Custom HTTPModule - How To Tell When Writing Last Block Of HTML In Write Method
Jul 2, 2010
I have written an Http Module that hooks onto the Response.Filter property of the current request and does various replacements within the HTML before it is sent to the client.All the work is done in the Write method which is overriding Write in the base class Stream.
The Write method is called multiple times for a single response - the HTML seems to be written to the output stream in chunks. My problem is that I don't have an efficient & reliable way of telling if the current chunk is the last chunk (for why I want to know this see below). The only way I have come up with is to check if the chunk contains a closing html tag - but this is not very efficient or reliable.
The reason this is needed is that the module must add the "Refresh" HTTP header to the response, but only if the HTML fulfills certain conditions (and there are certain conditions that mean the header must not be added). So, only when the last chunk has been seen does the code know if the header can be added or not. So, I either need a test for the last chunk, or on each call to Write I add the header if the current block of HTML passes the test (if it has not already been added) or remove the header if the current block of HTML fails the test (if it has already been added).
So, is there a better way to test for the last chuck OR is there a way to test for a particular header being in the response and delete it (there doesn't seem to be a way to do this - only to append headers)?
regarding one issue I am facing. I created a httpmodule for hadling the unhandled errors and I need to log those errors using log 4 net in database.Everting working fine but I am not getting any error information once the error was hadled and I need that info too. I want to make it as a centralize module which can trap all errors and log those errors.How call application_error event of httpmodule from catch block...so that I can log that info there and I no need log in every catch block..
On my page in the Page_Load event I add a collection of strings to the Context object. I have an HttpModule that will fire EndRequest and retrieve the collection of strings. What I then do is write out a script reference tag (based on the collection of strings) to the response. The problem is that the page reads the script reference but doesn't retrieve the contents of the file (I imagine because this is occurring in the EndRequest event). I can't fire the BeginRequest event because I won't have access to the Context Items collection.
I tried to also registering an HttpHandler which Processes the request of the script reference but I can't access the collection of strings in the Context.Items from there.
using System; namespace MvcApplication.Helpers { public class InputlHelper { public static string Input(this HtmlHelper helper, string name, string text) { return String.Format("<input name='{0}'>{1}</input>", name, text); } } }
Now how to turn it into a strongly typed helper method InputFor Like it is in the framework?I don't need the Html.TextBoxFor method, I know it exists. I am just curious in how to implement this behavior myself and used this as a simple example.PS. I was looking in the mvc source code but couldn't find a trace of this mysterious TextBoxFor. I only found TextBox. Am I looking at the wrong code?
Should I write it for each method or only in event handlers or ????
What happens when an exception occurrs? What is the stack for exception?
If I use it at entry point (event handlers) then how do I get actually at which line error occurred?
Suppose an exception was thrown from Data Access Layer How do I get it in presentation layer that exactly in which class method at which line why that error occurred?
Is it true that excessive use of try catch makes application slow?
am trying to write an HttpModule that will work in IIS7 with integrated pipeline mode AppPool. Within this module I need to access Session variables and to be able to capture the Session Start and End events. I have found a couple of articles on this topic that indicate the need to modify the behavior of the HttpHandler in PostAcquireRequestState to force the Session for the context to be initialized. The article I am using as a template is posted here:[URL]In my case I am getting the following error:
[NullReferenceException: Object reference not set to an instance of an object.] System.Web.PipelineModuleStepContainer.GetEventCount(RequestNotification notification, Boolean isPostEvent) +30 System.Web.PipelineStepManager.ResumeSteps(Exception error) +1112 System.Web.HttpApplication.BeginProcessRequestNotification(HttpContext context, AsyncCallback cb) +113 System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +616
I believe that this error implies a problem with attempting to attach an event handler multiple times. I am aware that the modules Init function can be called more than once and have set a static initialization flag which ensures that I will only ever attach the event handler once.In the most condensed form my code is as follows:
public class HttpModule : IHttpModule, IRequiresSessionState
Since everyone yells at me that MessageBox doesn't work when the project is uploaded to the server, I need to migrate to javascript alert box. As I was changing my MessageBoxes, I tested and found that they weren't being produced. I'm not sure if it matters, but they are in a try/catch block, which is shown here:[Code]....
This all worked before when I had MessageBox - it showed, then the page redirected when I clicked Ok.
I either don't understand how try/catch works, the javascript isn't adding, or Response.Redirect is executed before I can see the alert box and click Ok on it.
(just as a note, everything works fine, but the alert box doesn't show)........if I add the (javascript) code before the try block, the alert box comes up, so it's not something wrong with the writing of the javascript or executing it at least (I think).
