ASP.NET MVC - compression + caching - asp.net

I've seen a number of options for adding GZIP/DEFLATE compression to ASP.Net MVC output, but they all seem to apply the compression on-the-fly.. thus do not take advange of caching the compressed content.
Any solutions for enabling caching of the compressed page output? Preferably in the code, so that the MVC code can check if the page has changed, and ship out the precompressed cached content if not.
This question really could apply to regular asp.net as well.

[Compress]
[OutputCache(Duration = 600, VaryByParam = "*", VaryByContentEncoding="gzip;deflate")]
public ActionResult Index()
{
return View();
}

Use caching options using attributes (for MVC), and do not think about compression since IIS/IISExpress automatically compresses your output if you enable it.
the way it works, mvc does not enable caching of individual fragments or parts of output (partial content caching). if you want this, consider using a service like CloudFlare (is there any other like CF?). it automatically caches your output and caches fragments of your output and provides many other performance and security improvements, all without a change in your code.
If this is not an option for you, then you still may use IISpeed (it is a IIS port of Google's mod_pagespeed). It provides some interesting settings like whitespace removal, inline css and js compression, js file merge and many other.
Both CF and IISpeed does not care how your site is built, they work on http/html level, so they both work on MVC, Classic ASP.NET, php or even raw html files.

You can create a attribute like
public class EnableCompressionAttribute : ActionFilterAttribute
{
const CompressionMode Compress = CompressionMode.Compress;
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
HttpRequestBase request = filterContext.HttpContext.Request;
HttpResponseBase response = filterContext.HttpContext.Response;
string acceptEncoding = request.Headers["Accept-Encoding"];
if (acceptEncoding == null)
return;
else if (acceptEncoding.ToLower().Contains("gzip"))
{
response.Filter = new GZipStream(response.Filter, Compress);
response.AppendHeader("Content-Encoding", "gzip");
}
else if (acceptEncoding.ToLower().Contains("deflate"))
{
response.Filter = new DeflateStream(response.Filter, Compress);
response.AppendHeader("Content-Encoding", "deflate");
}
}
}
Add entry in Global.asax.cs
public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
filters.Add(new EnableCompressionAttribute());
}
Then you can use this attribute as:
[EnableCompression]
public ActionResult WithCompression()
{
ViewBag.Content = "Compressed";
return View("Index");
}
You can download working example from Github:
https://github.com/ctesene/TestCompressionActionFilter

This link seems fairly close to what you require. It caches compressed dynamically generated pages. Although the example uses Web forms, It can be adapted to MVC by using an OutputCache attribute
[OutputCache(Duration = 600, VaryByParam = "*", VaryByContentEncoding="gzip;deflate")]

You could create a Cache Attribute:
public class CacheAttribute : ActionFilterAttribute
{
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
HttpCachePolicyBase cache = filterContext.HttpContext.Response.Cache;
if (Enabled)
{
cache.SetExpires(System.DateTime.Now.AddDays(30));
}
else
{
cache.SetCacheability(HttpCacheability.NoCache);
cache.SetNoStore();
}
}
public bool Enabled { get; set; }
public CacheAttribute()
{
Enabled = true;
}
}

See Improving performance with output caching for a full introduction on the subject. The main recommendation is to use the [OutputCache] attribute on the Action to which caching should be applied.

use namespace
using System.Web.Mvc;
using System.IO.Compression;
create ClassName.cs in you main project
public class CompressAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
var _encodingsAccepted = filterContext.HttpContext.Request.Headers["Accept-Encoding"];
if (string.IsNullOrEmpty(_encodingsAccepted)) return;
_encodingsAccepted = _encodingsAccepted.ToLowerInvariant();
var _response = filterContext.HttpContext.Response;
if(_response.Filter == null) return;
if (_encodingsAccepted.Contains("deflate"))
{
_response.AppendHeader("Content-encoding", "deflate");
_response.Filter = new DeflateStream(_response.Filter, CompressionMode.Compress);
}
else if (_encodingsAccepted.Contains("gzip"))
{
_response.AppendHeader("Content-encoding", "gzip");
_response.Filter = new GZipStream(_response.Filter, CompressionMode.Compress);
}
}
}
--- and add in global.asax.cs
GlobalFilters.Filters.Add(new CompressAttribute());

Related

HttpContext.Response.Cache equivalent in .NET Core?

