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Preview: Rick Strahl's Web Log

Rick Strahl's Web Log



Life, Surf, Code and everything in between



 



Multi-Targeting and Porting a .NET Library to .NET Core 2.0

Thu, 22 Jun 2017 16:46:07 GMT

.NET Standard and .NET Core have been on my mind for a long time now - years really, but the reality is while I've been using the technology quite a bit, I've not jumped in with both feet. In fact, to date I have yet to build anything 'real' for customers beyond a few internal infrastructure projects and quite a few sample applications. For me personally, .NET Standard 2.0 and .NET Core 2.0 with their much bigger base library foot print and the real possibility of porting the majority of existing library code over to .NET Core really has been a deciding factor for me to start moving some of my existing full framework libraries that I've been using for as long as I have been using .NET to .NET Core 2.0. Being able to bring some of the tools I use to be productive over to .NET Core is actually pretty important factor to overcoming my reluctance to move into .NET Core. Nobody wants to rewrite code they already have just to get back to square one, but with .NET Core 2.0 it really looks like most code will migrate pretty easily. This isn't just important to me personally, but I think this is a vital requirement for moving much of the support libraries that exist for .NET into .NET Core and providing the full featured eco-system that we've come to expect from .NET applications. Currently with .NET Core 1.x it's been hit or miss feature wise to feel confident you can actually make it through a project without getting stuck with some missing core feature you can't easily find and have to build from scratch. My feeling is that .NET Core 2.0 will change all that by making it possible for most libraries to be ported with minimal effort. In this post I describe porting an existing full framework library to .NET Core 2.0 and multi-targeting the project to support .NET 4.5, 4.0 and .NET Standard 2.0. The porting process was even easier than I expected, although the tooling required a bit of patience to get on with. What you need to follow along: Visual Studio 2017 Update 3 Preview 2 or later .NET Core 2.0 SDK Preview Note that currently there's no support for .NET Core 2.0/.NET Standard 2.0 in the release version of Visual Studio, and that's why the Preview install is required. You can install the minimal .NET and .NET Core payload for a lightish install, and the install is side by side with Visual Studio 2017 RTM so both work. .NET Standard? A key concept to the porting process is .NET Standard 2.0 and how it relates to .NET Core 2.0. For those of you that don't know, .NET Standard is a specification that serves as a blue print for .NET runtime implementations. The standard specifies what base features the runtime has to implement to support it. .NET Standard describes the base API library - what we used to think of as the Base Class Library (BCL) in full framework that make up the core features of the platform. .NET Standard is a standard not an implementation and it's up to the runtime to implement the features set forth in the standard. The logistics of this involve some runtime magic where each runtime provides a set of .NET Standard forwarding assemblies that map the .NET Standard APIs to the actual underlying APIs on the specific runtime. For the purposes of this discussion, the salient point is that .NET Core 2.0 is an implementation of .NET Standard 2.0 which means that if I implement a .NET Standard 2.0 compliant DLL it will run on .NET Core 2.0. And any other platform like .NET 4.6.1, Xamarin, Mono, UWP and Unity all of which will eventually support .NET Standard 2.0. By targeting .NET Standard 2.0 I can insure that my DLL will run on any of the target platforms that .NET Standard supports. The big win with .NET Standard is that it provides a common interface to consumers of a library, as well as an official guideline to the actual runtime implementers. For Visual Studio purposes targeting .NET Standard for a class library is also what gives the new SDK project type that is required to make multi-targeting work. I don't want to rehash all the details about how .NET Standard works here, but you can read my earlier blog po[...]



