Develop Reference

UPnP ContentDirectory Browse returns null

I have been playing around with UPnP, to get an understanding of how it all works, before I try working with any of the APIs that are out there, or doing anything more substantial. I have been reading through the UPnP documentation, and have used that information to format the messages that I am sending. I am just working from the command line right now, and have gotten discovery messages to work without issue. Now, I'm trying to return content from a ContentDirectory Browse() request (I have also tried TransportAV GetMediaInfo() because it takes only one argument). However, no matter what I try, I am getting a Null response from the MediaServer.
public class SOAPSocket2 {
public static void main(String[] args) {
try {
String xmldata = "<?xml version=\"1.0\"?>" +
"<s:Envelope " +
"xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope/ \"" +
"s:encodingStyle=\"http://schemas.xmlsoap.org/soap/encoding/\">" +
"<s:Body>" +
"<u:GetMediaInfo xmlns:u=\"urn:schemas-upnp-org:service:AVTransport:1\">" +
"<InstanceID>0</InstanceID>" +
"</u:GetMediaInfo>" +
"</s:Body>" +
"</s:Envelope>";
//Create socket
String hostname = args[0];
int port = Integer.parseInt(args[1]);
Socket sock = new Socket(hostname, port);
//Send header
String path = args[2];
BufferedWriter wr = new BufferedWriter(new OutputStreamWriter(sock.getOutputStream(),"UTF-8"));
// You can use "UTF8" for compatibility with the Microsoft virtual machine.
wr.write("POST " + path + " HTTP/1.1\r\n");
wr.write("HOST: " + hostname + ":" + port +"\r\n");
wr.write("CONTENT-TYPE: text/xml; charset=\"utf-8\"\r\n");
wr.write("SOAPACTION: \"urn:schemas-upnp-org:service:AVTransport:1#GetMediaInfo\"");
wr.write("\r\n");
//Send data
wr.write(xmldata);
wr.flush();
// Response
BufferedReader rd = new BufferedReader(new InputStreamReader(sock.getInputStream()));
String line;
line = rd.readLine();
System.out.println(line);
while((line = rd.readLine()) != null)
System.out.println(line);
} catch (Exception e) {
e.printStackTrace();
}
}
}
I know this isn't the most proper code, but I borrowed it from here: http://users.skynet.be/pascalbotte/rcx-ws-doc/xmlpost.htm. I figured that if I could actually get some sort of data in a response, then I could work on building it properly. I have modified it so that I pass the IP address and Port of the Media Server from the command line, as well as the path to the Control URL. However, I am getting nothing but 'null' from the Media Server. Any thoughts on what I'm doing incorrectly? Thanks

I am getting a Null response from the MediaServer
Is that a response from MediaServer? I would imagine it's just BufferedReader telling you there's nothing to return.
You have two things here you can debug (sending and receiving) but the same tools should help with both. Use wireshark or another network traffic capture tool to see the actual data that goes through the network. Wireshark will tell you if the response is sent (but you are failing to receive it properly) or if the reply never comes (implying your message is incorrect). It will also show your message as it is on the wire, making it easier to notice mistakes.
Doing the above (and pasting the messages here if you can't figure it out) is the best way to continue debugging, but I can see some problems in the code already:
SOAPACTION-line is missing "\r\n" in the end
There is no CONTENT-LENGTH header (this is required in normal cases)
These aren't even UPnP problems really, the message just isn't proper HTTP. Still, the UPnP Device Architecture document will help with problems like this.