I'm trying to reproduce something I found here for a previous version of ASP.NET.
Basically, I want to be able to disable cache so my client's look to the server for information at all times. I've added an HTML meta tag for this, but for client's that already have this information, I wanted to experiment with handling cache policy on the back-end.
The post mentions doing this to set a cache policy as an action filter.
public class NoCacheAttribute : ActionFilterAttribute
{
public override void OnResultExecuting(ResultExecutingContext filterContext)
{
filterContext.HttpContext.Response.Cache.SetExpires(DateTime.UtcNow.AddDays(-1));
filterContext.HttpContext.Response.Cache.SetValidUntilExpires(false);
filterContext.HttpContext.Response.Cache.SetRevalidation(HttpCacheRevalidation.AllCaches);
filterContext.HttpContext.Response.Cache.SetCacheability(HttpCacheability.NoCache);
filterContext.HttpContext.Response.Cache.SetNoStore();
base.OnResultExecuting(filterContext);
}
}
However, HttpContext doesn't appear to have a Response.Cache in ASP.NET Core. Is there an alternative way of doing this?
Thanks!
You could directly set the corresponding response headers to the desired values:
public class NoCacheAttribute : ActionFilterAttribute
{
public override void OnResultExecuting(ResultExecutingContext filterContext)
{
filterContext.HttpContext.Response.Headers["Cache-Control"] = "no-cache, no-store, must-revalidate";
filterContext.HttpContext.Response.Headers["Expires"] = "-1";
filterContext.HttpContext.Response.Headers["Pragma"] = "no-cache";
base.OnResultExecuting(filterContext);
}
}
You can control it with build-on attribute:
[ResponseCache (NoStore = true, Location = ResponseCacheLocation.None)]

