A long running background process creates a text file to indicate the completion of the process. From the frontend, I'd need to check every few seconds if the text file has been created or not.
I am doing this check from http://DomainA.com However the file is created in http://DomainB.com/Mytext.txt
Can someone help me write a jquery script that checks for a file across domain?
PS: Currently, I am doing a ajax postback that executes a WebMethod in ASP.NET that creates HttpWebRequest. This works functionally, but I have major performance problems. So, I need a light weight way of finding if a URL is valid or not.
Thanks
I would set up a server-side script on your own server which pings the URL (using cURL or whatever) and responds with a JSONified version of the response.
Do not fire HttpWebRequest at the moment the jQuery script requests it. Run HttpWebRequest independently at same intervals in some background thread which in turn sets some shared boolean toggle. Finally let the code which should respond to jQuery requests return the state of this toggle (thus without firing the HttpWebRequest itself).
I ended up using YQL with JQuery that lets me do cross domain requests.
call it using jQuery ajax, then look at the result if it is 404? This is asynchronous though, so you need to use javascript continuations if you are in a workflow
Related
I am new to Web API and the tutorial I was watching uses Fiddler to sniff and send request.
My question is how to use the post, put and delete methods without using fiddler and where are these usually used in the when creating in software development? Fiddler allows you to compose a request body how about the browser though?
I don't seem to understand why you are only able to use these on a sniffing tool. I understand that I am most probably speaking out of ignorance.
(This answer is not specific to ASP.NET)
To avoid any confusion, I'm assuming you understand this much about RESTful webservices:
If you are creating a new entity, use POST.
If you are reading an entity, use GET.
If you are updating an entity, use PUT.
If you are deleting an entity, use DELETE.
As you noticed, only the GET and POST methods can be used in plain web forms. AJAX, however, supports using any HTTP method. Therefore, to use the PUT and DELETE methods, send your data to the server using JavaScript methods such as XMLHttpRequest, the newer Fetch API or a convenient wrapper like jQuery's $.ajax. (There are many tutorials for whichever you pick.) For example, if you have a form of updated values, replace your input button with a button element that has a JavaScript click event handler. The same principle applies to a delete link, swap the href for a click event handler that makes an AJAX request to your server.
If you simply want to create requests using some tool, then you can use tools like Fiddler, Postman, curl, etc. - as you have stated, Fiddler can also be used to monitor as well as create requests.
If you want to go beyond that,
you have HttpClient, WebClient to build requests on your own, and for testing.
If you want to get "full control" then look into HttpWebRequest.
VS debugging tools will allow you to inspect the full flow - from request to response - using things like breakpoints, watch, etc.
See previous/other answers if you want to build/create requests client-side (Javascript / XMLHttpRequest)
Hth.
I have the following use case:
A user can filter on my asp.net web project for some data and request the result as PDF. The PDF is generated per request new and returned to the user. I got already everything to run.
But: the processing can take up to two minutes and the user should be able to continue to use the page.
I tried to use a second tab, but both tabs are blocked. Even when I use the PageAsyncTask class and the async attribute. When I use a thread to perform the request, I am truly parallel, but I have no clue, how to interact with the user from inside the thread when the work is done.
How can I send an async request to the server and just get the result on the page, in whatever form, when its finished?
Dave Encosia does a great job explaining how you can do this:
Using jQuery to directly call ASP.NET AJAX page
methods
Using jQuery to Consume ASP.NET JSON Web
Services
3 mistakes to avoid when using jQuery with ASP.NET
AJAX
I'm new to this AJAX approach when you're not supposed to use UpdatePanel but rather go with WebMethods and WebServices. My main problem is authentication.
When page is entered or postback request is created, everything works fine. Authentication is passed correctly and I can access Thread.CurrentPrincipal.Identity and get my user identity object from there.
However this changes when I try to call WebMethod on my page. Call is passed correctly to server and everything seems to work just fine until i try to get user identity from thread. Then I get just Anonymous user instead of real one. Enabling session on webmethod didn't seem to help much.
Any ideas what might cause this problem and how to solve it? Someone mentioned that authentication cookie needs to be passed along with the request, but how am I supposed to do it?
Any help will be appreciated.
Edit:
Some clarification and code:
My application is written in standard asp.net. After some deeper research in legacy code I've found out, that all authentications are done in some base class from wchich all other pages inherit. Each time page is loaded, user principal are obtained from HttpContext.Current.Session("..."). I think this is far from good solution, but I'll need to stick with it right now. Problem was, WebMethod is not firing whole page lifecycle since it's static. I've fixed it right now by calling method that obtains user data from session.
I would like to get some ideas how this could be created correctly and what problems might be result of session based authentication.
PageMethods.SomeMethod(parameter, SuccessDelegate, FailureDelegate);
This is how I'm calling WebMethods right now. I assume it's passing all required cookies, am I right?
It depends on how you're calling the method and in what manner?
Jquery for instance with its Post method should push all cookies (including your FormsAuth / Session cookie) up with the request that should still authenticate as appropriate. Bare metal techniques might be making lightweight calls that simply do not push the cookie up...One way to monitor this is by using Fiddler to observe the request and a browser based development plugin like Firebug and see what is occuring and amend your JS code as appropriate.
Personally, if you are starting a brand new project and there is no pressing need to expose your services beyond your web application then I would suggest looking at ASP.NET MVC where you can make Jquery / client-side up to the controller and get your authentication wrapped up for free. I've recently created something simliar using WCF JSON endpoints and some inevitable pain, I then saw MVC and kinda kicked myself...
As noted in comment above, the issue lies in legacy code that handles users. It is needed to make call to special function that assigns appropriate user data to handling thread. Not a best solution, but that's how it sometimes is with legacy code. What you gonna do?
I was wondering if anyone had an easy way to wire up javascript event handlers to events happening on the server-side. I have a long running process that includes a lot of steps, and would like the client to be continually updated with new information as the steps transition. Will this involve some sort of polling mechanism?
Send an AJAX or JSON request from the client every so often asking for status.xml. Then, on the server, when something changes, just quickly write a new line to status.xml the same way you would to the console. You can use setInterval( function, timeBetweenRuns ) in Javascript to do this regularly.
would it be possible to use an update panel to do this with maybe a timer? it's sort of how I would do it.
Course, this depends on what you're doing already. I'm assuming you're using Forms...
Ajax calling a Web Service is how I would do it.
OK. I just want to know if this can be done.
I'm using C# asp.net language.
I want to send a structure to a webserver from a webpage (much like you you can pass a structure to a function). The server would act on the data found in the structure, and then return back the structure (with its contents modified) to the "client" webpage.
The webpage would then, based on the data received, do a particular task.
is it possible that information be passed between webpages & servers just like functions?
If not, is there any way that i may be able to accomplish what was said above?
Answer is yes, you can try calling a server-side function from a client-side script.
Here are a few good reads:
Client-Side Web Service Calls with AJAX Extensions
Client Side Callbacks in ASP.NET 2.0
Extend ASP.NET AJAX Client-Side Function - The Server-Side Way
ASP.NET 2.0 Client-Side Features: Bring Server-Side Power to the Client
Sure. You can encode your structure in a string, and then send it to the server as a query string or in a form POST, using either a dedicated link or plain JavaScript or Ajax (XMLHTTP). When the response arrives, you can similarly decode it with JavaScript and then take whatever action is appropriate.
There are several libraries to help automate this kind of thing, including XML-RPC.