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David Waddleton, and MSDN representative, is giving an MSDN event on InfoPath and ASP.NET 2.0 at the Gateway theater in Austin, TX.  InfoPath is quite interesting as an application client.  Currently my application client is a browser since I write ASP.NET apps, but if all the users have InfoPath on their computer, that can be the client.  Now, it’s a no-brainer for web apps because they can use any browser as the client, but I’m not sure that InfoPath would be viable for my use even though I work for a very large enterprise company.  I can see that a consulting company might be able to use it by building it into the minimum system requirements of their solution, but for my large company, I would have to sell the top IT big dogs on the idea of installing InfoPath on every workstation.  That’s a lot of licensing costs that are not present with web apps or even a click-once app.  Maybe in time it will look like a better option for me.

Just an overview of what I’m doing:

I have my laptop here running on battery power, and I’m connected to the Internet through a USB cable attached to my Sprint phone.  Very nice setup.  I can get on the Net anywhere I can get signal, and I really don’t go out into west Texas much.  I live out in the country, but Sprint has pretty good coverage even outside suburbs.

In response to the blog post: ?????????? , I agree with some of the stuff that was said.  If you are feeling tired, sometimes you have to take a break and get some coffee or tea – I got a Chinese coworker to translate for me :^), but I’m curious as to why http://weblogs.asp.net has chinese posts on it.  Maybe if you post in a different language, include a link to a site where that post can be translated into English.

I’ve been having frustrations with the v2.0 /Code directory.  Code files in it are dynamically compiled, and that’s great, but I have a /UserControls folder, and I have some usercontrols that have tightly-bound base classes that are also in the /UserControls folder.  In v2.0, to get use these class files, I have to move them to the /Code directory, or they won’t be dynamically compiled, or compiled at all.  And in Whidbey, there is no way to build a web app into a DLL like in VS 2003.  So either I move it to the /Code directory or I’m out of luck.  I want to be able to determine my own file hierarchy in my web project.  I want my class file right next to the user control that depends on it.  I need that class to be compiled to use it.  The solution I would recommend would be to make dynamically compiled folders configurable.  I want to specify multiple folders for dynamic compilation, and I know what I would do.  I’d set to root to be dynamically compiled so that everything would be compiled, and I wouldn’t have to worry about it.  As it stands now, I prefer the VS 2003 method of building code files into a DLL.  Dynamically compiled code isn’t a step forward if it requires taking a leap back by throwing away other functionality.

For those working with Whidbey, don’t rely on the /Code directory staying that way.  It will probably change.  The current though is having /Appllication_Code folders be dynamically compiled instead.  See Van’s comment about that.

Johan made a great post about adding web parts in your code instead of having to declare it in the markup at design time.  This is very powerful, and I’m sure the prefered method for any system with roles.  You can programmatically decide whether a particular webpart should be available to that particular user.  If so, go ahead and add it.  I will definitely have to incorporate this feature into EZWeb when I release my 2.0 version.

Anders Norås’ posted an interesting article about the intent of code-behind.  He says doing:

I labeled this post as 200 instead of 100 because I imagine that beginners in .Net won’t be creating their own custom collection classes.  I think once someone can create their own custom collections, they should be considered at least intermediate.

Today a colleague approached me with a problem.  He was foreaching through a custom collection in C#, and when he evaluated the object he wanted, he need the index of that object for the collection.  He was approaching the problem with calls to GetEnumerator(), etc, and I shared with him what I do for this situation:

• When you inherit from CollectionBase, your collection data structure is an ArrayList.  if you look at the InnerList protected member, it is of type ArrayList.  The ArrayList type has a method IndexOf(object) that returns int, the index of the object within the ArrayList.


• To make the index available to callers of your custom collection, define a method like so:

        public int IndexOf(object value)


        {


            return base.InnerList.IndexOf(value);


        }

• So now, when you have an object you can pass it to this method to get the index of that object within the instance of your collection.

