There’s an interesting opinion piece by Kathleen Dollard in last month’s Visual Studio magazine. The latest issue has another piece by Kathleen that is very similar. There’s no link to the latest one, because that issue has just come out (I got mine not 30 minutes ago).

In them, she’s essentially saying that the .NET framework, and all the various supporting enterprise frameworks, have become so large that no one can hope to be competent enough in them to be able to intelligently determine what to use, when to use it and when to stay away.

I couldn’t agree more. But despite comments in the article that she is “more optimistic today” and that “the revolution has begun”, I still come away from the articles sensing a muted dread. Fear that suddenly, skills you possess today and have honed over the years will become worthless. The value of the knowledge you currently have is drying up like last weeks doughnut holes.

And I’m just not down with that.

The fact is, my experiences seem to suggest that the less you know about these high level frameworks, the better off you are. I’m not saying don’t get familiar with them. I’m saying that if you spend time to learn the basics of computer functionality, hardware, interfaces, binary, and object oriented principles like encapsulation, polymorphism and inheritance, details of specific frameworks just tend to come out in the wash.

On the other hand, if you spend all your time focusing on a specific framework, when it’s no longer de rigeur, you’re screwed.

Microsoft has created some great stuff, to be sure, and some of the newest bits out of the pipe certainly seem compelling, WPF probably more so than anything else. But it’s also thrown out plenty of red herrings, costing companies untold money before people realized that “the silver bullet of the day” probably wasn’t a good idea after all.

Back to the knowledge issue though. When VB1 came out, and only a bit later VB3, everyone exclamed at how great it was because “you didn’t have to know the nuts and bolts of the Windows API to get something built for Windows”. Which was true, unless you wanted to build an program you could actually do something with.

The fact is, VB was like that first step down into the pool. It lets you get your feet wet and get used to cold water before you dive in headfirst. Plus you get to feel for sure whether there’s any water in the pool.

But eventually, you either dive in, or you decide you don’t like programming.

VB.Net has always been more like the diving board. You either walk away, or you dive in, and you won’t know if there’s water in the pool till you feel it or you bash your skull on the gunite.

I think there’s a bigger issue here, though. Emphasizing all these layers of Linq, Sharepoint, WPF, WF, WCF, Ajax, and blah blah blah, won’t help encourage anyone to dive in, and that’s what VB.net needs to be doing. Instead we get, what, the MY classes. Puh..leaze! At least edit and continue finally came back with VS 2005. Where’s the genius that decided it’d be a good idea to leave it out in the first VS releases, anyway?

Don’t get me wrong. You can create some hardcore stuff with VB.Net, a lot easier than was ever possible in VB. But you get some hardcore baggage coming along for the ride too. And that’s unfortunate, because falling CS enrollments may mean a pretty sweet employment future for me, but it bodes some not so sweet prospects for our long term technological advancement as a nation.

And dammit, I want my flying car before I GOTO END !

I once wrote an article about error handling in VB6 for Visual Basic Programmer’s Journal (Sept 2001, jeez that seems like a long time ago! {edit} and it would appear that that link is long since dead 🙁 ). It was born out of the need for a comprehensive framework for handling errors in an app I was working on at the time.

Since then, I’ve expanded the framework several times and it’s grown into something quite handy. Once I get it cleaned up a bit for public consumption, I’ll make the new and improved version available.

I’ve since been looking at the .NET error handler framework, and while it’s certainly much improved over the VB6 days, it still leaves a lot to be desired.

At the very core of handling errors is the division of error types into two distinct classes:

• Expected Errors
• Unexpected Errors

In a perfect world, every possible error is an Expected Error and there are no errors that can occur within your program that the code isn’t written to intelligently deal with.

At the other end of the spectrum, is, of course, where most textbook and magazine article sample code lies; where every error is an Unexpected Error that will crash the program.

Unfortunately, real world limitations on time, money, manpower, etc tend to force all code somewhere south of Nirvana.

