Develop Reference

What is the preferable method for sending request in mobile API in Rails

I have created an API controller to handle only json requests from an Android app. Naturally I'm using token authentication. What would be better:
To send a request using POST:
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://10.0.0.170:3000/api/get_all");
httppost.setHeader("content-type", "application/json; charset= utf-8");
httppost.setHeader("Accept", "application/json");
JSONObject json = new JSONObject();
json.put("token", token);
StringEntity entity = new StringEntity(json.toString(), "utf-8");
httppost.setEntity(entity);
HttpResponse response = httpclient.execute(httppost);
or GET:
httpget = new HttpGet("http://10.0.0.170:3000/api/get_all?"+"token="+token);
httpget.setHeader("content-type", "application/json; charset= utf-8");
httpget.setHeader("Accept", "application/json");
response = httpclient.execute(httpget);
result = EntityUtils.toString(response.getEntity());
clearly there is less code in GET, but is there some other reasons to prefer one over the other?

Even if you are using this token for simple lookup, i.e. without changing the state on server, use POST. If you use GET, web server will log all query parameters making it more vulnerable for log injection attacks for example.
You should also consider using HTTPS for authentication token in production.
In your code consider also handling return status from web server (e.g. when it is not 200).
In general, for the choice POST vs GET you can also refer to W3C:
Use GET if:
The interaction is more like a question (i.e., it is a safe operation such as a query, read operation, or lookup).
Use POST if:
The interaction is more like an order, or
The interaction changes the state of the resource in a way that the user would perceive (e.g., a subscription to a service), or
The user be held accountable for the results of the interaction.

Android: HttpClient remote vs. local server

I'm having problems with an app that works when connecting to a remote web server, running a php script against a database. However, when I point the same app to my local web server running on my machine, things doesn't work.
Here's the code I use for connecting to the remote web server (it needs authentication):
(All the networking code is done inside an AsyncTask class.)
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
StringBuilder authentication = new
StringBuilder().append("frankh").append(":").append("vriceI29");
result = Base64.encodeBytes(authentication.toString().getBytes());
httppost.setHeader("Authorization", "Basic " + result);
nameValuePairs.add(new BasicNameValuePair("date", date));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
For the connection to the local server, which doesn't use authentication, I'm commenting out these lines:
//StringBuilder authentication = new
// StringBuilder().append("frankh").append(":").append("vriceI29");
//result = Base64.encodeBytes(authentication.toString().getBytes());
//httppost.setHeader("Authorization", "Basic " + result);
However, I get two different errors, depending on how I phrase the url to the local web server.
If I use this url: "http://localhost.shoppinglistapp/fetchlist.php"
I get this error:
Error in http connectionjava.net.UnknownHostException: localhost.shoppinglistapp
If I skip the http part in the url, I get this error:
Error in http connectionjava.lang.IllegalStateException: Target host must not be null,
or set in parameters.
What am I doing wrong here? The remote server is a Linux Apache server, and the local server is IIS 7. The local server is supposed to be just for working on when I've got no or a bad internet connection, so it's not critical, but I hate not knowing why things doesn't work.

If you testing via your local emulator, you'll want to use 10.0.2.2 instead of 'localhost'.
Referring to localhost from the emulated environment

How can i improve performance of calling web services in android?

I developed an android application using web services. Here i am calling web services to get data from server and showed in my application views. Application is working fine but calling web services is gave me performance issues. It will take more time to get data.
I am using the below code to call api and used handler to parse the data. And my result is in XML format. I am using SAX parser to parse data. I don't know why the application is very slow to get data and parse. Please provide me good performance service hint for me.
Here is my api calling code:
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
StringEntity entity = null;
entity = new StringEntity(xmlRequest, HTTP.UTF_8);
httppost.setHeader("Content-Type", "text/xml");
httppost.setEntity(se);
BasicHttpResponse httpResponse = (BasicHttpResponse) httpclient.execute(httppost);
InputStream is = httpResponse.getEntity().getContent();
I am converting this input stream to string builder and parsing.
Thanks in advance.

How to get image from AppEngine Server into Android activity

I'm trying to fetch an image from the AppEngine server in development mode, using this code from here:
HttpGet httpRequest = new HttpGet(URI.create(url) );
HttpClient httpclient = new DefaultHttpClient();
HttpResponse resp = (HttpResponse) httpclient.execute(httpRequest);
HttpEntity entity = resp.getEntity();
BufferedHttpEntity bufHttpEntity = new BufferedHttpEntity(entity);
InputStream instream = bufHttpEntity.getContent();
bmp = BitmapFactory.decodeStream(instream);
When executing the 3rd line (httpclient.execute(..)) I get the error:
W/System.err(508): org.apache.http.conn.HttpHostConnectException:
Connection to http://0.0.0.0:8888 refused
This URL http://0.0.0.0:8888 is correct I believe, because in this App Engine connected Android project, I'm able to fetch images with this address on the browser client side of the project. (Again, I'm in local development mode)
Why is this connection being refused? Thanks.

http://0.0.0.0:8888 is certainly not correct. You need to use the IP address of the computer where the App engine development server is running. If you are on a local network that would be something like 192.168.x.xxx. Type ipconfig on Windows or /sbin/ifconfig on Linux in a a terminal to find out the address of your development machine. Then use that to access it from Android.

Android persistent HttpClient connection

Would it be possible to setup an HttpClient such that on a website that updates periodically, perhaps due to AJAX, the resulting changes would be captured by the HttpClient. Similar to keeping a connection to a website alive, and if there were an update, the HttpClient would send the updated response to a listener of some type. I feel as if there is an obvious answer to my question, but I just haven't found it because I may have some of my terminology wrong...
This is just an example snippet of how I usually set up a connection:
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
HttpResponse response = httpClient.execute(httpGet);

Welcome to Stack Overflow! I do not think keeping a constant connection open to your site would be the best solution. Why don't you just poll every once in awhile?