What causes HttpHostConnectException?

Question

I have a Auto Complete/type ahead feature on Search for my website. I see that some time their is an exception associated with it. We are using a proxy server.

org.apache.http.conn.HttpHostConnectException: Connection to http://proxy.xyz.com:60 refused    

at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:159)
at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:149)
at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:108)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:415)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:641)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:576)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:554)
at com.xxx.dd.sone.integration.SearchDAO.getJSONData(SearchDAO.java:60)
at com.xxx.dd.sone.integration.SearchDAO.searchAutoCompleteResults(SearchDAO.java:560)
at com.xxx.dd.sone.presentation.util.SearchAutoCompleteUtil.doGet(SearchAutoCompleteUtil.java:26)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:845)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:242)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:352)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:236)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3254)
at weblogic.servlet.provider.WlsSubjectHandle.run(WlsSubjectHandle.java:57)
at weblogic.servlet.internal.WebAppServletContext.doSecuredExecute(WebAppServletContext.java:2163)
at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2074)
at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1512)
at weblogic.servlet.provider.ContainerSupportProviderImpl$WlsRequestExecutor.run(ContainerSupportProviderImpl.java:255)
at weblogic.work.ExecuteRequestAdapter.execute(ExecuteRequestAdapter.java:22)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:147)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:119)

Caused by: java.net.ConnectException: Connection refused

Here is the how i have coded

public HashMap<String, Object> getJSONData(String url)throws Exception {
    DefaultHttpClient httpClient = new DefaultHttpClient();
    HttpParams params = httpClient.getParams();
    try {
        HttpConnectionParams.setConnectionTimeout(params, 10000);
        HttpConnectionParams.setSoTimeout(params, 10000);
    } catch (Exception e) {
        e.printStackTrace();
        throw e;
    }
    HttpHost proxy = new HttpHost(proxy.xyz.com, 60);
    ConnRouteParams.setDefaultProxy(params, proxy);
    URI uri;
    InputStream data = null;
        uri = new URI(url);
        HttpGet method = new HttpGet(uri);
        HttpResponse response=null;
        try {
        response = httpClient.execute(method);
        }catch(Exception e) {
            e.printStackTrace();
            throw e;
        }
        data = response.getEntity().getContent();
    Reader r = new InputStreamReader(data);
    HashMap<String, Object> jsonObj = (HashMap<String, Object>) GenericJSONUtil.fromJson(r);
    return jsonObj;
}

Can any one tell me why i am getting this exception some time only? is this possible that this exception is caused when a search request is made from Android applications as our website don't support a request is being made from android applications

Rhodarhodamine

Is your proxy host running on port 60? If not - that would result in the connection refused message. – Steinmetz

It is running on same port. Also this exception don't happen each and every time. some times only. – Rhodarhodamine

Unfortunately you'd have to look at why the proxy is denying the connection. Possibly an error in the proxy configuration? – Steinmetz

That proxy is being used my most of the applications company wide. I don't think their will be any issue with configuration the proxy. Also one question do proxies configuration differs based on different platforms (like Mac/Android) – Rhodarhodamine

Answer 1

A "connection refused" error happens when you attempt to open a TCP connection to an IP address / port where there is nothing currently listening for connections. If nothing is listening, the OS on the server side "refuses" the connection.

If this is happening intermittently, then the most likely explanations are (IMO):

• the server you are talking ("proxy.xyz.com" / port 60) to is going up and down, OR
• there is something¹ between your client and the proxy that is intermittently sending requests to a non-functioning host, or something.

Is this possible that this exception is caused when a search request is made from Android applications as our website don't support a request is being made from android applications.

It seems unlikely. You said that the "connection refused" exception message says that it is the proxy that is refusing the connection, not your server. Besides if a server was going to not handle certain kinds of request, it still has to accept the TCP connection to find out what the request is ... before it can reject it.

---

^{1 - For example, it could be a DNS that round-robin resolves the DNS name to different IP addresses. Or it could be an IP-based load balancer.}

Ramulose

Just to clear the search request is going to another service provider and we have implemented their service on our website. All we do is send the requests from the consumer and send it to the search service provider and display the info send by them – Rhodarhodamine

"there is something between your client and the proxy that is intermittently sending requests to a non-functioning host, or something" what do you mean by non functioning host? – Rhodarhodamine

Some host other than your proxy server that is not expecting those connection requests; i.e. it is not functioning as a proxy ... – Ramulose

how can we fix this problem ? – Springfield

I think the problem might also be because their is a auto complete on my search box and the action triggers as soon as user starts typing, So their is a possibility that proxy is refusing the call if it see lot of call happening in fraction of a second. One solution is that to trigger auto complete after user has typed in some minimum characters( like 3). – Rhodarhodamine

@Springfield - You have to UNDERSTAND what is causing the problem before you can fix it. – Ramulose

@Rhodarhodamine - That is possible. And if your theory is correct, then your proposed fix might work. However, you need real concrete evidence for that before you start blaming the proxy. – Ramulose

is that possible that the hosted website has no SSL? – Playwriting

Yes. If you attempted to send a request to the https port (443) of a server that did not support https, then you would get a connection refused. – Ramulose

Answer 2

In my case the issue was a missing 's' in the HTTP URL. Error was: "HttpHostConnectException: Connect to someendpoint.com:80 [someendpoint.com/127.0.0.1] failed: Connection refused" End point and IP obviously changed to protect the network.

Nelia

Answer 3

You must set proxy server for gradle at some time, you can try to change the proxy server ip address in gradle.properties which is under .gradle document

Armadillo