iphone application programming l09:...

Jan Borchersmedia computing group

iPhone Application ProgrammingL09: Networking

Prof. Dr. Jan Borchers, Florian Heller, Jonathan DiehlMedia Computing Group, RWTH Aachen

WS 2009/2010http://hci.rwth-aachen.de/iphone

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Networking

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• Bonjour Networking• Push Notifications• GameKit• Remote (Web) Objects

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Bonjour Networking

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Bonjour

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• Apples flavor of zeroconf networking• a.k.a. multicast DNS

• Service discovery framework• Does not transfer data• Likely to become an official standard• Also available for Unix/Linux & Windows

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Using Bonjour

• As Server (NSNetService)• Create a socket to provide the service• Define service

• Name: Service name• Type: Service type and transport layer (“_http._tcp.”)• Registration domain ("local.")• Port

• Publish service

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Using Bonjour

• As Client • Browse for available services / Create NSNetService directly• Check if service is still available with resolveWithTimeout:• Get socket information and connect

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Bonjour Example// set up network service

myService = [[NSNetService alloc] initWithDomain:@"" type:@"_neighbors._tcp"

! ! ! ! ! ! ! ! name:[[UIDevice currentDevice] name] ! ! ! ! ! ! ! ! port:9090];myService.delegate = self;// publish network service[myService publish];// published- (void)netServiceDidPublish:(NSNetService *)sender {! NSLog(@"published: %@", sender);}// not published- (void)netService:(NSNetService *)sender didNotPublish:(NSDictionary *)errorDict {! NSLog(@"not published: %@ -> %@", sender, errorDict);}- (void)netService:(NSNetService *)sender didUpdateTXTRecordData:(NSData *)data {! NSString *message = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];! NSLog(@"TXT: %@", message);}

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Bonjour Example// set up array

netServices = [[NSMutableArray alloc] init];!// set up the service browserserviceBrowser = [[NSNetServiceBrowser alloc] init];serviceBrowser.delegate = self;[serviceBrowser searchForServicesOfType:@"_neighbors._tcp" inDomain:@""];

// new service- (void)netServiceBrowser:(NSNetServiceBrowser *)netServiceBrowser didFindService:(NSNetService *)netService moreComing:(BOOL)moreServicesComing;{! [netServices addObject:netService];}

// service removed- (void)netServiceBrowser:(NSNetServiceBrowser *)netServiceBrowser didRemoveService:(NSNetService *)netService moreComing:(BOOL)moreServicesComing;{! [netServices removeObject:netService];}

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What’s a Socket

• Combination of Address and port• Listening socket handles data via callback

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Socket Networking

• Sockets are used to actually transmit data• CFSocket: C encapsulation of BSD sockets

• Runloop functionality, no blocking calls

• Objective C wrapper: CocoaAsyncSocket

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Setting up a Listening Socket

• Create a socket context• Create a socket• Bind the socket to an address• Handle events in a callback

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CFSocketContextstruct CFSocketContext {

CFIndex version; void *info; CFAllocatorRetainCallBack retain; CFAllocatorReleaseCallBack release; CFAllocatorCopyDescriptionCallBack copyDescription;};

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CFSocketCreateCFSocketRef CFSocketCreate (

CFAllocatorRef allocator, SInt32 protocolFamily, //default: PF_INET SInt32 socketType, //default:SOCK_STREAM, UDP:SOCK_DGRAM SInt32 protocol, //STREAM:IPPROTO_TCP DGRAM:IPPROTO_UDP CFOptionFlags callBackTypes, CFSocketCallBack callout, const CFSocketContext *context);

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CFSocket ExampleCFSocketContext socketCtxt = {0, self, NULL, NULL, NULL};ipv4socket = CFSocketCreate(kCFAllocatorDefault, PF_INET, SOCK_STREAM, IPPROTO_TCP, kCFSocketAcceptCallBack, (CFSocketCallBack)&TCPServerAcceptCallBack, &socketCtxt);

struct sockaddr_in socketAddress;memset(&socketAddress, 0, sizeof(socketAddress));socketAddress.sin_len = sizeof(socketAddress);socketAddress.sin_family = AF_INET; // Address family (IPv4 vs IPv6)socketAddress.sin_port = 0; // Actual port will get assigned automatically by kernel// We must use "network byte order" format (big-endian) for the value heresocketAddress.sin_addr.s_addr = htonl(INADDR_ANY); // Convert the endpoint data structure into something that CFSocket can useNSData *socketAddressData = [NSData dataWithBytes:&socketAddress length:sizeof(socketAddress)];

//Bind to addressCFSocketSetAddress(listeningSocket,(CFDataRef)socketAddressData)

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CFSocket Example (Continued)//Create a runloop source for the socket

CFRunLoopRef cfrl = CFRunLoopGetCurrent();CFRunLoopSourceRef source4 =

CFSocketCreateRunLoopSource(kCFAllocatorDefault, _ipv4socket, 0);CFRunLoopAddSource(cfrl, source4, kCFRunLoopCommonModes);CFRelease(source4);

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CFSocket Callbacksstatic void TCPServerCallBack(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info) { if (type == kCFSocketAcceptCallBack) {

! ! //handle a new connection}if (type == kCFSocketDataCallBack) {

//handle incoming data}

}

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Demo

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Push Notifications

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Push Notifications

• Notify the user that data is waiting• Does not transmit data• Behavior is defined by the user

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Apple Push Notification Service

• Central service provided by Apple• Your server connects to the APNS• The APNS transmits the message to the device• The user possibly starts your application• Your application retrieves the data

