Interoperable, Extensible and Efficient System Architectures
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The document discusses the importance of interoperability, extensibility, and efficiency in system architectures, specifically focusing on OpenSplice DDS and data-centric architectures (DCAs). It defines various levels of interoperability and extensibility, as well as the efficiency of data formats, illustrating these concepts with examples. The document concludes that DCAs provide a framework conducive to achieving these principles, supported by DDS as the underlying middleware technology.
![Data-Centric Architecture (DCA)
Abstract Definition
A Data Centric Architecture consists of:
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☐ Abstract Data Types: A, B, C, ...
☐ Arrows: f, g, h, ...
where arrows satisfy the following properties:
OpenSplice DDS
Given f: A → B, g: B → C, and h: C → D
then the following holds true:
∃ g ∘ f: A → C [Composition]
∃ 1A : A → A [Identity Arrow]
h ∘ (g ∘ f) = (h ∘ g) ∘ f [Associativity]
f ∘ 1A = f = 1B ∘ f [Unit]
A Data Centric Architecture is a Category](https://image.slidesharecdn.com/2013-01-23-ieesa-cready-130207093710-phpapp02/85/Interoperable-Extensible-and-Efficient-System-Architectures-25-320.jpg)
![Example: Space Traveller [1/3]
☐ Suppose we want to create a
distributed game in which we have
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2011,
PrismTech
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(some) UFOs that are trying to
destroy our spaceship
☐ UFO can be our allies/enemies and
can be played by other players or
OpenSplice DDS
computers
☐ Some UFOs, might just be space
travellers and should not be
destroyed
☐ The goal of the game is to destroy
the UFOs that have been classified
as threats](https://image.slidesharecdn.com/2013-01-23-ieesa-cready-130207093710-phpapp02/85/Interoperable-Extensible-and-Efficient-System-Architectures-27-320.jpg)
![Example: Space Traveller [2/3]
☐ The DCA for this game could be described as follows
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(keeping it simple...)
Data Types Arrows
OpenSplice DDS
☐ FlyingObject ☐ animate: Dynamics → Dynamics
☐ Dynamics ☐ classify: FlyingObject x Dynamics → Classification
☐ Classification ☐ collide: [FlyingObject x Dynamics] → [Collision]
☐ Collision ☐ pilot: IO → Dynamics x FlyingObject
☐ fire: IO → FlyingObject x Dynamics
☐ display: FlyingObject x Dynamics x Classification x Collision
→ IO](https://image.slidesharecdn.com/2013-01-23-ieesa-cready-130207093710-phpapp02/85/Interoperable-Extensible-and-Efficient-System-Architectures-28-320.jpg)
![Example: Space Traveller [3/3]
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2011,
PrismTech
–
All
Rights
Reserved.
FlyingObject FlyingObject
IO pilot Dynamics animate Dynamics classify Classification
Dynamics Dynamics
OpenSplice DDS
FlyingObject
FlyingObject [FlyingObject] Dynamics
IO fire [Dynamics]
collide [Collision] display IO
Dynamics Classification
Collision](https://image.slidesharecdn.com/2013-01-23-ieesa-cready-130207093710-phpapp02/85/Interoperable-Extensible-and-Efficient-System-Architectures-29-320.jpg)
![Example: Space Traveller [3/3]
Copyright
2011,
PrismTech
–
All
Rights
Reserved.