As we know when IIS receives the first request for a particular Asp.net application resource, IIS creates an instance of a HttpApplication (defined in global.asax codebehind).When this new instance is created it's initialization happens that also checks all configured HTTP modules.All modules are then instantiated and put in the application's Modules collection (of type HttpModuleCollection)modules are looped through and their Init() method is called (when they register for request events)
As far as I understand it the above scenario happens when a web application is started/initialized (hence application start event).What happens with modules?
Are they (re)instatiated on each request or reused from the Modules property on each consecutive request while the web application is alive? As I understand IIS and Asp.net they are reused through the whole life of a web application.
If they are reused, can we assume that their Init() method is actually a pseudo event handler for application start event? The thing is we can't attach to application level events within http modules. But if they are being reused we could use Init() as application start event and do whatever we'd put in global.asax instead.
Question,Can we assume that module's Init() method is called only on application start event? Could we use this assumption to i.e. register routes for applications whose global.asax codebehind we can't change? web.config is usually accessible and we can change it the way we want.Would this actually work?
Additional info,We can check HttpApplication code and check its InitModulesCommon() method. This one actually calls Init() of each registered HTTP module. What is more interesting is that this method is only used by InitIntegratedModules() and InitModules() methods. Which are both used only in HttpApplication.InitInternal() method. This is the basis of my assumptions, but I would like to know whether someone has abused IHttpModule.Init() for application start event.
I have an HttpModule and I'd like to choose the HttpHandler for the current request, is that possible? Also web.config is not an option because the condition is not based on path or extension. My googling skills have failed me, no matter what keywords I use all the results are "IHttpHandler vs IHttpModule".
I've a custom Httpmodule which handles PostAuthenticateRequest & PreRequestHandlerExecute events.
However, when I try to use the module on page with ReportViwer (which needs ScriptManager) I get a bunch of browser errors such as following and the report viewer does not work as expected i.e. it doesn't show any result.
ASP.NET Ajax client-side framewook failed to load. 'Sys' is undefined Syntax error (WebResource.axd) 'Type' is undefined (ReportViewerWebControl.axd)
If I comment out the module from web.config everything works as expected (obviously without the module code).
public static string[] GetCompletionList(string prefixText, int count, string contextKey) {
// Create array of movies [code]..
Problem: The above code works great for me in getting the Autocomplete AJAX control to work. However, what I need is to define the string[] variable outside of the above block. What I'm looking for is the way to define such a variable as a global, or whatever the technical term in asp.net is for a variable that is persistent and recognized wherever it is used in the code-behind. without massive amounts of technical wizardry?
Sys.Webforms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled. Details: Error parsing near ' i have kept button in updatepanel and i am getting this error
I have an extension method which I can use from the .cs codebehind of an aspx page, but if I try to do it in a code block in the aspx, it can't find the extension method. Is there something I need to add to the page?
the purpose of this HttpModule? It's showing up on my HttpModuleCollection list, but I don't know what's it's for.System.ServiceModel.Activation.HttpModule
l Im downloading Pdfs using WebClient I used below code
try { WebClient wc = new WebClient(); Uri uriadd = new Uri(@"ftp://xxx.yyy..../httpdocs/FH/Foldername/" + clientorder1[i].Cloi_id + ".pdf"); wc.Credentials = new NetworkCredential("xxxx", "zzzz"); }
Its working fine but some times Gives Error like Object synchronization method was called from an unsynchronized block of code.. Why this Error coming ....
I'm new to ASP.net 3.5 and creating a test web site. I have created a master page for my web site with page content blocks. Now I want to use some javascript on the client side to provide for more interaction. I would normally create page specific Javascript functions and insert them in a <script block on the page. Howevere the Javascript script block must be placed before the <HTLM block. If I'm using Master Pages, it doesn't seem that I can use page specific Javascript functions. How can I resolve this problem? I think my options are
1) Don't use Javascript. Use ? instead to write client-side code. 2) Don't use Master Pages because you cannot use Page Specific Javascript functions. 3) Here's how to insert Javascript Functions in a Page with a Master Page.
I like to convert html for example a table to and image and save as jpg.(what I mean is that a table displayed on web page, I only want to get that specific table and save as image) Is it possible using asp.net?
I have a web page (Provider) that creates an XML file to be send to the Requester in this fashion:
1. A Requester page needs to send an XML file to the provider page 2. Provider will read the XML file to authenticate the request 3. Provider will Create an xml file with some data. 4. Provider will send the xml file back to the Requester.
Can anyone provide sample code for both the Requestor page (step 1) and the Provider page (steps 2 & 3)
