I have a backend REST API and i have a front end with GWT. I'm on a network where my ip address is 192.168.1.4.
I've declared a constant URL as
public static final String DomainName="http://127.0.0.1/recess/restApp/";
with the ip 127.0.0.1, everything is working fine
but when i changing the ip to 192.168.1.4, the application is not working and i'm getting status code of 0.
The GWT app is on the web root same as the REST API.
In fact, this cannot be a same origin policy problem because its a web service??
Anyone has an idea about this??
I'm using xampp and the GWT project is in htdocs same as the REST API!!
It certainly sounds like you are running into a sandbox policy forbidding external connections.
One policy you may be running into is the GWT browser add-on connection limitation. In Chrome, add your ip addresses at tools | extensions | GWT Dev Plugin | options. In Firefox, it is at Tools | Add-ons | Extensions | Google... | Options
May I suggest that instead of using hard coded urls, to conform to the single source policy, you may want to use the exact url that loaded the web page. The web toolkit provides a mechanism for doing just that.
public static GWT.getHostPageBaseURL() is useful for prepending to paths of resources relative to the host page.
public static GWT.getModuleBaseURL() is useful for prepanding urls intended to be module-relative.
http://google-web-toolkit.googlecode.com/svn/javadoc/2.3/com/google/gwt/core/client/GWT.html#getHostPageBaseURL()
I'm afraid this is a Same-Origin Policy violation: if you ask your browser to load some URL using XMLHttpRequest (or in GWT a RequestBuilder), then that URL has to be on the same origin as the page trying to access it; unless the browser supports CORS (all, except IE; at least until IE10 is out the door) and the server you're trying to reach sends the appropriate HTTP headers to allow the cross-origin connection.
Related
I have tried everything but I cant seem to fix this issue that is happening for only one client behind a corporate proxy/firewall. Our Silverlight application connects to Amazon S3 for downloading/Uploading some documents. On one client and one client only it returns a 407 error and after that the application fails to save anything.
Inner Exception:
System.ServiceModel.ProtocolException: [UnexpectedHttpResponseCode]
Arguments: 407,Proxy Authentication Required
We had something similar at a different client but there was more of a CORS issue. to resolve this I used cloud-front to fake a sub-domain that then accesses the S3 bucket and it solved the issue. I was hoping it would fix it with this client as well but it didnt.
I have tried adding this code to web.config as suggested by a lot of answers
<system.net>
<defaultProxy useDefaultCredentials="true" >
</defaultProxy>
</system.net>
I have read articles about passing a proxy headers with basis authentication using username and password but I am not sure how this would help us. The Proxy server is used by client and any authentication it requires is outside our domain.
**Additional Information**
The Silverlight code references 2 services. One is our wcf service that retrieves all the data for the application. One is The Amazon S3 service that uses the amazon Soap api, the endpoint for which is at http://s3.amazonaws.com/doc/2006-03-01/AmazonS3.wsdl?
If I go into our app and only use part of the system that dont make any calls to the Amazon S3 api the application works fine. As soon as I go to a part of the system that makes a call to the S3, the problem starts. funny enough the call to S3 goes fine and I can retrieve the doc fine but then any calls to our wcf service return 407.
Any ideas?
**Update 2**
Based on comments from Elliot Nelson I check the stack we were using for making http requests in our application. Turns out we are using client http for both http and https requests by default. Here is the code we have in the App.xaml constructor
public App()
{
Startup += Application_Startup;
UnhandledException += Application_UnhandledException;
InitializeComponent();
WebRequest.RegisterPrefix("http://", WebRequestCreator.ClientHttp);
WebRequest.RegisterPrefix("https://", WebRequestCreator.ClientHttp);
}
Now, to understand the differences between clienthttp and browserhttp and when to use them. Also, the potential impacts/issues of switching to browserhttp.
**Update 3**
Is there a way to request browsers to run your in-browser Silverlight application in trusted mode and would it help bypass this issue?
(Answer #2)
So, most likely (for corporate environments like this network), almost nothing can be done without whatever custom proxy settings are set in IE, usually pushed by corporate policy. To take advantage of these proxy settings, you want to use WebRequestCreator.BrowserHttp, which automatically uses the browser's default settings when making requests.
There's a table of the differences between these two clients available in the Microsoft docs. I'm guessing you were using something (maybe setting custom headers or reading the raw response body) that wasn't supported in BrowserHttp.
For security reasons, you can't "ask" the browser what its proxy settings are and use them, so this is a tricky situation. You can specify Browser vs Client handling by domain, or even for a specific request (the same page above describes how); you may be able in this case to get away with just using ClientHttp for your service calls and BrowserHttp for your S3 calls, and avoid the problem altogether!
For next steps, I'd try that approach; if it doesn't work, I'd try switching wholesale to BrowserHttp just to see if it bypasses the proxy issue (there's almost no chance the application will actually work, since you're probably using ClientHttp-only options).
Long term, you may want to consider making changes to your services so they are usable by a BrowserHttp-only application (this would require you to be pretty basic in your requests/responses, but using only BrowserHttp would be a guarantee you'd work in pretty much any corp network).
Running in trusted mode is probably a group policy thing which would require their AD admins to approve / whitelist your app.
I think the underlying issue you are facing is that the proxy requires NTLM authentication and for whatever reason the browser declines to provide your app with that context.
