Porting of Real-Time Publish-Subscribe Middleware to Android - - PowerPoint PPT Presentation

Porting of Real-Time Publish-Subscribe Middleware to Android

M.Vajnar, M. Sojka, P. Píša Czech Technical University in Prague

RTLWS15, Lugano-Manno

2/23

Distributed applications – problems

3/23

Distributed applications – problems

4/23

Distributed applications – problems

Redundancy

5/23

Distributed applications – problems

Configuration

6/23

Distributed applications – problems

Scaling

7/23

Outline

• Data-Centric Publish Subscribe model
• Real-Time Publish-Subscribe protocol
• ORTE middleware
• Android porting
• Demo

8/23

Data-Centric Publish-Subscribe application model

9/23

Data-Centric Publish-Subscribe application model

10/23

How to implement this? RTPS.

• Real-Time Publish-Subscribe protocol
• OMG standard – interoperability wire protocol
• Transport independent part
• Transport specific part (UDP => control of timing)
• Implementation freedom

– Simple implementation, high network bandwidth demand – Complex implementation, optimized network bandwidth.

• Utilizes multicast communication (one to many communication)
• Offers best-effort and reliable communication
• CDR encoding (endianing)
• Parts

– Data exchange protocol – Discovery protocol

11/23

ORTE – Open Real-Time Ethernet

• Our open-source implementation of the RTPS protocol
• One of the first few implementations that supported standardization
• Uses custom API instead of the DDS API (another OMG standard)
• C language, based on POSIX
• IDL compiler to generate (de)serialization functions
• Suported platforms

– Linux, FreeBSD, Mac OS X, Solaris – Windows (MinGW, Cygwin, ReactOS) – RTEMS – BlackBerry – Android

12/23

Minimal ORTE application

O R T E I n i t ( ) ; d = O R T E D

• m

a i n A p p C r e a t e ( , N U L L , N U L L , ) ; O R T E T y p e R e g i s t e r A d d ( d , " H e l l

• M

s g " , N U L L , N U L L , N U L L , 6 4 ) ; p = O R T E P u b l i c a t i

• n

C r e a t e ( d , " E x a m p l e H e l l

• M

s g " , / / T

• p

i c " H e l l

• M

s g " , / / T y p e & i n s t a n c e 2 S e n d , / / D a t a b u f f e r T I M E ( 3 , ) , / / P e r s i s t a n c e 1 , / / S t r e n g t h N U L L , / / C a l l b a c k N U L L , / / P a r a m e t e r s N U L L ) ; . . . i n s t a n c e 2 S e n d = 1 2 3 ; O R T E P u b l i c a t i

• n

S e n d ( p ) ; O R T E I n i t ( ) ; d = O R T E D

• m

a i n A p p C r e a t e ( , N U L L , N U L L , ) ; O R T E T y p e R e g i s t e r A d d ( d , " H e l l

• M

s g " , N U L L , N U L L , N U L L , 6 4 ) ; s = O R T E S u b s c r i p t i

• n

C r e a t e ( d , I M M E D I A T E , B E S T _ E F F O R T S , " E x a m p l e H e l l

• M

s g " , / / T

• p

i c / " H e l l

• M

s g " , / / T y p e & i n s t a n c e 2 R e c v , / / D a t a b u f f e r & d e a d l i n e , & m i n i m u m S e p a r a t i

• n

, r e c v C B , / / c a l l b a c k N U L L , I P A D D R E S S _ I N V A L I D ) ; / / M u l t i c a s t v

• i

d r e c v C B ( c

• n

s t O R T E R e c v I n f

• *

i n f

• ,

v

• i

d * i n s t a n c e , v

• i

d * p a r a m ) { s w i t c h ( i n f

• >

s t a t u s ) { c a s e N E W _ D A T A : p r i n t f ( " % s \ n " , i n s t a n c e ) ; b r e a k ; c a s e D E A D L I N E : p r i n t f ( " d e a d l i n e

• c

c u r r e d " ) ; b r e a k ; } }

13/23

RTPS/ORTE internals

14/23

RTPS/ORTE internals

X X X

• Dynamic addition/removal of applications
• No single point of failure
• Fault tolerant applications

15/23

ORTE Discovery Protocol

16/23

Participant discovery

17/23

Endpoint discovery

18/23

Android

• Android is a Linux-based operating system developed by Google
• It runs on devices ranging from mobile phones and tablets to home

media centers and digital cameras

• Applications developed in Java or C/C++ using Google toolkits

– Android Software Development Kit – Java – Android Native Development Kit – C/C++

19/23

Porting ORTE to Android

• Overview:

– Update Java Native Interface (JNI) wrapper and make it Android compatible – Fix bugs that have not demonstrated themselves under the Oracle's VM – Add support for Android build system – Make Java version of ORTE Manager application to overcome problems with execution and termination of native processes

20/23

Performance comparison

` Android 4.0.3 Android 4.3 Oracle Java

• Reliable publisher and subscriber
• Publish as fast as possible
• Baseline: C publisher, C subscriber

Time to publish 10k integer values

21/23

Future development

• Make the ORTE compliant with the latest RTPS standard

– Data with key

• New type of data objects, that allows to distribute a set of data instances

under a single topic

• The key is used to distinguish between instances

– Discovery protocol

• Manager is replaced with the Simple Participant Discovery Protocol and the

Simple Endpoint Discovery Protocol integrated into an user application

– Data fragmentation

• Allow a fragmentation of big data instances and sent them as multiple

messages.

• Security

22/23

Demo

• Application for remote control of

a robot

• Monitors robot's state (battery

voltage, speed vector, output of Laser Range Finder)

• Controls robot's motion

(direction and speed)

23/23

Conclusion

• ORTE can simplify both development and deployment of distributed

applications

• We have successfully ported the ORTE library to Android
• http://orte.sourceforge.net/

Thank you!