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![The Data Distribution Service
[For Real-Time Systems]
OpenSplice DDS
Angelo CORSARO, Ph.D.
Chief Technology Officer
OMG DDS Sig Co-Chair
PrismTech
angelo.corsaro@prismtech.com](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-1-2048.jpg)
![Anatomy of a DDS Application
[Scala API]
Domain
Domain
Copyright
2011,
PrismTech
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Rights
Reserved.
val dp = DomainParticipant(domainId)
Participant
Publisher
Topic
Subscriber
OpenSplice DDS
DataWriter
DataReader](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-14-2048.jpg)
![Anatomy of a DDS Application
[Scala API]
Domain
Domain
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
val dp = DomainParticipant(domainId)
Participant
Session
// Create a Publisher / Subscriber
Publisher
Topic
Subscriber
OpenSplice DDS
val pub = Publisher(dp)
val sub = Subscriber(dp)
// Create a Topic
val topic = Topic[VehicleDynamics](dp, “TVehicleDynamics”)
DataWriter
DataReader](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-15-2048.jpg)
![Anatomy of a DDS Application
[Scala API]
Domain
Domain
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
val dp = DomainParticipant(domainId)
Participant
Session
// Create a Publisher / Subscriber
Publisher
Topic
Subscriber
OpenSplice DDS
val pub = Publisher(dp)
val sub = Subscriber(dp)
// Create a Topic
val topic = Topic[VehicleDynamics](dp, “TVehicleDynamics”)
Reader/Writers for User Defined for Types DataWriter
DataReader
// Create a DataWriter/DataWriter
val writer = DataWriter[TempSensor](pub, topic) Reader/Writer for
val reader = DataReader[TempSensor](sub, topic)
application defined
Topic Types](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-16-2048.jpg)
![Anatomy of a DDS Application
[Scala API]
Domain
Domain
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
val dp = DomainParticipant(domainId)
Participant
Session
// Create a Publisher / Subscriber
Publisher
Topic
Subscriber
OpenSplice DDS
val pub = Publisher(dp)
val sub = Subscriber(dp)
// Create a Topic
val topic = Topic[VehicleDynamics](dp, “TVehicleDynamics”)
Reader/Writers for User Defined for Types DataWriter
DataReader
// Write data
val data = new VehicleDynamics(101, 131, 107, 7, 5)
writer write data
Reader/Writer for
// But you can also write like this... application defined
writer ! data Topic Types
// Read new data and print it on the screen
(reader read) foreach (prinln)](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-17-2048.jpg)
![Anatomy of a DDS Application
[DDS C++ API 2010]
Domain
Domain
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
auto dp = DomainParticipant(domainId);
Participant
Session
// Create a Publisher / Subscriber
Publisher
Topic
Subscriber
OpenSplice DDS
auto pub = Publisher(dp);
auto sub = Subscriber(dp);
// Create a Topic
auto topic = Topic<VehicleDynamics>(dp, “TVehicleDynamics”);
Reader/Writers for User Defined for Types DataWriter
DataReader
// Create a DataWriter/DataWriter
auto writer = DataWriter<TempSensor>(pub, topic); Reader/Writer for
auto reader = DataReader<TempSensor>(sub, topic);
application defined
Topic Types](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-18-2048.jpg)
![Anatomy of a DDS Application
[DDS C++ API 2010]
Domain
Domain
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
auto dp = DomainParticipant(domainId);
Participant
Session
// Create a Publisher / Subscriber
Publisher
Topic
Subscriber
OpenSplice DDS
auto pub = Publisher(dp);
auto sub = Subscriber(dp);
// Create a Topic
auto topic = Topic<VehicleDynamics>(dp, “TVehicleDynamics”);
Reader/Writers for User Defined for Types DataWriter
DataReader
// Write data
writer.write(VehicleDynamics(101, 131, 107, 7, 5)); Reader/Writer for
// But you can also write like this...
writer << VehicleDynamics(101, 131, 107, 7, 5);
application defined
Topic Types
// Read new data
auto data = reader.read();](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-19-2048.jpg)
![QoS Policies
[T: Topic] [DR: DataReader] [DW: DataWriter] [P: Publisher] [S: Subscriber] [DP: Domain Participant]
QoS Policy Applicability RxO Modifiable
Copyright
2011,
PrismTech
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Rights
Reserved.
