Saturday, August 19, 2017

The SDK ‘Microsoft.NET.Sdk.Web’ specified could not be found

If you are working on Visual Studio 2017 with update 3, then you might have come across the error 'The SDK ‘Microsoft.NET.Sdk.Web’ specified could not be found' in netcoreapp1.1 for both web and console.

Unfortunately, I also landed up into this situation. So, one straight forward and temporary solution could be to edit the project file manually from Project Sdk = ”Microsoft.NET.Sdk.Web” to Project Sdk = ”Microsoft.NET.Sdk” and re-open the solution. Everything will work fine as expected. So, what are the reasons behind this error?

I explored many articles on MSDN forums as well as looked at github link and the primary reasons which are causing this error are:
  • Workstation is still holding an old preview version of CLI 1.0
  • Installed CLI version is correct but its path is incorrect.

Solution:
  • Uninstall all the older versions of CLI with 1.x as SDKs with version 1.x can break things
  • Verify the value of PATH- Open the developer command prompt and verify the value of the PATH variable and make sure that 'C:\\Program Files\\dotnet' appears on the path before any other entries that point to subdirectories of the dotnet folder.

If you are working with the web project, then you can also verify the SDK versions in global.json file and edit it manually if required.

Hope above post was useful for the newbies who just took Update 3 and are struggling to build their solution templates.

Friday, August 11, 2017

Is your client request missing from IIS log?

One can enable IIS logging by going to IIS Manager and checking the Enable logging checkbox. So, it means if IIS logging is enabled, then each and every request made by the client should be showing up in the IIS log. Isn’t it? But by any chance, if the request is not present in IIS log then the most probable reason would be either IIS was not running or may be request was not made.

But this statement is not 100% correct. Because whenever any request is made to the server, first it routes through HTTP.SYS then it comes to IIS. So, if anything is not visible under IIS logs, then one can see the logging for HTTP.SYS which is HTTPERR. The most common errors logged here are related to timeout or service unavailability.

The next question would be, where these logs are exactly saved?
You can find HTTPERR under C:\Windows\System32\LogFiles\HTTPERR

Interested in knowing more about HTTP.SYS, here you go.

Sunday, August 6, 2017

Unable to launch IIS Express from Visual Studio

Recently, while working on one of the web project, I came across a situation which ate up my almost an hour. Concern was, my IIS express was not launching automatically on running my web application from Visual Studio 2015. I tried various solutions like,
  • ran the Visual studio as an Administrator,
  • changed the port,
  • disabled the firewall,
  • reset the IISExpress folder.
But no luck :(
Then I thought, let's give a try by deleting the temporary folders which were created by Visual Studio and guess what? That worked for me. 

The culprit was the .vs folder which was the hidden folder in the project's root directory. One of my colleague checked-in that folder by mistake and as I was fetching the code for the first time, it came on my machine. Actual felon was the .suo file which was inside .vs folder. This .suo file contains user specific settings. Hence same user settings didn’t work for me. 

Solution - Deleting .vs folder did the trick :)

Happy troubleshooting !!!

Wednesday, May 24, 2017

Possible Multiple Enumeration of IEnumerable

If you have worked with IEnumerable and using ReSharper, then you may land up into this warning, "Possible Multiple Enumeration of IEnumerable". So, what this warning is all about?
Well, before proceeding further, let’s see how we can store something into IEnumerable object .
IEnumerable items = GetAllItems()
So, above code itself speaks that items is a variable of type IEnumerable which will hold some values/objects we can iterate through.
Now here lies the performance hit, which is also indicated in the form of ReSharper warning. This performance hit may not be significant for a small number of items. But this can be noticed while dealing with a huge number of items.
Reason behind this is, whenever you are iterating through items collection, GetAllItems method will be called for the same number of times.
Solution: It is always good to materialized the result in a list or array like below:
IEnumerable items = GetAllItems().ToList()

Once you are done with mentioned code changes, you will notice that above warning doesn't exist any more.
Hope you like this small post.

Tuesday, May 16, 2017

.Net Architecture Guidance announced

Few days back, Microsoft announced the draft version of the .NET architecture guidance. This guidance is the combined effort of the Visual Studio team and the Microsoft Developer Division. As of today, it covers only 4 areas:
  • ASP.NET Web applications
  • Azure Cloud Deployment
  • Xamarin Mobile Applications
  • MicroServices and Docker
You can find more about this guidance on Microsoft’s official page.

Saturday, March 25, 2017

Why normal .NET exception handling doesn't work in WCF?

Errors and exceptions are part of our programming life and WCF is no different. So, when we get errors in WCF, we would like to propagate those errors to our WCF client so that they can accordingly take actions. In order to demonstrate this, let’s go through the code of a simple service:
       public int Add(int number1, int number2)
        {
            return number1 + number2;
        }

        public double Divide(int number1, int number2)
        {
            return number1 / number2;
        }        
Both the above methods will perform some calculation and return the result to the client. Let’s say, now for some reason someone sent 2nd parameter of Divide method as 0. 