The .NET fanclub used to decry VB’s on error goto as antiquated technology, and trumpeted try catch as the silver bullet of the day. And I suppose:

On Error Goto Catch
Try:
...code to try...
Goto EndTry
Catch:
...code to handle any error in the try block...
EndTry:

is quite different from

Try
...code to try... 
Catch ex as exception 
...code to handle any error in the try block... 
End Try

as long as you’re only looking at their checksums<g>.

Sure .NET incorporates a wealth of metadata about the exception. The module, function, line number, etc are all available directly while handling the error. But something’s missing.

Oh, yeah, What about those Unexpected Errors?

.NET does have the Exception Handling Application Block and it looks very promising, although it also looks very involved. And do you really want to be able to configure exception handling policies via config files? I mean, beyond indicating the level of logging you want (verbose, medium, low, off), and the email address to send exception report to (unluckysupporttech@mycompany.com), I’m having a hard time coming up with anything else I’ve ever needed to dynamically configure in my apps for exception handling. But, I won’t say it couldn’t be useful.

In the end, I suppose the thing that bothers me most about the EHAB, and the whole structured exception movement in general, is that it really does nothing to address the Unexpected Errors in an application. You still have to wrap your entire procedure in a TRY block in order to be sure that you catch any exception raised in that procedure. Otherwise, the exception is simply propagated up the call stack to the first point that is covered by an exception handler. The good news about .NET, though, is that at least, in those cases, you can still retrieve a call stack back to the real source of the exception and log it. With VB6, no such luck without some sort of framework.

My other issue is that Try Catch style exception handling forces the declaration of how you intend on handling errors to the END of the function you’re looking at. In this age of declarative programming and metadata-attributed interfaces, that just seems so…yesterday.

Take my above comparison of try catch and on error. What actually happens to the error is stated down at the end of the procedure in both styles. Now. I can understand that approach if you have code dedicated to handling specific errors, but then, those are Expected Errors. For the Unexpected Errors, I’d rather know, declared right up front, how the prodecure intends to handle them.

That was the impetus of my article way back when:

• Provide a framework that could provide a call stack that VB6 was lacking
• Provide a means of clearly declaring how the procedure intends on handling Unexpected Errors.

Compare a typical Try Catch structure:

Public Sub Test()
   Try                                          
   .....Lots and lots and lots of code....
   Catch Ex as Exception
   ....how to handle specific exceptions, plus how to handle general exceptions...
   End Try
End Sub

with a prologue style declaration like I use in my error handling framework for VB6:

Public Sub Test()
'############### ERR HANDLING #############
Dim Err As CErr: Set Err = New CErr: On Error GoTo Problem
Problem:
Select Case Err.Handle(EHF_PRESENT or EHF_ALLOWRETRY, MODULE, "Test")
Case EHE_NONE: Case EHE_RETRY: Resume: Case EHE_PASS: Resume Next: Case EHE_RESET: Resume Problem
End Select
'##########################################
   .....Lots and lots and lots of code....
End Sub

The code states right up front how unexpected errors are handled (in this case, EHF_PRESENT or EHF_ALLOWRETRY indicates that the user will be shown a dialog and allowed to retry the operation). There’s a bit more verbiage here because of the requirements of VB6, but that’s not the point.

Personally, I’d prefer it if every routine in .NET could be (or maybe even had to be) attributed as to how unexpected errors are to be handled. Those that need to show a dialog would do so based on one or more “predefined” dialogs that depended on where in the app the error was thrown.

And for those apps that you never want to show an error dialog, you could instead indicated that any unexpected errors should be logged to the Event Log (or somewhere else) and then press on as best as possible.

Unlike the implications in so many magazine articles, error handling is hard. Proper error handling is like a prostate exam; you know you have to do it, but you’d really rather not bother.

I’ve played a bit now with the .NET configuration model and while I can certainly see some elements in there to like, it seems to me that it falls short in a number of different ways.