When I create my own collection types, I normally expose all the helper methods of the InnerList so that my collection is as functional as possible.  Inheriting from CollectionBase just strongly types the ArrayList object for you.  With generics in v2.0, if you don’t need any extra functionality from your collections, then you’ll just want to go with ArrayList<T> or you can use the new Collection<T> class:

    public class Junk<T> : Collection<T>


    {


        private int m_myExtraMember;


        public Junk(int myExtraMember)


        {


            m_myExtraMember = myExtraMember;


        }


        public new int IndexOf(T value)


        {


            return base.IndexOf(value);


        }


    }

With v2.0 and generics, you may still want to implement your own custom collections if you need to track a member that isn’t included, but still, this method is simplified.  I have overriden the IndexOf() method unnecessarily just to show some syntax.  With 2.0, all you would need is the m_myExtraMember field.  IndexOf is inherited.

Another tip about collections:  Know what data structure the collection uses internally.  Collection<T> uses the List<T> structure internally which is similar to ArrayList in that it keeps the objects in the same order in which they were inserted.  With HashTable-based collections, the objects are retrieved via key, and the order is not guaranteed, so if  you foreach on a HashTable, you can never know in what order the objects will be retrieved.  I hope this post helps someone.

I was planning on posting this anyway, but Steve’s post has convinced me to do it sooner.  Here are methods and tools I use to track down memory leaks in my applications. 

• First, I profile my app.  I do web applications, so I’ll use Application Center Test that comes with VS 2003 EA, but you can also use the free tool, Microsoft Application Stress Tool.


• I run perfmon while the stress tool is running.  The stress tool will push my app to the limit and simulate heavy traffic.  Here are counters I ALWAYS look at:




• # of Excepts Thrown /sec (0 is the number you are shooting for.


• Gen 0 heap size


• Gen 1 heap size


• Gen 2 heap size (this is where your memory will likely accumulate.  If you have objects that won’t go away, they will end up here and end up taking up ALL your memory)


• Large Object Heap size


• Application Restarts (if your memory usage gets too high, ASP.NET might automatically restart the AppDomain, and you’ll be able to see it here).


• Any others you feel are appropriate.


• Run the stress tool while watching the performance counters.  Your memory usage should go up and down but overall remain consistent.  If your gen 2 keeps getting bigger and bigger and bigger, then you probably have a memory leak.


• Here is how I go about finding out exactly what objects are taking up all my gen 2 memory




• Bookmark the C# Team’s Tools page.  There are several memory profilers to choose from.  There are several commercial products you can buy, but I chose to try the free one: Allocation Profiler.  I also tried NProf, but it seemed to profile processor performance and not memory (unless I used it wrong).


• Note, for AllocationProfiler or NProf to work, you have to modify your machine.config file’s <processModel/> node to have username=“SYSTEM“ instead of “machine“.


• Open AllocationProfiler, and have it start profiling your app.


• I would run the stress tool on my web apps to generate a lot of traffic.  When I’m done, I stop profiling.  Application Profiler generates some good graphs from its logfile.  I look at where the memory is allocated, and I see generation 2 has a bunch of stuff.  I can see what types make up the most memory.  You can also look at the contents of the managed heap with other views, and you can drill down and determine what is taking up all your memory.  Once you have found the offending type, you can dig into your code and look for no-nos.


• Read my previous post about my nasty memory leak.


• If would also do you good to read Jeffrey Richter’s book: Applied Microsoft .Net Programming in C#.  It has a great section about the managed heap and garbage collector.


• Once you know how the managed heap and garbage collector work in .Net (and no sooner), you can evaluate your code for scenarios where long-lived objects keep references to other objects and thereby prohibit the garbage collector from reclaiming their memory.


• Example:  If you have a long-lived object that has long strings as members, the memory those strings consume cannot be collected as long as the long-lived object is alive. 

I hope this helps someone find memory leaks in their application.  Practice makes perfect, and I had to read books and articles to understand the inner workings of the CLR before I could effectively analyze my code for leaks.

