I couldn't find a way to control how Glassfish (v3) handles HTTP(s) headers it sends whenever I request a resource (image, css...). The problem is that inside a security-enabled web application it forces a 0 expiry date for everything (even images and css), which makes the whole application feel like a slow and buggy piece of junk by forcing the reload of every image (IE is especially sensitive for this).
I could work around this by putting the image resources in another WAR, or even a separate directory on the server, but that would defeat the point of easy (re)deployment of an EAR file.
I also have a requirement that the files MUST come through an HTTPS connection. Does it cause any problems with certificates etc. if the image context path is different from the application context path (eg. the application is at https://foo.bar.org/sm/MyApp, and the images are at https://foo.bar.org/img)?
Well, I implemented my own resource Servlet, and finally.... it works!
I'm still interested in the Glassfish solution though.
Related
I have way too many pages in the application that basically load the same set of xml and js files for client side interaction and validation. So, I have about dozen lines like this one <script type="text/javascript" src="JS/CreateMR.js"></script> or like this one <xml id="DefaultDataIslands" src="../XMLData/DataIslands.xml">.
These same files are included in every page and as such browser sends request to read them every time. It takes about 900ms just to load these files.
I am trying to find a way to load them on just the login page, and then use that temp file as source. Is it possible to do so? If yes, how and where should I start?
P.S. A link to a tutorial will work too, as I have currently no knowledge about that.
Edit:
I can't cache the whole page, because the pages are generated at runtime based on the different possible view modes. I can only cache the js and xml file. Caching everything might be a problem.
Anyway, I am reading through the articles suggested to figure out how to do it. So, I may not be able to accept any answer right away, while I finish reading and try to implement it in one page.
Edit:
Turns out caching is already enabled, it is just that my server is acting crazy. Check the screenshot below.
With Cache
Without cache
As you see, with cache, it is actually taking more time to process some of the requests. I have no idea what that problem is, but I guess I should go to the server stack exchange to figure this out.
As for the actual problem, turns out I don't have to do anything to enable caching of xml and js files. Had no idea browsers automatically cache js files without using specific tag.
Totally possible and in fact recommended.
Browsers cache content that have been sent down with appropriate HTTP caching headers and will not request it again until the cache has expired. This will make your pages faster and more responsive and your server's load much lighter.
Here is a good read to get you started.
Here is ASP.NET MVC caching guide. It focuses on caching content returned from controllers.
Here is a read about caching static content on IIS with ASP.NET MVC.
Basically, you want to use browser caching mechanism to cache the src files after the first request.
If you're using F12 tools in your browser to debug network requests, make sure you have disable cache option unchecked. Otherwise, it forces browser to ignore cached files.
Make sure your server sends and respects cache headers - it should return HTTP status 304 Unmodified after first request to a static file.
Take a look at Asp.Net Bundling and minification - if you have for example multiple js source files, you could bundle them into one file that will be cached on the first request.
Additionally, if you use external js libraries, you could download them from a CDN instead of your server - this will both offload your server and enable user browser to use cached script version (meaning - if some other page that user has visited also used the same script, browser should already have it cached).
One approach is caching static files via IIS by adding <clientCache> element in web.config file. The <clientCache> element of the <staticContent> element specifies cache-related HTTP headers that IIS and later sends to Web clients, which control how Web clients and proxy servers will cache the content that IIS and later returns.
How to configure static content cache per folder and extension in IIS7?
Client Cache
for more info on client side caching read this part of Ultra-Fast ASP.NET 4.5 book:
Browser Cache and Caching Static Content
Other approach is caching portions of page.
if your are using Web Form:
Caching Portions of an ASP.NET Page
and if you are using MVC, use Donut Hole Caching
ASP.NET MVC Extensible Donut Caching
Donut Caching and Donut Hole Caching with Asp.Net MVC
The browser has to ask the server if the file has been modified or not since it put it to the cache, therefore the http statuscode 304. Read more from https://httpstatuses.com/304.
As this is asp.net please make sure you are first running it with
<compilation debug="false"/>
as enabling debugging has some side effects which include.
"All client-javascript libraries and static images that are deployed via
WebResources.axd will be continually downloaded by clients on each page
view request and not cached locally within the browser."