Override host of webapi odata links

I'm using WebAPI 2.2 and Microsoft.AspNet.OData 5.7.0 to create an OData service that supports paging.
When hosted in the production environment, the WebAPI lives on a server that is not exposed externally, hence the various links returned in the OData response such as the #odata.context and #odata.nextLink point to the internal IP address e.g. http://192.168.X.X/<AccountName>/api/... etc.
I've been able to modify the Request.ODataProperties().NextLink by implementing some logic in each and every ODataController method to replace the internal URL with an external URL like https://account-name.domain.com/api/..., but this is very inconvenient and it only fixes the NextLinks.
Is there some way to set an external host name at configuration time of the OData service? I've seen a property Request.ODataProperties().Path and wonder if it's possible to set a base path at the config.MapODataServiceRoute("odata", "odata", GetModel()); call, or in the GetModel() implementation using for instance the ODataConventionModelBuilder?
UPDATE: The best solution I've come up with so far, is to create a BaseODataController that overrides the Initialize method and checks whether the Request.RequestUri.Host.StartsWith("beginning-of-known-internal-IP-address") and then do a RequestUri rewrite like so:
var externalAddress = ConfigClient.Get().ExternalAddress; // e.g. https://account-name.domain.com
var account = ConfigClient.Get().Id; // e.g. AccountName
var uriToReplace = new Uri(new Uri("http://" + Request.RequestUri.Host), account);
string originalUri = Request.RequestUri.AbsoluteUri;
Request.RequestUri = new Uri(Request.RequestUri.AbsoluteUri.Replace(uriToReplace.AbsoluteUri, externalAddress));
string newUri = Request.RequestUri.AbsoluteUri;
this.GetLogger().Info($"Request URI was rewritten from {originalUri} to {newUri}");
This perfectly fixes the #odata.nextLink URLs for all controllers, but for some reason the #odata.context URLs still get the AccountName part (e.g. https://account-name.domain.com/AccountName/api/odata/$metadata#ControllerName) so they still don't work.
Rewriting the RequestUri is sufficient to affect #odata.nextLink values because the code that computes the next link depends on the RequestUri directly. The other #odata.xxx links are computed via a UrlHelper, which is somehow referencing the path from the original request URI. (Hence the AccountName you see in your #odata.context link. I've seen this behavior in my code, but I haven't been able to track down the source of the cached URI path.)
Rather than rewrite the RequestUri, we can solve the problem by creating a CustomUrlHelper class to rewrite OData links on the fly. The new GetNextPageLink method will handle #odata.nextLink rewrites, and the Link method override will handle all other rewrites.
public class CustomUrlHelper : System.Web.Http.Routing.UrlHelper
{
public CustomUrlHelper(HttpRequestMessage request) : base(request)
{ }
// Change these strings to suit your specific needs.
private static readonly string ODataRouteName = "ODataRoute"; // Must be the same as used in api config
private static readonly string TargetPrefix = "http://localhost:8080/somePathPrefix";
private static readonly int TargetPrefixLength = TargetPrefix.Length;
private static readonly string ReplacementPrefix = "http://www.contoso.com"; // Do not end with slash
// Helper method.
protected string ReplaceTargetPrefix(string link)
{
if (link.StartsWith(TargetPrefix))
{
if (link.Length == TargetPrefixLength)
{
link = ReplacementPrefix;
}
else if (link[TargetPrefixLength] == '/')
{
link = ReplacementPrefix + link.Substring(TargetPrefixLength);
}
}
return link;
}
public override string Link(string routeName, IDictionary<string, object> routeValues)
{
var link = base.Link(routeName, routeValues);
if (routeName == ODataRouteName)
{
link = this.ReplaceTargetPrefix(link);
}
return link;
}
public Uri GetNextPageLink(int pageSize)
{
return new Uri(this.ReplaceTargetPrefix(this.Request.GetNextPageLink(pageSize).ToString()));
}
}
Wire-up the CustomUrlHelper in the Initialize method of a base controller class.
public abstract class BaseODataController : ODataController
{
protected abstract int DefaultPageSize { get; }
protected override void Initialize(System.Web.Http.Controllers.HttpControllerContext controllerContext)
{
base.Initialize(controllerContext);
var helper = new CustomUrlHelper(controllerContext.Request);
controllerContext.RequestContext.Url = helper;
controllerContext.Request.ODataProperties().NextLink = helper.GetNextPageLink(this.DefaultPageSize);
}
Note in the above that the page size will be the same for all actions in a given controller class. You can work around this limitation by moving the assignment of ODataProperties().NextLink to the body of a specific action method as follows:
var helper = this.RequestContext.Url as CustomUrlHelper;
this.Request.ODataProperties().NextLink = helper.GetNextPageLink(otherPageSize);
The answer by lencharest is promising, but I found an improvement on his method. Rather than using the UrlHelper, I created a class derived from System.Net.Http.DelegatingHandler. This class is inserted (first) into the message handling pipeline and thus has a crack at altering the incoming HttpRequestMessage. It's an improvement over the above solution because in addition to altering the controller-specific URLs (as the UrlHelper does, e,g, https://data.contoso.com/odata/MyController), it also alters the url that appears as the xml:base in the OData service document (e.g., https://data.contoso.com/odata).
My particular application was to host an OData service behind a proxy server, and I wanted all the URLs presented by the server to be the externally-visible URLs, not the internally-visible ones. And, I didn't want to have to rely on annotations for this; I wanted it to be fully automatic.
The message handler looks like this:
