Introducing VORTEX Lite

Chief  Technology  Officer  PrismTech

angelo.corsaro@prismtech.com

Angelo  Corsaro,  PhD

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Specialised device implementations optimally addressing requirements of OT and IT platforms

VORTEX can readily deal with data ingestion seamlessly integrating with other protocols, e.g. MQTT, CoAP, etc.

VORTEX leverages the DDS standard for interoperability and uniquely extends it with support for Internet Scale systems, mobility and Web 2.0 applications

The VORTEX PlatformVortex Device

Tools

Integration

Vortex Cloud

MaaS

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All VORTEX Device implementation, i.e. OpenSplice, Café, Lite and Web are Fog ready

VORTEX Device implementations feature efficient peer-to-peer communication

VORTEX Device implementations are also cloud-enabled, in the sense that they can also communicate via VORTEX Cloud

VORTEX Device

Vortex Device

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VORTEX Architecture

IP

UDP TCP

DTLS TLS

WebSocketDDSI Wire Protocol

VORTEX Café

VORTEX Cloud

VORTEX Web

VORTEX Gateway

VORTEX Lite VORTEX OpenSplice

MQTT AMQP XMPP HTTP HBase DMBS TCP/IP, UDP/IP

…

VORTEX Café

DDS API

DDS Security

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VORTEX supports both the Cloud and the Fog Computing Paradigm

VORTEX natively supports:

- Device-to-Device Communication

- Device-to-Cloud Communication

Cloud and Fog/Edge Computing

Fog Computing

Cloud Computing

Fog Computing

Fog Computing

Device-to-Cloud Communication

Device-to-Device Communication

Fog-to-Cloud Communication

Cloud-to-Cloud Communication

Device-to-Device Communication

Collect | Store | Analyse | Share

Collect | Store | Analyse | Share

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Abstracting Connectivity

Fog Computing

Cloud Computing

Fog Computing

Fog Computing

Device-to-Cloud Communication

Device-to-Device Communication

Fog-to-Cloud Communication

Cloud-to-Cloud Communication

Device-to-Device Communication

Deployment Models

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Fog + Cloud

Fog Computing Fog Computing

Fog Computing

Device-to-Cloud Communication

Peer-to-Peer (Brokerless)

Device-to-Device Communication

Devices communicate peer-to-peer within a fog-domain and through Cloud across fog-domains

Some device concurrently communicate with peers and the cloud

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Fog + Cloud-Link + CloudDevices communicate peer-to-peer within a fog-domain

A Cloud-Link controls which data is exchanged with the could

Fog Computing Fog Computing

Fog Computing

Device-to-Cloud Communication

Peer-to-Peer (Brokerless)

Device-to-Device Communication

Cloud-LinkCloud-Link

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Federated Fog

Fog Computing Fog Computing

Fog Computing

Peer-to-Peer (Brokerless)

Device-to-Device Communication

Cloud-Link

Cloud-Link

Fog domain are federated by Cloud-Link instances

A Cloud-Link controls which data is exchanged with the could

VORTEX Abstractions

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VORTEX provides a Distributed Data Space abstraction where applications can autonomously and asynchronously read and write data

Its built-in dynamic discovery isolates applications from network topology and connectivity details

Global Data Space

DDS Global Data Space

...

Data Writer

Data Writer

Data Writer

Data Reader

Data Reader

Data Reader

Data Reader

Data Writer

TopicAQoS

TopicBQoS

TopicCQoS

TopicDQoS

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A Topic defines a domain-wide information’s class

A Topic is defined by means of a (name, type, qos) tuple, where

• name: identifies the topic within the domain

• type: is the programming language type associated with the topic. Types are extensible and evolvable

• qos: is a collection of policies that express the non-functional properties of this topic, e.g. reliability, persistence, etc.

Topic

TopicType

Name

QoS

DDS Global Data Space

...