FlyingObject FlyingObject
IO pilot Dynamics animate Dynamics classify Classification
Dynamics Dynamics
OpenSplice DDS
FlyingObject
FlyingObject [FlyingObject] Dynamics
IO fire [Dynamics]
collide [Collision] display IO
Dynamics Classification
Collision](https://image.slidesharecdn.com/2013-01-23-ieesa-cready-130207093710-phpapp02/85/Interoperable-Extensible-and-Efficient-System-Architectures-50-320.jpg)
Interoperable, Extensible and Efficient System Architectures
- 1. Interoperable, Extensible and Efficient System Architectures OpenSplice DDS Angelo CORSARO, Ph.D. Chief Technology Officer OMG DDS Sig Co-Chair PrismTech angelo.corsaro@prismtech.com
- 3. SESAR: The Single Sky ☐ Enable operational interoperability Copyright 2011, PrismTech – All Rights Reserved. across ATM/ATC in EU ☐ Allow information to flow seamlessly within the ATC/ATM OpenSplice DDS ecosystem and across Europe ☐ Ensure the system is incrementally extensible and evolvable ☐ Ensure the system makes efficient use of resources such as network
- 4. Smart City / Smart Grid Copyright 2011, PrismTech – All Rights Reserved. ☐ Make relevant information available in real-time to an open ended number of OpenSplice DDS consumers ☐ Ensure interoperability with third parties, efficient use of resources and extensibility
- 6. Defining Interoperability Copyright 2011, PrismTech – All Rights Reserved. The ability of two or more systems or components to exchange information and to use the information that has been exchanged. OpenSplice DDS
- 7. Syntactic Interoperability Copyright 2011, PrismTech – All Rights Reserved. ☐ The ability of two or more systems to communicate and exchange data ☐ Requires specified data formats and communication protocols OpenSplice DDS ☐ Syntactical Interoperability is a necessary condition for higher- level of interoperability
- 8. Semantic Interoperability Copyright 2011, PrismTech – All Rights Reserved. ☐ The ability to meaningfully and accurately interpret exchanged information ☐ Semantic interoperability requires communication parties to agree OpenSplice DDS on a common information model
- 9. Interoperability in Summary Copyright 2011, PrismTech – All Rights Reserved. ☐ Interoperability requires agreements at a syntactic and semantic level ☐ Syntactic Interoperability is commonly achieved by agreeing OpenSplice DDS a communication protocol and a data representation standard ☐ Semantic Interoperability is commonly achieved by agreeing on a Common Information Model
- 10. Measuring Interoperability Copyright 2011, PrismTech – All Rights Reserved. Based on the previous definitions we can define 3 levels of interoperability: OpenSplice DDS ☐ Level 0: No Interoperability (closed interfaces) ☐ Level 1: Syntactic Interoperability (open protocol/data format) ☐ Level 2: Semantic Interoperability (common information model)
- 11. Example: Syntactic Interoperability ☐ Suppose that we define legal messages as any word created over alphabet, more formally: Copyright 2011, PrismTech – All Rights Reserved. ☐ ∑ = {a, b, ..., z, ?, !} Che ora? ☐ words := { x ∈ ∑ } + ☐ sentence = words+ Sapresti dirmi OpenSplice DDS che ore sono? What? ☐ Example: ☐ Can Talk and hear w/o problems ☐ Don’t necessarily “understand”
- 12. Example: Semantic Interoperability ☐ Suppose now that we constrain our grammar to a subset of legal Copyright 2011, PrismTech – All Rights Reserved. English phrases: Thanks! Excuse me, do you OpenSplice DDS Sure, it’s 11 know the time? o’clock.
- 13. OpenSplice DDS Extensibility
- 14. Defining Extensibility Copyright 2011, PrismTech – All Rights Reserved. Extensibility is a systemic measure of the ability to extend a system and the level of effort required to implement the extension Extensions can be through the addition of new functionality or the OpenSplice DDS modification of an existing functionality Modularity and loose coupling foster extensibility
- 15. Forward Compatibility Copyright 2011, PrismTech – All Rights Reserved. ☐ Forward compatibility (at times considered as part of extensibility) OpenSplice DDS aims at the ability of a system to gracefully accept input intended for a later version of the system
- 16. Measuring Extensibility ☐ Extensibility can be measured w.r.t. the cost associated with Copyright 2011, PrismTech – All Rights Reserved. adding a new functionality to the system OpenSplice DDS Extensibility = CDNF/(CINF + CDNF) ☐ Where: ☐ CDNF: Cost of developing the new feature ☐ CINF: Cost of integration for the new feature ☐ For any system: 0 < Extensibility ≤ 1
- 17. Measuring Forward Compatibility Copyright 2011, PrismTech – All Rights Reserved. ☐ For simplicity we will assume that forward compatibility is binary, thus either is supported or not OpenSplice DDS ☐ In general, many systems support forward compatibility under certain conditions. Yet for our discussion it is OK to consider it as a binary property.
