In IIS7 I am trying to set a really far future expires header for all content that have the file name that has a specific word in it. For example I would like to set this header on any file being requested from IIS7 that is
*cached*.js
I know that it is possible to set far future expires headers, But I want to know if it is possible to set it on specific files like in the example above.
I want to use this method on a .NET application I am trying to serve up, but I want to make it more efficient so that certain files will be cached for a very long time, because it virtually never changes. At the same time I don't want to be restricted to doing it for all files in a certain folder or all files of certain type.
I am open to doing this through modifying my Asp.Net application to achieve this, or through IIS7 settings.
So guys, what do you think, is There a way to do this?
An HttpModule will let you do this. That would let you look at the incoming URL then add the correct response headers.
Edit: Added Example
You can use this URL to create a basic HttpModule. Then in the Application_BeginRequest event, I think this code will be close to what you want:
if (context.Request.FilePath.ToLower().IndexOf("cached") != -1)
context.Response.Cache.SetExpires(DateTime.Now.AddYears(1));
Related
I'm generating dynamic CSS URLs for cache-busting. I.e. they're in the format styles-thisisthecontenthash123.css.
I also want to use HTTP Link headers to load the files slightly faster. I.e. have the header Link: <styles-thisisthecontenthash123.css>; rel=stylesheet
I'm pretty sure it's possible to do this in Fastly using VCL, but I'm not familiar enough with the ecosystem to figure it out. The CSS URL is in index.html, which is cached. I'm thinking I can open index.html and maybe use regex to parse out the CSS URL. How would I do this?
If I'm understanding your question correctly, you want to include a link header for all requests for index.html. You can do that with Fastly, but if the URL for the CSS file is changing you're not going to be able to pull that info out with VCL (you can't inspect the response body).
You could use edge dictionaries and whenever your CSS filename changes, update the reference via the API.
Thing is, if you're going to make an API call whenever the file changes, might as well just keep the filename consistent (styles.css) and whenever you publish a new version send a cache invalidation (purge). Fastly will clear the cache in ~150ms, so you then all you have to do is add the header which is can be done in the Fastly web portal with a condition.
I'm building a backend admin system which edits json files that control the look and feel of the main site. I want to add a 'preview' button before the user hits save. To do that, I want to use the main site, but instead of calling the actual json file in production, save a temp version of it and redirect this user's traffic for that file to the temp file - from the original site code.
i've considered both chrome pluggins, configuring iframe somehow or, in worst case scenario, grabbing the production front-end, parsing out the call to the prod json file and replacing with new temp json file. That is obviously not ideal as it would entail a lot of work and if anything changes on the prod site, this will have to be updated.
I would love your ideas!
Do you have access to the main site's source code? You could implement a preview option from the main site which accepts a GET parameter and uses a temporary JSON setting based on this GET parameter.
From the backend admin system's point of view, it's just a matter of adding the JSON as part of the ajax GET request.
Unfortunately though, there is no easy way of doing this if you don't have access to the main site's source code or if you can't reach out to whoever maintains that main site.
Your cleanest option might be to recreate the main site's look and feel instead and pass it off as a "preview".
For a long time I've been updating ASP.NET pages on the server and never find the correct way to make changes visible on files like CSS and images.
I know if a append something in the URL the browser will think the file is another one:
<img src="/images/myLogo.png?v=1"/>
or perhaps changing its name:
<img src="/images/myLogo.v1.png"/>
Unfortunately it does not look the correct way. In a case were I'm using App_Themes the files in this folder are automatically injected in the page in a way I can't easily change the URL.
So my question is:
When I'm publishing de ASP.NET Application on the server what is the correct way to signal to IIS (and it notify browser after that) that a file was changed? It is not automatic? Should I change some configuration in IIS or perhaps make some "decoration" in the code?
I've already tried many questions here in SO like "ASP.NET - Invalidate browser cache", "How to refresh the browser cache of an image?", "Handle cached images? How to get the browser to show the new version?", and even "What is an elegant way to force browsers to reload cached CSS/JS files?" but none of them actually take another aproach else in a way you must handle it manually in the code instead of IIS or ASP.NET configuration.
The closer I could find is "Asking browsers to cache our images (ASP.NET/IIS)" where they set expiration but not based on the fact the files were update. Instead they used days or hour to cache those file so they would updated even when no changes were made.
I'm want to know if IIS or ASP.NET offers something related to this, automatically send to the browser that the files was changed. Is it possible/built in?
The options you have to update the browser side, cached item are:
Change the file name
Add url parameter
Place it on cache for a limited time (eg for couple of hours)
Compare the date-time of creation.
Signaling with eTag.
With the three two you avoiding one server call for each item, but the third option load it again after some time.
With the others you have to make one call to the server to see if needs to be load it again.
So you can not have all here, there is not correct way, and you need to chose what is the best for you, and what you can do. The faster from client perspective is the (1) and (2) options.
The direct answer to your question is to use eTag, or date-time compare of the file creation, but you loose that way, a call to the server, you only win the size of what is travel back.
