Develop Reference

HttpRequest from app engine endpoint. Connection reset

I am trying to send an HTTP request from an APP Engine endpoint, from experiments on Postman I know the result is quite big, and the the request usually takes about a minute.
here is my Code:
void testRequest() {
String test = getConnectionString();
URL url = new URL(YARDI_URL);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setInstanceFollowRedirects(false);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-Type", "text/xml");
connection.setConnectTimeout(1000000);
OutputStream os = connection.getOutputStream();
PrintWriter p = new PrintWriter(os);
p.print(test);
p.close();
YardiResponse response = new
YardiResponse(connection.getInputStream().toString());
System.out.println(response.getResponse());
connection.disconnect();
}
I am getting two errors,
the first is: java.net.ProtocolException: Cannot write output after reading input.
and after a long time I am getting a java.net.SocketException: Connection reset message.
Obviously I am mishandling the steams, and the way I send them.

I higly recomend http-request built on apache http api.
private static final HttpRequest<String.class> HTTP_REQUEST =
HttpRequestBuilder.createPost(YARDI_URL, String.class)
.responseDeserializer(ResponseDeserializer.ignorableDeserializer())
.contentTypeOfBody(ContentType.TEXT_XML)
.connectTimeout(someIntValue)
.socketTimeOut(someIntValue)
.connectionRequestTimeout(someIntValue).
.build();
void testRequest() {
ResponseHadler<String> yardiHandler = HTTP_REQUEST.executeWithBody(yourXml);
int statusCode = yardiHandler.getStatusCode();
String content = yardiHandler.get(); //returns response body as String in this case
}
Note: I recomend see javadocs of connectTimeout, socketTimeOut and connectionRequestTimeout methods.

Is a way to set Connection refused time to HTTPGet Apache ?

I want to get a web page but if return Connection refused I want to wait only 1 second
My code :
final DefaultHttpClient client = HTTPSHelper.getClientThatAllowAnyHTTPS(connectionManager);
client.getParams().setParameter(ClientPNames.COOKIE_POLICY,
CookiePolicy.BROWSER_COMPATIBILITY);
client.getParams().setParameter("http.socket.timeout", 1000);
client.getParams().setParameter("http.connection.timeout", 1000);
client.addRequestInterceptor(new RequestAcceptEncoding());
client.addResponseInterceptor(new ResponseContentEncoding());
final HttpGet get = new HttpGet(url.getUrl());
final HttpResponse resp = this.httpClient.execute(get, localContext);
When returns connection refused I have to wait a lot ...Is there a way to specify time to wait on connection refused ? Thanks

You can set the timeout for the connection this way:
final HttpParams p = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(p, 1000);
client = new DefaultHttpClient(httpParams) ;

Subsequent HTTPS POST request in Java with cookies retained

I need to obtain the input stream to a HTTPS URL eg. https://baseurl.com/mypdfgenerated.php?param=somevalue. In order to access this URL I need to get through the login page (eg. https://baseurl.com/login.php) by supplying BODY parameters:
user_name, web_pwd and submit_login
I'm assuming the only way to successfully access the first URL is by a POST to the /login.php followed by storing the cookies and then reusing the cookie-session-ID in the next GET request; if this is the correct approach then could someone please share a solution with the correct/recent libraries?

Not sure which is the best way but what helped me achieve this is the CloseableHttpClient class which along with BasicCookieStore retains cookies for subsequent requests once logged in, implemented below:
BasicCookieStore cookieStore = new BasicCookieStore();
CloseableHttpClient httpclient = HttpClients.custom().setDefaultCookieStore(cookieStore).build();
HttpUriRequest login = RequestBuilder.post()
.setUri(new URI(url_login))
.addParameter("login", "loginuname")
.addParameter("password", "pwd")
.addParameter("submit", "sub_mit");
CloseableHttpResponse response = httpclient.execute(login);
List<Cookie> cookies = cookieStore.getCookies();
response.close();
HttpGet httpget2 = new HttpGet(url_to_get_after_login);
CloseableHttpResponse response2 = httpclient.execute(httpget2);
response2.close();