- 18. OpenSplice DDS Efficiency
- 19. Defining Efficiency Copyright 2011, PrismTech – All Rights Reserved. In general terms, efficiency describes the extent to which a valuable resource, such as time, space, network bandwidth, etc., is well used for the intended task of purpose OpenSplice DDS
- 20. Measuring Efficiency ☐ Efficiency can be measured as follows: Copyright 2011, PrismTech – All Rights Reserved. Efficiency = CO/CA OpenSplice DDS ☐ Where: ☐ CO: Optimal Cost to perform the given task/operation ☐ CA: Actual Cost to perform the given task/action ☐ For any system: 0 < Efficiency ≤ 1
- 21. Example: Data Encoding Copyright 2011, PrismTech – All Rights Reserved. ☐ As an example of efficiency, let’s consider different data encoding for a relatively simple Temperature Sensor ☐ Let’s assume a very simple temperature sensor defined as OpenSplice DDS follows: struct TempSensor { short temp; short hum; };
- 22. Example: Data Encoding Copyright 2011, PrismTech – All Rights Reserved. TempSensor t = {35, 75}; CDR JSON OpenSplice DDS byte 0 1 2 3 byte 0 1 2 3 { “ t e 0 23 0 4B m p “ : 3 5 , “ h u m “ 4 bytes : 7 5 } 16 bytes
- 23. Example: Data Encoding ☐ Let’s compute now the efficiency. If we ignore variable length Copyright 2011, PrismTech – All Rights Reserved. encoding, then the cost of encoding two short integers is 4 bytes, thus CO = 4 bytes ☐ CDR Efficiency. The actual cost of encoding our temperature sensor OpenSplice DDS in CDR was CA = 4 bytes this leads to EfficiencyCDR = 4/4 = 1 ☐ JSON Efficiency. The actual cost of encoding our temperature sensor in JSON was CA = 16 bytes this leads to EfficiencyJSON = 4/16 = 0.25 ☐ Note: We have taken a few short cuts here since a formally sound derivation of CO should have considered the entropy of the data source. Instead we have silently assumed a binary entropy function.
- 25. Data-Centric Architecture (DCA) Abstract Definition A Data Centric Architecture consists of: Copyright 2011, PrismTech – All Rights Reserved. ☐ Abstract Data Types: A, B, C, ... ☐ Arrows: f, g, h, ... where arrows satisfy the following properties: OpenSplice DDS Given f: A → B, g: B → C, and h: C → D then the following holds true: ∃ g ∘ f: A → C [Composition] ∃ 1A : A → A [Identity Arrow] h ∘ (g ∘ f) = (h ∘ g) ∘ f [Associativity] f ∘ 1A = f = 1B ∘ f [Unit] A Data Centric Architecture is a Category
- 26. Data-Centric Architecture (DCA) Copyright 2011, PrismTech – All Rights Reserved. The abstract definition of a Data-Centric Architecture formally captures its key properties: ☐ The Abstraction Barrier is defined in terms of Abstract Data Types OpenSplice DDS ☐ The System Behaviour is specified in terms of transformations (functions or arrows) over these Abstract Data Types Note: From this emerges a natural relationship between DCA and Functional Programming Languages
- 27. Example: Space Traveller [1/3] ☐ Suppose we want to create a distributed game in which we have Copyright 2011, PrismTech – All Rights Reserved. (some) UFOs that are trying to destroy our spaceship ☐ UFO can be our allies/enemies and can be played by other players or OpenSplice DDS computers ☐ Some UFOs, might just be space travellers and should not be destroyed ☐ The goal of the game is to destroy the UFOs that have been classified as threats
- 28. Example: Space Traveller [2/3] ☐ The DCA for this game could be described as follows Copyright 2011, PrismTech – All Rights Reserved. (keeping it simple...) Data Types Arrows OpenSplice DDS ☐ FlyingObject ☐ animate: Dynamics → Dynamics ☐ Dynamics ☐ classify: FlyingObject x Dynamics → Classification ☐ Classification ☐ collide: [FlyingObject x Dynamics] → [Collision] ☐ Collision ☐ pilot: IO → Dynamics x FlyingObject ☐ fire: IO → FlyingObject x Dynamics ☐ display: FlyingObject x Dynamics x Classification x Collision → IO
- 29. Example: Space Traveller [3/3] Copyright 2011, PrismTech – All Rights Reserved. FlyingObject FlyingObject IO pilot Dynamics animate Dynamics classify Classification Dynamics Dynamics OpenSplice DDS FlyingObject FlyingObject [FlyingObject] Dynamics IO fire [Dynamics] collide [Collision] display IO Dynamics Classification Collision
- 30. Data-Centric vs. Service-Centric Data-Centric and Service-Centric architectures, such as SOA, Distributed Objects, etc., differ in several dimensions: Copyright 2011, PrismTech – All Rights Reserved. ☐ Abstraction Barrier: ☐ Data-Centric architectures rely on data abstractions ☐ Service-Centric architectures rely on service abstractions OpenSplice DDS ☐ Level of Coupling ☐ Data-Centric architectures rely solely on the shared knowledge of abstract data types (agree on the “what”) ☐ Service-Centric architectures rely on the shared knowledge of operational interfaces along with the knowledge of the service provider and of its existence (agree on “what”, “who”, and “when”)
