I am new to web services. I am dealing with testing APIs in my project. In the previous version the company used GET and POST methods but not PUT and DELETE methods. For the HTTP DELETE method, I have browsed various websites where I found the example code snippets for GET and POST methods, but not for DELETE and PUT methods (why?).
Can anyone give me an example code snippet (C#) for RESTful HTTP DELETE method and explain how to call the DELETE request?
Check out the following code snippet:
string sURL = "<HERE GOES YOUR URL>";
WebRequest request = WebRequest.Create(sURL);
request.Method = "DELETE";
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
In the response object you should check the StatusCode property (it should be 200 or 204 if everything goes right, see here for more info).
Related
I am trying to submit some data to an API using RestSharp in C# and it seems all of my parameters are added to the Headers collection - or that is just how they are catalogued in VS.
Here is my code
var client = new RestClient("https://api.com");
var request = new RestRequest("/recognize", Method.POST);
request.AddHeader("app_id", "");
request.AddHeader("app_key", "");
request.AddHeader("Content-Type", "multipart/form-data");
request.AddParameter("gallery_name", model.gallery_name);
request.AddParameter("image", model.image);
var response = client.Execute(request);
The error back from the API says the request is missing the gallery_name and image parameters, but looking into the request object they are there in the Headers collection.
I can make the call in Postman where the method is set to Post and the Body is set to form-data, along with 2 key/value pairs listed.
What am I doing wrong?
In your question you says "I can make the call in Postman ...".
Normally if the Postman request is successful then should the generated RestSharp code from Postman works, if there are no open issues in the RestSharp library that can cause your problem.
It's hard to debug and reproduce the problem from here, but I can give the following that you can check.
Check this:
If your Postman request works and is successful then check the Restsharp code generated by Postman:
Click on "code"
Choose in the combobox for "C# (RestSharp)"
Try the RestSharp code that you see in the window, if the code doesn't work check this URL for known issues.
On a sidenote: If you see a known issue that can cause your error, try to test with a previous version of RestSharp or an alpha version.
I hope you can now further investigate and debug the problem.
(I had similar problems and resolved it successful with this way of investigating and debugging)
I am trying to get some data downloaded from a URL using HttpWebRequest from a C# console applicaiton. In browser and Postman, it works fine but not from the applicaiton - it does not return the expected data. Using Fiddler, I inspected the request and I figured out that the request initially sent is actually gets redirected thrice (I see three http 302 in Fiddler before the final Http 200 response) and eventually returns the data. However, from my C# console application I get only the final response - the HttpWebResponse status always gives"OK" (200).
I noticed in fiddler that the http 302 returns few cookies and the subsequent request sends the cookies in its header. This is handled correctly in browser/postman but I am not able to do this in my application. Any help will be highly appreciated.
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
I believe that you are looking for AllowAutoRedirect property of HttpWebRequest class. Setting it to false should do the thing:
HttpWebRequest request = new HttpWebRequest(someUri);
request.AllowAutoRedirect = false;
You can read more info about HttpWebRequest here.
I've hit a strange bit of behaviour and I'm pretty sure is related to my code rather than the RTC instance I'm working with.
I've got a web request setup and configured:
var cookies = new CookieContainer();
var request = (HttpWebRequest)WebRequest.Create(getCreationFactoryUri);
var xmlString = getRDF.ToString();
request.CookieContainer = cookies;
request.Accept = "application/rdf+xml";
request.Method = "POST";
request.ContentType = "application/rdf+xml";
request.Headers.Add("OSLC-Core-Version", "2.0");
request.Timeout = 40000;
request.KeepAlive = true;
byte[] bytes = Encoding.ASCII.GetBytes(xmlString);
request.ContentLength = bytes.Length;
Stream dataStream = request.GetRequestStream();
dataStream.Write(bytes, 0, bytes.Length);
dataStream.Close();
This is passed to another method wrote based on an RTC example using forms authentication for RTC.
Under the OSLC v2 spec, I'm using a creation factory URL to post to. I know the URL is fine because I've setup a call using RESTClient in Firefox. Added the headers that are needed (Content-Type: application/rdf+xml, Accept: application/rdf+xml, OSLC-Core-Version: 2.0) and used the generated XML that my code is trying to pass. My manual call works perfectly and the ticket is created.
In my logs I captured the response from RTC, which is a list of tickets rather than a response showing my ticket as being created. I can re-create this behavior by doing a GET on the creation factory URL I'm using to create an event ticket.
So although I know I'm sending a POST to the creation factory (I debugged to check that my web request method was 100% set to 'POST') RTC instead returns a list of tickets and I can only conclude somewhere my request is treated as a 'GET'.
As a test I changed my request to use PUT instead of POST. This isn't permitted for use on the creation factory URL and in testing it indeed throws an error. So I'm totally miffed as to why RTC isn't creating my ticket, but instead treating my request as a GET and returning a list of tickets.
Anyone have any ideas?
Thanks.
If the server using form authentication, as you state, then I expect what is happening is that the POST is resulting in an HTTP redirection to the authentication form. Even if your other code is handling that authentication (which it sounds like it is), the result of that authentication will be an HTTP redirection to the URL of the original request. However, that redirection is likely to result in a GET to that URL, not the original POST. (Also, I don't believe the redirection after authentication is 100% reliable, if your requests are multi-threaded).