One way to prove that it's an NTLM auth issue is to test with curl - get it to make a req through the proxy, then it should be a bit easier to code to. EG the following curl will get you through 99% of Windows corporate proxies (assuming the proxy is at proxy-host.corp:3128):
C:\> curl.exe -v --proxy proxy-host:3128 --proxy-user : --proxy-ntlm https://www.google.com
NOTE The --proxy-user : tells curl to use the current user session to perform the NTLM challenge.
So if you can get the client to run that, you can at least identify that NTLM works, then it's a just a matter of getting the app to perform the NTLM challenge using the default credentials (which may or may not be provided by the browser session)
Since you described this as a silverlight application, I'm going to assume you can't use classic browser-proxy troubleshooting like "move browser to public network" or "try a different browser", to isolate the problem.
You should try to isolate the proxy server, and have the customer use the required proxy-auth.
The application is making request, but it might be intercepted by a transparent proxy, or the result might be coming from what you consider a web server.
In the early days, the 401 error was pretty strictly associated with web-auth, and 407 was for proxy-auth.
Architecturally, the separation is a convenience, a web server can have both web server, proxy, and reverse-proxy behaviors.
What happens is your customer's environment is making a web connection to the destination, but it receives a HTTP 407 status from some host, probably their network, or sometimes the provider. Almost certainly the request is received not forwarded. The HTTP client your application lives in needs to provide the credentials that host requires. Companies have environments that are complex enough where often your customer will say this is the first time they have heard of this (some proxy-auth is also dynamic or destination specific).
Also, in some corporate environments, the operator will allow temporary or permanent white-listing from the proxy-auth service. You should see if they can do this, even temporarily, to confirm there aren't going to be other problems.
In the end, it sounds like your application might not robustly support proxy-auth, or the proxy-auth type they use in their environment.
We have created a website which is served right now on Heroku. This website has a search bar in the navbar and I wanted to use Freefind search service for the backend. The search result I receive from it are all over the HTTP server and Heroku server will not load it.
I want them to work fine just as they work on localhost. What can I do?
The app is Django based and I tried to google custom search but it didn't work for me.
You can't load most HTTP content on HTTPS domains. Loading HTTP images is fine, but is still discouraged. This is called mixed content blocking, which is a browser's feature.
The only thing you can do is to find out if freefind's search service supports HTTPS. You can try changing the URL to https://search.freefind.com/... and see if it works. Or contact freefind and ask them if they support HTTPS. If they don't support HTTPS, you have to find a different company's search service.
I am relatively new to javascript, and I got an uploader tool called fineuploader that I was considering to use. However locally (development machine) I got it to work (vb.net), but when I put it on my external server, I noticed that there is a post done in http and directly to the server's domain name (e/g/ mydomain.com), instead of mydomain.com/testproject. The site only allows for https traffic.
Is there an easy way to change this? (so it should point at https://mydomain.com/testproject/FileUpload.aspx
The code used by fineuploader shows a parameter called 'endpoint: '/FileUpload.aspx'
Do I have to make changes in the settings of IIS for this webservice?
If you need to enable CORS (cross-domain requests), Fine Uploader supports this. You should read my blog post on how CORS support is implemented in Fine Uploader and how you can support such requests in your server-side code.
I want to know when I'm using IE8 open a website (like www.yahoo.com), which API will be called by IE8? so I can hook these API to capture which website that IE8 opening currently.
When you enter a URL into the browser, the browser (usually) makes an HTTP request to the server identified by the URL. To make the request, the IP address of the server is required, which is obtained by a DNS lookup of the host (domain) name.
Once the response -- usually containing HTML markup -- is received, the browser renders it to display the webpage.
More details available here: what happens when you type in a URL in browser
So, in the general case, no "API" request as such is made. (Technically speaking, you can think of the original HTTP request to the server as an API request). The sort of "API" request you presumably mean, however, is not made in this general case just described. Those requests happens when the JavaScript executing on the page makes an Ajax HTTP request (XmlHttpRequest) to the web server to carry out some operation.
I am not sure about IE8, but the "developer tools" feature of most modern browsers (including IE9 and IE10), would let you see the Ajax HTTP requests that the webpage made as it carried out different operations.
Hope this helps.
IE uses Microsoft's WinSock library API to interact with web servers.
You may want to look for a network monitoring/sniffing API, which you could use to examine HTTP requests, and determine the URLs the browser is using.
We have installed an ASP.NET web site on a client's server. This site has a web service with a couple of web methods that are called by a Flash object in order to display a news feed. If you browse to their site (ex: www.domain.com), everything's working fine except the flash.
The issue is that when we browse to the .asmx, the header shows that the Host is a subdomain internal to their network (internal.domain.com). Obviously this doesn't resolve to any public IP when browsing from outside of their network. This causes the Flash to fail since the flash object is embedded on a page and is therefore running client side.
I checked the computer name on the server in question, and it doesn't even match "internal.domain.com" - it is something completely different. Where is it getting this information from. It is not coming from IIS, since we have no host headers set up, and the IP for the site is set to (all unassigned).
We either need to force the web service to run against a specific host, or we need to change something on the server so that it resolves to a valid public-facing host name. Any and all help is greatly appreciated!!!!
The solution is to add a host header for www.domain.com
More details here
While you probably did this already, it's always a good first step:
Do a global Find in the source code of both the Flash object and the web service for the string in question.
It sounds like someone may have configured/coded the internal.domain.com string into the Flash object's request. (Host: is a HTTP Request header, not Response header, IIRC.)
Does the Flash object get the web service URL from the C# code? If so, it might be getting the default web service URL that you choose when adding a Web Reference to your project in VS. Therefore it might be pointing to a URL locally to the developer's machine/server which is not recognized on the live server.