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Registering a Device

• registerForRemoteNotificationTypes:(UIRemoteNotificationType)types

• UIRemoteNotificationTypeNone• UIRemoteNotificationTypeBadge• UIRemoteNotificationTypeSound• UIRemoteNotificationTypeAlert

• Receive unique device token

• Communicate this token to your own server

• Your server specifies token when sending a payload to APNS

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Registering a Device// Add registration for push nofication

[[UIApplication sharedApplication] registerForRemoteNotificationTypes: (UIRemoteNotificationTypeBadge | UIRemoteNotificationTypeSound | UIRemoteNotificationTypeAlert)];

!- (void)application:(UIApplication *)app didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken { ! ! NSLog(@"devToken=%@",deviceToken);}- (void)application:(UIApplication *)app didFailToRegisterForRemoteNotificationsWithError:(NSError *)err { ! ! NSLog(@"Error in registration. Error: %@", err);}

- (void)unregisterForRemoteNotifications- (UIRemoteNotificationType)enabledRemoteNotificationTypes

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Message Delivery

• Server connects to APNS via TCP connection• SSL Secured• Payload delivery not guaranteed• Check the feedback service regularly

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Example Payload

{ "aps" : { "alert" : "You got your emails.", "badge" : 9, "sound" : "bingbong.aiff" }, "acme1" : "bar", "acme2" : 42}

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Clear a Badge Number

{ "aps" : { }, "acme2" : [ 5, 8 ]}

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APNS Requirements

• Own Server providing the service• SSL certificate for your server• Defined App ID registered for Push Notifications

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GameKit

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• High-level Framework for Bluetooth Networking• Automatic Service Discovery• Efficient, low-latency communication• Integrated voice chat

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GameKit Classes

• GKSession• Discover peers and manage connections

• GKPeerPickerController• Controller for showing and connecting to peers• Comes with its own UI

• GKVoiceChatService• control voice chat

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GKPickerController Example- (void)viewDidLoad {

! session = [[GKSession alloc] initWithSessionID:@"chat" displayName:nil sessionMode:GKSessionModePeer];! peerPickerController = [[GKPeerPickerController alloc] init];! peerPickerController.delegate = self;! [peerPickerController show];}!# pragma mark GKPeerPickerControllerDelegate

- (GKSession *)peerPickerController:(GKPeerPickerController *)picker sessionForConnectionType:(GKPeerPickerConnectionType)type {! return session;}

- (void)peerPickerController:(GKPeerPickerController *)picker didConnectPeer:(NSString *)peerID toSession:(GKSession *)session {! ...}

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GKSession

• peersWithConnectionState:• list all peers with the given state (e.g. available)

• connectToPeer:withTimeout:• request a connection to the peer

• acceptConnectionFromPeer:error:• accept a connection request

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GKSessionDelegate

• session:peer:didChangeState:• informs delegate about new peers and state changes• Possible states: available, unavailable, connecting,

disconnecting, connected

• session:didReceiveConnectionRequestFromPeer:• respond to connection request from peer

• Error handling• session:connectionWithPeerFailed:withError:• session:didFailWithError:

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GKSession Communication

• setDataReceiveHandler:withContext:• define receive handler (controller) for the session

• receiveData:fromPeer:inSession:context:• implemented by receive handler

• sendData:toPeers:withDataMode:error:• send NSData to given peers• Possible data modes: reliable, unreliable

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GKVoiceChatService

• Singleton • Service to control voice chat

• Manage connections• Record audio from microphone

• Delegate: Client• Transmit audio data• Playback audio data

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Remote (Web) Objects

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Web-Backend

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Database

Database Database

DatabaseDatabase DatabaseDatabase

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Web-Backend

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Web Backend

XMLHTTP

Database

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Ruby on Rails

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• Open Source Web Application Framework• Runs as its own service• Main Components:

• ActionController: interface controller and routing• ActiveRecord: database abstraction• ActiveResource: remote objects

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Ruby on Rails: Quickstart• create the app:

• rails sample_application

• generate a model• script/generate model person

• generate a “scaffold” controller• script/generate scaffold person

• migrate the database• rake db:migrate

• launch the server• script/server

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Representational State Transfer

• Data is made available through (web-)resources• Each resource has its own URI• http://server/people

• HTTP operations are used to manipulate resources• POST http://server/people?id=1person[name]=Paul

• Communication via XML or JSON

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REST Operations

• GET: request all resources (or by id)• GET http://server/people• GET http://server/people?id=1

• POST: update resource• POST http://server/people?id=1&person[...]=...

• PUT: create resource• PUT http://server/people?person[...]=...

• DELETE: delete resource• DELETE http://server/people?id=1

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Ruby on Rails & REST

• Scaffold controller supports all REST operation• script/generate scaffold people• supports HTML (backend website) and XML

• Routes can be created automatically• map.resources :people in routes.rb

• Format and id can be specified in URI• http://server:3000/people.xml• http://server:3000/people/1.xml

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iPhone HTTP RequestsNSURL *url = [NSURL URLWithString:@"http://server:3000/people.xml"];

NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];

// set the HTTP operation[request setHTTPMethod:@"POST"];

// set the post dataNSData *postData = [@"id=1&person[name]=Paul" dataUsingEncoding:NSUTF8StringEncoding];[request setHTTPBody:postData];

// fire the requestNSURLConnection *con = [NSURLConnection connectionWithRequest:request delegate:self];[con start];

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Summary

• Discover services with Bonjour• Receive notifications• Connect to other devices vie BlueTooth• Access remote objects• Reading Assignment:

• Net Services Programming Guide• Push Notification Service Programming Guide• GameKit Guide

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