In my previous post about a memory leak, I was talking about EZWeb, and I’ve fixed the problem, profiled the app and have now released v1.1 of EZWeb on GotDotNet.  For those of you who don’t know, EZWeb is an ASP.NET web application framework as well as a content management system all in one.  It incorporates master pages functionality as well as Theming and skinning.  But it does this in .Net v1.1.  It takes building a web application from coding to configuring.  ASP.NET 2.0 says you’ll write less code, but what if you could write even less code than that!  With EZWeb, you could write a .Net application, and you would only have to write your business logic and screens specific to YOUR functionality.  You wouldn’t have to worry about writing code or markup to keep the site consistent.  I’m currently working on a port to ASP.NET 2.0, and I’ll take advantage of master pages and the actual theme feature in v2.0, but for now, EZWeb can give you those features using ASP.NET 1.1.  Go check it out.

As I’ve posted before, (and Jay has recently concurred),  SQL Server reporting services is very cool.  Some people think that it is an extension of SQL Server.  What you may not know is that it is an ASP.NET library that installs on your web server.  It also has a designer add-in for designer reports (very simple to use like MS Access reports) for VS.  The reports are deployed to the web server, and served through a new ASP.NET HTTP Handler.  You can put .Net code in them and fully integrate a report with your web application.  One thing I plan to do in the future is take a screen where formatting has to be pretty and make a report from it.  Then I’ll automatically get the cool features like export to Excel, PDF, .tif, CSV, etc.

I hadn’t done any profiling on EZWeb in a while, so I thought that I had better do some.  I like Application Center Test that comes with VS 2003 EA, and I also watch my performance counters while it’s running.  I tell you, it’s easy to cause a memory leak in .Net.  I predict that fixing .Net memory leaks will be a sizable consulting niche in the near future as more .Net apps go into production.  Especially web applications where the Page object is being created and handed over to the garbage collector many hundred times per second.  I found a really nasty memory leak in EZWeb this morning, and it can happen to anyone with normal code.  If you are currently using version 0.9 or 1.0 of EZWeb, I’ll tell you what code to change to fix it, and I’m going to post a v1.1 release to GotDotNet as well.  So, here is the scenario.  I define my own user object, and to conform to Forms-based authentication, I never wanted my User property to be null – System.Web.UI.Page.User is never null.  If no one is authenticated, it comes back with an empty GenericPrincipal object.  I created an “Empty” property of my User (WebPrincipal) object much like string.Empty and Color.Empty, so whenever there is no user logged in, the User will be WebPrincipal.Empty:

protected static WebPrincipal m_empty = WebPrincipal.InstantiateEmpty();

Then I have my Empty property, so I can test against WebPrincipal.Empty because as a static member, there will only be one instance.  Well, I forgot about some code from when my User property was null:

        private void SetUserEventListeners()


        {


            if(m_user != null)


            {


                m_user.LoggingOut += new EventHandler(User_LoggingOut);


                m_user.LoggedOut += new EventHandler(User_LoggedOut);


            }


        }

So, this is what happens:  m_user is an instance of WebPrincipal.Empty (a referenced by a static member that lives as long as the AppDomain).  I am adding delegates in my Page class to events of WebPrincipal.Empty, so a persistent instance is maintaining references to methods of my Page class (EVERY SINGLE INSTANCE OF MY PAGE CLASS).  What does this mean?  It means that the garbage collector see that references are held to the Page instances, so it doesn’t garbage collect them.  The gen 2 heap keeps getting bigger and bigger and bigger. 

So watch out for this in your code.  If you have long-lived objects that have references to short-lived objects, those short-lived objects become long-lived!

To fix this code, I only wire up event handlers when the User object is an actual good instance of WebPrincipal:

        private void SetUserEventListeners()


        {


            if (m_user.Identity.IsAuthenticated)


            {


                m_user.LoggingOut += new EventHandler(User_LoggingOut);


                m_user.LoggedOut += new EventHandler(User_LoggedOut);


            }


        }