F9 Group Marketing and Technology Blog

The .NET Framework is big. Really big. The System.Web assembly, which contains the guts of ASP.NET, is comprised of nearly 2,000 types, over 23,000 methods, and more than 12,500 properties. And that’s not counting any of the functionality added to ASP.NET since version 2.0. ASP.NET AJAX, the ListView control, Dynamic Data, URL routing, and other features add hundreds of new types and thousands of new methods and properties.

The Microsoft Chart Controls provide ASP.NET developers with an API and a Web control for creating and displaying charts in a web page. Behind the scenes, the Microsoft Chart Controls take the data to be plotted and dynamically generates an image. This image can be generated using one of three techniques: the Chart Web control can generate the image and save it to the web server’s file system in a specified location; the Chart control can generate the image and store it in memory, session, or elsewhere, and have that image served by a built-in HTTP Handler, ChartHttpHandler ; or the Chart control can send back the binary contents of the chart image directly to the browser. The chart image can be rendered using one of four image types: PNG , JPG , BMP , or EMF . And when rendering a JPG you can specify its compression level. Regardless of the image file type and the technique used to generate the image, the Chart Web control renders an <img> element whose src attribute references the image (or the image-producing HTTP Handler or ASP.NET page). When a browser requests a web page with a Chart control on it, it receives this <img> element as part of the page’s rendered markup and then makes a request to the URL specified in the src attribute (just like it does for any other image on a web page). The chart image file the browser requests either already exists in which case its contents are returned, or the image is dynamically-generated. Either way, the end result is that the browser is sent back the chart as an image file, which is displays. This article explores the three different techniques the Microsoft Chart Controls has at its disposal for generating chart images. We’ll look at how to use each option, enumerate the pros and cons, and discuss when to consider using one option over another. Read on to learn more! Read More >

Exceptions are a construct in the .NET Framework that are (ideally) used to indicate an unexpected state in executing code. For example, when working with a database the underlying ADO.NET code that communicates with the database raises an exception if the database is offline or if the database reports an error when executing a query. Similarly, if you attempt to cast user input from one type to another – say from a string to an integer – but the user’s input is not valid, an exception will be thrown. You can also raise exceptions from your own code by using the Throw keyword. When an exception is thrown it is passed up the call stack. That is, if MethodA calls MethodB , and then MethodB raises an exception, MethodA is given the opportunity to execute code in response to the exception. Specifically, MethodA can do one of two things: it can catch the exception (using a Try … Catch block) and execute code in response to the exception being throw; or it can ignore the exception and let it percolate up the call stack. If the exception is percolated up the call stack – either by MethodA not catching the exception or by MethodA re-throwing the exception – then the exception information will be passed up to the method that called MethodA . If no method in the call stack handles the exception then it will eventually reach the ASP.NET runtime, which will display the configured error page (the Yellow Screen of Death , by default)

As discussed in An Introduction to LINQ , one of the cornerstones of LINQ is the standard query operators , which are a set of extension methods on the IEnumerable interface added to the .NET Framework version 3.5. The standard query operators can be applied to any enumeration – any collection of “things.” In The Standard Query Operators installment we looked at some of the more common query operators, such as Where , Select , OrderBy , and others. Each standard query operator can be classified as a certain type of operator. There are aggregation operators like Count , Sum , and Max ; element operators like First , Last , and ElementAt let you pick out a specific element from a sequence; and the ordering operators OrderBy and OrderByDescending order the elements of a sequence based on a specified sorting criteria. Another class of query operators that we’ve yet to explore are grouping and joining operators . The grouping and joining operators work with two (or more) sequences and combine them together, much like how a JOIN in SQL combines records from two (or more) tables into a single resultset. Through LINQ’s standard query operators (or via its query syntax ), it is possible to perform: nested (or grouped) queries; cross joins, or the Cartesian product of two sequences; inner joins; and left outer joins. This article explores the grouping and joining operators available in LINQ with a number of examples in both Visual Basic and C#. As with the previous installments in this article series, the complete code is available for download. Read on to learn more! Read More >