TopicAQoS

TopicBQoS

TopicCQoS

TopicDQoS

QoS Policies

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DDS provides a rich set of QoS-Policies to control local as well as end-to-end properties of data sharing

Some QoS-Policies are matched based on a Request vs. Offered (RxO) Model

QoS Policies

HISTORY

LIFESPAN

DURABILITY

DEADLINE

LATENCY BUDGET

TRANSPORT PRIO

TIME-BASED FILTER

RESOURCE LIMITS

USER DATA

TOPIC DATA

GROUP DATA

OWENERSHIP

OWN. STRENGTH

LIVELINESS

ENTITY FACTORY

DW LIFECYCLE

DR LIFECYCLE

PRESENTATION

RELIABILITY

PARTITION

DEST. ORDER

RxO QoS Local QoS

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For data to flow from a DataWriter (DW) to one or many DataReader (DR) a few conditions have to apply:

The DR and DW domain participants have to be in the same domain

The partition expression of the DR’s Subscriber and the DW’s Publisher should match (in terms of regular expression match)

The QoS Policies offered by the DW should exceed or match those requested by the DR

QoS ModelDomain

Participant

DURABILITY

OWENERSHIP

DEADLINE

LATENCY BUDGET

LIVELINESS

RELIABILITY

DEST. ORDER

Publisher

DataWriter

PARTITION

DataReader

Subscriber

DomainParticipant

offered QoS

Topicwrites reads

Domain Idjoins joins

produces-in consumes-from

RxO QoS Policies

requested QoS

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Support for fine grained access control

Support for Symmetric and Asymmetric Authentication

Standard Authentication, Access Control, Crypto, and Logging plug-in API

Security

Arthur Dent

Arthur Dent

Ford Prerfect

Zaphod Beeblebrox

Marvin

Trillian

A(r,w), B(r)

A(r,w), B(r,w), X(r)

*(r,w)

*(r)

A(r,w), B(r,w), C(r,w)

Ford Prerfect

Zaphod Beeblebrox

Trillian

Marvin

A

B

A,BX

*

*

A,B,C

Identity Access RightsSessions are authenticated and communication is encrypted

Only the Topic included as part of the access rights are visible and accessible

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Anatomy of a DDS Application

Vortex Lite

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Bring software-based DDS implementation to a range of resource constrained devices

Allow for variability on functionalities, transport and support of underlying OS/BSP

Provides very low footprint and very high performance

v1.0 runtime footprint ~450 KB

v1.0 latency as low as ~30 usec (on Gigabit network)

Vortex Lite

DDSI$$

DDS$API C99 ISO&C++

OS/RTOS$$ BSP

Abstraction$OS

Abstraction$Transport

Architecture

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The Vortex Lite architecture aims at optimising performance on constrained environment.

By default, Lite performs reads and writes on a single thread.

Writes can be multi-threaded when using TCP/IP

Vortex Lite Architecture

DDSI

DCPS

Listeners/ WaitSets

Network Packets

DDSI Messages

Samples

Cache Changes

n threads (n=1 by default)

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By default, Lite uses the same thread to:

- reads data from the socket

- execute the DDSI protocol state machine

- de-serialise data

- invoke listeners (if any)

This ensures that no context switch happens on the dispatch path thus, reducing overhead on single-core procures, as well as providing very low and deterministic latency

Default Read Path

DDSI

DCPS

Listeners/ WaitSets

Network Packets

DDSI Messages

Samples

Cache Changes

n threads (n=1 by default)

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Lite can be configured to use a separate thread pool to notify listeners

In this case the bottom thread (pool) takes care of:

- reading data from the socket

- executing the DDSI protocol state machine

While the other thread (pool) takes care of:

- de-serialising data

- invoking listeners (if any)

This configuration improves throughput on multi-core processors

Async Read Path

DDSI

DCPS

Listeners/ WaitSets

Network Packets

DDSI Messages

Samples

Cache Changes

n threads (n=1 by default)

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For UDP/IP communication Lite uses a write through strategy leveraging the application thread for executing the entire stack