Bypassing IIS Error Messages in ASP.NET

Thu, 01 Jun 2017 22:30:42 GMT

IIS Error messages can be a bear to manage when building ASP.NET applications. IIS has a boatload of locations where error handling can be configured. When building Web applications, most of the time you want IIS to get out of your way and let your application handle serving error messages. Note: this post discusses error handling in full framework ASP.NET - not ASP.NET Core Unfortunately if you leave the default behavior in place you'll end up getting error pages like this: Figure 1 - Default IIS Error Messages are a bit terse. Which is a rather terrible experience for an end user. You'll see similar pages for 404's and full 500 pages. The Short of it Let's fast forward to the quick solution, which is to explicitly tell IIS to get out of the way of error messages. To let your application handle errors and control the error display, there are two steps: Use the Response.IisTrySkipIisCustomErrors flag Context.Server.ClearErrors() Context.Response.IisTrySkipIisCustomErrors Set the HttpRuntime to pass through all Response output This should be all that you need to get ASP.NET (full framework) to pass through all HTTP responses from your application. For more detailed information, read on. Response.TrySkipIisCustomErrors As the name of the property suggests this flag can be used to turn off IIS custom error handling on a per request basis. It's easy enough to do this whenever you have access the HttpContext.Response property. Server.ClearError() Response.TrySkipIisCustomErrors = true; once you are sure you've handled the error. Note that in most cases you'll also want to clear the error. If you don't, IIS either throws up a default error page, or in some cases, an empty response as the request leaves the ASP.NET pipeline. Clearing the error takes care of that. However, don't clear the error before you've captured Server.GetLastError() - otherwise you can't access the error information. You can set this TrySkipIisCustomErrors property anytime before the Response gets sent out to IIS - ie. anytime before any output is sent explicitly. Passing through the Error Response If you use Response.TrySkipIisCustomErrors alone you'll find that even with the flag set to true, the response still fires IIS errors rather than the content you return. It's necessary to explicitly force the original response to pass through to IIS when an error occurs with the following configuration setting in web.config: CustomErrors in IIS A huge cause for confusion around errors in IIS and ASP.NET is the config element. Because it has so many options and dependent behaviors it's often difficult to figure out exactly what combinations of error handlers are in effect. The CustomError section in web.config lets you configure how errors are processed in an ASP.NET/IIS application. Essentially this setting lets you control what happens if your application doesn't handle an error in the application. RemoteOnly shows detailed error information on localhost, and IIS error messages if remotely connecting. Other choices here are On and Off. If CustomErrors are On (or you're remote), the default custom error handling behavior pushes any error status code from an ASP.NET application to the IIS Custom Error Messages. On a remote machine you get a very simple error message: Figure 2 - Standard IIS error display On the local machine you often get detailed IIS error messages that point at a faulting module or component: Figure 3 - The local IIS error page has a lot more information about the error. As you can see this page has a lot more info on it compared to Figure 1 meant to help a local developer potentially troubleshoot an error which is quite nice. Locally error pages often have a wea[...]



Automating IIS Feature Installation with Powershell

Thu, 25 May 2017 19:30:28 GMT

IIS often gets a bad wrap for being diffcult to install and configure. However, using some of the built-in tooling for administration using PowerShell it's actually quite easy to configure IIS and even set up a new site and application pool with a few short scripts that are much quicker, and more repeatable than using the various Windows UI features. Here's how.(image)



Upgrading to .NET Core 2.0 Preview

Tue, 16 May 2017 04:42:00 GMT

With the release of the first preview of .NET Core 2 and ASP.NET Core 2.0 I decided to upgrade my AlbumViewer sample application to the latest bits and preview tools. Overall the experience was pretty smooth, but I ran into a couple of breaking changes and a few tooling snags that I'll describe in this post.(image)



IIS and ASP.NET Core Rewrite Rules for Static Files and Html 5 Routing

Fri, 28 Apr 2017 02:26:44 GMT

If you're running ASP.NET Core under Windows with IIS, you'll want to take advantage of letting IIS serve up your static content and handle your HTML 5 Client and home routes. IIS is very efficient at handling static content and content re-routing and in this post I describe how you can properly configure ASP.NET Core applications using the AspNetCoreModule and IIS Rewrite Rules(image)



Creating a Markdown Monster Addin: Save Images to Azure Blob Storage

Mon, 17 Apr 2017 16:30:29 GMT

The Markdown Monster Markdown Editor and Weblog Publishing tool has a .NET based addin model that makes it relatively easy to extend its core feature set with custom functionality. In this post I show how you can quickly create an addin of your own, and then show a practical example that demonstrates how add Image uploading to Azure Blob storage as an interactive addin.(image)



