Drew Marsh: Drew's Blog::.NET

Heads Up: Sam Gentile Has Moved His Weblog

Thu, 30 Jan 2003 18:45:32 GMT

Ok, I've had it with Radio and its many bugs, lack of updates, quirks, etc. This is not anything new. I have wanted to move for a very long time to something .NET based but I have not had the time. Scott Watermasysk has graciously volunteered access to his ASP.NET solution and hosting. So I am moving. My new site will be here. The new RSS feed is here. It will take some time to move over and get things squared away especially with project and book deadlines, and a new baby so please be patient with me. I hope all my loyal readers will continue to read at the new site and as always, I thank each and every one of you for reading my stuff and hope that it continues to help you in youyr work. [Sam Gentile's Weblog]

Hmm... I might have to try this out myself.

Re-Selecting The Currently Selected Row After A DataGrid Sort

Wed, 22 Jan 2003 18:13:50 GMT

This is a follow-up to this previous post about sorting a DataGrid. It turns out that the person who originally asked the question about knowing when the sort would occur, wanted to know this for the purpose of re-selecting the currently selected row after the sort. Well, as it turns out this is entirely possible, but it requires some deeper digging into the data-binding aspects of WinForms (which I love btw). ;)

So here's what you'll need to do. First things first, you're going to need to watch for the sort to happen as was detailed in the previous post. Upon detecting the sort about to happen you must record a key value for the currently selected row in a state field (probably in your Form). Now, here's where the deeper knowledge of data-binding comes into play. You must also attach an event listener to the ItemChanged event of the CurrencyManager for the DataTable/DataView you've bound your DataGrid to. The ItemChanged event will fire after the sort takes place at which point you use the DataView's (DataTable::DefaultView if you're bound directly to a DataTable) Find method to locate the row in the view by the key value that you stored in your state field in the sort detection event logic. Once you've found the new position of the row in the DataView after the sort, you set the CurrencyManager's Position property to that index.

Ok, this might sound complex, but lemme show you just how easy it is with some code. For the purposes of keeping this code concise, assume this code is in a Form subclass which contains a DataGrid in a member variable called "myDataGrid". This DataGrid is then bound to a DataTable, stored in a member variable called "myDataTable" which has a key column named "key" of type int:

<codeSnippet language="C#"> public class MyForm : Form { private int currentlySelectedRowId = -1; public MyForm() { this.InitializeComponent(); // Get the CurrencyManager for the bound DataTable CurrencyManager dataTableCurrencyManager = (CurrencyManager)this.myDataGrid.BindingContext[this.myDataTable]; // Hook up to the ItemChanged event dataTableCurrencyManager.ItemChanged += new ItemChangeEventHandler(this.myDataTableCurrencyManager_ItemChanged); } private void myDataGrid_MouseUp(object sender, MouseEventArgs args) { DataGrid.HitTestInfo hitTestInfo = this.myDataGrid.HitTest(args.X, args.Y); if(hitTestInfo.Type == DataGrid.HitTestType.ColumnHeader) { // Get the CurrencyManager for the bound DataTable CurrencyManager dataTableCurrencyManager = (CurrencyManager)this.myDataGrid.BindingContext[this.myDataTable]; // Get the current DataRowView DataRowView currentRowView = (DataRowView)dataTableCurrencyManager.Current;

// Remember the currently selected row ID this.currentlySelectedRowId = (int)currentRowView["key"]; } } private void myDataTableCurrencyManager_ItemChanged(object sender, ItemChangeEventArgs args) { // Only execute this logic if we're in the state of sorting if(this.currentlySelectedRowId != -1) { // Find the new position of the row now that it's been sorted int newPosition = this.myDataTable.DefaultView.Find(this.currentSelectedRowId); // Get the CurrencyManager for the bound DataTable CurrencyManager dataTableCurrencyManager = (CurrencyManager)this.myDataGrid.BindingContext[this.myDataTable]; // Change the position of the currency manager dataTableCurrencyManager.Position = newPosition; // Reset sorting state this.currentSelectedRowId = -1; } } } </codeSnippet>

Detecting When A DataGrid Is About to Be Re-Sorted

Wed, 22 Jan 2003 16:08:54 GMT

A good question came up on a the DOTNET-WINFORMS mailing list this morning. I had to think about it which makes me realize that plenty of other people are probably wondering the same thing: How do you detect when a DataGrid is about to be re-sorted?