Write Path

DDSI

DCPS

Writer

Network Packets

DDSI Messages

Samples

Cache Changes

application thread

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When communicating over TCP/IP Lite can be configured to use a thread-pool to write over TCP/IP sockets

This helps with parallelising some of the fan-out

TCP/IP Write Path

DDSI

DCPS

Writer

Network Packets

DDSI Messages

Samples

Cache Changes

application thread

n threads (n=1 by default)

Lite in Numbers

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488 KBytes footprint for the dds library

4 KB for all the DDS entities required to publish data

- Domain Participant

- Topic

- Subscriber

- Data Reader

- Listener

Adding more Writer on the same participant has very little overhead

Subscriber Memory Usage (pmap -x)

Address Kbytes RSS Dirty Mode Mapping08048000 4 4 0 r-x-- subscriber08049000 4 4 4 r---- subscriber0804a000 4 4 4 rw--- subscriber748a000 1700 572 0 r-x-- libc-2.19.sob7633000 8 8 8 r---- libc-2.19.sob7635000 4 4 4 rw--- libc-2.19.sob763a000 96 72 0 r-x-- libpthread-2.19.sob7652000 4 4 4 r---- libpthread-2.19.sob7653000 4 4 4 rw--- libpthread-2.19.sob766d000 588 488 0 r-x-- libdds.so.0.9.2b7700000 12 12 12 r---- libdds.so.0.9.2b7703000 4 4 4 rw--- libdds.so.0.9.2b770c000 128 100 0 r-x-- ld-2.19.sob772c000 4 4 4 r---- ld-2.19.sob772d000 4 4 4 rw--- ld-2.19.so

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456 KBytes footprint for the dds library

4 KB for all the DDS entities required to publish data

- Domain Participant

- Topic

- Publisher

- Data Writer

Adding more Writer on the same participant has very little

Publisher Memory Usage (pmap -x)

Address Kbytes RSS Dirty Mode Mapping08048000 4 4 0 r-x-- publisher08049000 4 4 4 r---- publisher0804a000 4 4 4 rw--- publisherb74ae000 1700 564 0 r-x-- libc-2.19.sob7657000 8 8 8 r---- libc-2.19.sob7659000 4 4 4 rw--- libc-2.19.sob765e000 96 72 0 r-x-- libpthread-2.19.sob7676000 4 4 4 r---- libpthread-2.19.sob7677000 4 4 4 rw--- libpthread-2.19.sob7691000 588 456 0 r-x-- libdds.so.0.9.2b7724000 12 12 12 r---- libdds.so.0.9.2b7727000 4 4 4 rw--- libdds.so.0.9.2b7730000 128 100 0 r-x-- ld-2.19.sob7750000 4 4 4 r---- ld-2.19.sob7751000 4 4 4 rw--- ld-2.19.so

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Median Latency as low as 31.5 micro-secs for small data

Latency of 51 micro-secs for 1024 data size!

Lite is by far the fastest DDS implementation on the market!

LatencyMedian Latency

mic

ro-s

ecs

30

36

43

49

55

data size (bytes)0 300 600 900 1200

31,5

34,5

51,0Lite 0.9.2

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Latency nicely fit by the quadratic polynomial:

Latency

mic

ro-s

ecs

30

55

80

105

130

data size (bytes)0 2250 4500 6750 9000

y = -7,86E-7x2 + 0,0176x + 32,8

31,534,5

51,0

66,0

91,0

124,5

Lite 0.9.2

y = -7.86E-7x2+0.0176x + 32.8

NB: This quadratic fit should be used for data up to 8192 bytes. Otherwise the conservative linear fit y = 0,0113x + 37,425 can be used for bigger sizes

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Saturates a 1 Gbps network for data as small as 1024 bytes

Throughput

Mbp

s

0

250

500

750

1000

data-size (bytes)4 1253 2502 3751 500050

294

560

780

903928 948

Lite 0.9.2

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Throughput

Kmsg

s/se

c

1

10

100

1000

data-size (bytes)1 10 100 1000 10000 100000

523 506

11056

2914

7,33,7

1,8

Lite 0.9.2

Cloud Connectivity

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Vortex Lite can be easily configured to use cloud by enabling TCP/IP and adding the Vortex-Cloud address as one of the peers