Running .NET Core Apps under Windows Subsystem for Linux (Bash for Windows)

Thu, 13 Apr 2017 19:53:07 GMT

The Windows Shell for Linux (WSL or Bash on Ubuntu on Windows) provides a nice way for Windows and Linux to interact without the overhead of dealing with a separate VM. Using the WSL you can now also run your .NET Core applications directly under Linux without requiring a VM or Docker. In this post I demonstrate how the shell works and how you can run your .NET and ASP.NET Core applications to test operation under Linux.(image)



Virus Scanning Madness for Software Distribution

Sun, 02 Apr 2017 19:22:35 GMT

I've been having having lots of problems recently with VirusTotal, which is used by Chocolatey to scan for malware in Chocolatey distribution packages. VirusTotal is a Web based service that aggregates around 60 virus scanners against an installation binary. The problems is that I frequently see random malware hits by various obscure scanners. In this post I describe the problem and the farce that this has become as some of the malware hits are obviously false positives that actually reverse in a rescan.(image)



Updating my AlbumViewer Sample to ASP.NET Core 1.1 and Angular 4

Fri, 31 Mar 2017 08:05:54 GMT

I updated my AlbumViewer sample application recently to the latest versions of ASP.NET Core (1.1) and the new .csproj project as well Angular 4(image)



More on ASP.NET Core Running under IIS

Fri, 17 Mar 2017 05:40:45 GMT

Since my last post about hosting ASP.NET Core on IIS I've gotten quite a few questions and comments in regards to working with this mixed IIS/Kestrel hosting environment. There are quite a few not so obvious arrangement in this set up and some surprising discoveries in terms of performance and segragation of feature usage between IIS and Kestrel.(image)



Dragging and Dropping Images and Files into the Web Browser Control

Fri, 10 Mar 2017 09:23:34 GMT

Dragging content into the Web Browser control and capturing the content dropped can be tricky. The Web Browser Control is based on Internet Explorer and is actually an ActiveX control hosted inside of a container and because of that is difficult to deal with. In this post I describe how you can get around this issue and still capture images and files dropped on the control and handle the drop operations.(image)



Debugging the Web Browser Control with FireBug

Wed, 08 Mar 2017 10:09:31 GMT

If you need to debug JavaScript code or layout issues in a Web Browser control inside of a Windows desktop application, you've probably found that the experience sucks. Although Internet Explorer on which the control is based suppports rich developer tools, those are not available in the Web Browser control. Enter an oldie but goodie: FireBug which is an embeddable Console implementation that provides a lot of the features that you find in modern browser developer tools and with a couple of lines of html you can add this debugger into your application.(image)



Getting JavaScript Properties for Object Maps by Index or Name

Sat, 04 Mar 2017 21:59:11 GMT

Getting value out of maps that are treated like collections is always something I have to remind myself how to do properly. In this post I look at JavaScript object iteration and picking out values from a JavaScript object by property name or index.(image)



Video Rendering Issues for WPF Windows

Tue, 14 Feb 2017 00:57:23 GMT

Recently I ran into a few reports of black screen of death rendering of Markdown Monster when starting up from a very few users of the application. They reported the screen just shows black, while actually being responsive to moving and showing menus etc. Also moving to another screen often fixes the problem. It turns out this is a hardware related issue with WPF with certain video hardware/monitor combinations. In this post I describe the problem and the workaround to get the application to render properly even on compromised hardware.(image)



Empty SoapActions in ASMX Web Services

Sun, 12 Feb 2017 19:12:01 GMT

Recently I had to deal with an ASMX Web Service that was receiving empty SoapActions from the client. ASMX doesn't like that, but luckily there's an easy work to strip out the errant Soap header.(image)



Creating a portable and embedded Chocolatey Package

Sun, 29 Jan 2017 21:05:40 GMT

Chocolatey is an awesome tool to install software. As a publisher you have a lot of choices of how to create packages and in this post I describe the two packages that I use with Markdown Monster, which is a full downloaded installer package and a fully self contained embedded portable package. Here I cover the basics of Chocolatey package creation and some of the steps required to create a portable package from a full installation and some of the challenges you might run into along the way.(image)



