When my activity loads, I am connecting to a web service. As and when I get the response from service, I again call then service 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 am connecting to 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 connect to the service only once at the start, then the connection remains open and application keeps on reading data from service till connection is forcefully closed.
Please let me know if more code is required.
Update: I then tried with ClientConnectionManager but still connection is again and again initialising. Though it is getting data. What I want is that connection remains open, and keeps on reading data from 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) {
….
}
It sounds like what you really need is a socket connection (see here). A socket will stay connected and allow you to stream data back and forth with the socket server until you are finished.
you just need to close the InputStream you get from HttpResponse.getEntity().getContent() after you are done using/reading-it. This will officially indicate the end of your current request.
You can then proceed to execute another request, the same HttpClient connection will be used.
Add a close
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);
Is it possible that I connect to the service only once at the start,
then the connection remains open...
The web server has a role to play in this. If the server "ends" the HTTP response, there is no further communication going to happen on same HTTP call.
It is possible to keep an HTTP connection open, with help of server. In this case, server never really ends the response but keeps writing data to response stream after some time intervals, so client can keep listening.
The new replacement for the above technique is a duplex socket connection. Both client and server can send and receive messages over a socket. Again, both client and server have to support it properly, and necessary handling for connection drops etc has to be there.
There are android specific client implementations available like https://github.com/nkzawa/socket.io-client.java that take care of most of connection management for you.
I think you could try to use the AsyncTask class to try to keep your thread 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() { ... }
}
Check the API documentation for more information ;)
Related
I want to fire a blocking call to my php file which queries my db. I want it to be blocking and not async as i don't want the user shown anything until this call is successful or not.
I run the below code, it stops at response = httpclient.execute(httpget); for a minute or two before going into catch for error. I cant see an error in the e item.
Anybody know whats going on here - my php file works with async task.
public static String blockingHttpCallToUrl(String url)
{
String result="nothingReturned";
HttpClient httpclient = new DefaultHttpClient();
// Prepare a request object
HttpGet httpget = new HttpGet(url);
// Execute the request
HttpResponse response;
try {
response = httpclient.execute(httpget);
// Examine the response status
Log.i("Praeda", response.getStatusLine().toString());
// Get hold of the response entity
HttpEntity entity = response.getEntity();
// If the response does not enclose an entity, there is no need
// to worry about connection release
if (entity != null) {
// A Simple JSON Response Read
InputStream instream = entity.getContent();
result= convertStreamToString(instream);
// now you have the string representation of the HTML request
instream.close();
}
} catch (Exception e) {}
return result;
}
I'm developing a program that sends some Logs to a database.
As logs, the main idea is to save as much information as it can, I want to avoid the part if the server where I store logs is down. What I'm trying to do is to make an http request and totally ignore server response, it doesn't matter if is online or offline. What I'm done so far is to set a timeout to my request but that doesn't resolve my problem. Here is my code:
public synchronized void LOG_sendERROR(String token, String channelnumber, String type)
{
HttpResponse response = null;
HttpParams httpParameters = new BasicHttpParams();
int timeout = 3000;
HttpConnectionParams.setConnectionTimeout(httpParameters,timeout);
int timeoutsocket = 5000;
HttpConnectionParams.setSoTimeout(httpParameters, timeoutsocket);
DefaultHttpClient httpclient = new DefaultHttpClient(httpParameters);
try
{
if (ep.getString("username", "").length() == 0)
return ;
String url = Server.Log_Server + "/LOG_CHANNEL_LOGS.aspx?params=1";
log.i("LOGS", url);
HttpGet c = new HttpGet(url);
response = httpclient.execute(c);
return ;
}
catch (Exception e)
{
e.printStackTrace();
try
{
if (response != null)
response.getEntity().consumeContent();
}
catch (Exception f)
{
}
return ;
}
}
If server is down my application stuck for 3 seconds. I want to send the logs, it doesn't matter for the client application to know whether the server saved the logs the client just send. How can I make a http request and ignore response?
