cases these checks can be done at the UI level, really quickly and prevent a lot of background processing that clogs the servers.  The other big problem is that some of these reasonableness checks are missed because "I thought the client was going to do that".

Just remember, there is a lot of data checking that needs to be done and reasonableness is just another item in the list.

Temporary (Expires yyyy/mm/dd)

My wife renewed her drivers license recently, as she turned 29, again, on September 24th.  She went into the Registry near our place, filled out the form, paid her money, got her picture taken and was given a "temporary" drivers license to last her until her real license was sent to her.  If the real license takes too long her temporary license is going to expire on her and that could cause no end of grief.

My bus takes a little bit longer to get to work in the morning as there is a "temporary" detour on it's normal route.  The city has dug a hole in the road, the entire width of the road, in order to do some emergency repair on the pipes.  They don't have a lot of time to get this done as it impacts a lot of traffic, a lot of buses (both ETS and school) and a lot of residents.  The only way to get to certain houses is to wind your way through back alleys.  Oh yeah, this is definitely going to be temporary.

My daughter has a temporary spacer in her mouth.  One of her baby teeth, incorrectly filled by an earlier dentist, developed some severe damage and needed to be pulled.  A temporary spacer was inserted so that her teeth would grow in their proper place until the adult tooth comes in.  The spacer is going to be removed either when the adult tooth comes in, or when the baby tooth to which it is attached falls out.  No choice, it is temporary.

We have servers, both physical and virtual, which were set up for temporary purposes.  We now have to face the task of upgrading them from NT 4 to something supported.  (OK, I lied, but you get the point, don't you?)  If things are temporary, give us a date and we will set up the system to self destruct on the day after.  If things aren't temporary, for goodness sake, tell us!!!!!  The "Oh, it was temporary, but the client said ..." story is getting old and, quite frankly, has been done better by other teams. 

Remember temporary means that it goes away.  Pick a date.  Any date.  Please....

Weapons of Mass Destruction

America went to war with Iraq because they wanted to find and destroy the Weapons of Mass Destruction.

In many respects that what I do by looking at the way applications are installed, operate and behave when encountering errors:  I'm looking for weapons of mass destruction.

My first IT job was with a construction company and my crowning achievement was an application that accurately allocated work site costs to various job codes in the accounting system on a daily basis.  It was rather tricky due to the fact that the company I worked for was a multinational company and each country, indeed province/state, had different holidays so it needed to take into account when costs should be allocated based on whether or not the previous day had been a holiday or not, in the location where the construction site was located.  Jobs on which 7x24 construction was occurring had other conditions that needed to be met.  All in all it was a masterpiece of software engineering.

Almost.

You see, I was under a tight timeframe for getting this done, as the VP in charge of construction had told the CEO that it would be in place by July 1st.  I only had 4 more weeks to finish the coding and then implement the application in the main production batch jobs.  Time was tight so I did what every rookie (and many seasoned professionals) do when faced with something that is difficult to compute:  I hard coded the answers.  I hard coded the holidays for all jobs sites for the next 18 months inside the application. 

It was simple to do and saved me a lot of trouble, because, you see, I left the company 2 months later, leaving behind a ticking time bomb in their production systems.  In sixteen months things were going to blow up, all because I took the easy way out instead of doing it properly.

Tick, tick, tick, tick ...

Groceries and Software

When you buy groceries from a grocery store, one of the things that they do for you is pack your groceries into plastic bags so you can take them home.  (OK, some grocery stores don't do that, but they will charge you a couple of pennies to give you a plastic bag so that you can do it yourself.)  When they pack the plastic bag they have certain, spoken and unspoken, rules.  For instance, you don't put a pound ... err, kilo... of hamburger in the same bag as fruits and veggies unless one of them is wrapped in an additional plastic bag.  You don't put a bag of potato chips at the bottom of the bag and potatoes on top of them and eggs are packed flat.