USER_DATA DP, DR, DW N Y
TOPIC_DATA T N Y Configuration
GROUP_DATA P, S N Y
DURABILITY T, DR, DW Y N
OpenSplice DDS
DURABILITY T, DW N N
SERVICE Data Availability
HISTORY T, DR, DW N N
PRESENTATION P, S Y N
RELIABILITY T, DR, DW Y N
PARTITION P, S N Y
Data Delivery
DESTINATION T, DR, DW Y N
ORDER
LIFESPAN T, DW N Y](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-22-2048.jpg)
![QoS Policies
[T: Topic] [DR: DataReader] [DW: DataWriter] [P: Publisher] [S: Subscriber] [DP: Domain Participant]
QoS Policy Applicability RxO Modifiable
Copyright
2011,
PrismTech
–
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Rights
Reserved.
DEADLINE T, DR, DW Y Y
LATENCY T, DR, DW Y Y
BUDGET Temporal/
TRANSPORT T, DW N Y Importance
PRIORITY Characteristics
OpenSplice DDS
TIME BASED DR N Y
FILTER
OWNERSHIP T, DR, DW Y N
OWNERSHIP DW N Y Replication
STRENGTH
LIVELINESS T, DR, DW Y N Fault-Detection](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-23-2048.jpg)
![Temporal Properties
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
TimeBasedFilter Deadline
[Inbound]
OpenSplice DDS
Throughput LatencyBudget Latency
[Outbound]
TransportPriority](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-24-2048.jpg)
![Filters
[Scala API]
struct VehicleDynamics {
long vid;
long x; long y;
long dx; long dy;};
#pragma keylist VehicleStatus vid
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2011,
PrismTech
–
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Rights
Reserved.
/**
** NOTE: The Scala API if not provided with DP/Sub/Pub assumes default domains and
** default partition.
**/
// Create a Topic
val topic = Topic[VehicleDynamics](“TVehicleDynamics”)
OpenSplice DDS
// Define filter expression and parameters
val filter = “x < %0 AND y < %1”
val params = List(“200”, “300”)
// Define content filtered topic
val cftopic =
ContentFilteredTopic[VehicleDynamics](“CFTVehicleDynamics”, topic, filter, params)
// Create a DataReader for the content-filtered Topic
val reader =
DataReader[VehicleDynamics](cftopic)](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-46-2048.jpg)
![QueryAPI 2010] struct VehicleDynamics {
[DDS C++ long vid;
long x; long y;
long dx; long dy;};
#pragma keylist VehicleStatus vid
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
// Define the query and the parameters
OpenSplice DDS
std::vector<std::string> p;
p.push_back("100");
p.push_back("100");
dds::core::Query q("x < %0 AND y < %1", p.begin(), p.end());
auto data = reader
.selector()
.filter_content(q)
.read();](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-47-2048.jpg)
![References
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
OpenSplice | DDS Escalier
¥ #1 OMG DDS Implementation ¥ Fastest growing JVM Language ¥ Scala API for OpenSplice DDS
¥ Open Source ¥ Open Source ¥ Open Source
¥ www.opensplice.org ¥ www.scala-lang.org ¥ github.com/kydos/escalier
OpenSplice DDS
[C++] [Java] DDS-PSM-Cxx 2010
¥ Simple C++ API for DDS ¥ DDS-PSM-Java for OpenSplice DDS ¥ DDS-PSM-Cxx API Standard
¥ Open Source ¥ Open Source ¥ Open Source
¥ code.google.com/p/simd-cxx ¥ github.com/kydos/simd-java ¥ github.com/kydos/dds-psm-cxx](https://image.slidesharecdn.com/2012-03-01-dds-intro-v1-1-cready-120302024517-phpapp02/75/The-Data-Distribution-Service-56-2048.jpg)
Uploaded byAngelo Corsaro
The Data Distribution Service
OpenSplice DDS is a data distribution service designed for real-time systems, addressing challenges of data distribution in defense and aerospace applications since 2004. It supports features such as publish/subscribe mechanisms, dynamic discovery, and rich Quality of Service (QoS) policies to ensure high performance and reliability. OpenSplice DDS is widely used in various domains, including SCADA systems and automated trading, and facilitates complex data management and interoperability through a common data model.