After i tried many methods, the best way is to execute as a parallel task. In this way client wont ignore the response of the server but at least the application will be running normaly.
private Runnable LOG_CHANNEL_LOGS = new Runnable()
{
public void run()
{
new LOG_CHANNEL_LOGS().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
}
};
I've an app that call a webservice. I've logged the time it takes to complete this call with and without GZIP. I ran the app 5 times with and 5 time without GZIP and it actually took longer with GZIP. So i can only think GZIP had no effect or i have implemented it badly. Any ideas why there is no change?
public String connect(String url) {
HttpClient httpclient = new DefaultHttpClient();
// Prepare a request object
HttpGet httpget = new HttpGet(url);
httpget.addHeader("Accept-Encoding", "gzip");
// Execute the request
HttpResponse response;
try {
long start = System.currentTimeMillis();
response = httpclient.execute(httpget);
// Examine the response status
Log.i(TAG, response.getStatusLine().toString());
// Get hold of the response entity
HttpEntity entity = response.getEntity();
// If the response does not enclose an entity, there is no need
// to worry about connection release
if (entity != null) {
InputStream instream = response.getEntity().getContent();
Header contentEncoding = response.getFirstHeader("Content-Encoding");
if (contentEncoding != null && contentEncoding.getValue().equalsIgnoreCase("gzip")) {
instream = new GZIPInputStream(instream);
}
// A Simple JSON Response Read
//InputStream instream = entity.getContent();
result = convertStreamToString(instream);
Log.i(TAG, result);
// A Simple JSONObject Creation
//json = new JSONObject(result);
// Closing the input stream will trigger connection release
instream.close();
long end = System.currentTimeMillis();
long elapsed = (end - start);
Log.e(TAG, "web call took ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" + elapsed);
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return result;
}
.
RESULTS:
Without GZIP: average of 5 runs = 2923ms
With GZIP: average of 5 runs = 3179ms
There are at least two major contributions in the timing:
client side: connection speed vs. decoding speed
server side: connection speed vs. encoding speed
The gzip encoding can be static or dynamic on the server side. For some content it would make sense to store query data in already compressed form. For some content it can't be done and the server may have the "compression engine" occupied.
The timings are likely to change between ADSL, WLAN or direct ethernet connections.
I'm experiencing some odd behavior in my HTTP requests. I have some users that are saying that this call isn't ever coming back (the spinner marking it's asynchronous call never goes away). I have seen this happen before, but I attributed it to the emulator going through Charles Proxy. I haven't yet seen it on actual phone until now.
I'm not sure what would cause this to happen, which is why I'm posting it here. Here's the call, using Jackson to deserialize the result into a Value Object. The two spots I saw the emulator freeze are httpclient.execute(httpGet); and getObjectMapper().readValue(jp, SyncVO.class);.
While debugging, stepping over the offending statement caused the debugger to never gain control back of stepping. Meanwhile, I see the request go out AND come back from the server through Charles. It's just that the app doesn't seem to get the response and just sits there.
So, here's the code. Thanks for any help!
public SyncVO sync(String userId, long lastUpdate, boolean includeFetch) throws IOException {
SyncVO result = null;
String url = BASE_URL + "users/" + userId + "/sync" + "?" + "fetch=" + includeFetch;
if (lastUpdate > 0) {
url += "&updatedSince=" + lastUpdate;
}
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
httpGet.setHeader("Accept", "application/json");
httpGet.setHeader("Accept-Encoding", "gzip");
httpGet.setHeader(AUTHORIZATION, BEARER + " " + mOAuthToken);
httpclient.getParams().setParameter(CoreProtocolPNames.USER_AGENT, USER_AGENT_STRING);
httpclient.getParams().setBooleanParameter(CoreProtocolPNames.USE_EXPECT_CONTINUE, false);
HttpResponse response = httpclient.execute(httpGet);
if (isUnauthorized(response)) {
APPLICATION.needReauthentication();
return null;
}
if (response != null) {
InputStream stream = response.getEntity().getContent();
Header contentEncoding = response.getFirstHeader("Content-Encoding");
if (contentEncoding != null && contentEncoding.getValue().equalsIgnoreCase("gzip")) {
stream = new GZIPInputStream(stream);
}
InputStreamReader inReader = new InputStreamReader(stream, "UTF-8");
JsonParser jp = mJsonFactory.createJsonParser(inReader);
result = getObjectMapper().readValue(jp, SyncVO.class);
}
return result;
}
private ObjectMapper getObjectMapper() {
return (new ObjectMapper()
.configure(Feature.AUTO_DETECT_FIELDS, true)
.configure(Feature.FAIL_ON_UNKNOWN_PROPERTIES, false)
.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true));
}
don't forget to consume entities content after each request.