If you want to enable only communication through cloud then you may disable support for multicast (see side example )

Vortex Cloud Connectivity<DDSI2EService> <General> <NetworkInterfaceAddress>AUTO</NetworkInterfaceAddress> <AllowMulticast>false</AllowMulticast> <EnableMulticastLoopback>false</EnableMulticastLoopback> <EnableLoopback>false</EnableLoopback> </General> <TCP> <Enable>True</Enable> </TCP> <Discovery> <Peers> <Peer>demo-eu.prismtech.com:7400</Peer> </Peers> </Discovery> <Compatibility> <StandardsConformance>lax</StandardsConformance> </Compatibility> <Tracing> <Verbosity>warning</Verbosity> </Tracing></DDSI2EService>

API

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Writing Data#include "generated/Test.h"

int main (int argc, char ** argv) { dds_entity_t ppant; dds_entity_t topic; dds_entity_t writer;

/* Initialize DDS */ dds_init (argc, argv);

/* Create participant */ dds_participant_create (&ppant, DDS_DOMAIN_DEFAULT, NULL, NULL);

/* Create topic */ dds_topic_create (ppant, &topic, &Test_Topic_desc, "TestTopic", NULL, NULL, 0);

/* Create writer with QoS */ dds_writer_create (ppant, &writer, topic, NULL, NULL, 0);

/* Topic instance */ Test_Topic sample = { 1, 2 };

/* Write topic */ dds_write (writer, &sample);

dds_sleepfor (DDS_SECS (10));

/* Clean up */ dds_entity_delete (ppant); dds_fini ();}

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Reading Data#include "generated/Test.h"

int main (int argc, char ** argv) { dds_entity_t ppant; dds_entity_t topic; dds_entity_t reader; dds_sample_info_t info; void * samples[1];

/* Initialize DDS */ dds_init (argc, argv);

/* Create participant */ dds_participant_create (&ppant, DDS_DOMAIN_DEFAULT, NULL, NULL);

/* Create topic */ dds_topic_create (ppant, &topic, &Test_Topic_desc, "TestTopic", NULL, NULL, 0);

/* Create writer with QoS */ dds_reader_create (ppant, &reader, topic, NULL, NULL, 0);

while (true) { /* Wait for valid sample then print and exit */ ret = dds_read (reader, samples, 1, &info, 0); if (ret > 0 && info.valid_data) { printf ("Test Sample (%d, %d)\n", sample.d1, sample.d2); break; } dds_sleepfor (DDS_SECS (1)); }

/* Clean up */ dds_entity_delete (ppant); dds_fini ();}

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Listener Declarationstatic void data_available_handler (dds_entity_t reader) { int ret; const uint32_t max = 1; dds_sample_info_t info[max]; void * samples[max]; Test_Topic sample; uint32_t mask = 0;

samples[0] = &sample;

/* Set type of samples required. */ mask = DDS_ALIVE_INSTANCE_STATE;

/* Read samples. */ dds_read (reader, samples, max, info, mask); printf ("Data Received ...\n"); printf ("Sample (%d, %d)\n", sample.d1, sample.d2);}

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Listener Registration

memset (&listener, 0, sizeof (listener)); listener.on_data_available = data_available_handler; listener.on_subscription_matched = subscription_matched_handler;

/* Create reader with DATA_AVAILABLE status condition enabled */

dds_reader_create (sub, &reader, topic, qos, &listener, DDS_DATA_AVAILABLE_STATUS);

Summing Up

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Lite expands Vortex connectivity to embedded devices

Vortex Lite is highly efficient in time and space and simple to use

Concluding Remarks

Fog Computing

Cloud Computing

Fog Computing

Fog Computing

Device-to-Cloud Communication

Device-to-Device Communication

Fog-to-Cloud Communication

Cloud-to-Cloud Communication

Device-to-Device Communication

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