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Desktop, Embedded and Mobile Apps with Vortex Café
 

Desktop, Embedded and Mobile Apps with Vortex Café

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In the past few years we have been experiencing an amazing proliferation of mobile and embedded platforms. Contemporary developers are increasingly faced with the challenge of writing applications ...

In the past few years we have been experiencing an amazing proliferation of mobile and embedded platforms. Contemporary developers are increasingly faced with the challenge of writing applications that can run on desktop, mobile (e.g. Android), and on low-cost embedded platforms (e.g. Raspberry-Pi and Beaglebone). This is causing a rejuvenated interest in the Java platform as the mean to achieve the holy grail of write-once and run-everywhere. With the availability of Java environments supporting almost any kind of device in several different form factors, the missing element to the picture is an effective way of enabling communication between them.

Vortex Café is a pure Java implementation of the OMG Data Distribution Service (DDS) that enables seamless, efficient and timely data sharing across many-core machines, mobile and embedded devices.

This presentation will (1) introduce the main abstractions provided by Vortex Café, (2) provide an overview of its architecture and explain how it exploits Staged Event Driven Architectures to optimize its runtime depending of the target hardware, (3) provide an overview of the typical performance delivered by Vortex Café, and (3) get you started developing distributed Java and Scala applications with Vortex Café.

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    Desktop, Embedded and Mobile Apps with Vortex Café Desktop, Embedded and Mobile Apps with Vortex Café Presentation Transcript