When creating a deployment for DeCo, think of ZIP files as being the similar to plastic bags from the grocery store.  Here are a few simple rules that you can follow to fill those bags:

• Create a ZIP file for each item type that you are migrating.  For instance, if you are migrating a web components and COM+ components, create two zip files, one for each.
• In each ZIP file put all of the pieces necessary to do the work for that type of deployment.  If it is a web zip file, include the MSI, any config files and even the documentation. 

The rules are really simple, but make life much easier for everyone.  For instance, by using ZIP files instead of a list of separate files, you reduce the number of times you need to attach a file to the request and you reduce the amount of space needed on the back end to store the files.  We current have over 9760 files that we are tracking from over 6800 deployments and these files take up over 19,680,000,000 bytes.  While some of those files are compressed, not all of them are. 

By using ZIP files you can help us keep a handle on the storage requirements for DeCo as well as making it easier for the Deployment Analyst or DBA to get all of the files they need for the deployment in one simple package.

Schopenhauer's Law of Entropy

So, just what is Schopenhauer's Law of Entropy?  Simply put, it is this:

If you put a spoonful of sewage in a barrel full of wine, you get sewage

So, what does sewage have to do with programming?  It's not sewage that I'm looking at, but rather the concept behind it.  In IT terms, what Schopenhauer is saying is that no matter how good the overall application, if one part doesn't work the whole application gets tarred with the bad brush. 

It is unfortunate that a single poorly designed, written or executed page can make someone believe that the entire application is poor.  Their perception of the application is what is important, not reality.  Kind of scary, isn't it, when perceptions are more important than reality.  But this is what happens in our business and it is something that we need to understand and do our best to influence.

So what influences this perception?  Well, consider this:  two web applications side by side on your desktop.  You push a button on the left one and you get the ASP.NET error page:  unfriendly, cryptic and somewhat unnerving.  You push a button on the right one and you get an error message in English, that explains there is a problem and that steps are being taken to resolve the issue.  Which one would you perceive to be better written and robust? 

How about another example?  You push a button on the left application and you get an error message that says "Unexpected Error.  Press the OK button".  You push a button on the right application and you get an error message that says "Our search engine is currently experiencing some difficulties and is offline.  Please try again later."  Which one do you perceive to be better?  Which one do you think your business clients will think is better?

It's not just one thing (error message or not) that gives you a feeling of confidence when dealing with an application, it is a multitude of little things.  Making things more personalized helps.  Translating from Geek ("Concurrency error") to English ("Someone else has updated the data before you") helps a lot.  Making it seem that you spent some effort to foolproof the system (i.e. don't make every error number in your application the same error number).

No matter how good the rest of your application, one bad move can create sewage.

Initialize All Variables at Their Points of Declaration

I was reading a book recently called Code Craft - The Practice of Writing Excellent Code and one of the comments struck a particular chord with me as it brought back memories of an upgrade that went horribly wrong.  At least for me.

There was a brief section called "Initialize All Variables at Their Points of Declaration".  Now, this may seem self explanatory and quite normal to some people, but others think that this is rather strange.  "Why would I initialize a variable that I may never use?"  The problem is, that not everyone follows the same coding practices in real life.  Sometimes the compilers help/hurt us in this regard.  Back when I was predominantly working on the mainframe, we were switching from an older version of COBOL to COBOL II.  Ooh.  COBOL.  I can see your eyes glazing over.  Stay with me, there is method to my madness.

The process of conversion was really quite simple.  Recompile.  It wasn't that hard.  However, we discovered a little bit of a problem.  When we did our testing we discovered that we were occasionally getting OC7 (data exception) errors when everything should have been working.  Indeed, running the program multiple times against the same data actually generated different results.  After a lot of head scratching we determined that the problem lay in the fact that the old compiler, by default, initialized variables when they were defined.  COBOL II did not do this by default.  When the application was loaded into memory it would occasionally access memory that had been initialized for some other purpose and the program would work.  Other times, however, it was accessing "garbage" and the program would blow up.  If the original developer had initialized the variables in the fist place we never would have had a problem.

So, we made a small change and everything was perfect.