Some more links:
http eTag
How do I support ETags in ASP.NET MVC?
Configuring ETags with Http module in asp.net
How to control web page caching, across all browsers?
Jquery getScript caching
and you can find even more.
I have a page as part of my IIS 7 (ASP.NET) website which serves images from a database. It uses a querystring to select the image and sets the content type header appropriately (image/jpeg) so that, for example, image.aspx?ID=1234 will be displayed in the browser as a jpeg image.
What I want to do instead is offer a URI formed in a manner such as image/1234.jpg which will produce the same result. In other words, there is no actual file on the server named 1234.jpg, it's just the contents of a database record, but from the browser's perspective, it will appear as if there is such a file.
I'm sure this is possible, but I can't figure out how it's accomplished, or where to look for answers. I'm thinking it may be done with an ISAPI filter, but I haven't found an accessible path into the docs to know if that's even the correct basis for a solution.
Possibly the best option here would be to implement a URL rewrite rule that changes image/1234.jpg to image.aspx?ID=1234
You can find more on URL rewrite for IIS here.
If, for whatever reason, URL rewrite isn't an option to you, then another possible method might be to implement a custom 404 page. When your request to image/1234.jpg doesn't result in a real file, it'll end up there.
You should be able to detect the URI at that point and serve up the image.
An architect at my work recently read Yahoo!'s Exceptional Performance Best Practices guide where it says to use a far-future Expires header for resources used by a page such as JavaScript, CSS, and images. The idea is you set a Expires header for these resources years into the future so they're always cached by the browser, and whenever we change the file and therefore need the browser to request the resource again instead of using its cache, change the filename by adding a version number.
Instead of incorporating this into our build process though, he has another idea. Instead of changing file names in source and on the server disk for each build (granted, that would be tedious), we're going to fake it. His plan is to set far-future expires on said resources, then implement two HttpModules.
One module will intercept all the Response streams of our ASPX and HTML pages before they go out, look for resource links and tack on a version parameter that is the file's last modified date. The other HttpModule will handle all requests for resources and simply ignore the version portion of the address. That way, the browser always requests a new resource file each time it has changed on disk, without ever actually having to change the name of the file on disk.
Make sense?
My concern relates to the module that rewrites the ASPX/HTML page Response stream. He's simply going to apply a bunch of Regex.Replace() on "src" attributes of <script> and <img> tags, and "href" attribute of <link> tags. This is going to happen for every single request on the server whose content type is "text/html." Potentially hundreds or thousands a minute.
I understand that HttpModules are hooked into the IIS pipeline, but this has got to add a prohibitive delay in the time it takes IIS to send out HTTP responses. No? What do you think?
A few things to be aware of:
If the idea is to add a query string to the static file names to indicate their version, unfortunately that will also prevent caching by the kernel-mode HTTP driver (http.sys)
Scanning each entire response based on a bunch of regular expressions will be slow, slow, slow. It's also likely to be unreliable, with hard-to-predict corner cases.
A few alternatives:
Use control adapters to explicitly replace certain URLs or paths with the current version. That allows you to focus specifically on images, CSS, etc.
Change folder names instead of file names when you version static files
Consider using ASP.NET skins to help centralize file names. That will help simplify maintenance.
In case it's helpful, I cover this subject in my book (Ultra-Fast ASP.NET), including code examples.
He's worried about stuff not being cached on the client - obviously this depends somewhat on how the user population has their browsers configured; if it's the default config then I doubt you'd need to worry about trying to second guess the client caching, it's too hard and the results aren't guaranteed, also it's not going to help new users.
As far as the HTTP Modules go - in principle I would say they are fine, but you'll want them to be blindingly fast and efficient if you take that track; it's probably worth trying out. I can't speak on the appropriateness of use RegEx to do what you want done inside, though.
If you're looking for high performance, I suggest you (or your architect) do some reading (and I don't mean that in a nasty way). I learnt something recently which I think will help -let me explain (and maybe you guys know this already).
Browsers only hold a limited number of simultaneous connections open to a specific hostname at any one time. e.g, IE6 will only do 6 connections to say www.foo.net.
If you call your images from say images.foo.net you get 6 new connections straight away.
The idea is to seperate out different content types into different hostnames (css.foo.net, scripts.foo.net, ajaxcalls.foo.net) that way you'll be making sure the browser is really working on your behalf.
http://code.google.com/p/talifun-web
StaticFileHandler - Serve Static Files in a cachable, resumable way.
CrusherModule - Serve compressed versioned JS and CSS in a cachable way.
You don't quite get kernel mode caching speed but serving from HttpRuntime.Cache has its advantages. Kernel Mode cache can't cache partial responses and you don't have fine grained control of the cache. The most important thing to implement is a consistent etag header and expires header. This will improve your site performance more than anything else.
Reducing the number of files served is probably one of the best ways to improve the speed of your website. The CrusherModule combines all the css on your site into one file and all the js into another file.
Memory is cheap, hard drives are slow, so use it!