I'm inheriting a legacy project, and there's a page that calls a method that makes a web service call. Load and performance testing has detected that this page sometimes takes a really long time to close, but usually it's fine, and if there is one hanging, all other requests for that page hang until the first one resolves, and then they all resolve.
I think this might have something to do with the web service being instantiated and not disposed, but I don't know how I can be more sure. I tried to add a delegate to the Dispose method but that doesn't seem to ever fire. (I'm not sure it would without Dispose being called explicitly, but that doesn't really matter.)
So what can I look for on the production server or any deployed environment to watch those requests pile up and go out (or get handled in an orderly manner, if they aren't the problem)?
You might consider using a tool like .NET Memory Profiler. You can use it to attach to your running application, and it can find and report all undisposed objects.
I think they have a free two week trial.
In your web app code, you could write to a log (event log, text file) right before you send a request, and again right after you get the response. Include some identifying information about the request. Add timestamps.
If you only want to use this while debugging, wrap it in #debug.
Or if you want to test in release mode, you could put a boolean in appSettings in web.config so you could turn the logging off and on.
Related
For manually testing an HTTP client in my application, I'd like to use a tool which starts an HTTP server my application can connect to and that lets me respond to request from my application manually. I'm basically looking for a tool with a GUI that lists all incoming requests and allows me to select a status code and type a response message. I've already tested the functionality with unit tests but I also want to verify it manually with no mocking etc.
Sounds simple but I didn't find such a tool. I've found some that can be scripted but no interactive one. Do you know one?
This can probably be written relatively easily by creating the Swing GUI dialog popup inside the servlet servicing methods. Have never seen Tomcat running this way but probably it would. Only, mind the server time out. It may be not long enough for you to make an input and require to be configured, also on the client side. Also, parallel calls will make multiple popups that may be difficult to respond but probably this is a single client app.
As a simplest solution, server GUI can be simply disposed after call and newly created as the next call arrives. This will make eveything indepenent on how servlet container is managing the servlets (does it stays, is it destroyed, maybe class is unloaded, who knows). Advanced solution could include the "server servlet" that would interact through its own JSP page but then it may be complex to update it when the new call arrives (unless maybe refresh periodically).
We have a flex application that connects to a proxy server which handles authentication. If the authentication has timeout out the proxy server returns a json formatted error string. What I would like to do is inspect every URLRequest response and check if there's an error message and display it in the flex client then redirect back to login screen.
So I'm wondering if its possible to create an event listener to all URLRequests in a global fashion. Without having to search through the project and add some method to each URLRequest. Any ideas if this is possible?
Unless you're only using one service, there is no way to set a global URLRequest handler. If I were you, I'd think more about architecting your application properly by using a delegate and always checking the result through a particular service which is used throughout the app.
J_A_X has some good suggestions, but I'd take it a bit farther. Let me make some assumptions based on the limited information you've provided.
The services are scattered all over your application means that they're actually embedded in multiple Views.
If your services can all be handled by the same handler, you notionally have one service, copied many times.
Despite what you see in the Adobe examples showing their new Service generation code, it's incredibly bad practice to call services directly from Views, in part because of the very problem you are seeing--you can wind up with lots of copies of the same service code littered all over your application.
Depending on how tightly interwoven your application is (believe me, I've inherited some pretty nasty stuff, so I know this might be easier said than done), you may find that the easiest thing is to remove all of those various services and replace them by having all your Views dispatch a bubbling event that gets caught at the top level. At the top level, you respond to that event by calling one instance of your service, which is again handled in one place.
You may or may not choose to wrap that single service in a delegate, but once you have your application archtected in a way where the service is decoupled from your Views, you can make that choice at any time.
Would you be able to extend the class and add an event listener in the object's constructor? I don't like this approach but it could work.
You would just have to search/replace the whole project.
How do you capture errors that happen on client side when building RIA apps using Flex and Silverlight? What are the common practices? I have seen some asynch js calls to a web service implemented but would like to know how the community is dealing with it.
First, I use client side logging all of the times.
the way I handle it depends on the entire application.
if I use an AMF gateway then there's a call for an application error, with every error that occurs the server is notified, in the server side a bug is open in BugZilla (this is what we use, you can use any other hook you want).
If I use a web-service based application then there's a web-service call for a client error.
one would say you shouldn't sample the server with every error, I disagree with this comment because an error in the client side is rare, it goes thorough QA before being released to the client so I want to know immediately on every error the client is experiencing.
In Silverlight I like to use a WebClient to log back to a web service somewhere -- you can do this directly in the Silverlight application without calling out to JavaScript.
To catch exceptions that are fired when your code isn't on the stack, you can use the Application.UnhandledException event.
I've used the same approach as Avi Tzurel - you need to know on the server side when an error appeared in the Flex client. If you want to collect more data (all the log messages, warnings) I would use an internal buffer and I will flush it asynchronously.
Anyway, you need to take into consideration if your customers are ok with this approach..maybe you need their agreement before sending the error message to the server.