public class BehindProxyMessageHandler : DelegatingHandler
{
protected async override Task<HttpResponseMessage> SendAsync(
HttpRequestMessage request, CancellationToken cancellationToken)
{
var builder = new UriBuilder(request.RequestUri);
var visibleHost = builder.Host;
var visibleScheme = builder.Scheme;
var visiblePort = builder.Port;
if (request.Headers.Contains("X-Forwarded-Host"))
{
string[] forwardedHosts = request.Headers.GetValues("X-Forwarded-Host").First().Split(new char[] { ',' });
visibleHost = forwardedHosts[0].Trim();
}
if (request.Headers.Contains("X-Forwarded-Proto"))
{
visibleScheme = request.Headers.GetValues("X-Forwarded-Proto").First();
}
if (request.Headers.Contains("X-Forwarded-Port"))
{
try
{
visiblePort = int.Parse(request.Headers.GetValues("X-Forwarded-Port").First());
}
catch (Exception)
{ }
}
builder.Host = visibleHost;
builder.Scheme = visibleScheme;
builder.Port = visiblePort;
request.RequestUri = builder.Uri;
var response = await base.SendAsync(request, cancellationToken);
return response;
}
}
You wire the handler up in WebApiConfig.cs:
config.Routes.MapODataServiceRoute(
routeName: "odata",
routePrefix: "odata",
model: builder.GetEdmModel(),
pathHandler: new DefaultODataPathHandler(),
routingConventions: ODataRoutingConventions.CreateDefault()
);
config.MessageHandlers.Insert(0, new BehindProxyMessageHandler());
There is another solution, but it overrides url for the entire context.
What I'd like to suggest is:
Create owin middleware and override Host and Scheme properties inside
Register the middleware as the first one
Here is an example of middleware
public class RewriteUrlMiddleware : OwinMiddleware
{
public RewriteUrlMiddleware(OwinMiddleware next)
: base(next)
{
}
public override async Task Invoke(IOwinContext context)
{
context.Request.Host = new HostString(Settings.Default.ProxyHost);
context.Request.Scheme = Settings.Default.ProxyScheme;
await Next.Invoke(context);
}
}
ProxyHost is the host you want to have. Example: test.com
ProxyScheme is the scheme you want: Example: https
Example of middleware registration
public class Startup
{
public void Configuration(IAppBuilder app)
{
app.Use(typeof(RewriteUrlMiddleware));
var config = new HttpConfiguration();
WebApiConfig.Register(config);
app.UseWebApi(config);
}
}
A couple of years later, using ASP.NET Core, I figured that the easiest way to apply it in my service was to just create a filter that masquerades the host name. (AppConfig is a custom configuration class that contains the host name, among other things.)
public class MasqueradeHostFilterAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext context)
{
var appConfig = context.HttpContext.RequestServices.GetService<AppConfig>();
if (!string.IsNullOrEmpty(appConfig?.MasqueradeHost))
context.HttpContext.Request.Host = new HostString(appConfig.MasqueradeHost);
}
}
Apply the filter to the controller base class.
[MasqueradeHostFilter]
public class AppODataController : ODataController
{
}
The result is a nicely formatted output:
{ "#odata.context":"https://app.example.com/odata/$metadata" }
Just my two cents.
Using system.web.odata 6.0.0.0.
Setting the NextLink property too soon is problematic. Every reply will then have a nextLink in it. The last page should of course be free of such decorations.
http://docs.oasis-open.org/odata/odata-json-format/v4.0/os/odata-json-format-v4.0-os.html#_Toc372793048 says:
URLs present in a payload (whether request or response) MAY be
represented as relative URLs.
One way that I hope will work is to override EnableQueryAttribute:
public class myEnableQueryAttribute : EnableQueryAttribute
{
public override IQueryable ApplyQuery(IQueryable queryable, ODataQueryOptions queryOptions)
{
var result = base.ApplyQuery(queryable, queryOptions);
var nextlink = queryOptions.Request.ODataProperties().NextLink;
if (nextlink != null)
queryOptions.Request.ODataProperties().NextLink = queryOptions.Request.RequestUri.MakeRelativeUri(nextlink);
return result;
}
}
ApplyQuery() is where the "overflow" is detected. It basically asks for pagesize+1 rows and will set NextLink if the result set contains more than pagesize rows.
At this point it is relatively easy to rewrite NextLink to a relative URL.
The downside is that every odata method must now be adorned with the new myEnableQuery attribute:
[myEnableQuery]
public async Task<IHttpActionResult> Get(ODataQueryOptions<TElement> options)
{
...
}
and other URLs embedded elsewhere remains problematic. odata.context remains a problem. I want to avoid playing with the request URL, because I fail to see how that is maintainable over time.
Your question boils down to controlling the service root URI from within the service itself. My first thought was to look for a hook on the media type formatters used to serialize responses. ODataMediaTypeFormatter.MessageWriterSettings.PayloadBaseUri and ODataMediaTypeFormatter.MessageWriterSettings.ODataUri.ServiceRoot are both settable properties that suggest a solution. Unfortunately, ODataMediaTypeFormatter resets these properties on every call to WriteToStreamAsync.
The work-around is not obvious, but if you dig through the source code you'll eventually reach a call to IODataPathHandler.Link. A path handler is an OData extension point, so you can create a custom path handler that always returns an absolute URI which begins with the service root you desire.
public class CustomPathHandler : DefaultODataPathHandler
{
private const string ServiceRoot = "http://example.com/";
public override string Link(ODataPath path)
{
return ServiceRoot + base.Link(path);
}
}
And then register that path handler during service configuration.
// config is an instance of HttpConfiguration
config.MapODataServiceRoute(
routeName: "ODataRoute",
routePrefix: null,
model: builder.GetEdmModel(),
pathHandler: new CustomPathHandler(),
routingConventions: ODataRoutingConventions.CreateDefault()
);

