Keep the connection open and read data until it is forcibly closed
When my activity loads, I connect to the web service. When and when I receive a response from the service, I call the service again and so on.
@Override
protected void onCreate(Bundle savedInstanceState) {
….
callWebMethod();
}
// Called on getting response
@Override
public void run(String value) {
….
callWebMethod();
}
This is how I connect to the service
HttpGet request = new HttpGet(url + combinedParams);
HttpClient client = new DefaultHttpClient(httpParameters);
HttpResponse httpResponse;
httpResponse = client.execute(request);
responseCode = httpResponse.getStatusLine().getStatusCode();
message = httpResponse.getStatusLine().getReasonPhrase();
HttpEntity entity = httpResponse.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
response = convertStreamToString(instream);
response = StringUtils.remove(response, "\n");
response = StringUtils.remove(response, '"');
}
Is it possible that I only connect to the service once at the beginning, then the connection remains open and the application continues to read data from the service until the connection is forcibly closed.
Please let me know if more code is required.
Refresh . Then I tried with ClientConnectionManager, but still the connection is initialized over and over again. Although he is receiving data. I want the connection to remain open and continue to read data from the service.
HttpParams httpParameters = new BasicHttpParams ();
SharedPreferences preferences = context.getSharedPreferences(
"MyPreferences", Context.MODE_PRIVATE);
int timeoutConnection = Integer.parseInt(preferences.getString(
"timeout", "60")) * 1000;
HttpConnectionParams.setConnectionTimeout(httpParameters,
timeoutConnection);
HttpConnectionParams.setSoTimeout(httpParameters, 2000);
System.setProperty("http.keepAlive", "true");
HttpClient client = new DefaultHttpClient(httpParameters);
ClientConnectionManager mgr = client.getConnectionManager();
client = new DefaultHttpClient(new ThreadSafeClientConnManager(
client.getParams(), mgr.getSchemeRegistry()),
client.getParams());
while (true) {
HttpResponse httpResponse;
try {
httpResponse = client.execute(request);
responseCode = httpResponse.getStatusLine().getStatusCode();
message = httpResponse.getStatusLine().getReasonPhrase();
HttpEntity entity = httpResponse.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
response = convertStreamToString(instream);
response = StringUtils.remove(response, "\n");
response = StringUtils.remove(response, '"');
((Activity) context).runOnUiThread(new Runnable() {
public void run() {
callback.run(response); // This calls activity callback function.
}
});
// Closing the input stream will trigger connection release
// instream.close();
}
} catch (ConnectTimeoutException e) {
….
}
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you just need to close InputStream
which you get from HttpResponse.getEntity().getContent()
after you finish using / read -it. This will officially indicate the end of your current request.
Then you can make another request, the same HttpClient connection will be used.
Add closure
InputStream instream = entity.getContent();
response = convertStreamToString(instream);
// close the InputSream
instream.close()
// you can now reuse the same `HttpClient` and execute another request
// using same connection
httpResponse = client.execute(request);
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Is it possible that I only connect to the service once at the beginning, then the connection remains open ...
The web server must play a role in this. If the server "completes" the HTTP response, no further communication will take place on the same HTTP call.
You can open an HTTP connection using a server. In this case, the server never finishes the response, but continues to write data to the response stream at regular intervals, so the client can keep listening.
A new replacement for the above method is a duplex socket connection. The client and server can send and receive messages over the socket. Again, both the client and the server need to support it properly, and the necessary processing to reset the connection, etc. Should be there.
There are special versions of Android apps like https://github.com/nkzawa/socket.io-client.java that take care of most of the connection management for you.
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I think you could try using a class AsyncTask
to try and keep your stream open and do what you want, like this:
public class ConnectToWebService extends AsyncTask<Void, Void, Boolean> {
@Override
protected Boolean doInBackground(Void... params) { ... }
@Override
protected void onPostExecute(final Boolean success) { ... }
@Override
protected void onCancelled() { ... }
}
Read more on the API documentation for more information;)
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