Develop Reference

Performance diagnostics of an ASP .NET MVC 5 website

I have an ASP .NET MVC 5 website which runs perfectly on my local machine, but after publishing it to a hosting provider response time from the server is always about 30 seconds (on localhost it is about 100-500ms depending on a page). And I am not talking about first response after some timeout, I am talking about every response, even to pages like "Hello world" with a very simple ViewModel and maybe a couple of strings in ViewBag. At the same time, the static content (like .css and .js files) are returned quickly. I have performed several optimizations, such as:
Installed Razor Generator and compiled all .cshtml files
Got rid of dynamic variables and ViewBags
Made sure that I'm using "release" configuration
Unfortunately, my hosting provider doesn't allow me to configure IIS Application pool, so I couldn't optimize Idle Timeout etc.
Sometimes (very rarely) response time becomes normal (about 200-500ms) but this is for a very short period of time. I've tried several hosting providers and the issue is still there, so it seems to me that there are performance problems with my website but unfortunately I cannot locate and fix them. I'm using shared hosting, by the way, not VDS. So, the question is: Are there any standard diagnostic procedures intended locate and fix performance problems with ASP .NET MVC websites?

After several times of trying to find out solution for the issue with bad performance, I tried to deploy one of Visual Studio's included MVC projects (like #mjwills advised) and it didn't have any performance issues so I was pretty sure that there were problems with my project, not hosting provider. So, the solution for me was to create a new project from scratch and move all code from previous one to the new project, also deleting all the junk code and unnecessary nuget packages. I think that problems were caused either by bad entity framework configuration or by problems with nuget packages installed.

Advice on new project: additional functionality into existing ASP.NET app

Looking for suggestions regarding an upcoming project that I am involved in which revolves around adding certain functionality to an existing ASP.NET application running on IIS 6.0 programmed in VB.NET.
To aid in future development the client wants the additional functionality to be as future proof as possible. Ideally I have said that I would like to push for a solution using ASP.NET MVC3, running off IIs 7.5 and .NET 4, written in C#. This solution would act as a seamless addition to the current web-portal appearing probably just as an extra tabbed page.
But they will be completely separate web-apps. Which is crucial.
The main problems I can foresee are firstly sharing session particulars between the asp.net web app and the new application. Particularly with regard to maintaining session state (and not having IIS timing out on one of the apps). Also, conjoining the two "apps" appears problematic in my head, although this may be far simpler than I fear.
I'm asking for suggestions for these two problems if anyone has any ideas please say!
So far I've come up with the following solutions be they terrible or not:
1) Embed the new functionality into the existing codebase (not a great option). This would mean losing any potential future upgrade-ability and also means not following better OO conventions by utilising the MVC framework.
2) Using an iFrame to link to the razor pages of a seperate MVC3 app (the one I'm favouring currently). Allows uses of all new technologies, however downside is sharing session data. Either through iFrame "attributes" (is this possible?) through persisting a session state to a db? (slow?) or even some kind of web service interaction between the applications to push/pull user/session data?
Any advice/suggestions greatly appreciated!

I agree with you that C# and MVC is the "way to go", but unfortunately mixing two applications together is going to give you a whole bunch of headaches, not least the different session IDs. You'd probably have to have a shared database table to map them together and, as you can probably imagine already this reeks of "Band-aid".
What are the ramifications in rebuilding what is existing, in to C#? Perhaps you could suggest a complete upgrade. The client themselves seem to extol the virtues of future-proofing and therefore this would be the way to go. And no, I wouldn't promote the use of a "code-converter", but it really shouldn't be that difficult.
The next thing to consider, I guess, is "future-proof". Is the client worried that VB.NET is going to disappear any-time soon or that it cannot handle anything in the future? I find that a very unlikely scenario, honestly.
I think I've waffled on a bit, but essentially combining two applications, one with old and one with new functionality will cause a headaches. This could be solved by migrating the old site to C#/MVC, and then adding the extra functionality. True, this may seem like a large commitment today - but further on down the road, it will pay dividends.