Best way to abort/cancel action and response from ActionFilter

Best way to abort/cancel action from ActionFilter
I've got this ActionFilter, and it's suppose to end the connection immediately and return a 401 Unauthroized:
public class SignInRequired : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
// User is verified, continue executing action
if (Acme.Web.CurrentUser != null)
{
return;
}
// End response with 401 Unauthorized
var response = HttpContext.Current.Response;
response.StatusCode = (int)HttpStatusCode.Unauthorized;
response.End();
// Prevent the action from actually being executed
filterContext.Result = new EmptyResult();
}
}
I learned how you can cancel the action from executing by setting 'context.Result = new EmptyResult()` here, but I'm not sure if this is the best way to flush the response and close the connection.
Setting the response will mean the action doesn't get called.
public override void OnActionExecuting(HttpActionContext actionContext)
{
actionContext.Response = new HttpResponseMessage(HttpStatusCode.Unauthorized);
}
As other answers have said, though, authentication should be done with an AuthorizeAttribute (Docs for Web.API or for MVC).
On .net core 2.2, 3.0 and 3.1 and .net 5 the below example works fine
public override void OnActionExecuting(ActionExecutingContext context)
{
context.Result = new UnauthorizedObjectResult("user is unauthorized");
}
The answer that #OdeyinkaOlubunmi is correct for Web API or specifically System.Web.Http.Filters.ActionFilterAttribute but it can't be used for System.Web.Mvc.ActionFilterAttribute. AuthorizeAttribute and overriding AuthorizeCore is a good way to go but if you use #Vadim's example for a GlobalFilter you will end up with the following error in a standard configuration:
HTTP Error 404.15 - Not Found The request filtering module is
configured to deny a request where the query string is too long.
This is because the default /Login?ReturnUrl= will keep appending new values until the query string causes an exception.
The way I have solved it for MVC is like this:
public class DebugActionFilter : System.Web.Mvc.ActionFilterAttribute
{
public override void OnActionExecuting(System.Web.Mvc.ActionExecutingContext actionContext)
{
actionContext.Result = new HttpStatusCodeResult(HttpStatusCode.Unauthorized);
return;
}
}
You can set the result of filterContext for the Exception page like this:
filterContext.Result = new RedirectResult("~/Error/Unauthorized");
See more details here on section Canceling Filter Execution
You probably want to make it an AuthorizeAttribute. That will set the result to be an UnAuthorizedResult automatically, plus it has the benefit of being run before any other filters. Alternatively you can set the Result to be a new HttpUnauthorizedResult
public class SignInRequiredAttribute : AuthorizeAttribute
{
protected override bool AuthorizeCore(HttpContextBase httpContext)
{
return !Acme.Web.CurrentUser != null;
}
}
using .net core 2.1 the solutions above did not work for me , so i tried this and it worked :-
context.HttpContext.Response.StatusCode = 401;
return;
if there is better solutions for .net core 2.1 i am open for suggestions

