Doubts in web service

In this case, the connection to the database will be the responsibility of server-side , in this case PHP, ASP.NET or Python (using framework or not).

Application

If the app is for Android you can use ADT or Eclipse to develop a webservice, you should make an HTTP request (android is usually java, source for example

Getting Data (GET)

String url = "http://[webservice].com";

URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();

con.setRequestMethod("GET");

int responseCode = con.getResponseCode();
System.out.println("Código de resposta: " + responseCode);

BufferedReader in = new BufferedReader(
        new InputStreamReader(con.getInputStream()));
String inputLine;

//Pega a resposta
StringBuffer response = new StringBuffer();

while ((inputLine = in.readLine()) != null) {
    response.append(inputLine);
}

in.close();

//Mostra a resposta no console
System.out.println(response.toString());

Sending Data (POST)

String url = "http://[webservice].com/create";
URL obj = new URL(url);
HttpsURLConnection con = (HttpsURLConnection) obj.openConnection();

//envia via POST
con.setRequestMethod("POST");

//Dados POST
String urlParameters = "arg2=foo&arg2=baz";

//Cria o POST
con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();

int responseCode = con.getResponseCode();
System.out.println("Código de resposta: " + responseCode);

BufferedReader in = new BufferedReader(
        new InputStreamReader(con.getInputStream()));
String inputLine;

StringBuffer response = new StringBuffer();

while ((inputLine = in.readLine()) != null) {
    response.append(inputLine);
}

in.close();

//Mostra a resposta no console
System.out.println(response.toString());

1 - The web service is the part of the Android application or any other application that uses this service.

2 - You can create by Eclipse, PHP, Python or whatever is easiest or convenient for you.

3 - The WebService accesses MYSQL, FIREBIRD, ORACLE or any other bank via IP. So your bank can be on the same machine as the WEBSERVICE or another machine on the network.

4 - The WebService responds to all requests that arrive regardless of who requested it, unless it is programmed not to do so.

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