I basically percolate all errors to the top, and capture them in the unhandled exception. I display a friendly message to the user. However, throughout my application I implement an ILogger interface. This interface can be initialized with various levels and handles any messaging. You can set it up so the user can add an init param to determine whether or not to transmit the errors to a service, and I typically have the logger write the messages with Debug.WriteLine if the debugger is attached to make it very easy to trace issues in debug mode.
In Silverlight you may want to consider the Logging and Exception Handling Application Blocks from the Silverlight Integration Pack for Enterprise Library.
Other than using a web service, is there anyway to call a method in a web app from a windows application? Both run on the same machine.
I basically want to schedule a job to run a windows app which updates some file (for a bayesian spam filter), then I want to notify the web app to reload that file.
I know this can be done in other ways but I'm curious to know whether it's possible anyway.
You can make your windows app connect to the web app and do a GET in a page that responds by reloading your file, I don't think it is strictly necessary to use a web service. This way you can also make it happen from a web browser.
A Web Service is the "right" way if you want them to communicate directly. However, I've found it easier in some situations to coordinate via database records. For example, my web app has bulk email capability. To make it work, the web app just leaves a database record behind specifying the email to be sent. The WinApp scans periodically for these records and, when it finds one with an "unprocessed" status, it takes the appropriate action. This works like a charm for me in a very high volume environment.
You cannot quite do this in the other direction only because web apps don't generally sit around in a timing loop (there are ways around this but they aren't worth the effort). Thus, you'll require some type of initiating action to let the web app know when to reload the file. To do this, you could use the following code to do a GET on a page:
WebRequest wrContent = WebRequest.Create("http://www.yourUrl.com/yourpage.aspx");
Stream objStream = wrContent.GetResponse().GetResponseStream();
// I don't think you'll need the stream Reader but I include it for completeness
StreamReader objStreamReader = new StreamReader(objStream);
You'll then reload the file in the PageLoad method whenever this page is opened.
How is the web application loading the file? If you were using a dependency on the Cache object, then simply updating the file will invalidate the Cache entry, causing your code to reload that entry when it is found to be null (or based on the "invalidated" event).
Otherwise, I don't know how you would notify the application to update the file.
An ASP.NET application only exists as an instance to serve a request. This is why web services are an easy way to handle this - the application has been instantiated to serve the service request. If you could be sure the instance existed and got a handle to it, you could use remoting. But without having a concrete handle to an instance of the application, you can't invoke the method directly.
There's plenty of other ways to communicate. You could use a database or some other kind of list which both applications poll and update periodically. There are plenty of asynchronous MQ solutions out there.
So you'll create a page in your webapp specifically for this purpose. Use a Get request and pass in a url parameter. Then in the page_load event check for this paremter. if it exists then do your processing. By passing in the parameter you'll prevent accidental page loads that will cause the file to be uploaded and processed when you don't want it to be.
From the windows app make the url Get request by using the .Net HttpWebRequest. Example here: http://www.codeproject.com/KB/webservices/HttpWebRequest_Response.aspx
In my asp.net applications, I've typically used the Application_Error global event handler to log the error and redirect the user to a user-friendly error page.
However, I have read about ELMAH and while that seems interesting, Application_Error seems like the simpler approach.
I've read other questions where people, including myself, have suggested one way or the other. What I'm wondering is if there is any significant benefit to using one over the other and why?
Elmah is a fantastic project and we use it for all of our ASP.NET applications. Not only does it log unhandled errors for you, it grabs the entire original page that the user saw, which contains a lot of detail for you.
It has email support, RSS feeds (both itemized and digest) and has an attractive console.
For 3 lines in config and a dll reference, I'd say that's a slam dunk.
I guess the main drawback of ELMAH is that it might be overkill for what you need. If it's logging and storing more info than you would in your own implementation, that's an unnecessary overhead in storage and processing. You also need to think about how you secure access to ELMAH's console since those exception details could contain juicy details of your app (that needn't be hard, but it's a worry that you didn't have before).
On the other hand, your own implementation will probably grow to log all that extra information once you decide that some stubborn bug requires it, and do you really care about shaving fractions of a second off the time that it takes for the error page to be displayed? Chances are you'll eventually end up building your own version of ELMAH, so why not just use ELMAH and save yourself the time.
I'd recommend that if you do want to write your own error logging rather than using ELMAH, you at least put it in a module rather than straight into Application_Error in global.asax. Just subscribe to the application's Error event in your module's Init method, and you can easily reuse your error handling code in another application with a line in web.config.
I also find it useful to handle any exception logging through ASP.NET's health monitoring. This makes it easy to control the type and level of logging in web.config, and also allows logging of exceptions that were handled in a try...catch without getting as far as Application_Error. Create a custom HandledExceptionEvent class that extends WebRequestErrorEvent, and you can create and raise those events in any catch block where you'd really like to know that the exception happened even though it was handled.