Disable Session state per-request in ASP.Net MVC

I am creating an ActionResult in ASP.Net MVC to serve images. With Session state enabled, IIS will only handle one request at a time from the same user. (This is true not just in MVC.)
Therefore, on a page with multiple images calling back to this Action, only one image request can be handled at a time. It's synchronous.
I'd like this image Action to be asynchronous -- I'd like multiple image requests to each execute without needing the previous one to complete. (If the images were just static files, IIS would serve them up this way.)
So, I'd like to disable Session just for calls to that Action, or to specify that certain requests do not have Session state. Anyone know how this is done in MVC? Thanks!
If anyone is in the situation I was in, where your image controller actually needs read only access to the session, you can put the SessionState attribute on your controller
[SessionState(SessionStateBehavior.ReadOnly)]
See http://msdn.microsoft.com/en-us/library/system.web.mvc.sessionstateattribute.aspx for more info.
Thanks to https://stackoverflow.com/a/4235006/372926
Rather than implementing an action filter for this, why don't you implement a RouteHandler?
Here's the deal - IRouteHandler has one method - GetHttpHandler. When you make an ASP.Net MVC request to a controller, by default the routing engine handles the request by creating a new instance of MvcRouteHandler, which returns an MvcHandler. MvcHandler is an implementation of IHttpHandler which is marked with the (surprise!) IRequiresSessionState interface. This is why a normal request uses Session.
If you follow my blog post on how to implement a custom RouteHandler (instead of using MvcRouteHandler) for serving up images - you can skip returning a session-tagged IHttpHandler.
This should free IIS from imposing synchronicity on you. It would also likely be more performant because it's skipping all the layers of the MVC code dealing with filters.
I also came across the same problem and after doing R&D this link worked for me
Reference:
https://techatfingers.wordpress.com/2016/06/14/session-state-on-action/
Create custom Attribute
Override the “GetControllerSessionBehavior” method present in class DefaultControllerFactory.
Register it in global.aspx
1> Create custom Attribute
public sealed class ActionSessionStateAttribute : Attribute
{
public SessionStateBehavior SessionBehavior { get; private set; }
public ActionSessionStateAttribute(SessionStateBehavior sessionBehavior)
{
SessionBehavior = sessioBehavior;
}
}
2. Override
public class SessionControllerFactory : DefaultControllerFactory
{
protected override SessionStateBehavior GetControllerSessionBehavior(RequestContext requestContext, Type controllerType)
{
if (controllerType == null)
return SessionStateBehavior.Default;
var actionName = requestContext.RouteData.Values["action"].ToString();
Type typeOfRequest=requestContext.HttpContext.Request.RequestType.ToLower() =="get"?typeof(HttpGetAttribute):typeof(HttpPostAttribute);
// [Line1]
var cntMethods = controllerType.GetMethods()
.Where(m =>
m.Name == actionName &&
( ( typeOfRequest == typeof(HttpPostAttribute) &&
m.CustomAttributes.Where(a => a.AttributeType == typeOfRequest).Count()>0
)
||
( typeOfRequest == typeof(HttpGetAttribute) &&
m.CustomAttributes.Where(a => a.AttributeType == typeof(HttpPostAttribute)).Count() == 0
)
)
);
MethodInfo actionMethodInfo = actionMethodInfo = cntMethods != null && cntMethods.Count() == 1 ? cntMethods.ElementAt(0):null;
if (actionMethodInfo != null)
{
var sessionStateAttr = actionMethodInfo.GetCustomAttributes(typeof(ActionSessionStateAttribute), false)
.OfType<ActionSessionStateAttribute>()
.FirstOrDefault();
if (sessionStateAttr != null)
{
return sessionStateAttr.Behavior;
}
}
return base.GetControllerSessionBehavior(requestContext, controllerType);
}
3. Register class in Global.asax
public class MvcApplication : System.Web.HttpApplication
{
protected void Application_Start()