Sample code snippet from Java Samples
try {
System.setProperty("java.protocol.handler.pkgs", "com.sun.net.ssl.internal.www.protocol");
java.security.Security.addProvider(new com.sun.net.ssl.internal.ssl.Provider());
URL url = new URL("https://www.yourwebsite.com/"); // Some URL
HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setRequestMethod("POST");
connection.setFollowRedirects(true);
String query = "UserID=" + URLEncoder.encode("username");
query += "&";
query += "password=" + URLEncoder.encode("password");
query += "&";
// open up the output stream of the connection
DataOutputStream output = new DataOutputStream( connection.getOutputStream() );
// write out the data
output.writeBytes( query );
}catch(Exception err){
err.printStackTrace();
}
Have a look at Usage of cookies

You should use a library which handles cookies for you, such as Apache HTTPClient.

Apache HttpClient: set timeout for NoRouteToHostException

I am using Apache HttpClient 4.2.5 and need to set connection timeout for 30 seconds. I do the following:
int timeout = 30 * 1000;
HttpParams params = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(params, timeout);
HttpConnectionParams.setSoTimeout(params, timeout);
HttpClient client = new DefaultHttpClient(params);
HttpGet request = new HttpGet(url.toURI());
client.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT, timeout);
client.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, timeout);
HttpResponse response = client.execute(request);
But after 12 seconds NoRouteToHostException is thrown form client.execute(request). As I understand, CONNECTION_TIMEOUT and SO_TIMEOUT is useless here. Have you any idea, how to set timeout for NoRouteToHostException? I should hope that server became available within this time. Thanks for any comment and advice!

How to check if web service is available, and then connect to it in one go?

I want to check if a web service is available before connecting to it, so that if it is not available, I can display a dialog that says so. My first attempt is this:
public void isAvailable(){
// first check if there is a WiFi/data connection available... then:
URL url = new URL("URL HERE");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestProperty("Connection", "close");
connection.setConnectTimeout(10000); // Timeout 10 seconds
connection.connect();
// If the web service is available
if (connection.getResponseCode() == 200) {
return true;
}
else return false;
}
And then in a separate class I do
if(...isAvailable()){
HttpPost httpPost = new HttpPost("SAME URL HERE");
StringEntity postEntity = new StringEntity(SOAPRequest, HTTP.UTF_8);
postEntity.setContentType("text/xml");
httpPost.setHeader("Content-Type", "application/soap+xml;charset=UTF-8");
httpPost.setEntity(postEntity);
// Get the response
HttpClient httpclient = new DefaultHttpClient();
BasicHttpResponse httpResponse = (BasicHttpResponse) httpclient.execute(httpPost);
// Convert HttpResponse to InputStream for parsing
HttpEntity responseEntity = httpResponse.getEntity();
InputStream soapResponse = responseEntity.getContent();
// Parse the result and do stuff with the data...
}
However I'm connecting to the same URL twice, and this is inefficient and probably slowing down my code.
First of all, is it?
Secondly, what's a better way to do this?

I would just try connecting, if it times out, handle the exception, and display an error.

May be you should consider looking at HttpConnectionParams class methods.
public static void setConnectionTimeout (HttpParams params, int
timeout)
Sets the timeout until a connection is etablished. A value of zero
means the timeout is not used. The default value is zero.
public static void setSoTimeout (HttpParams params, int timeout)
Sets the default socket timeout (SO_TIMEOUT) in milliseconds which is
the timeout for waiting for data. A timeout value of zero is
interpreted as an infinite timeout. This value is used when no socket
timeout is set in the method parameters.
Hope this helps.

As above and here is how you check for times out:
HttpParams httpParameters = new BasicHttpParams();
// Set the timeout in milliseconds until a connection is established.
// The default value is zero, that means the timeout is not used.
int timeoutConnection = 3000;
HttpConnectionParams.setConnectionTimeout(httpParameters, timeoutConnection);
// Set the default socket timeout (SO_TIMEOUT)
// in milliseconds which is the timeout for waiting for data.
int timeoutSocket = 5000;
HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);
And then pass the HttpParameters to a constructor of httpClient:
DefaultHttpClient httpClient = new DefaultHttpClient(httpParameters);