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The Data Distribution Service
- 1. The Data DistributionService [For Real-Time Systems] OpenSplice DDS Angelo CORSARO, Ph.D. Chief Technology Officer OMG DDS Sig Co-Chair PrismTech angelo.corsaro@prismtech.com
- 2. OpenSplice DDS Background
- 3. Data Distribution Service For Real-Time Systems Copyright 2011, PrismTech – All Rights Reserved. ☐ Introduced in 2004 to address the Data Distribution Real-Timeliness Scale challenges faced by a wide class of Defense and Aerospace Applications OpenSplice DDS Key requirement for the Parallelism Determinism Throughput, Availability Scalability, Persistence, Security ☐ standard were to deliver very Systemic Signal Data Real-Time Information Near Real-Time Fault- Tolerant Information Complex Information high and predictable Processing Processing Management Processing Processing performance while scaling from embedded to ultra- Parallel Systems Distributed Systems large-scale deployments
- 4. Data Distribution Service For Real-Time Systems Copyright 2011, PrismTech – All Rights Reserved. ☐ Recommended by key Real-Timeliness Scale administration worldwide, e.g. DoD, MoD, EUROCAE, etc. OpenSplice DDS Widely adopted across Parallelism Determinism Throughput, Availability Scalability, Persistence, Security ☐ several different domains, Systemic Signal Data Real-Time Information Near Real-Time Fault- Tolerant Information Complex Information e.g., Automated Trading, Processing Processing Management Processing Processing Simulations, SCADA, Telemetry, etc. Parallel Systems Distributed Systems
- 5. Some Use Cases Copyright 2011, PrismTech – All Rights Reserved. Integrated Modular Vetronics Training & Simulation Systems Naval Combat Systems OpenSplice DDS Air Traffic Control & Management Large Scale SCADA Systems High Frequency Auto-Trading
- 6. Standards: What For? Copyright 2011, PrismTech – All Rights Reserved. Common “Language” Data Model + OpenSplice DDS QoS Requirements Interoperability DDSI Wire Interoperability
- 7. OpenSplice DDS DDS Application API Standard Standards: What For? Portability Copyright 2011, PrismTech – All Rights Reserved.
- 8. OpenSplice DDS D D BaS ics
- 9. Data Distribution Service For Real-Time Systems DDS provides a Topic-Based Publish/ Copyright 2011, PrismTech – All Rights Reserved. Subscribe abstraction based on: Data Reader Data Writer ☐ Topics: data distribution subject’s OpenSplice DDS Data Reader Data TopicD Writer DataWriters: data producers TopicA ☐ Data TopicB Reader Data Writer ☐ DataReaders: data consumers TopicC ... Data Data Writer Reader DDS Global Data Space
- 10. Data Distribution Service For Real-Time Systems Copyright 2011, PrismTech – All Rights Reserved. ☐ DataWriters and DataReaders Data Reader are automatically and Data Writer dynamically matched by the OpenSplice DDS Data Reader Data TopicD DDS Dynamic Discovery Writer TopicA Data TopicB Reader Data ☐ A rich set of QoS allows to Writer TopicC ... control existential, temporal, Data Data and spatial properties of data Writer Reader DDS Global Data Space
- 11. DDS Topics ☐ A Topic defines a class of “TVehicleDynamics” streams Copyright 2011, PrismTech – All Rights Reserved. Name ☐ A Topic has associated a user defined extensible type and a Topic Typ set of QoS policies S DURABILITY, Qo OpenSplice DDS e DEADLINE, ☐ The Topic name, type and QoS VehicleDynamics PRIORITY, defines the key functional and … non-functional invariants struct VehicleDynamics { IDL ☐ Topics can be discovered or long vid; locally defined long x; long y; long dx; long dy;}; #pragma keylist VehicleDynamics vid
- 12. Topic Instances ☐ Each unique key value Copyright 2011, PrismTech – All Rights Reserved. identifies a unique stream of data vid =701 DDS not only vid =809 struct VehicleStatus { ☐ Topic long vid; OpenSplice DDS long x; long y; long dx; long dy;}; demultiplexes “streams” #pragma keylist VehicleStatus vid vid =977 but provides also lifecycle Instances Instances information ☐ A DDS DataWriter can write multiple instances
- 13. OpenSplice DDS Anatomy of a DDS Application Copyright 2011, PrismTech – All Rights Reserved.