There is no SortChanged event on the DataGrid. This turns out to be quite annoying, considering the "manual" way to detect a sort. So here's how to do it:

According to the documentation for the DataGrid::AllowSorting property, clicking on the column header will result in the DataGrid being re-sorted by that column. So with that in mind, take the following steps to detect when a column header has been clicked:

Attach to the DataGrid's MouseUp event.
In your handler, call DataGrid::HitTest
Using the DataGrid.HitTestInfo returned, inspect the DataGrid.HitTestInfo::Type property and check the resulting DataGrid.HitTestType for the ColumnHeader value.

It would look a little something like this:

<codeSnippet language="C#"> private void myDataGrid_MouseUp(object sender, MouseEventArgs args) { DataGrid sourceGrid = (DataGrid)sender; // Perform hit-test DataGrid.HitTestInfo hitTestInfo = sourceGrid.HitTest(args.X, args.Y); // Check if a column header was clicked if(hitTestInfo.Type == DataGrid.HitTestType.ColumnHeader) { // A column header was clicked, which means a sort occurred. // Perform any custom logic here. } } </codeSnippet>

Update: Corrected to use MouseUp event instead of Click event since DataGrid doesn't seem to fire Click event.

Update 2: I don't know what I missed the first time I tried it, but the Click event does work for this scenario. If you choose to hook up to that event you can make the HitTest using Control::MousePosition.

Serialization and Versioning

Sat, 18 Jan 2003 19:23:46 GMT

evolution. So I'm sure I've read how to do this somewhere (perhaps in Ingo's book ?) but I have a .NET struct that has the [Serializable] attribute applied to it, and have a bunch of them serialized to a disk file. Now I want to revise the struct by adding a new field, how do I control the deserialization process that I restore my existing serialized data into the new format structs ? Back in the days where I used to implement IPersistStream by hand, I always had a version # in the serialized stream, so that the deserialization code could rev old formats upto the current format. [Simon Fell]

I believe the only way to control serialization across versions of components is to implement ISerializable and read/write the members yourself to the serializer implementation using the provided SerializationInfo. Then, in order to get the serializer to instantiate the new version of your component for deserialization is to use a bindingRedirect.

Update: Correction. I forgot all about SerializationBinder... it's designed for exactly this scenario. Have a look at the BindToType method documentation for an example of how to implement your own binder.

Update 2: I just walked up to work for a weekend release we're doing and along the way I was thinking about the SerializationBinder scenario some more. I realized that, even though that will help you redirect to a different version of a component, it still won't handle scenario's where serialized fields are changed by name or type or, worse, removed all together. The only way that I can see to have true version safe serializability is by implementing ISerializable on your type and reading the values into your serialized fields yourself. So I think the original scenario I suggested is the right way to go.

The Return Of Peter Drayton

Tue, 07 Jan 2003 04:14:49 GMT

Blog is back (hopefully). OK, here goes nothing... deep breath... The blog is back. [Peter Drayton's Radio Weblog]

Looks like the assimilation is complete, Peter's back! Welcome back Peter, you were missed and we all look forward to hearing from you on a regular basis again.

XML-RPC.NET v0.7.0 Delivered

Mon, 06 Jan 2003 14:26:17 GMT

XML-RPC.NET v0.7.0. I've just uploaded version 0.7.0 of XML-RPC.NET. Its available here. The changes/fixes in this release are: error reporting of parsing...... [Cook Computing]

I'm pretty sure anyone who has to work with XML-RPC in .NET uses Charles' implementation. I've been using it lately to implement a blogging client capable of talking to any server implementation that speaks Blogger 1.0. The Blogger 2.0 API is currently in the RFC stages and while I've offered what I think it some decent feedback on a couple of issues via the bloggerDev mailing list, I haven't really gotten much of a response (yet).

The Future of .NET

Fri, 08 Nov 2002 21:29:58 GMT

Visual C++ and C# Updates In Everette. That release of Visual C# will include four new features: support for "generics," which is a form of a C++ template that can help C# developers build software more quickly; support for "iterators," which help developers create new code; anonymous methods, which ease development of what's known as "event-driven" code; and support for "partial types," which make it easier to use C# for building large projects. [sellsbrothers.com: Windows Developer News]

Woah, I wish, but no these features are not going to be in the Everett release. Everett is more like a bug-fix/performance enhancement release as far as the framework goes. They will be part of a future, major release. Have a look at the whole article right here.