HttpEntity entity = response.getEntity();
try {
if (entity != null)
entity.consumeContent();
} catch (IOException e) {
e.printStackTrace();
}
You should definitely use connection timeout and socket read and be prepared for the worst from the server. Network operations will never be 100% predictable and there is not much your client can do then so make sure you code optimally.
httpParameters = httpclient.getParams();
HttpConnectionParams.setConnectionTimeout(httpParameters, 5000);
HttpConnectionParams.setSoTimeout(httpParameters, 10000);
You can also cancel a task with asyncTask.cancel(true);
The reason is because you have left stream open. As such, the response is left in limbo. This means your global variable httpClient is also left in limbo, and unable to get a new entity when it re-uses the client.
You should call close() after finishing with the stream.
stream.close();
Network calls take a while and will block the UI thread. Same with your jackson deserialization code. This stuff needs to be put on a separate thread. See AsyncTask for an easy way to do it.
I'm developing an Android app that gets a JSON_encoded result from a php middleware script that connects to a MySQL database. I have given the application Internet permissions.
The problem I'm having is that the program gives an UnknownHostException error the first time it is run. I have the program on a timer, and subsequent calls to the timer handler function do not return the UnknownHostException error. Do you have any idea why this would occur? I have tested the domain and made sure that it connects correctly through a web browser.
Here's a snippet from the code:
public final void timerAlert(){
final Handler handler = new Handler();
final Runnable r = new Runnable()
{
public void run() {
Timer_Method();
handler.postDelayed(this,1000);
}
};
handler.postDelayed(r, 1000);
}
public void Timer_Method()
{
//See if this buzzer is being signaled.
String result = null;
InputStream is = null;
StringBuilder sb=null;
//http post
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("BuzzerID",BuzzerID.toString()));
Toast.makeText(getBaseContext(), "BuzzerID="+BuzzerID.toString() ,Toast.LENGTH_LONG).show();
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://domain/getBuzzStatus.php?BuzzerID="+BuzzerID.toString());
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection"+e.toString());
Toast.makeText(getBaseContext(), "Hm, problem here="+e.toString() ,Toast.LENGTH_LONG).show();
}
Note that domain has something else there in the actual code and that this is just a snippet but is where the first issue occurs. Also note that I am mixing get and post, something I'd rather not do, but for some reason passing the nameValuePair to the php script doesn't send anything to $_REQUEST.
A snippet from the very simple PHP script:
$sql_string="SELECT Signal FROM BuzzCustomer WHERE idBuzzCustomer=" . $_GET['BuzzerID'];
$sql = mysql_query($sql_string);
while($row=mysql_fetch_assoc($sql))
$output[]=$row;
print(json_encode($output));
mysql_close();
I switched to $_GET here because I could not get $_REQUEST to work. Any help would be appreciated. Thanks in advance!
May be their will be no Internet connection in the simulator......Check a url in browser
Instead of
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
Use
ResponseHandler<String> response = new BasicResponseHandler();
String result = httpclient.execute(httppost,response);
Also put Internet permission in the Manifest
Just a guess, but maybe the DNS request takes too long and your HttpClient gives up, but the request is finished and cached so the next time it does not fail?
This With Apache HttpClient, why isn't my connection timeout working? seems to be a question about how to set the timeout for HttpClient.