- 14. Anatomy of aDDS Application [Scala API] Domain Domain Copyright 2011, PrismTech – All Rights Reserved. val dp = DomainParticipant(domainId) Participant Publisher Topic Subscriber OpenSplice DDS DataWriter DataReader
- 15. Anatomy of aDDS Application [Scala API] Domain Domain Copyright 2011, PrismTech – All Rights Reserved. val dp = DomainParticipant(domainId) Participant Session // Create a Publisher / Subscriber Publisher Topic Subscriber OpenSplice DDS val pub = Publisher(dp) val sub = Subscriber(dp) // Create a Topic val topic = Topic[VehicleDynamics](dp, “TVehicleDynamics”) DataWriter DataReader
- 16. Anatomy of aDDS Application [Scala API] Domain Domain Copyright 2011, PrismTech – All Rights Reserved. val dp = DomainParticipant(domainId) Participant Session // Create a Publisher / Subscriber Publisher Topic Subscriber OpenSplice DDS val pub = Publisher(dp) val sub = Subscriber(dp) // Create a Topic val topic = Topic[VehicleDynamics](dp, “TVehicleDynamics”) Reader/Writers for User Defined for Types DataWriter DataReader // Create a DataWriter/DataWriter val writer = DataWriter[TempSensor](pub, topic) Reader/Writer for val reader = DataReader[TempSensor](sub, topic) application defined Topic Types
- 17. Anatomy of aDDS Application [Scala API] Domain Domain Copyright 2011, PrismTech – All Rights Reserved. val dp = DomainParticipant(domainId) Participant Session // Create a Publisher / Subscriber Publisher Topic Subscriber OpenSplice DDS val pub = Publisher(dp) val sub = Subscriber(dp) // Create a Topic val topic = Topic[VehicleDynamics](dp, “TVehicleDynamics”) Reader/Writers for User Defined for Types DataWriter DataReader // Write data val data = new VehicleDynamics(101, 131, 107, 7, 5) writer write data Reader/Writer for // But you can also write like this... application defined writer ! data Topic Types // Read new data and print it on the screen (reader read) foreach (prinln)
- 18. Anatomy of aDDS Application [DDS C++ API 2010] Domain Domain Copyright 2011, PrismTech – All Rights Reserved. auto dp = DomainParticipant(domainId); Participant Session // Create a Publisher / Subscriber Publisher Topic Subscriber OpenSplice DDS auto pub = Publisher(dp); auto sub = Subscriber(dp); // Create a Topic auto topic = Topic<VehicleDynamics>(dp, “TVehicleDynamics”); Reader/Writers for User Defined for Types DataWriter DataReader // Create a DataWriter/DataWriter auto writer = DataWriter<TempSensor>(pub, topic); Reader/Writer for auto reader = DataReader<TempSensor>(sub, topic); application defined Topic Types
- 19. Anatomy of aDDS Application [DDS C++ API 2010] Domain Domain Copyright 2011, PrismTech – All Rights Reserved. auto dp = DomainParticipant(domainId); Participant Session // Create a Publisher / Subscriber Publisher Topic Subscriber OpenSplice DDS auto pub = Publisher(dp); auto sub = Subscriber(dp); // Create a Topic auto topic = Topic<VehicleDynamics>(dp, “TVehicleDynamics”); Reader/Writers for User Defined for Types DataWriter DataReader // Write data writer.write(VehicleDynamics(101, 131, 107, 7, 5)); Reader/Writer for // But you can also write like this... writer << VehicleDynamics(101, 131, 107, 7, 5); application defined Topic Types // Read new data auto data = reader.read();
- 20. OpenSplice DDS QoS
