Creating Network-Enabled Applications

1. CSCI 7010 UGA March 23rd, 2010 Creating Network-Enabled Applications

2. Ways to Connect • BES/MDS • TCP/IP • BIS • WiFi • WAP 2.0 • WAP 1.0

3. BES/MDS • Blackberry Enterprise Server/Mobile Data System • used if the Blackberry device is owned by a company and is set up to run through their servers • lets the Blackberry device make a secure connection to corporate servers

4. TCP/IP • Transmission Control Protocol/Internet Protocol • a “regular” internet connection • works with most devices

5. BIS • Blackberry Internet Service • for devices that aren’t under a BES • used to send email • Internet connections, but less secure than BES • but you need to be part of the Blackberry Alliance Program to use it

6. WiFi • 802.11 B/G and sometimes A • allows device to connect to network via a WiFi router • device user has to configure device to connect to the router • Pro: better speed, lower latency, no carrier data charges • Con: WiFi coverage less than wireless network coverage • can write app so that it looks for WiFi first and then falls back to BES or BIS

7. WAP 2.0 • Wireless Access Protocol • connects through wireless carrier’s WAP gateway • no Blackberry-specific infrastructure • but user’s plan must support WAP 2.0 (most do) • don’t need to configure as with TCP/IP

8. WAP 1.0 • older version of WAP • supported by all Blackberry devices • but doesn’t support secure connections as do other methods

9. So many choices ... • What should you do? • If activated on a BES: • use BES/MDS • If not activated on a BES: • use WAP 2.0 • fall back to TCP/IP • In either case, might want to check for WiFi

10. The “Service Book” • how the device maintains info about its configuration • records about optional applications • email account configuration • connection methods available on a device

11. Service Book • open device Options • click Advanced Options • Service Book • Demo on the simulator

12. Service Book records • Two parts: • CID – defines the type of record • UID – a unique identifier • most connection methods have a record in the service book

13. The Connector class • javax.microedition.io.Connector • used it before to open files • can also use it to open network connections • Example: • HttpConnection connection = (HttpConnection) Connector.open(“http://www.cnn.com”); • or • HttpConnection connection = (HttpConnection) Connector.open(“http://www.apress.com”);

14. In general ... • Connection_type connectionName= (Connection_type) Connector.open(URL); • Connection_type is some subclass of Connection • connectionName is a variable name that you choose • URL takes the form scheme://host:port/path[optional parameters] • Example URLs: • file://myfile.html • http://www.apress.com:80/book/catalog • socket://www.apress.com:80 • https://www.amazon.com/gp/flex/sign-in/select.html

15. HTTP Basics • Hypertext transfer protocol • protocol of the World Wide Web • connectionless • request-response

16. http client • opens a connection to an http server • sends a request message • receives the response • displays result

17. http server • listens for a connection from client • receives a request • delivers a response • closes the connection

18. http message • initial line (different for request & response) • header lines (zero or more) • blank line • optional message body

19. initial request line • METHOD path http_version • GET /path/to/file/index.html HTTP/1.0 • METHOD: • GET – “Please send this resource” • POST – “Here are some details about it” • HEAD – “Just checking some info about it” • PATH: • the part of the URL after the host name

20. initial response line • also know as “status line” • HTTP_versionstatus_codereason_phrase • HTTP/1.0 200 OK • HTTP/1.1 404 Not Found • status codes: • 100s – informational • 200s – success of some kind • 300s – redirect to another URL • 400s – client error • 500s – server error

21. The Sample Application • Let’s run it from a web browser first ...

22. NetworkingApplication.java package com.beginningblackberry.networking; import net.rim.device.api.ui.UiApplication; public class NetworkingApplication extends UiApplication { public NetworkingApplication() { NetworkingMainScreenscr = new NetworkingMainScreen(); pushScreen(scr); } public static void main(String[] args) { NetworkingApplication app = new NetworkingApplication(); app.enterEventDispatcher(); } }

23. NetworkingMainScreen.java package com.beginningblackberry.networking; import net.rim.device.api.ui.container.MainScreen; public class NetworkingMainScreen extends MainScreen { private EditField urlField; private BitmapField imageOutputField; private RichTextField textOutputField; .... methods on following slides }

24. Constructor public NetworkingMainScreen() { setTitle("Networking"); urlField = new EditField("URL:", ""); textOutputField = new RichTextField(); imageOutputField = new BitmapField(); add(urlField); add(new SeparatorField()); postDataField = new EditField("Post data:", ""); add(postDataField); add(new SeparatorField()); add(new LabelField("Image retrieved:")); add(imageOutputField); add(new SeparatorField()); add(new LabelField("Text retrieved:")); add(textOutputField); }

25. Creating a menu protected void makeMenu(Menu menu, int instance) { super.makeMenu(menu, instance); menu.add(new MenuItem("Get", 10, 10) { public void run() {getURL();} } ); menu.add(new MenuItem("Post", 10, 10) { public void run() {postURL();} } ); menu.add(new MenuItem("Socket Get", 10, 10) { public void run() {socketGet();} } ); }

26. Threads http://www.purpletech.com/talks/Threads.ppt More on multi-threading (if you’re interested): http://www.cs.uga.edu/~eileen/Concurrency_tutorials