Adding Files to Visual Studio Projects

Wed, 25 Jan 2017 19:35:31 GMT

Visual Studio has a boat load of ways to add new files to a project and various extensions and tools provide even more ways to do the same. Even so the experience to add new files to a project in Visual Studio is one of the most tedious tasks. Here's what bugs me and how I try to work around the verbosity of it all.(image)



New CODE Magazine Article: Getting down to Business with ASP.NET Core

Thu, 12 Jan 2017 20:19:27 GMT

The latest issue of CODE magazine features my `Getting down to Business with ASP.NET` Core article as the cover article. The article focuses on building an ASP.NET Core backend for an Angular 2 front application, covering all aspects of separating business and Web app logic, dealing with EF Core data access in related tables, CORS to be able to run across domains and simple authentication in a client centric REST service application. Check it out.(image)



Faking out the .NET Runtime Version

Tue, 10 Jan 2017 07:04:01 GMT

I've been struggling with DPI Scaling issues in WPF in Markdown Monster and .NET 4.6.2 has a few fixes that address the problems I've been working on. However, requiring 4.6.2 is a problem due to lowish adoption rates and skittishness about installing new versions of .NET. In this post I show a little hack that allows me to compile my app to .NET 4.6.2 but don't require user to have that version installed so those that have it can take advantage of the updates.(image)



Back to Basics: String Interpolation in C#

Tue, 27 Dec 2016 08:12:59 GMT

String Interpolation provides string templating for string literals in C#. Rather than using string.Format you can use string interpolation to produce much more readable code that embeds expression values directly into string literals rather than escaping numeric arguments as you do with string.Format(). In this post I look at how string interpolation works, what the compiler does under the covers and some common use cases where it makes life easier.(image)



Downgrading a .NET Applications from 64 bit to 32 bit for the WebBrowser Control

Fri, 23 Dec 2016 09:14:52 GMT

Recently while working on Markdown Monster I ran into some odd crashes and behaviors when interacting with the Web Browser control in this WPF application. It turns out that some of these inconsistent behaviors are apparently caused by running hte application in 64 bit mode. Switching to 32 bit mode has made the application and Web Browser interaction much more responsive and has stopped the nagging unexplainable crashes. In this post I look at 32 and 64 bit applications in .NET and outline some of the issues I ran into and how I fixed the problem by switching to building a 32 bit app.(image)



Visual Studio Debugging and 64 Bit .NET Applications

Mon, 19 Dec 2016 08:26:59 GMT

Recently while debugging a 64 bit application I found out the hard way that Visual Studio by default will use 32 bit debugging even when running what would otherwise be a 64 bit .NET application. There are a number of options that determine the bitness of your application, but the debugger often behaves differently than your standalone application. In this post I describe, why this might be a problem in some situations and how you can get the debugger to run in 64 bit.(image)



WPF Rendering DUCE.Channel Crashes due to Image Loading

Thu, 15 Dec 2016 09:43:47 GMT

I ran into a nasty WPF rendering bug that affected only a few select machines. Rendering problems in WPF can be terribly difificult to debug because there often is no additional information on what failed and the exceptions that occur are not trappable but fall back to application wide error handling. In this post I describe a specific failure caused by a 'bad' image WPF can't deal with and how I tracked it down and fixed it.(image)



Loading .NET Assemblies out of Seperate Folders

Mon, 12 Dec 2016 09:49:25 GMT

In the process of updating the Addin manager in Markdown Monster I ran into a few snags with loading .NET assemblies out of separate folders. Assembly loading out of non base folders in .NET can be problematic and sure enough I ran into a few issues that took a while to find a work around for. In this post I describe some of the issues of folder based assembly loading and a brute force solution to deal with assembly resolution.(image)



.NET Standard 2.0 - Making Sense of .NET Again

Wed, 23 Nov 2016 09:29:40 GMT

It's taken awhile but it seems Microsoft is finally nailing the message for .NET going forward and .NET Standard with its common API specification is a huge part in making sure that the same base library of .NET is available on all .NET platforms. In this post I look at what .NET Standard is, how it works and what some of the surrounding issues and impacts are for the .NET Eco system.(image)