- 21. QoS Model ☐ QoS-Policies control local and end-to-end properties of DDS Copyright 2011, PrismTech – All Rights Reserved. entities Type Matching QoS matching QoS QoS QoS QoS QoS QoS QoS ☐ Local properties controlled by Topic QoS are related resource usage Publisher Name Subscriber ... DataWriter writes Type reads DataReader ... ☐ End-to-end properties OpenSplice DDS ... controlled by QoS are related DomainParticipant DataWriter writes Type reads DataReader DomainParticipant Name to temporal and spatial aspects Topic of data distribution QoS QoS QoS ☐ Some QoS-Policies are matched based on a Request vs. Offered Model thus QoS- enforcement
- 22. QoS Policies [T: Topic] [DR: DataReader] [DW: DataWriter] [P: Publisher] [S: Subscriber] [DP: Domain Participant] QoS Policy Applicability RxO Modifiable Copyright 2011, PrismTech – All Rights Reserved. USER_DATA DP, DR, DW N Y TOPIC_DATA T N Y Configuration GROUP_DATA P, S N Y DURABILITY T, DR, DW Y N OpenSplice DDS DURABILITY T, DW N N SERVICE Data Availability HISTORY T, DR, DW N N PRESENTATION P, S Y N RELIABILITY T, DR, DW Y N PARTITION P, S N Y Data Delivery DESTINATION T, DR, DW Y N ORDER LIFESPAN T, DW N Y
- 23. QoS Policies [T: Topic] [DR: DataReader] [DW: DataWriter] [P: Publisher] [S: Subscriber] [DP: Domain Participant] QoS Policy Applicability RxO Modifiable Copyright 2011, PrismTech – All Rights Reserved. DEADLINE T, DR, DW Y Y LATENCY T, DR, DW Y Y BUDGET Temporal/ TRANSPORT T, DW N Y Importance PRIORITY Characteristics OpenSplice DDS TIME BASED DR N Y FILTER OWNERSHIP T, DR, DW Y N OWNERSHIP DW N Y Replication STRENGTH LIVELINESS T, DR, DW Y N Fault-Detection
- 24. Temporal Properties Copyright 2011, PrismTech – All Rights Reserved. TimeBasedFilter Deadline [Inbound] OpenSplice DDS Throughput LatencyBudget Latency [Outbound] TransportPriority
- 25. Data Availability History Copyright 2011, PrismTech – All Rights Reserved. Data OpenSplice DDS Lifespan Durability Availability Ownership Ownership Strength
- 26. OpenSplice DDS Partition Data Delivery Reliability Presentation Data Delivery Order Destination Copyright 2011, PrismTech – All Rights Reserved.
- 27. Setting QoS Policies Copyright 2011, PrismTech – All Rights Reserved. C++ // Setting Partition QoS-Policy on Publisher qos::PublisherQos pubQos; pubQos << policy::Partition("Partition"); Publisher pub(dp, pubQoS); OpenSplice DDS // Setting various QoS-Policy on a Topic qos::TopicQos tqos; tqos << policy::Reliability::Reliable() << policy::Durability::Transient() << policy::History::KeepLast(5); Topic<VehicleDynamics> topic(dp,"Partition", tqos);
- 28.
- 29. DDS Model Topic Instances DataWriter DataReader DataReader Copyright 2011, PrismTech – All Rights Reserved. ... ... ... ... ... ... ... ... ... ... ... ... ... OpenSplice DDS DataWriter Cache DataReader Cache DataReader Cache Writer History Reader History network
- 30. DDS Model DataWriter DataReader DataReader Copyright 2011, PrismTech – All Rights Reserved. ... ... ... ... ... ... ... ... ... ... ... ... ... OpenSplice DDS DataWriter Cache DataReader Cache DataReader Cache QoS Policies ‣ History ‣ Destination Order ‣ Presentation network ‣ Partition ‣ Time Based Filter QoS Policies ‣ Ownership ‣ Reliability ‣ Durability ‣ History ‣ Transport Priority ‣ Latency Budget ‣ Time Based Filter
- 31. Dynamic View ofa Stream Copyright 2011, PrismTech – All Rights Reserved. OpenSplice DDS ... Stream: Set of samples written over time for a given topic instance.
- 32. Dynamic View ofa Stream Assumptions: Reader History = KeepLast (n) WriterHistory = KeepLast (m) Copyright 2011, PrismTech – All Rights Reserved. Writer History OpenSplice DDS ... Stream: Set of samples written over time for a given topic instance.