If the current site can be upgrade to .NET 4.0 there's no reason why you wouldn't extend the existing application.
There's nothing to stop you mixing MVC and web forms (indeed there are several articles on how to do just this). There's nothing to stop you mixing VB.NET and C# (or, so far as I'm aware, to stop you doing MVC in VB.NET).
You'd have to work very hard to convince me of the merits of using iFrames. Very hard. You might be able to persuade me of the merits of running two applications side by side - with the functionality split by folder - but to be honest I'd be much happier upgrading the existing site and then building from there.

C# Application Cache Block

I am looking for an efficient cache strategy for C#. I am constructing an MVC application however one of my queries targets a historical table with states, etc. Needless to say, the query is highly nested and complex, and I do not want to run it every time a person hits the site, so I decided to cache the data (either the results or the tables themselves). I dont want to store my cache in the Managed heap due to the stop-the-world garbage collection problem which is common with generational GC's and Caches. I was wondering, does the Cache Application Block (http://msdn.microsoft.com/en-us/library/ff650180.aspx) use Unmanaged memory (off the managed heap?). Is there a way to access memory directly via native IO? Any other cache tools worth looking into?

I highly suggest you look at AppFabric Caching. I just implemented for my MVC app and it worked great.
I used this blog to get started:
http://www.hanselman.com/blog/InstallingConfiguringAndUsingWindowsServerAppFabricAndTheVelocityMemoryCacheIn10Minutes.aspx
Let me know if you need some code samples.

.Net caching frameworks that I am aware of:
The built in ASP.Net System.Web.Caching (which can be used in non-web applications as long as you don't mind referencing System.Web)
NCache
The Microsoft Caching Application Block
Built in Systen.Runtime.Caching (.Net 4.0 only)
Windows Azure AppFabric Caching (How to: Configure ASP.NET to use Windows Azure AppFabric Caching)
Although I've looked into various caching frameworks I'm afraid I don't have very much experience with any of them except for System.Web.Caching - this works fine for our purposes.

You can as well explore the distributed caching options like Memcached or SharedCache. We had used SharedCache for one of our project and it worked well. As suggested in one of the answers you could also try AppFabric. If you are looking at Microsoft based solution then there is a distributed caching famework by Microsoft called Velocity.
Hope this helps.

What are some useful strategies for converting a Classic ASP application to ASP.NET

We have a ten-year-old ASP application that we are considering planning an update for. We want to take advantage of the new technologies that ASP.NET has to offer, as well as the opportunity to fix some issues with the existing framework (the existing code-base is highly fragmented, nearly impossible to test, let alone debug, and the entire application appears to have been constructed according to the "Farmhouse Pattern".)
To that end, it seems that the time has come to rebuild this application. But, we are a small business, and we simply don't have the resources to either hire out the rebuild, nor to dedicate our small team of developers solely to the task of rebuilding (we've got other tasks on our plate, and can't concentrate on this one particular task for the length of time it would take to fully reconstruct the application).
What, then, are some useful strategies we can employ to help us convert this app, without having it consume all of our limited resources for the duration of the re-write?

Sounds like an interesting challenge. It's definitely not going to be easy, especially if you can't dedicate any resources to the project full time.
If you have a 10 year old application that is working, I would suggest not going for a complete re-write at all. I would start by sitting down and figuring out what you want your end product to be.
Is it going to be an ASP.NET MVC Web Application, an ASP.NET WebForms App, or something else? Once that decision is made, come up with a loose design for an architecture. If you do things correctly, you can build out bits and pieces of the business logic in .NET and utilize it from your Classic ASP code until you're ready to re-write the UI in .NET as well.

I agree with what Justin said; if you have a working application in place, you'll need a compelling reason (i.e., money) to justify the expense in rewriting the application for a new platform.
Although ASP classic and ASP.NET share a similar-looking syntax and some common coding conventions, they are very very different from each other. If you tried to simply copy-paste classic ASP code into an ASP.NET application, you might be able to get it to work, but you'd be missing out of a lot of the advantages of ASP.NET Web Forms or ASP.NET MVC (and their respective frameworks, of course).
You can, however, extend the functionality of the existing site with .NET code through web services or COM interop. We have a 10+ year old classic ASP web site and I've used both .NET web services (.asmx) and COM-callable .NET DLLs to enhance our existing application. In both cases, I wrote all of my new business logic in the .NET component and provided a chunky interface to work with the existing ASP page. That allowed my .NET code to be very easily testable and still use our existing (huge) investment in our classic ASP site.