Blackberry Bold 9000 Internet Connection works fine and then breaks

I've read a lot posts on the web, but I haven't found solution.
I've developed a BlackBerry App ( SDK 5 ) that's using HttpConnection to get/set data from server.
I tried to connect via Wireless and G2/G3 connection.
In both cases Application works fine for some time and then suddenly internet connection breaks (sometimes in the middle of the loading data from the server).
After that happens Application doesn't work and I also can't go to any web page (in BB Browser). It looks like BB disables internet.
When I try it in BB Browser I get the following message:
Unable to connect to the Internet please try again later. If the
problem persists please contact your service provider
The only way to get the internet back is to go to settings and disable WiFi and then re-Enable it again. After that it works, but again for some time.
It never breaks at the same point.
Here is the code that I'm using to get data from the server:
String urlPath = "http://www.mysite.com/api/?debug=true";
//debug is my variable on the site, it's not necessary
if(DeviceInfo.isSimulator()){
urlPath += ";deviceside=true";
} else {
if (WLANInfo.getWLANState() == WLANInfo.WLAN_STATE_CONNECTED) {
urlPath += ";interface=wifi";
}else{
urlPath += ";deviceside=true";
}
}
HttpConnection httpConn = (HttpConnection) Connector.open( urlPath );
httpConn.setRequestMethod(HttpConnection.POST);
httpConn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
httpConn.setRequestProperty("User-Agent", "Profile/MIDP-2.0 Configuration/CLDC-1.0");
httpConn.setRequestProperty("Content-Language", "en-US");
httpConn.setRequestProperty("Connection", "close");
OutputStream os = httpConn.openOutputStream();
os.write(temp1.getBytes());
os.flush();
os.close();
StringBuffer sb = new StringBuffer();
DataInputStream is = httpConn.openDataInputStream();
int chr;
while ((chr = is.read()) != -1) {
sb.append((char) chr);
}
String response = new String(sb.toString().getBytes(), "UTF-8");
What am I doing wrong?
Is there a way to fix this and keep the connection stable and responsive?
Thanks.

Blackberry HTTP Connection Issue

I have a simple app written the connects to web service (restful). The app works fine on the blackberry simulator however I'm having problems using it on a blackberry 9300.
I keep getting the error "java.io.ioexception: tunnel down" when the apps attempts to call the web service.
The service I am calling is a simple HTTP post and I'm trying to run this over WIFI (the WIFI connection is working fine for browsing the internet).
I'm using a connection string of "http://127.0.0.1:8080/test/restws;interface=wifi" with the IP address changed to the actual Ip address of the server I'm calling. I can call the restful web service on this server on my laptop browser fine.
The code Im using is similar to below & works fine on the simulator. The only thing im changing between the simulator and the code on the phone is the connection string (using "interface=wifi" as oppose to "deviceside=true")
Is this a code problem or is it a setting I need to change on the handset? Any ideas on what I need to do to overcome this.
Thanks
StreamConnection s = (StreamConnection) Connector
.open(connectionString);
httpConn = (HttpConnection) s;
httpConn.setRequestMethod("POST");
httpConn.setRequestProperty("Content-Length", Integer.toString(postData.length()));
OutputStream output = httpConn.openOutputStream();
output.write(postData.getBytes());
output.flush();
output.close();
String response = httpConn.getResponseMessage();
int statusCode = httpConn.getResponseCode();
if (statusCode != HttpConnection.HTTP_OK) {
}
InputStream is = httpConn.openInputStream();
int ret = 0;
while ((ret = is.read(buf)) > 0) {
os.write(buf, 0, ret);
}
result = new String(os.toByteArray());

I had problems in here .After getting HttpConnection everything is the same i guess. Try this:
ConnectionFactory cf = new ConnectionFactory();
ConnectionDescriptor cd = cf.getConnection("YourUrl");
httpConnector = (HttpConnection) cd.getConnection();
httpConnector.setRequestMethod(HttpConnection.POST);

Trying to speed up reads from a Socket in java

I'm trying to make a client that can send HTTP requests and receive responses from web servers. I tried using Java's HttpURLConnection class but it doesn't give me enough control over what actually gets sent to the server, so I'd like to compose my own HTTP request messages and send them over a Socket. However, reading from the Socket's InputStream is prohibitively slow for some servers, and I'd like to speed that up if possible. Here's some code that I used to test how slow the reads were for the socket as compared to the HttpURLConnection:
public static void useURLConnection() throws Exception
{
URL url = new URL("http://" + hostName + "/");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
InputStream in = conn.getInputStream();
byte[] buffer = new byte[buffersize];
long start = System.currentTimeMillis();
while(in.read(buffer) != -1) { }
System.out.println(System.currentTimeMillis() - start);
}
public static void useSocket() throws Exception
{
byte[] request = ("GET / HTTP/1.1\r\nHost: " + hostName + "\r\n\r\n").getBytes();
Socket socket = new Socket(hostName, 80);
OutputStream out = socket.getOutputStream();
InputStream in = socket.getInputStream();
out.write(request);
byte[] buffer = new byte[buffersize];
long start = System.currentTimeMillis();
while(in.read(buffer) != -1) { }
System.out.println(System.currentTimeMillis() - start);
}
Both methods run in about the same amount of time for some servers, such as www.wikipedia.org, but reading from the socket is much slower -- minutes as opposed to milliseconds -- for others, such as www.google.com. Can someone explain why this is, and perhaps give me some pointers as to what, if anything, I can do to speed up the reads from the socket? Thanks.