{
// --- other code ---
ControllerBuilder.Current.SetControllerFactory(typeof(SessionControllerFactory));
}
}
Try serving the images from another domain. So something like images.mysite.com.
This will provide you two benefits: One, sessions are tracked by a cookie, so images.mysite.com won't have the cookie. Two, it will give you an additional two concurrent requests to retrieve images.
Have you considered setting up a HttpHandler to serve up your images?
SessionState attribute is quite helpful if u use mvc3. How to achieve this with mvc2 needs a little more coding.
Idea is to tell the asp.net that specific request wont use session object.
So, Create a custom route handler for specific requests
public class CustomRouteHandler : IRouteHandler
{
public System.Web.IHttpHandler GetHttpHandler(RequestContext requestContext)
{
requestContext.HttpContext.SetSessionStateBehavior(System.Web.SessionState.SessionStateBehavior.ReadOnly);
return new MvcHandler(requestContext);
}
}
SessionStateBehavior enum has 4 members, you should use "disabled" or "readonly" modes to get async behavior.
After creating this custom route handler, be sure that your specific requests goes through this handler. This can be done via defining new routes at Global.asax
routes.Add("Default", new Route(
"{controller}/{action}",
new RouteValueDictionary(new { controller = "Home", action = "Index"}),
new CustomRouteHandler()
));
Adding this route makes all your requests to be handled by your custom route handler class. You can make it specific by defining different routes.
Change DefaultCOntrollerFactory to custom ControllerFactory class. Default Controller.TempDataProvider use SessionStateTempDataProvider. you can change it.
1.Set web.config/system.web/sessionState:mode="Off".
2.create DictionaryTempDataProvider class.
public class DictionaryTempDataProvider : ITempDataProvider
{
public IDictionary<string, object> LoadTempData(ControllerContext controllerContext)
{
return new Dictionary<string, object>();
}
public void SaveTempData(ControllerContext controllerContext, IDictionary<string, object> values)
{
}
}
3.Create DictionaryTempDataControllerFactory
public class DictionaryTempDataControllerFactory : DefaultControllerFactory
{
public override IController CreateController(System.Web.Routing.RequestContext requestContext, string controllerName)
{
var controller = base.CreateController(requestContext, controllerName) as Controller;
if (controller!=null)
controller.TempDataProvider = new DictionaryTempDataProvider();
return controller;
}
}
4.In global.asax.cs Apprication_Start event set DictionaryTempDataControllerFactory.
protected void Application_Start()
{
RegisterRoutes(RouteTable.Routes);
ControllerBuilder.Current.SetControllerFactory(
new DictionaryTempDataControllerFactory()
);
}
On our server, IIS doesn't even know about sessions - it's the ASP.NET stack that handles one request per session at a time. Static files, like images, are never affected.
Is it possible that your ASP.NET app is serving the files instead of IIS?
Create new Controller
Decorate controler with [SessionState(SessionStateBehavior.Disabled)]
Refactor code you want seesion stated disabled for to that controller
I would to share my solution for disable ASP.NET Session for an specific request (in my case, a WCF Service) using an HttpModule:
public class AspNetSessionFilterModule : IHttpModule
{
public void Init(HttpApplication context)
{
context.PostMapRequestHandler += OnPostMapRequestHandler;
}
private void OnPostMapRequestHandler(object sender, EventArgs e)
{
var context = (sender as HttpApplication).Context;
DisableSessionForSomeRequests(context);
}
private void DisableSessionForSomeRequests(HttpContext context)
{
if ("~/Services/MyService.svc".Equals(context.Request.AppRelativeCurrentExecutionFilePath, StringComparison.InvariantCultureIgnoreCase))
{
context.SetSessionStateBehavior(System.Web.SessionState.SessionStateBehavior.Disabled);
}
}
public void Dispose()
{ }
}