It is awesome to hear that generics are going to be implemented though, a lot of people are gonna be psyched about that (myself included). I'm not sure why the article says:

support for "iterators," which help developers create new code

The definition I'm aware of for an iterator is something more akin to an enumerating pattern... so something tells me the author mixed up a term or definition.

Finally, I'm sure that even though these are mentioned as enhancements to C# they are really enhancements to the runtime and framework classes in general so that every language can use these features. Whether or not they choose to expose them is another question. For example: Will the VB.NET language have support for generics? I guess only time will tell.

Pragmatic ADO.NET

Fri, 08 Nov 2002 20:48:59 GMT

Pragmatic ADO.NET in stock!. Shawn Wildermuth's new book, Pragmatic ADO.NET: Data Access for the Internet World, is awailable now. Shawn's a long-time friend of mine and I wrote the forward to the book, so I'm hardly unbiased, but it rocks! Enjoy. [sellsbrothers.com: Windows Developer News]

More quality .NET books are rolling out these days. I think I'm going to have to check this one out too.

Essential .NET Is Here

Wed, 06 Nov 2002 20:26:05 GMT

Essential .NET, by Don Box, in stock!. According to the AW web site, Essential .NET, by Don Box, with Chris Sells, is in stock and ships within 24 hours, and Amazon seems to agree. Enjoy! [sellsbrothers.com: Windows Developer News]

Looks like it's time to do some more reading. :)

Adding Custom Functions to XPath

Tue, 05 Nov 2002 02:15:43 GMT

Here's a great article on adding custom functions for use in XPath expressions via the .NET XSLT framework classes. I was aware of passing custom obejects via extension objects, but I had no clue this functionality existed. The author does a good job demonstrating the extensibility of the XsltContext class for all sorts of purposes. Great stuff!

Update: Thanks to Jason Diamond for pointing out that I forgot to actually link to the article itself. Duh! :)

Understanding DIME and WS-Attachments

Tue, 05 Nov 2002 02:09:37 GMT

Yet another useful article from the MSDN Web Services center. The DIME specification is one that I wish was better established about two years ago when we (meaning my company) revamed our upload protocols. Come to think of it, even SOAP wasn't established enough. So we've hand rolled our own XML message format and in between there's a straight HTTP 1.1 chunked upload. The XML messages are custom schema and are used to initiate, resume, finalize and terminate uploads. Next version will be definitely be SOAP+DIME... can't wait!

Using System.DirectoryServices to Search the Active Directory

Tue, 05 Nov 2002 02:00:02 GMT

New article posted under the .NET center of MSDN. If you haven't already guessed from the title, this one's about using the System.DirectoryServices namespace to search Active Directory. I see a lot of requests on how to do this on the mailing lists, so this will be a good article to point to for future requests.

Visual XSLT Comments

Tue, 05 Nov 2002 01:50:22 GMT

Visual XSLT TryOut. I've been hearing about ActiveState's Visual XSLT tool quite a bit, and I was quite intrigued by it, but never found the time to give it a through test. This weekend finally the opportunity presented itself, so I downloaded the trial version and gave it a go.

...

Although I did run into a few gotchas, I did get a feel for the power of the tool (it even works with includes and all). Most definitely, this is a tool I'd love to have on my arsenal, so I guess it's savings time so that I can afford it in a few months... not very soon, though :( [Commonality]

I agree. I tried it out back when it was originally released and was quite impressed with it's capabilities as well. I wasn't doing all that much work with XSLT at the time, so I didn't really have the need to buy it. However, we're migrating our systems over to .NET and XSLT should play a bigger role. If so, I'll definitely recommend purchasing a copy for my company.

Congratulation To Peter Drayton

Thu, 31 Oct 2002 16:54:05 GMT

A belated congratulations going out to Peter Drayton who has landed his "dream job": working as a Program Manager for the .NET CLR team. Awesome! I hope to join the MS legion some day, but not until I collect on my current venture. ;)

Creating Asynchronous Business Objects for Use in .NET Windows Forms Clients

Thu, 31 Oct 2002 16:49:44 GMT

There's a new article up in the .NET Development section of MSDN. While the article is about adding asynchronus support to your objects, I think the most important thing the article touches on is something that a lot of people new to WinForms and multi-threading get stuck on: marshalling calls to the UI thread when interacting with controls.