So, HTTP/1.1 turns on keepalive by default for client requests. In your socket example, you're sending HTTP/1.1 as your version string, so you're implicitly accepting that you can support keepalive, yet you're completely disregarding it.
Basically, you're blocking trying to read more from the server, despite the fact that the server is waiting for you to do something (either send another request or close the connection.)
You need to either send a header "Connection: close" or send HTTP/1.0 as your version string.

how to keep multiple Java HttpConnections open to same destination

We are using HttpURLConnection API to invoke a REST API to the same provider often (kind of an aggregation usecase). We want to keep a pool of 5 connections always open to the provider host (always the same IP).
What is the proper solution? Here is what we tried:
System.setProperty("http.maxConnections", 5); // set globally only once
...
// everytime we need a connection, we use the following
HttpURLConnection conn = (HttpURLConnection) (new URL(url)).openConnection();
conn.setRequestMethod("GET");
conn.setDoInput(true);
conn.setDoOutput(false);
conn.setUseCaches(true);
...
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
...
At this point we read the input stream until the BufferedReader returns no more bytes. What do we do after that point if we want to reuse the underlying connection to the provider? We were under the impression that if the input stream is completely read, the connection is then added back to the pool.
It's been working for several weeks this way, but today it stopped working producing this exception: java.net.SocketException: Too many open files
We found numerous sockets in the CLOSE_WAIT state like this (by running lsof):
java 1814 root 97u IPv6 844702 TCP colinux:58517->123.123.254.205:www (CLOSE_WAIT)
Won't either conn.getInputStream().close() or conn.disconnect() completely close the connection and remove it from the pool?

We had this problem also on Java 5 and our solution is to switch to Apache HttpClient with pooled connection manager.
The keepalive implementation of Sun's URL handler for HTTP is very buggy. There is no maintenance thread to close idle connections.
Another bigger problem with keepalive is that you need to delete responses. Otherwise, the connection will be orphaned also. Most people don't handle error stream correctly. Please see my answer to this question for an example on how to read error responses correctly,
HttpURLConnection.getResponseCode() returns -1 on second invocation

From here:
The current implementation doesn't buffer the response body. Which means that the application has to finish reading the response body or call close() to abandon the rest of the response body, in order for that connection to be reused. Furthermore, current implementation will not try block-reading when cleaning up the connection, meaning if the whole response body is not available, the connection will not be reused.
I read this as if your solution should work, but that you are also free to call close and the connection will still be reused.

The reference cited by disown was what really helped.
We know Apache HttpClient is better, but that would require another jar and we might use this code in an applet.
Calling HttpURLConnection.connect() was unnecessary. I'm not sure if it prevents connection reuse, but we took it out. It is safe to close the stream, but calling disconnect() on the connection will prevent reuse. Also, setting sun.net.http.errorstream.enableBuffering=true helps.
Here is what we ended up using:
System.setProperty("http.maxConnections", String.valueOf(CONST.CONNECTION_LIMIT));
System.setProperty("sun.net.http.errorstream.enableBuffering", "true");
...
int responseCode = -1;
HttpURLConnection conn = null;
BufferedReader reader = null;
try {
conn = (HttpURLConnection) (new URL(url)).openConnection();
conn.setRequestProperty("Accept-Encoding", "gzip");
// this blocks until the connection responds
InputStream in = new GZIPInputStream(conn.getInputStream());
reader = new BufferedReader(new InputStreamReader(in));
StringBuffer sb = new StringBuffer();
char[] buff = new char[CONST.HTTP_BUFFER_SIZE];
int cnt;
while((cnt = reader.read(buff)) > 0) sb.append(buff, 0, cnt);
reader.close();
responseCode = conn.getResponseCode();
if(responseCode != HttpURLConnection.HTTP_OK) throw new IOException("abnormal HTTP response code:"+responseCode);
return sb.toString();
} catch(IOException e) {
// consume error stream, otherwise, connection won't be reused
if(conn != null) {
try {
InputStream in = ((HttpURLConnection)conn).getErrorStream();
in.close();
if(reader != null) reader.close();
} catch(IOException ex) {
log.fine(ex);
}
}
// log exception
String rc = (responseCode == -1) ? "unknown" : ""+responseCode;
log.severe("Error for HttpUtil.httpGet("+url+")\nServer returned an HTTP response code of '"+rc+"'");
log.severe(e);
}