    • Desktop, Embedded and Mobile Distributed Apps with Angelo  Corsaro,  PhD   Chief  Technology  Officer   angelo.corsaro@prismtech.com Café
    • Vortex
    • CopyrightPrismTech,2014 Vortex enable seamless, ubiquitous, efficient and timely data sharing across mobile, embedded, desktop, cloud and web applications The Vortex Platform
    • CopyrightPrismTech,2014 One Standard, One set of Tools, One Goal — Ubiquitous Data Sharing The Vortex Platform VORTEX Web VORTEX Lite VORTEX Gateway VORTEX Cloud Private Clouds VORTEX Tools • Insight   • Record/Replay   • Tuner   • Tester   • Configurator OpenSplice Enterprise VORTEX Café
    • Vortex Café
    • CopyrightPrismTech,2014 Pure Java version of Vortex targeting JVM and embedded JVMs DDSI Protocol Stack optimised for mobility and Android OS Only DDS on the market designed and Engineered for Android Vortex Café J2SE DDSI$$ (Optimised*for*Mobility)* DDS$API Java Scala JavaScript
    • CopyrightPrismTech,2014 Vortex Café has a Staged Event Driven Architecture (SEDA) that allows it to be easily configured to trade off between throughput and latency A Staged Event Driven Architecture
    • CopyrightPrismTech,2014 Decomposes a complex, event-driven application into a set of stages connected by queues Avoids the high overhead associated with thread-based concurrency models, and decouples event and thread scheduling from application logic. Through admission control on each event queue, SEDAs can be well-conditioned to load, preventing resources from being overcommitted when demand exceeds service capacity SEDA [Matt Welsh, David Culler, and Eric Brewer, SEDA:An Architecture for Well-Conditioned, Scalable Internet Services]
    • CopyrightPrismTech,2014 The Vortex Café architecture is organized around three stages Packet Processing Message Processing Data Processing The channel that connect each stage can be configured to be active or passive Vortex Café Architecture Packet Processor Message Processor Data Processor Network Packet DDSI Messages Cache Changes
    • CopyrightPrismTech,2014 Channels can be active or passive (and zero-copy). That means that channels can be configured with threading resources, or not Messages posted in a passive channel are executed in the context of the posting thread This allows to configure Vortex Café to optimize the use case at hand Configurability Processor Channel
    • CopyrightPrismTech,2014 Single Thread per Message Sample Configurations Packet Processor Message Processor Data Processor Network Packet DDSI Messages Cache Changes Fully Asynchronous Packet Processor Message Processor Data Processor Network Packet DDSI Messages Cache Changes
    • CopyrightPrismTech,2014 Vortex Café is SEDA architecture as well as all the protocol parameters can be configured through configuration file or via command line properties , i.e. providing -D options to the JVM Configuration parameters are listed on the user manual Example: Configuration in Practice java  -­‐server    -­‐cp  .:./target/vortex-­‐cafe-­‐demo-­‐assembly-­‐2.0.jar       -­‐Ddds.listeners.useTransportThread=true     -­‐Dddsi.writers.heartbeatPeriod=0.001       -­‐Dddsi.writers.nackResponseDelay=0       -­‐Dddsi.readers.heartbeatResponseDelay=0     -­‐Dddsi.timer.threadPool.size=1       -­‐Dddsi.receiver.threadPool.size=0       -­‐Dddsi.dataProcessor.threadPool.size=0     -­‐Dddsi.acknackProcessor.threadPool.size=0     -­‐Dddsi.writers.reliabilityQueue.size=128       com.prismtech.cafe.demo.perf.RoundTripDemoReader  $*
    • Anatomy of a Vortex-Cafe App
    • CopyrightPrismTech,2014 • DomainParticipant: Provides access to a data cloud -- called a domain in DDS • Topic: Domain-wide definition of a kind of Information • Publisher/Subscriber: Provide scope to data sharing through the concept of partitions • DataReader/DataWriter: Allow to read/write data for a given topic in the partitions their Subscriber/Publisher are associated with. DDS Entities
    • CopyrightPrismTech,2014 Brewing Vortex-Cafe int  domain_id  =  18;   DomainParticipantFactory  dpf  =                DomainParticipantFactory.getInstance(env)   ! DomainParticipant  dp  =            dpf.createParticipant(domainId);   Topic<Post>  topic  =            dp.createTopic(“Post”,  Post.class); struct  Post  {      string  name;      string  msg;   };                   #pragma  keylist  Post  name   Publisher  pub  =  dp.createPublisher();   DataWriter<Post>  dw  =          pub.createDataWriter<Post>(topic);   dw.write(new  Post(“Barman”,                                        “Would  you  like  an  espresso?”); Subscriber  sub  =  dp.createSubscriber();   DataReader<Post>  dr  =            sub.createDataReader<Post>(topic);   LoanedSamples<Post>  samples  =  dw.read();
    • CopyrightPrismTech,2014 Escalating Vortex-Cafe val  topic  =  Topic[Post](“Post”) struct  Post  {      string  name;      string  msg;   };                   #pragma  keylist  Post  name   val  dw  =  DataWriter[Post](topic)     dw  write(new  Post(“Barman”,                                        “Would  you  like  an  espresso?”) val  dr  =  DataReader[Post](topic)   dr.listen  {        case  DataAvailable(_)  =>                          dr.read.foreach(println(_.getData())   }
    • Android
    • CopyrightPrismTech,2014 Android applications are written in the Java programming language Support for native code is available, but this often leads to worse performance (due to the JNI layer) and worse battery utilisation Thus unless you have very good reasons not to, you are strongly encouraged to write android applications in Java and to leverage on Java libraries! Android Fundamentals
