Desktop, Embedded and Mobile Apps with PrismTech Vortex Cafe
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The document discusses the Vortex Café platform, which facilitates data sharing across various applications by employing a staged event-driven architecture for optimized performance. It covers the setup of a chat application for Android using DDS entities, emphasizing management of lifecycle and threading. Additionally, it provides practical guidance on programming with Raspberry Pi and configuring environments for Java and Scala.
![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]](https://image.slidesharecdn.com/desktop-embedded-mobile-vortex-cafe-jun2014-140620055709-phpapp01/85/Desktop-Embedded-and-Mobile-Apps-with-PrismTech-Vortex-Cafe-8-320.jpg)
 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())
}](https://image.slidesharecdn.com/desktop-embedded-mobile-vortex-cafe-jun2014-140620055709-phpapp01/85/Desktop-Embedded-and-Mobile-Apps-with-PrismTech-Vortex-Cafe-16-320.jpg)
![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]](https://image.slidesharecdn.com/desktop-embedded-mobile-vortex-cafe-jun2014-140620055709-phpapp01/85/Desktop-Embedded-and-Mobile-Apps-with-PrismTech-Vortex-Cafe-28-320.jpg)
![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]](https://image.slidesharecdn.com/desktop-embedded-mobile-vortex-cafe-jun2014-140620055709-phpapp01/85/Desktop-Embedded-and-Mobile-Apps-with-PrismTech-Vortex-Cafe-29-320.jpg)
![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](https://image.slidesharecdn.com/desktop-embedded-mobile-vortex-cafe-jun2014-140620055709-phpapp01/85/Desktop-Embedded-and-Mobile-Apps-with-PrismTech-Vortex-Cafe-44-320.jpg)
![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](https://image.slidesharecdn.com/desktop-embedded-mobile-vortex-cafe-jun2014-140620055709-phpapp01/85/Desktop-Embedded-and-Mobile-Apps-with-PrismTech-Vortex-Cafe-45-320.jpg)
Desktop, Embedded and Mobile Apps with PrismTech Vortex Cafe
- 1. Desktop, Embedded and Mobile Distributed Apps with Angelo Corsaro, PhD Chief Technology Officer angelo.corsaro@prismtech.com Café
- 2. Vortex
- 3. CopyrightPrismTech,2014 Vortex enable seamless, ubiquitous, efficient and timely data sharing across mobile, embedded, desktop, cloud and web applications The Vortex Platform
- 4. 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
- 5. Vortex Café
- 6. 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
- 7. 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
- 8. 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]
- 9. 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
- 10. 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
- 11. 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
- 12. 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 $*
- 13. Anatomy of a Vortex-Cafe App
- 14. 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
- 15. 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();
- 16. 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()) }
- 17. Android
- 18. 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
- 19. 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
- 20. 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
- 21. 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
- 22. 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
- 23. CopyrightPrismTech,2014 Tasks and Back Tasks
- 24. 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
- 25. DDS Chat
- 26. 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
- 27. 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
- 28. 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]
- 29. 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]
- 30. 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);! }! !
- 31. 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();! }! }!
- 32. 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>!
- 33. 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"/>!
- 34. 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"! />! !
- 35. 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>!
- 36. 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
- 37. 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 }!
- 38. 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 }!
- 39. 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
- 40. 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 !
- 41. 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 }!
- 42. Raspberry Pi
- 43. 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
- 44. 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
- 45. 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
- 46. 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
- 50. 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
- 51. 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?