How to use output caching on .ashx handler

How can I use output caching with a .ashx handler? In this case I'm doing some heavy image processing and would like the handler to be cached for a minute or so.
Also, does anyone have any recommendations on how to prevent dogpiling?
There are some good sources but you want to cache you processing server side and client-side.
Adding HTTP headers should help in the client side caching
here are some Response headers to get started on..
You can spend hours tweaking them until you get the desired performance
//Adds document content type
context.Response.ContentType = currentDocument.MimeType;
context.Response.Cache.SetCacheability(HttpCacheability.Public);
context.Response.Cache.SetExpires(DateTime.Now.AddMinutes(10));
context.Response.Cache.SetMaxAge(new TimeSpan(0,10,0));
context.Response.AddHeader("Last-Modified", currentDocument.LastUpdated.ToLongDateString());
// Send back the file content
context.Response.BinaryWrite(currentDocument.Document);
As for server side caching that is a different monster... and there are plenty of caching resources out there...
you can use like this
public class CacheHandler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
OutputCachedPage page = new OutputCachedPage(new OutputCacheParameters
{
Duration = 60,
Location = OutputCacheLocation.Server,
VaryByParam = "v"
});
page.ProcessRequest(HttpContext.Current);
context.Response.Write(DateTime.Now);
}
public bool IsReusable
{
get
{
return false;
}
}
private sealed class OutputCachedPage : Page
{
private OutputCacheParameters _cacheSettings;
public OutputCachedPage(OutputCacheParameters cacheSettings)
{
// Tracing requires Page IDs to be unique.
ID = Guid.NewGuid().ToString();
_cacheSettings = cacheSettings;
}
protected override void FrameworkInitialize()
{
// when you put the <%# OutputCache %> directive on a page, the generated code calls InitOutputCache() from here
base.FrameworkInitialize();
InitOutputCache(_cacheSettings);
}
}
}
Old, question but the answer didn't really mentioned the server-side handling.
As in the winning answer, I would use this for the client side:
context.Response.Cache.SetCacheability(HttpCacheability.Public);
context.Response.Cache.SetExpires(DateTime.Now.AddMinutes(10));
context.Response.Cache.SetMaxAge(TimeSpan.FromMinutes(10));
and for the server side, since you are using a ashx instead of a web page, I'm assuming that you are directly writing the output to the Context.Response.
In that case you could use something like this (in this case I want to save the response based on parameter "q", and Im using a sliding window expiration)
using System.Web.Caching;
public void ProcessRequest(HttpContext context)
{
string query = context.Request["q"];
if (context.Cache[query] != null)
{
//server side caching using asp.net caching
context.Response.Write(context.Cache[query]);
return;
}
string response = GetResponse(query);
context.Cache.Insert(query, response, null, Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(10));
context.Response.Write(response);
}
I used the following with success and thought it worthwhile to post here .
Manually controlling the ASP.NET page output cache
From http://dotnetperls.com/cache-examples-aspnet
Setting cache options in Handler.ashx files
First, you can use HTTP handlers
in ASP.NET for a faster way to server
dynamic content than Web Form pages.
Handler.ashx is the default name for
an ASP.NET generic handler. You need
to use the HttpContext parameter and
access the Response that way.
Sample code excerpted:
<%# WebHandler Language="C#" Class="Handler" %>
C# to cache response for 1 hour
using System;
using System.Web;
public class Handler : IHttpHandler {
public void ProcessRequest (HttpContext context) {
// Cache this handler response for 1 hour.
HttpCachePolicy c = context.Response.Cache;
c.SetCacheability(HttpCacheability.Public);
c.SetMaxAge(new TimeSpan(1, 0, 0));
}
public bool IsReusable {
get {
return false;
}
}
}
The solution with the OutputCachedPage works fine, however at a price of the performance, since you need to instantiate an object derived from the System.Web.UI.Page base class.
A simple solution would be to use the Response.Cache.SetCacheability, as suggested by some of the above answers. However for the response to be cached at the server (inside Output Cache) one needs to use HttpCacheability.Server, and set a VaryByParams or VaryByHeaders (note that when using VaryByHeaders URL can't contain a query string, since the cache will be skipped).
Here's a simple example (based on https://support.microsoft.com/en-us/kb/323290):
<%# WebHandler Language="C#" Class="cacheTest" %>
using System;
using System.Web;
using System.Web.UI;
public class cacheTest : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
TimeSpan freshness = new TimeSpan(0, 0, 0, 10);
DateTime now = DateTime.Now;
HttpCachePolicy cachePolicy = context.Response.Cache;
cachePolicy.SetCacheability(HttpCacheability.Public);
cachePolicy.SetExpires(now.Add(freshness));
cachePolicy.SetMaxAge(freshness);
cachePolicy.SetValidUntilExpires(true);
cachePolicy.VaryByParams["id"] = true;
context.Response.ContentType = "application/json";
context.Response.BufferOutput = true;
context.Response.Write(context.Request.QueryString["id"]+"\n");
context.Response.Write(DateTime.Now.ToString("s"));
}
public bool IsReusable
{
get
{
return false;
}
}
}
Hint: you monitor the caching in the Performance Counters "ASP.NET Applications__Total__\Output Cache Total".

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