    • CopyrightPrismTech,2014 An Android application runs in its own JVM and (by default) on its own linux process An application may be composed of the following elements: - Activities: a single screen with a user interface - Services: a component that runs in the background to perform long-running operations or to perform work for remote processes. - Content Providers: a component that manages shared data for a set of applications - Broadcast Receivers: a component that responds to system-wide broadcast announcements Android allows any applications to start any other application component and potentially consume the data it produces Android Application in a Nutshell
    • CopyrightPrismTech,2014 Activities, Services and Broadcast Receivers are activated through an asynchronous message, called Intent For Activities and Services the intent specifies the action to perform For Broadcast Receivers it specifies the event being broadcasted, e.g. battery-low Component Activation
    • CopyrightPrismTech,2014 The manifest is an XML file containing several important information about the application Among, other things, the manifest includes the authorization necessary for your application -- for instance, it is in this file that you have to mention that your application requires access to the network, etc. Application Manifest
    • CopyrightPrismTech,2014 Notice that Activities are also destroyed each time there is a screen rotation (unless you don’t explicitly manage it) Activities Life-Cycle
    • CopyrightPrismTech,2014 Tasks and Back Tasks
    • CopyrightPrismTech,2014 Considering the Android application lifecycle, we should ask ourselves a few questions: When should we create DDS entities and who should hold a reference to them? What happens when an application is no more visible? Can I control when my application exits? How do I deal with multi-threading? DDS Considerations for Android
    • DDS Chat
    • CopyrightPrismTech,2014 To learn how to write an Android Application that uses Vortex Café we’ll develop a very simple Chat To keep things simple this chat will have a single “chat room” DDS Chat for Android
    • CopyrightPrismTech,2014 Our Chat application will have a very simple architecture with simply one Activity that will take care of: - Sending Posts into the ChatRoom - Displaying Posts in the room since when we joined In terms of information modelling, we’ll have a single topic representing the user post Step 1: Architecture struct  Post  {      string  name;      string  msg;   };                   #pragma  keylist  Post  name  
    • CopyrightPrismTech,2014 Creating DDS entities, such as DomainParticipants, DataReaders and DataWriters involves network communication, such as discovery information In addition when an a DDS entity is destroyed it looses its state As such, tying the life-cycle of DDS entities to activities should be done with great care Step 2: Lifecycle Management[1/2]
    • CopyrightPrismTech,2014 In general, it is a better idea to tie the life-cycle of DDS entities to the Application as opposed to Activities In some cases, it may make sense to tie the life- cycle of DataReaders/DataWriters to that of the activity that relies on them -- Usually this makes sense for activities that are “one-off” Step 2: Lifecycle Management[2/2]
    • CopyrightPrismTech,2014 Application public class ChatApplication extends Application {! ! DataReader<Post> dr;! DataWriter <Post> dw;! DomainParticipant dp;! ! @Override! public void onCreate() {! super.onCreate();! // This should be defined via a resource -- but for a small! // demo that’s OK.! System.setProperty(ServiceEnvironment.IMPLEMENTATION_CLASS_NAME_PROPERTY,! "com.prismtech.cafe.core.ServiceEnvironmentImpl");! ServiceEnvironment env = ServiceEnvironment.createInstance(! ChatApplication.class.getClassLoader());! DomainParticipantFactory dpf =! DomainParticipantFactory.getInstance(env);! ! dp = dpf.createParticipant(0);! Topic<Post> topic = dp.createTopic("Post",Post.class);! Publisher pub = dp.createPublisher();! Subscriber sub = dp.createSubscriber();! ! dw = pub.createDataWriter(topic);! dr = sub.createDataReader(topic);! }! !
    • CopyrightPrismTech,2014 Application ! public DataReader<Post> reader() {! return this.dr;! }! ! public DataWriter<Post> writer() {! return this.dw;! }! ! ! @Override! public void onTerminate() {! super.onTerminate();! this.dp.close();! }! }!
    • CopyrightPrismTech,2014 Manifest... <application! android:allowBackup="true"! android:icon="@drawable/ic_launcher"! android:label="@string/app_name"! android:theme="@style/AppTheme" android:name="ChatApplication" >! <activity! android:name=“com.ddschat.MainActivity"! android:label="@string/app_name" >! <intent-filter>! <action android:name="android.intent.action.MAIN" />! <category android:name="android.intent.category.LAUNCHER" />! </intent-filter>! </activity>! </application>!
    • CopyrightPrismTech,2014 When using Vortex Café you need to grant the proper permissions for networking: More Manifest... <uses-permission android:name="android.permission.INTERNET"/>! <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>! <uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE"/>!
    • CopyrightPrismTech,2014 Activity GUI <?xml version="1.0" encoding="utf-8"?>! <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"! xmlns:tools="http://schemas.android.com/tools"! android:layout_width="match_parent"! android:layout_height="match_parent"! android:orientation="vertical" >! ! <TextView android:id="@+id/chatMessages"! android:layout_width="match_parent"! android:layout_height="wrap_content"! android:text="@string/chat_msgs"! android:visibility="gone"! android:background="#666"! android:textColor="#fff"! android:paddingLeft="5dp"! />! <ListView! android:id="@+id/messageList"! android:layout_width="match_parent"! android:layout_height="0dp"! android:layout_weight="1"! />! !