Almost.  Because of how we were doing the upgrade process I had to baby sit the recompilation of 1900 COBOL programs in 4 different environments (7600 recompiles altogether).  Took almost 48 hours to do it and I got almost no sleep, and all because someone failed to initialize a couple of variables.

Antacids for the PM

PMs, can you imagine the look on the faces of those developers when I said that they needed to supply you with things like estimates and time sheets?  I bet some of them were knocked off their feet!

I mean it's not like you were asking them for anything difficult.  I mean, how hard can it be to create an estimate for a project?  It's not like it's rocket science.  Every developer should be able to do it.  I mean, the National Gun Registry hit it's target.  Well, maybe it didn't.  Well, what about the Denver luggage handling system?  Another fiasco?  OK, the FBIs Trilogy Project, now that was ... a disaster?

Everybody can look into the past and come up with failed estimate, but sometimes, the Project Manager does it to themselves.  This may be a shock for some of you, but sometimes Project Managers are under different pressures than you realize.  Back when I was younger I worked for a consulting company.  My job was to come up with the technical work plan and estimates for the projects the local office undertook.  I would then, using historical data and some darn fine guessing, come up with what the effort would be on the technical staff for the project (technical staff meaning project DBA and internal technical support). 

One of my proudest, and saddest, estimating moments came for a relatively simple business project that had a number of interesting technical complexities.  My estimate of the technical cost was 179 days.  When combined with the other parts of the project it turned out that this simple application was going to cost the client a lot of money.  In an effort to reduce the impact tot he client the scope was shuffled, but this did not reduce the technical effort that needed to be spent, so in a classic PM moment the number of days was arbitrarily reduced to 79.  I am proud/sad to say that this is one of the few times in my life where I was dead on with regard to the effort.

Project Managers, if your team says that something is going to take a certain amount of time, ask them questions, make sure they understand both the problem and their own estimate, but don't arbitrarily change it unless you know for a fact it can be done for less.  The odds are they understand what needs to be done better than you and by changing their estimate you are telling them that you don't trust them.  If you still feel the estimate is high, have them sit down with you and walk you through the estimating process they used.  But, if the numbers still add up to something you don't like, take a tums.

Load Balancing Failures

It shouldn't come as a surprise to anyone when I say that our Production environment is load balanced.  I have mentioned this before and I will be mentioning it again in the future.  But, for those who may have missed my previous tirades, let me explain the impact of load balancing on Session State.

One of the features of ASP.NET is to store information specific to a browser session (aka user) into something called Session State.  Session State is kind of like the junk drawer you have at home where you have batteries, twist ties, plastic spoons, stud finders and assorted other "stuff".  Session State allows you store what you need to store in order to keep track of where the user is in the application and what data you need to save on their behalf.  The next time the user accesses the application the session state is automatically loaded and you're ready to rock.

There are a number of places to store session state:  In Process, Out of Process or in SQL Server. 

In Process means that Session State is going to be stored in the Application Pool running the web site.  So, if the application pool recycles, all session state is going to be lost.  A number of projects currently use this method and are in danger of losing Session State, if they use Session State, as we use Application Pool recycling to solve a number of application issues.  In addition, if, for some reason, BigIP sends the user to a different web server to service the request then the Session State is not going to be present, potentially causing a number of application failures to occur

Out of Process is where the session state is hosted by ASP.NET in a different process, potentially on a different machine.  While somewhat safer than storing it in the same Application Pool, a problem arises if this service needs to be reset whereby the Session State is again lost.  Indeed, if the process is hosted on the same server as the web site, moving the request to another part of the load balanced cluster is going to be a problem as Session State will not be available for the request.  If Session State is stored on a separate machine then the biggest problem is that of durability of the data.  Any problems with the service may wipe out all session state for all machines.

Storing Session State in SQL Server is the slowest method, but is by far the safest method for durability and the best method when utilized in a cluster.  Each request for Session State goes out to SQL Server to ensure that the latest and greatest version of Session State for that user is retrieved and used.