The jazz.net information on form authentication says "After authentication succeeded, you always have to replay the original request at least once to get to the protected resource. More replays may be required if the first replay led to another set of redirections and the original request had a non-GET method."
So if your code received an authentication challenge, you will need to re-send the original POST.
I believe the reason why the RESTClient plug-in in your browser is working first time is that it is sending the cookies from your previous log-in to the RTC web UI in the browser. (I had this experience recently, and also found it very confusing).
Also, if you are not preserving cookies between requests to RTC in your client app, then you will meet an auth challenge for every request. If you preserve cookies between calls from your client app (how you do that will depend on your client library - I'm not familiar with the code in your examples) then my experience is that you won't receive an auth challenge for every request. (However, you still need to be able to handle an auth challenge on every request - including POSTs - otherwise it may fail intermittently if the session times out just before you send a POST).
I'm doing research into web programming in ASP .NET and came across these two classes. I was wondering what might these be used for?
My first thought is that they could be used if you were setting up a proxy between the client and server, but I'm not sure if this is the main purpose or not.
Thanks
edit: classes not methods
They can indeed be used for that. This isn't specific to ASP.NET however.
You can create a HttpWebRequest object by doing:
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://url.com");
And you invoke it to retrieve an HttpWebResponse:
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
There's a lot of customization you can do here, but hopefully this will give you a starting point for reading data off the web.
As their names imply, these are classes to either create a request (HttpWebRequest) or create a response (HttpWebResponse).
Using HttpWebRequest you define a request to a URI using the HTTP-protocol. Whereas the HttpWebResponse class delivers you an answer of an HTTP-server providing all the information like HTTP-headers and actual body of the request.
This is an example from MSDN
HttpWebRequest HttpWReq =
(HttpWebRequest)WebRequest.Create("http://www.contoso.com");
HttpWebResponse HttpWResp = (HttpWebResponse)HttpWReq.GetResponse();
// Insert code that uses the response object.
HttpWResp.Close();
Consider the casting from the base-class WebRequest.
See HttpWebRequest and HttpWebResponse.
They are used for communicating with another process using the HTTP protocol.
In the context of ASP.NET, your process could use them to talk to another service. Maybe your database uses the HTTP protocol, such as CouchDB. Perhaps you have a rest service that your ASP.NET application needs to talk to.
I'm narrowing in on an underlying problem related to two prior questions.
Basically, I've got a URL that when I fetch it manually (paste it into browser) works just fine, but when I run through some code (using the HttpWebRequest) has a different result.
The URL (example):
http://208.106.250.207:8192/announce?info_hash=-%CA8%C1%C9rDb%ADL%ED%B4%2A%15i%80Z%B8%F%C&peer_id=01234567890123456789&port=6881&uploaded=0&downloaded=0&left=0&compact=0&no_peer_id=0&event=started
The code:
String uri = BuildURI(); //Returns the above URL
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(uri);
req.Proxy = new WebProxy();
WebResponse resp = req.GetResponse();
Stream stream = resp.GetResponseStream();
... Parse the result (which is an error message from the server claiming the url is incorrect) ...
So, how can I GET from a server given a URL? I'm obviously doing something wrong here, but can't tell what.
Either a fix for my code, or an alternative approach that actually works would be fine. I'm not wed at all to the HttpWebRequest method.
I recommend you use Fiddler to trace both the "paste in web browser" call and the HttpWebRequest call.
Once traced you will be able to see any differences between them, whether they are differences in the request url, in the form headers, etc, etc.
It may actually be worth pasting the raw requests from both (obtained from Fiddler) here, if you can't see anything obvious.
Well, the only they might differ is in the HTTP headers that get transmitted. In particular the User-Agent.
Also, why are you using a WebProxy? That is not really necessary and it most likely is not used by your browser.
The rest of your code is fine.. Just make sure you set up the HTTP headers correctly. Check this link out:
I would suggest that you get yourself a copy of WireShark and examine the communication that happens between your browser and the server that you are trying to access. Doing so will be rather trivial using WireShark and it will show you the exact HTTP message that is being sent from the browser.
Then take a look at the communication that goes on between your C# application and the server (again using WireShark) and then compare the two to find out what exactly is different.
If the communication is a pure HTTP GET method (i.e. there is no HTTP message body involved), and the URL is correct then the only two things I could think of are:
make sure that your are send the right protocol (i.e. HTTP/1.0 or HTTP/1.1 or whatever it is that you should be sending)
make sure that you are sending all required HTTP headers correctly, and obviously that you are not sending any HTTP headers that you shouldn't be sending.
There could be something wrong with the URL. Instead of using a string, it's usually better to use an instance of System.Uri:
String url = BuildURI(); //Returns the above URL
Uri uri = new Uri(url);
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);
req.Proxy = new WebProxy();
using (WebResponse resp = req.GetResponse()) {
using (Stream stream = resp.GetResponseStream()) {
// whatever
}
}
I think you need to see exactly what's flowing to your server in the HTTP request. Does sound likely that the headers are interestingly different.
You can introduce a some kind of debugging proxy between your request and the server (for example RAD has such a capability in the box).