The only approach that has worked for me is to carve of areas of functionality in small slices, and rewrite. "Converting" first, then refactoring seemed like a good idea a few times, but in the end just became horrible messes of code written in ASP.NET instead of ASP - and that added no value.
If you have a site that has distinct areas of functionality, carve one off and start with that (I chose "contact us"). Write it the way you think it should be written - that is, assume your new part is fitting into the end design of your well-written app. If you have to add "hacks" to interface with the old system, make sure they are isolated and commented.
When working on an update, think "can I carve of some of the functionality here into it's own bit?" - if so, convert it then update it. I found that if you insist on keeping the NEW app clean and allow yourself to add small hacks to the OLD app for communication, you get the best results.
This does mean you'll have two separate apps (two IIS web apps) for a while, and can make cookie/url and session management a bit hairy, as well as adding one more deployment concern. To combat this, make sure that you minimize state in your web app (always a good idea anyway), and share state through something other than Session.
If you do this a piece at a time, make the pieces small enough, and have a good design up-front, this works well - at least in my experience, it's the way that works best. Note that my experience may not match reality.

Offline synchronization options with .NET

I've been asked to research approaches to deal with an app we're supposed to be building. This app, hypothetically a Windows form written in C#, will issue commands directly to the server if it's connected, but if the app is offline, the state must be maintained as if it was connected and then sync up and issue data changes/commands to the server once it is connected.
I'm not sure where to start looking. This is something akin to Google Gears, but I don't think I have that option if we go a Winform route (which looks likely, given that there are other functions the application needs that a web app couldn't perform). Is the Microsoft Sync framework a viable option? Does Silverlight do anything like this? Any other options? I've Googled around a bit but would like the community input on what's best given the scenario.

The Microsoft Sync Framework definitely supports the scenario you describe, although I would say that it's fairly complicated to get it working.
One thing to understand about the Sync Framework is that it's really two quite distinct frameworks shipping in the same package:
Sync Framework
ADO.NET Sync services v. 2
The ADO.NET Sync services are by far the easiest to set up, but they are constrained to synchronizing two relational data stores (although you can set up a web service as a remote facade between the two).
The core Sync Framework has no such limitations, but is far more complex to implement. When I used it about six months ago, I found that the best source to learn from was the SDK, and particularly the File/Folder sync sample code.
As far as I could tell, there was little to no sharing of code and types between the two 'frameworks', so you will have to pick one or the other.
In either case, there are no constraints on how you host the sync code, so Windows Forms is just one option among many.

If I understand correctly, this doesn't sound like an actual data synchronization issue to me where you want to keep two databases in sync. it sounds more like you want a reliable mechanism for a client to call functions on a server in an environment where the connection is unstable, and if the connection is not present at the time, you want the function called as soon as the connection is back up.
If my understanding is right, this is one option. if not, this will probably not be helpful.
This is a very short answer to an in-depth problem, but we had a similar situation and this is how we handled it.
We have a client application that needs to monitor some data on a PC in a store. When certain events happen, this client application needs to update our server in the corporate offices, preferably Real-Time. However, the connection is not 100% reliable, so we needed a similar mechanism.
We solved this by trying to write to the server via a web service. If there is an error calling the web service, the command is serialized as an XML file in a folder named "waiting to upload".
We have a routine running in our client app on a timer set for every n minutes. When the timer elapses, it checks for XML files in this folder. If found, it attempts to call the web service using the information saved in the file, and so on until it is successful. Upon a successful call, the XML file is deleted.
It sounds hack-ish, but it was simple to code and has worked flawlessly for five years now. It's actually been our most trouble-free application all-around and we've implemented the pattern elsewhere successfully