First off, it doesn’t really have any concept of “multi-level configuration.” In fact, it’s basically a single level XML file (granted, you could create a hierarchical organization within that single xml file, but there’s other issues with that). .NET does help a bit with the concept of a machine config file, but from what I can tell that’s about as far as it goes.

Second, the default behavior is to locate the application config file in the same path as the application itself. That’s great if your user is running as administrator, but not so great in more locked-down situations where users do not have full admin rights. In those cases, configuration that’s writable needs to be stored somewhere within the user’s profile directory structure. This is just going to get worse with Vista, too.

Ok, sounds good but what, you may be asking, is a multi-level configuration scheme, and why would I want one? Almost every app I’ve ever worked on, short of the trivial utilities I’ve built, has required this sort of configuration scheme (or at the very least greatly benefited from having it). It almost always follows along this line:

• Administrator specified User specific configuration (rarely used, the user cannot change this configuration)
• User specific configuration (that the user can change dynamically)
• Group specific configuration (typically set by a system administrator or group admin and read only to users)
• Machine specific configuration (typically set by a system admin, and rarely used, read only to users)
• Application global configuration (typically set by the system admin, read only to users)
• OEM defaults (typically set by the app developers to provide default config values, generally readonly by everyone except the developers)

At each level, the system provides for an essentially unlimited number of name value pairs that can be cordoned off into groups (or sections as they used to be called in INI files). Some may argue that a section-name-value system like this is too limiting and you should always accomodate full hierarchical structures, but I’ve found the extra functionality rarely necessary.

Of course, the type of value (string, int, date, etc) for a particular setting is defined within the application, but value types might also be defined as OEM default settings. Should sysadmins really be able to change setting X from a string to a date? I’d imagine not usually.

The trick and the real beauty of the system is in the way that setting values are resolved. The resolution logic basically says that if the app can find a setting at a higher level in the hierarchy, it uses that value. Otherwise it searches down the hierarchy till it either finds a value, or till it drops to the OEM defaults. If no setting is specified at the OEM level, the system defaults to blanks, or 0’s depending on the data type.

So, for instance, the code might ask for the setting “AskOnExit” from the “Prompts” section. The config handler needs to look first at the “level of most significance” which, in the above list of levels, would be the Administrator specified user specific settings (ie those settings that are set on a per user basis, but that the user himself doesn’t have the authority to change.

If the setting isn’t found there, the code continues down the hierarchy, looking at each level in turn until eventually in run through them all and returns the default or a blank or 0.

And, of course, you also have to provide a means to retrieving and writing a setting at a specific level in the hierarchy, for those settings that are always application level or machine level or what not.

Obviously, such a scheme requires a little more work up front, but the configuration flexibility (especially when you’re talking about major, multi user systems with lots of configuration options, typically off-the-shelf, reseller-friendly applications like accounting systems or CRM packages), is a huge selling point to admins and users alike.

Why, then does configuration handling in .NET seem so archaically primitive?

Could you roll all these levels into that singular .config file? Sure, when where would you put it? In the Application path? No, users won’t typically have write rights there. Under the user’s Application Data folder in the Profile? No, can’t put app wide settings somewhere that only a single user can access it. How about that machine config file. Again, not writable by typical users.

It’s funny that Windows already has a rights system that is very stable, quite flexible and easy to work with, both manually and from within code and yet it often goes completely unused by larger apps. I’m talking, of course, of the file system.

These days, though, web apps are de rigueur and you can’t go assigning file system rights to web users. There’s no way that would fly with most web developers (you weren’t really thinking of something like that, right?). So, roll it up into a simple table, with a getSetting and a setSetting stored procedure to simplify the coding. With proper indexing, and a little intelligent caching, it’ll be every big as fast as using the .NET configuration functions, and whole lot more flexible.

Long story short. If your sideline utility needs to save a few settings, use the .NET configuration. It’s fast, relatively easy and convenient. But for just about everything else, take a little time and do it right.

Your users and their sysadmins will thank you.