In our environment we have asked people to use SQL Server Session State, and yet, by looking trough the web.config files of a number of projects I've noticed that they have their Session State set to In Process.  If Session State is actively being used, this is a recipe for disaster.  I urge each project team to take a quick look at their web.config files and change it to use SQL Server instead of In Process.  Even if you don't currently use Session State, you may in the future and this will prevent you from having a nasty accident.

In Memoriam

There were a number of comments yesterday from people wondering what the heck I was talking about when I told everyone to take a break.

Recently, Wednesday to be precise, we lost a companion that we had known for more than thirteen years.  When my wife and I first moved into our house we found it to be a large, lonely place.  In order to fill up some of the space we went to the SPCA and picked up a pair of cats, a brother and sister pair.  We named him Spike, because of his spiky hair and we named her Willow.

For thirteen years they were our companions.  Through three kids, hundreds of hair balls conveniently coughed up in the middle of the path to the bathroom, tainted cat food scandals (yes we found a few cans), Spike and Willow were there.  Recently Willow had been having some trouble with her hips.  Old age seemed to setting in quite quickly for her and the doctor recommended a special diet for her kidneys and glucosamine for her joints.  She seemed good, for her, for almost two years, but swiftly went down hill about 10 days ago.  A visit to the vet confirmed the worst:  kidney failure, liver disease, and a host of other problems were manifesting themselves at the same time.  When asked how many months she had, the vet told us "one week".

We made the most of the week with Willow and spent a lot of time petting her and keeping her company, much like she had kept us company for thirteen years.  We soon saw, however, that her time had come to let her go.  The whole family had a good cry on Tuesday night.  Wednesday, a friend of the family helped my wife with the final details and we all had another good cry that night.

I enjoy my work.  I enjoy the people the people I work with, even the ones I yell at a lot.  But I also enjoy other things.  My work does not define who I am, however, just what I do for a living.  Sometimes you need to take a break, step back from the work and look at everything around you.  If you've spent so much time working that you can't remember the last time you truly relaxed, take a break.  If you can't remember the last time you hugged someone or something close to you, take a break. 

Enjoy life.

Take a Break

Today's message is short and simple. Tomorrow we'll explain why.

No matter who you are. No matter what you do. Sometimes you need to stop working and enjoy life.

Take a break from work. Take a break from education. Take a break from stress. Just take a break.

Really Simple Solution

Really Simple Syndication.  RSS.

The concept behind RSS is really quite simple:  users, on their own timetable, download an XML file that contains headlines and/or stories on a particular topic.  For instance, I subscribe to a RSS feed that is created based on the Blog of J.D. Meier.  He is the Project Manager for "security and performance on the patterns & practices team".  His blog contains a variety of interesting topics, but I never actually have to visit his web site to get the latest from him.  I have an RSS reader (in this case Outlook 2007, but there are hundreds of others) that periodically goes out and checks his RSS feed to see if there are any changes.  If there is new stuff it shows up in Outlook.  I subscribe to a variety of blogs and web sites this way:

• Electronic Freedom Foundation
• Mark Russinovich's technical blog covering topics such as Windows troubleshooting, technologies and security.
• MSDN: Canada featured articles
• Scott Berkun, author of The Art of Project Management has a feed talking about innovation and creativity.

While RSS feeds are not new, their use in business environments is relatively new.  There are some businesses that have an RSS feed per major application and they post outages, tips, tricks and, most importantly, changes that are or have occurred to the application.  This way their business area is not surprised Tuesday morning when a completely new version of their favorite application shows up.  Larger project teams can create an RSS feed that contains status reports, meeting updates or even updates on when the implementation party is occurring.

RSS feeds can solve a number of issues, but it is not a hammer that can be used on every nail.  It has specific benefits in specific situations.  Like everything else, it is a tool that you have in your toolbox, but it is not necessarily a tool that you need to use.

Apologies

My apologies for the flood of posts today, but I haven't updated the external blog in a long time, whereas the internal email was still being distributed daily. I will try to do better in the future.