How does the view in browser option work in Visual Studio without IIS?

Question

It seems like the View in Browser option doesn't really require IIS and it seems to process ASP pages fine. So how does it really work without a web server?

They used to have a developer web server (Cassini) which is dead long time back so is there some kind of built in capability in visual studio? Who processes the requests by asp pages if it doesn't require IIS?

I already have IIS installed so I am not sure if is servicing the pages but seems like it will work without IIS because I don't configure anything in IIS and new ASP.NET projects work out of the box as well View in Browser option for an asp page option which just directly executes that page.

Answer 1

Actually this is what occurs: Your web web.config is copied. Then VS spools up a WHOLE running copy of IIS (it is the express version - but it is the same for the most part as the full edition of II).

Once VS spools up and starts and configures that running copy of IIS?

Then your web page and web application can run. If you look at your system try, you see this:

So in above that 2nd from the left in the tray shows that blue thing icon. I have right clicked on it to show the options you see.

So now you have a running copy of IIS on your computer. So you ARE running a full web server here. (well, ok IIS express - but the base parts and what that means is much the same as the full edition).

Around about VS version 2010, they USED to have a smaller built in web server as part of VS. The problem of course was for Microsoft to maintain 100% compatibility was VERY hard. So while for a considerable time frame and history of VS? Yes, they had a built in web server as part of VS. But they dropped it a number of versions ago in VS, and as noted now use IIS express.

So Now? Well, when you install VS, they also install a working copy of IIS. (the express version). The express version is quite much the same as the full pop edition of IIS. What is removed is "most" if not "all" of the IIS management screens and setup. (and sometimes I wish they would just install that part too.).

Your experience thus that a copy of IIS is launched. Once launched IIS does keep running during your development process (depends on your VS config and setup). But, if you go file->close solution, then you find that IIS express then also shuts down.

So, to view that web page? Yes, VS does config, and then does spool up and start inte.net services and that web server. So this running of IIS on your computer is what allows those web pages to work and run correctly. As noted, while this is a copy of IIS, it is for the most part the same as the full edition - just with most of the management tools removed. As noted, you SHOULD see that new icon appear in the system tray.

And as noted, I believe around VS 2010, they made that switch from the VS built in IIS to that of now using IIS express edition. As noted, this change was made to ensure a greater probability that when coding and debugging your web site in VS, that the end result will be much the same when running a full edition.

I do find that over time, the production (web hosted site) does get so many config and tweaks and changes, that I now can't include my web.config file in the publish (can't risk overwriting the server production web.config). So, over time, we added things like https security certificates and installed them, and set them up for the production web site. I don't have those same security certificates setup on my local machine. And of course there are some virtual folders and few more things that exist on the production web site as opposed to the dev copy I use. So, it somewhat my fault to let the production web.config over time to become "different" then what I run local when coding and debugging the web site. So now, when I publish - I remove the web.config file before I actually copy the new updated web application to the final production server (which of course is running the full edition of IIS).

But to make a long story short?

Yes, a whole copy of IIS web server is configured for you, and that whole copy of IIS is spooled up, launched, and once that occurs, then your web page option "view in browser" can run. But make no mistake here - IIS services is setup, is started, and is running for that web page preview to occur.