    • CopyrightPrismTech,2014 Activity GUI ! <LinearLayout! android:layout_width="fill_parent"! android:layout_height="wrap_content"! android:orientation="horizontal" >! ! <EditText! android:id="@+id/message"! android:layout_width="0dp"! android:layout_height="wrap_content"! android:layout_weight="1"! android:hint="@string/edit_message" />! ! <Button! android:layout_width="wrap_content"! android:layout_height="wrap_content"! android:onClick="sendChatMessage"! android:text="@string/button_send" />! </LinearLayout>! ! ! </LinearLayout>!
    • CopyrightPrismTech,2014 Activity 1 ! 2 public class MainActivity extends Activity {! 3 ! 4 private static final String TAG = "ChatMainActivity";! 5 private final Handler handler = new Handler();! 6 private ArrayAdapter<String> chatMessages;! 7 ! 8 public class ChatMessageListener extends ChatMessageDataListener { ! 9 // ...! 10 }! 11 ! 12 @Override! 13 protected void onCreate(Bundle savedInstanceState) {! 14 super.onCreate(savedInstanceState);! 15 setContentView(R.layout.activity_main);! 16 chatMessages = new ArrayAdapter<String>(this, R.layout.messages);! 17 chatMessages.add("Welcome to the DDS Chat Room");! 18 ListView mview = (ListView) findViewById(R.id.messageList);! 19 mview.setAdapter(chatMessages);! 20 ChatApplication app = (ChatApplication) getApplication();! 21 ! 22 app.reader().setListener(new ChatMessageListener());! 23 ! 24 }! 25
    • CopyrightPrismTech,2014 Activity ! 25 ! 26 @Override! 27 public boolean onCreateOptionsMenu(Menu menu) {! 28 // Inflate the menu; this adds items to the action bar if it is present.! 29 getMenuInflater().inflate(R.menu.main, menu);! 30 return true;! 31 }!
    • CopyrightPrismTech,2014 Activity 32 ! 33 public void sendChatMessage(View view) {! 34 EditText editText = (EditText) findViewById(R.id.message);! 35 String msg = editText.getText().toString();! 36 editText.setText("");! 37 // chatMessages.add(msg);! 38 ChatApplication app = (ChatApplication) getApplication();! 39 try {! 40 Log.i(TAG, ">>> Sending data " + msg);! 41 app.writer().write(new Post(usr, msg));! 42 } catch (TimeoutException te) {! 43 }! 44 }! 45 ! 46 }!
    • CopyrightPrismTech,2014 Receiving data is a bit trickier since in Android only the thread that runs an activity has the right to change the UI This means, that from a DDS listener it is not possible to change an the UI directly! The solution is to use an Android Handler  to which we can post Runnable to be executed by the activity thread Let’s see how this works... Receiving Data
    • CopyrightPrismTech,2014 DDS Listener & Android Handler 1 public class ChatMessageListener extends ChatMessageDataListener {! 2 ! 3 private DataReader<Post> dr;! 4 ! 5 public ChatMessageListener() {! 6 ChatApplication app = (ChatApplication) getApplication();! 7 dr = app.reader();! 8 }! 9 !
    • CopyrightPrismTech,2014 DDS Listener & Android Handler 10 @Override! 11 public void onDataAvailable(DataAvailableEvent<Post> dae) {! 12 final Iterator<Post> i = dr.read();! 13 ! 14 Log.i(TAG, ">>> DataReaderListener.onDataAvailable");! 15 if (i.hasNext()) {! 16 Runnable dispatcher = new Runnable() {! 17 public void run() {! 18 while (i.hasNext()) {! 19 Sample<Post> s = i.next();! 20 ! 21 if (s.getSampleState() == SampleState.NOT_READ) {! 22 Post cm = s.getData();! 23 chatMessages.add(cm.name + " > " + cm.msg);! 24 }! 25 }! 26 }! 27 };! 28 handler.post(dispatcher);! 29 }! 30 }! 31 }!
    • Raspberry Pi
    • CopyrightPrismTech,2014 The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse Raspberry Pi can interact with the outside world, and is used in a wide array of digital maker projects, from music machines and parent detectors to weather stations and tweeting birdhouses with infra-red cameras, etc. Raspberry Pi
    • CopyrightPrismTech,2014 Several Images are available nowadays, I tend to use Raspbian To get started get the image from: http://www.raspberrypi.org/downloads/ Then copy the image on an SD card following instruct ructions available at http:// www.raspberrypi.org/documentation/installation/installing-images/ For MacOS X: -­‐ diskutil  list  [to  check  the  SD  card  /dev/diskN]   -­‐ diskutil  unmontDisk  /dev/diskN   -­‐ sudo  dd  bs=1m  if=2014-­‐01-­‐07-­‐wheezy-­‐raspbian.img  of=/dev/diskN   -­‐ sudo  diskutil  eject  /dev/diskN Raspberry Pi Image
    • CopyrightPrismTech,2014 Getting the Java JDK on raspberry is as easy as executing the following command: - sudo apt-get update - sudo apt-get install oracle-java7-jdk [jdk8 is also available] Getting Java on Raspberry
    • CopyrightPrismTech,2014 You can get Scala and SBT using curl: - curl -O http://downloads.typesafe.com/scala/2.11.1/scala-2.11.1.tgz - http://dl.bintray.com/sbt/native-packages/sbt/0.13.5/sbt-0.13.5.tgz Then simply extract and properly set the PATH environment variable Getting Scala and SBT
    • CopyrightPrismTech,2014 Chat App
    • CopyrightPrismTech,2014 Chat App
    • Let’s get Action!
    • CopyrightPrismTech,2014 Vortex enable seamless, ubiquitous, efficient and timely data sharing across mobile, embedded, desktop, cloud and web applications It is the first platform to address the data-sharing needs of Business Critical IoT, and Industrial Internet Systems Vortex is fully interoperable with DDS compliant implementations Concluding Remarks
    • CopyrightPrismTech,2014 Vortex v1.0 will be available in June 2014 Starting from May will be providing a series of webcasts to get you started in building IoT and I2 applications with Vortex What’s Next?