.NET vs J2EE - Pet Shop 2.0 Benchmark

Mon, 28 Oct 2002 20:20:02 GMT

Someone just posted a link to this benchmarking research done by Middleware Company on the WinTech Offtopic list. Considering Middleware Co. specializes in Java technology training, you'd be skeptical of some skewing in favor of Java, but all the benchmarks clearly show the .NET implementation blowing the doors off the Java implementation. Not only that, but in less lines of code!

What's more remarkable to me are the differences between the 1.0 .NET framework and upcoming 1.1 .NET framework (Everett... still in beta), especially in the SOAP category. It looks like Microsoft's framework teams have done some performance tuning for this upcoming release which is a bonus for any application built using the framework.

In the end this looks like an excellent, unbiased comparison that should prove useful to those that have to justify .NET in any technology debates when it comes to performance.

Introduction to IL

Tue, 22 Oct 2002 17:59:35 GMT

Here is an article (first of a series) that provides an Introduction to IL. [Sam Gentile's Weblog]

Good stuff! Actually though, parts one and two are available. I found the link to the second at the bottom of the first. No mention is made of when the next installment is to be expected, but I'll certainly be keeping my eyes peeled.

Using .NET Sockets

Tue, 22 Oct 2002 17:45:34 GMT

A brief article was just added to the .NET center of The O'Reilly Network which covers the basics of the System.Net.Sockets namespace. Defines what a socket is, explains the basics of DNS and finally touches on how data is sent and received. Not a bad article if you're new to socket programming or just new to .NET and want to get familiar with its implementation.

.NET Petshop 2.0 Released

Tue, 22 Oct 2002 16:44:04 GMT

Was just scanning the .NET developer center over on MSDN and noticed that the .NET Petshop reference application has been upgraded to version 2.0. Here's a quick snip about it:

The .NET Pet Shop 2.0 application is functionally equivalent to the Sun® Microsystems Java™ Pet Store 1.2 blueprint application, and can be used to compare the coding concepts, basic application server features, and architectures of .NET and J2EE™.

Essential .NET Security

Tue, 22 Oct 2002 15:26:43 GMT

Essential .NET Security. Keith Brown has *finally* decided to write Essential .NET Security and he'll be posting it to HTML as he writes it. He's already got the ASP.NET security chapter posted. Wahoo! [sellsbrothers.com: Windows Developer News]

Awesome! Keith is well known for his security knowledge of Win32 and COM(+). Seeing as how security permeates almost every aspect of .NET, this is definitely going to be a must have for any serious .NET developer.

Dissecting Regsvcs.exe

Fri, 18 Oct 2002 17:44:38 GMT

Tomas posted some interesting details on his dissection of the Regsvcs.exe tool supplied with the .NET Framework. He reveals that the executable is little more than a façade for built in framework classes which perform typelibrary generation and handle various forms of registration. Very useful stuff to know, especially if you ever wanted to control some of this process yourself.

Performance Comparison: Security Design Choices

Thu, 17 Oct 2002 18:14:14 GMT

There's a great article up on the MSDN site that covers various security design options and the advantages and disadvantages of each. There are a lot of performance comparisons for each topic that is discussed, but as the author points out in his conclusion:

"When designing a secure system, the implementation techniques should be chosen based on threat mitigation first and performance second."

XQuery Preview

Thu, 17 Oct 2002 16:56:16 GMT

There's a good article up on The O'Reilly Network that contains a quick, but thorough introduction to the upcoming XQuery specification. The technology seems pretty well thought out and should certainly make working with XML documents much more robust. I'm not thrilled about the syntax of the language, but then again it's just syntax... it's the features that matter to me.

The question on my mind is: When will we see support for it in .NET?

Article: .NET Object Serialization

Tue, 27 Aug 2002 04:03:51 GMT

Another article* from The O'Reilly Network. This time they're covering serialization in .NET. The article covers the main facets of serialization: SerializableAttribute, ISerializable and IFormatter. Then the author goes into detail with a nice sample Windows Forms drawing application that uses serialization to persist the shapes drawn on the canvas to and from a Stream. In all, a good read for anyone looking to get a basic understanding of serialization in .NET.

(note: The actual title is C# Object Serialization, but you all know how I feel by now about making unecessary ties to languages when it comes to .NET neutral technologies)

Microsoft Web Services Development Kit (Technology Preview)

Mon, 26 Aug 2002 18:41:46 GMT

Microsoft has just announced it's tech. preview of the WSDK for ASP.NET. I haven't had a chance to check it out yet, but this is certainly great news for anyone building more advanced web services which require GXA.