- 33. Dynamic View ofa Stream Assumptions: Reader History = KeepLast (n) WriterHistory = KeepLast (m) Copyright 2011, PrismTech – All Rights Reserved. Samples ‘on Writer History the wire’ OpenSplice DDS ... Stream: Set of samples written over time for a given topic instance.
- 34. Dynamic View ofa Stream Assumptions: Reader History = KeepLast (n) WriterHistory = KeepLast (m) Copyright 2011, PrismTech – All Rights Reserved. Samples ‘on Writer History the wire’ Reader History OpenSplice DDS ... Stream: Set of samples written over time for a given topic instance.
- 35. Dynamic View ofa Stream Assumptions: Reader History = KeepLast (n) WriterHistory = KeepLast (m) Copyright 2011, PrismTech – All Rights Reserved. Samples ‘on Writer History the wire’ Reader History ‘Past’ Samples OpenSplice DDS ... Stream: Set of samples written over time for a given topic instance.
- 36. Eventual View ofa Stream Assumptions (Default Settings): Reader History = KeepLast (1) WriterHistory = KeepLast (1) Copyright 2011, PrismTech – All Rights Reserved. Writer History Reader History ‘Past’ Samples OpenSplice DDS Stream: Set of samples written over time for a given topic instance.
- 37. Eventual View ofa Stream Assumptions: Reader History = KeepLast (n) with n > 1 WriterHistory = KeepLast (1) Copyright 2011, PrismTech – All Rights Reserved. Writer History Reader History ‘Past’ Samples OpenSplice DDS Stream: Set of samples written over time for a given topic instance.
- 38. Eventual View ofa Stream Assumptions: Reader History = KeepLast (n) with n > 1 WriterHistory = KeepLast (m) with n > m > 1 Copyright 2011, PrismTech – All Rights Reserved. Writer History Reader History ‘Past’ Samples OpenSplice DDS Stream: Set of samples written over time for a given topic instance.
- 39. Reading Data Samples ☐ Samples can be read from the Data Reader History Cache Copyright 2011, PrismTech – All Rights Reserved. ☐ The action of reading a sample is non-destructive. Samples are not removed from the cache OpenSplice DDS DataReader DataReader ... read ... DataReader Cache DataReader Cache
- 40. Taking Data Samples ☐ Samples can be taken from the Data Reader History Cache Copyright 2011, PrismTech – All Rights Reserved. ☐ The action of taking a sample is destructive. Samples are removed from the cache OpenSplice DDS DataReader DataReader ... ... take DataReader Cache DataReader Cache
- 41. Read vs. Take Copyright 2011, PrismTech – All Rights Reserved. ☐ The read operation should always be access the latest know value for topics that represent distributed state OpenSplice DDS ☐ The take operation should be used to get the last notification from a topic that represent an event
- 42.
- 43. Cherry Picking inDDS Copyright 2011, PrismTech – All Rights Reserved. ☐ DDS provides some very flexible mechanisms for selecting the data to be read: OpenSplice DDS ☐ Data Content ☐ Data Status ☐ These mechanisms are composable
- 44.
- 45. Filters and Queries Application ☐ DDS Filters allow to control what gets into a DataReader cache Copyright 2011, PrismTech – All Rights Reserved. Query ☐ DDS Queries allow to control what gets out of a DataReader cache DataReader OpenSplice DDS ☐ Filters are defined by means of ... ContentFilteredTopics ... ... ... ☐ Queries operate in conjunction with DataReader Cache read operations Filter ☐ Filters and Queries are expressed as SQL where clauses
- 46. Filters [Scala API] struct VehicleDynamics { long vid; long x; long y; long dx; long dy;}; #pragma keylist VehicleStatus vid Copyright 2011, PrismTech – All Rights Reserved. /** ** NOTE: The Scala API if not provided with DP/Sub/Pub assumes default domains and ** default partition. **/ // Create a Topic val topic = Topic[VehicleDynamics](“TVehicleDynamics”) OpenSplice DDS // Define filter expression and parameters val filter = “x < %0 AND y < %1” val params = List(“200”, “300”) // Define content filtered topic val cftopic = ContentFilteredTopic[VehicleDynamics](“CFTVehicleDynamics”, topic, filter, params) // Create a DataReader for the content-filtered Topic val reader = DataReader[VehicleDynamics](cftopic)
- 47. QueryAPI 2010] struct VehicleDynamics { [DDS C++ long vid; long x; long y; long dx; long dy;}; #pragma keylist VehicleStatus vid Copyright 2011, PrismTech – All Rights Reserved. // Define the query and the parameters OpenSplice DDS std::vector<std::string> p; p.push_back("100"); p.push_back("100"); dds::core::Query q("x < %0 AND y < %1", p.begin(), p.end()); auto data = reader .selector() .filter_content(q) .read();
- 48. Instances ☐ DDS provides a very efficient way of reading data belonging to a Copyright 2011, PrismTech – All Rights Reserved. specific Topic Instance ☐ Obviously, one could use queries to match the key’s value, but this is not as efficient as the special purpose instance selector OpenSplice DDS // C++ auto data = reader .selector() .instance(handle) .read(); // Scala val data = reader read(handle)
- 49.