More read from https://blogs.msdn.microsoft.com/prashant_upadhyay/2011/07/14/why-debugfalse-in-asp-net-applications-in-production-environment/
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 wanted to know that, is there some special requirement for a website to make use of CDN ?
i mean is there some special scheme(or atleast considerations) on which your website must be build right from the start to make use of CDN (Content delivery network).
is there anything that can stop a website from making use of CDN, for example the way it references the content files, static file paths or any other thing conceivable.
Thanks
It depends.
You have two kinds of CDN services:
Services like AWS Cloudfront that require you to upload the files in some special place that they read from (eg. AWS S3) - In this case you need have a step in your build process to correctly upload the files and handle the addresses somehow inside your application
Services like Akamai that just need you to change and tweak your DNS records so they will serve the request to your users instead of you - In this case you would have two domains (image.you.com and image2.you.com) and have the image.you.com pointing to Akamai and image2.you.com pointing to the original source of the file. Whenever a user requested an image in Akamai, they would come to you through the "back door", fetch it and starting serving that file always.
If you use the second approach it's really simple to have a CDN supporting your application.
There are a whole bunch of concerns when dealing with CDN solutions.
The first one is that a CDN can't serve a dynamic page - i.e. a page that is unique to every user. Typically, that includes PHP, ASPX, JSP, RubyOnRails etc. - so if you're hoping to support lots of users for a dynamic site, you have to come up with another solution. Some CDN providers support "Edge Side Includes" - this allows you to glue dynamic pages together with cached content on the CDN, but this creates quite a complex application.
Of course, even on a dynamic application, a CDN can still serve static files - images, stylesheets, javascript files, videos etc.
#Tucaz explains the two major options here (actually, Akamai also provides a "filestore" CDN option). If you select the second option - effectively, the CDN becomes a caching reverse proxy in front of your website - it makes sense to tweak the cache headers on your HTTP server, and tell the CDN to honour those. Make sure you set your .ASPX files to not cache!
How can I make sure that static content (images, css, javascript) is cached? What is the best approach?
Will recommend you to go through this tutorial to understand how caching happens on web (HTTP) in general.
Simply speaking, the web server needs to generate appropriate HTTP headers while sending the content to the client in order to control client-side caching. In ASP.NET/IIS environment, its IIS that typically handles the static file contents and therefore, you must configure IIS appropriately to control caching static files as per you needs. See below links for more information about configuring IIS caching for static content:
http://www.iis.net/ConfigReference/system.webServer/staticContent/clientCache
How to configure static content cache per folder and extension in IIS7?
EDIT: As you have asked about the best approach, the most prevalent approach that I see now days is to version static content (say by appending some version identifier at the end of file or URL). Once version-ed, you can treat it as immutable and then emit cache headers for caching it for infinite duration. In ASP.NET application, you can probably append the assembly version (or product version) to each static content URL. So essentially, you will invalidating the cache for every build (or every product release).
You can also make use of the HTML5 Offline web applications manifest. It allows you to set up a manifest where you define which files will be cached locally.
It is a nice, clear to understand broadly implemented, way of avoiding having to learn about IIS and HTML Caching.
http://www.w3schools.com/html/html5_app_cache.asp
(you should totally read up about those things)
I have a flex app running on my server.
I have had a request from some clients to have the swf loaded on their server, so that their customers dont have to be transferred to my server to login; i.e. from the user's point of view it looks like they are logging in from theirsite.com instead of mysite.com
I tried something really simple, and that was to give them a html wrapper to host on their site. The only modification that I made was to change the "src" var to:
"src", "https://www.mysite.com/app/myapp.swf"
and
embed src="https://www.mysite.com/app/myapp.swf"
To my surprise, this worked perfectly. And best of all, the service calls still seem to come from mysite.com, so I dont have to bother with modifying the crossdomain.xml file.
All good it seems.
Are there any issues or downsides to the above that I should be aware of?
If you're doing an ExternalInterface calls to JavaScript in the enclosing page, this may cause a security error; since the SWF from your domain shouldn't be able to access HTML content served from your client's domain.
I expect that is a fringe case though. Aside from that, what you're doing is not much different than what YouTube does. I've done the same thing with The Flex Show player. I don't think you'll have any issues. And I do not believe that this approach makes your app any less (or less) secure.