27. MenuItem, in more detail • You can learn about any component by looking at the API documentation. See: http://www.blackberry.com/developers/docs/4.1api/index.html to learn more about the MenuItem component

28. When the user clicks “Get” private void getURL() { HttpRequestDispatcher dispatcher = new HttpRequestDispatcher(urlField.getText(), "GET", this); dispatcher.start(); } • ... creates a new thread for the network-related operation • ... and starts it up

29. HttpRequestDispatcher package com.beginningblackberry.networking; /* * Class to handle creating the request, sending it off, * and receiving the response */ public class HttpRequestDispatcher extends Thread { private String url; private String method; // GET or POST private NetworkingMainScreen screen; private byte[] postData; ... }

30. Constructors public HttpRequestDispatcher(String url, String method, NetworkingMainScreen screen) { this.url = url; this.method = method; this.screen = screen; } public HttpRequestDispatcher(String url, String method,NetworkingMainScreen screen, byte[] postData) { this.url = url; this.method = method; this.screen = screen; this.postData = postData; }

31. run() – simple version public void run(){ try{ HttpConnection connection = (HttpConnection) Connector.open(url); intresponseCode = connection.getResponseCode(); if (responseCode != HttpConnection.HTTP_OK){ screen.requestFailed(“Unexpected response code: “ + responseCode); connection.close(); return; } ...

32. run() – simple version, continued String contentType = connection.getHeaderField(“Content-type”); ByteArrayOutputStreambaos = new ByteArrayOutputStream(); InputStreamresponseData = connection.openInputStream(); byte[] buffer = new byte[10000]; intbytesRead = responseData.read(buffer); while (bytesRead > 0){ baos.write(buffer, 0, bytesRead); bytesRead = responseData.read(buffer); } baos.close(); connection.close(); screen.requestSucceeded(baos.toByteArray(), contentType); } catch (IOException ex){ screen.requestFailed(ex.toString()); } }

33. requestSucceeded(...) public void requestSucceeded(byte[] result, String contentType) { if (contentType.equals("image/png") || contentType.equals("image/jpeg") || contentType.equals("image/gif")) { Bitmap bitmap = Bitmap.createBitmapFromBytes(result, 0, result.length, 1); synchronized (UiApplication.getEventLock()) { imageOutputField.setBitmap(bitmap); } } else if (contentType.startsWith("text/")) { String strResult = new String(result); synchronized (UiApplication.getEventLock()) { textOutputField.setText(strResult); } } else { synchronized (UiApplication.getEventLock()) { Dialog.alert("Unknown content type: " + contentType); } } }

34. requestFailed(...) public void requestFailed(final String message) { UiApplication.getUiApplication().invokeLater (new Runnable() { public void run() { Dialog.alert("Request failed. Reason: " + message); } }); } }

35. ... .... and we’ve skipped some gory detail for now

36. Let’s run the web application from a browser again ... • See: http://beginningblackberry.appspot.com • Enter some words in the form – • apple berry cinnamon doughnut • returns • doughnut cinnamon berry apple

37. Two-way interaction:Sending data with HTTP POST • What’s in the web application? <html> <head><title>Form</title></head> <body><imgsrc="img/apress_logo.png" /> <br /> <form action="/" method="POST"><br /> <input type="text" name="content"></input> <input type="submit" value="Go!"/> </form> </body></html>

38. <form> <form action="/" method="POST"> • defines a form that the browser uses to send data to the web application • send data to the ULR “/” (the base URL ) • using HTTP POST

39. <input> • <input type="text" name="content"></input> • defines the text box • gives it the name “content” • the application expects the content to be something like: • content = ONE+TWO+THREE • “+” interpreted as a space

40. <input type="submit" value="Go!"/> • defines the “Go” button as invoking POST • </form> • indicates end of the form

41. Modified HttpRequestDispatcher private byte[] postData; - to pass the POST body to the dispatcher public HttpRequestDispatcher(String url, String method, NetworkingMainScreen screen, byte[] postData){ this.url = url; this.method = method; this.screen = screen; this.postData = postData; } - constructor to initialize

42. check for POST data before sending if (method.equals(“POST”) && postData != null){ connection.setRequestProperty(“Content-type”, “application/x-www-form-urlencoded”); OutputStreamrequestOutput = connection.openOutputStream(); requestOutput.write(postData); requestOutput.close(); }

43. postURL private void postURL(){ String postString = postDataField.getText(); URLEncodedPostDataencodedData = new URLEncodedPostData(null, false); encodedData.append(“content”, postString); HttpRequestDispatcher dispatcher = new HttpRequestDispatcher(urlField.getText(), “ POST”, this, encodedData.getBytes()); dispatcher.start(); }

44. ... stop here today ...

45. HEAD • let’s look at the code

46. Socket Basics • explanation • ... and let’s look at the code ...

47. private void socketGet() { • SocketConnector connector = new SocketConnector(urlField.getText(), this); • connector.start(); • } • private void postURL() { • String postString = postDataField.getText(); • URLEncodedPostDataencodedData = new URLEncodedPostData(null, false); • encodedData.append("content", postString); • HttpRequestDispatcher dispatcher = new HttpRequestDispatcher(urlField • .getText(), "POST", this, encodedData.getBytes()); • dispatcher.start(); • }