- 50. Sample, Instance, andView State ☐ The samples included in the DataReader cache have associated Copyright 2011, PrismTech – All Rights Reserved. some meta-information which, among other things, describes the status of the sample and its associated stream/instance ☐ The Sample State (READ, NOT_READ) allows to distinguish between OpenSplice DDS new samples and samples that have already been read ☐ The View State (NEW, NOT_NEW) allows to distinguish a new instance from an existing one ☐ The Intance State (ALIVE, NOT_ALIVE_DISPOSED, NOT_ALIVE_NO_WRITERS) allows to track the life-cycle transitions of the instance to which a sample belongs
- 51. State Selector inAction Copyright 2011, PrismTech – All Rights Reserved. // Read only new samples auto data = reader C++ Scala .selector() // Read only new samples .filter_state(status::DataState::new_data()) val data = reader read .read() OpenSplice DDS // Read any samples from live instances // Read any samples from live instances val data = reader read(SampleSelector.AnyData) auto data = reader .selector() .filter_state(status::DataState::any_data()) .read()
- 52. Putting all Together Copyright 2011, PrismTech – All Rights Reserved. ☐ Selectors can be composed in a flexible and expressive manner OpenSplice DDS C++ auto data = reader ! .selector() .instance(handle) ! ! .filter_state(status::DataState::new_data()) ! ! .filter_content(q) .read();
- 53. OpenSplice DDS S D D tandard
- 54. DDS Standard Ecosystem Application Application Copyright 2011, PrismTech – All Rights Reserved. 2012 API 2012 DDS RMI DDS RMI 2012 2010 2010 2012 ANSI C ISO C++ Java-5 Scala OpenSplice DDS 2004 2010 2010 201x Security Security X-Types X-Types DDS 2004 Wire Protocol DDSI-RTPS network DDSI-RTPS 2006 2006
- 55. Concluding Remarks Copyright 2011, PrismTech – All Rights Reserved. ☐ The Data Distribution Service for Real-Time Systems provides a powerful and feature-rich topic-based publish/subscribe abstraction OpenSplice DDS ☐ This technology is widely used in mission and business critical systems and it being swiftly adopted in data- centric/big-data systems
- 56. References Copyright 2011, PrismTech – All Rights Reserved. OpenSplice | DDS Escalier ¥ #1 OMG DDS Implementation ¥ Fastest growing JVM Language ¥ Scala API for OpenSplice DDS ¥ Open Source ¥ Open Source ¥ Open Source ¥ www.opensplice.org ¥ www.scala-lang.org ¥ github.com/kydos/escalier OpenSplice DDS [C++] [Java] DDS-PSM-Cxx 2010 ¥ Simple C++ API for DDS ¥ DDS-PSM-Java for OpenSplice DDS ¥ DDS-PSM-Cxx API Standard ¥ Open Source ¥ Open Source ¥ Open Source ¥ code.google.com/p/simd-cxx ¥ github.com/kydos/simd-java ¥ github.com/kydos/dds-psm-cxx
- 57. :: Connect withUs :: ¥opensplice.com ¥forums.opensplice.org ¥@acorsaro ¥opensplice.org ¥opensplicedds@prismtech.com ¥@prismtech OpenSplice DDS ¥ crc@prismtech.com ¥sales@prismtech.com ¥youtube.com/opensplicetube ¥slideshare.net/angelo.corsaro