What will happen? Definitely code will throw an error or say DivideByZero exception. Isn’t it?

Know how to handle this error? Most of the developers will simply decorate Divide method with Try-catch block and throw the exception, similar to our normal .NET exception handling mechanism as shown in below code:
       
public double Divide(int number1, int number2)
        {
            try
            {
                return number1 / number2;
            }
            catch (DivideByZeroException exception)
            {
                throw exception;
            }
        }       
 
This normal exception handling mechanism will not work in WCF world. Now before discussing on WHY, let’s quickly see what is passed from the client:
       
MathClient math = new MathClient();
            try
            {
                math.Divide(10, 0);
            }
            catch (Exception exception)
            {
                Console.WriteLine(exception.Message);
                Console.ReadLine();
            }       
 

Now if we will run this client application, we will land upon such error message:














Now by looking at the error message, we cannot figure out what went wrong as it only mentions it is an internal error :(

Now coming back to the same question, why is this happening like this?

Well, reason behind this is the message format being used by WCF. WCF uses, XML or XML SOAP to communicate with clients. So, even if any exception is raised, it has to be in XML format. Hence normal .NET exception handling mechanism doesn’t work here because the error is not sent to clients in the form of XML.

So, the solution here is Fault Exceptions and rather than throwing a normal .NET exception, we have to throw a fault exception as shown below:
       
public double Divide(int number1, int number2)
        {
            try
            {
                return number1 / number2;
            }
            catch (DivideByZeroException exception)
            {
                throw new FaultException(exception.Message);
            }
        }
       
 

Now re-run our application and we will be able to see proper error message.





On a summary note, we cannot use normal .NET exceptions to propagate exceptions to the client but same can be used within WCF service.

Hope you like this small but very useful tip. Happy learning!

Friday, February 17, 2017

Which WCF template to be used?

Recently, one of my colleague asked me, which WCF template should I use to create a service? For experienced people, it may be a silly question, but it is one of the common question among beginners, who just entered into the world of services. That’s the motivation who made me write this small post.

Well, let’s first have a look at what all templates are available in Visual Studio 2015 for WCF: 










The developer can choose any of the above templates as per project need. Let’s go through them one-by-one.

WCF Service Library: This template is nothing but a simple service library which uses App.config as its configuration file.

WCF Service Application: This template will create a web site which in turn will be hosting a service in it. Here Web.Config will be used to serve configuration settings.

WCF Workflow Service Application: This template is useful when you want your workflow to be accessed as a web service.

Syndication service Library: This template is useful when you want to expose RSS as a web service.

Hope now you are comfortable on which template to be chosen.Happy learning!

Monday, January 2, 2017

DependencyObject in ViewModelBase - Good or Bad?

First of all, a very-very Happy New Year to all my readers. If you are reading this post, then I’m assuming that you have a working experience of WPF using MVVM. 
Don’t worry, I’m not going to re-write a huge post on what MVVM is and where to use it? This blog is very small which talks about one of the best practices any developer implementing MVVM should follow.

Well, let me provide you the context first. Last week I was going through one of my colleagues’ code and noticed few interesting things in his ViewModelBase class:
  • It was holding few Dependency properties 
  • It was inheriting DependencyObject 

How it sounds to you? Good or … ? 
Of course, that is not at all a good practice as ViewModelBase is the base class for all the ViewModels and is not supposed to contain such code. Well, this is not the only reason. 

There are many other reasons which are making this implementation a BIG NO. 
1st Reason – A DependencyObject was never meant to be a Source of a binding, but rather it is a Target, which means its existence should be in the UI layer. So, if we are inheriting DependencyObject in ViewModelBase class, then we are not adding dependencies on view related objects.

2nd Reason – DependencyObject overrides and then seal two methods Equals and GetHashCode with a reason to prevent derived classes to define value equality for a DependencyObject as such sort of value equality will never be accurate due to value changing capabilities of DependencyObject and its dependency properties. Hence inheriting DependencyObject class in ViewModelBase will never let you override Equals and GetHashCode methods. Official link  

3rd Reason - Serialization – If you want to Serialize anything in VM, it’s not gonna happen because our Base class which is DependencyObject in our case is not Serializable. In other words, DependencyObject class is not marked as [Serializable]. So, the only solution left and can be used as a workaround is to implement ISerializable in ViewModelBase class which is not recommended solution here. 

4th Reason - CLR properties still needs INotifyPropertyChange implementation. 

5th Reason - Thread affinity – It says that an object created on one thread cannot be used by another. A DependencyObject has thread affinity means it can only be used on the thread that created it.

Hence never ever derive ViewModelBase class from DependencyObject. Enjoy learning!!!