- 31. DCA Benefits ☐ Loose Coupling Copyright 2011, PrismTech – All Rights Reserved. ☐ Anonymicity (e.g. only things to be known are the data types and not who produces/consumes them) Composability (especially when combined with functional OpenSplice DDS ☐ languages) ☐ Extensibility ☐ Ease of Integration ☐ Performance (easier to parallelize)
- 32. DCA Interoperability Copyright 2011, PrismTech – All Rights Reserved. ☐ To enable Interoperability DCA should rely on middleware technology that provides a Level 2 Interoperability OpenSplice DDS ☐ In other terms, middleware technologies that define ☐ open/standard communication protocols ☐ open/standard data representation format, and ☐ open/standard ways of describing a Common Information Model
- 33. DCA Extensibility ☐ Extensibility is enabled by DCA through modularity, composability Copyright 2011, PrismTech – All Rights Reserved. and loose coupling ☐ Modularity is tied to the granularity of the “arrows/functions” that defined in the system OpenSplice DDS ☐ Composability follows from the properties (refer to definition) of DCA ☐ Loose coupling follows from the fact that the only “contract” between the different element of a system are the abstract data types and nothing else. Neither topological nor existential informations, e.g. it does not matter if there are consumer for a given type T nor how many of those are there and where they are located
- 34. DCA Forward Compatibility Copyright 2011, PrismTech – All Rights Reserved. ☐ Forward compatibility depends entirely from the technology used to implement the DCA OpenSplice DDS ☐ However, the presence of a typed Common Information Model can facilitate the implementation of efficient and safe “forward compatibility” mechanism
- 35. Efficiency Copyright 2011, PrismTech – All Rights Reserved. ☐ The efficiency of a DCA depends on OpenSplice DDS ☐ The definition of the Common Information Model (e.g. its level of normalization), and ☐ The efficiency of the infrastructure used to implement the DCA
- 36. OpenSplice DDS DDS and DCA
- 37. DDS Core Standard Copyright 2011, PrismTech – All Rights Reserved. ☐ DDS is a family of Application standards addressing the Data Centric Publish Subscriber (DCPS) communication needs of Content Ownership Durability Data Centric Architectures Subscription OpenSplice DDS Minimum Profile ☐ The two standards at the core are: DDS Interoperability Wire Protocol - DDSI-RTPS ☐ DDS v1.2 -- API UDP/IP Application ☐ DDSI v2.1 -- Wire Protocol
- 38. 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
- 39. DCAs with DDS Copyright 2011, PrismTech – All Rights Reserved. ☐ DDS provides first class support for DCAs ☐ DCAs Abstract Data Types are captured in DDS via Topics OpenSplice DDS ☐ DDS does not provide primitive support for specifying DCAs Arrows. These are defined by the architect using her/his favorite formalism / programming language
- 40. DDS Topics “net.gva.VehiclePosition” ☐ A Topic defines a typed data Copyright 2011, PrismTech – All Rights Reserved. stream Name ☐ A Topic has associated a data type and QoS Topic Typ S OpenSplice DDS Qo ☐ The Topic name, type and QoS DURABILITY, e DEADLINE, defines the key functional and PRIORITY, … non-functional invariants struct Position2D { ☐ Topics can be discovered or long long vid; //@Key x; locally defined }; long y;
- 42. DDS: Level 2 Interoperability Copyright 2011, PrismTech – All Rights Reserved. Semantic Common “Language” Interoperability Data Model + QoS Requirements OpenSplice DDS Interoperability Syntactic Interoperability DDSI Wire Interoperability
- 43. OpenSplice DDS DDS Application API Standard DDS: Portability Portability Copyright 2011, PrismTech – All Rights Reserved.
- 44. DDS: Extensibility & OpenSplice DDS Forward Compatibility
- 45. Extensibility Copyright 2011, PrismTech – All Rights Reserved. ☐ DDS-based applications feature all the extensibility benefits deriving from DCA OpenSplice DDS ☐ In addition, due to the built-in dynamic discovery, DDS-based Systems are completely decoupled from deployment details
- 46. Forward Compatibility Copyright 2011, PrismTech – All Rights Reserved. ☐ DDS supports Forward Compatibility, specifically, it allows for both monotonic as well as generalized type extensions OpenSplice DDS ☐ Monotonic type extensions allow old systems to consume new types as far as changes consist of additions to the tail of the type ☐ Generalized type extensions allows attribute reordering and removal
- 47. OpenSplice DDS Efficiency
- 48. DDS Efficiency OpenSplice DDS Performance Metrics The DDS standard was Copyright 2011, PrismTech – All Rights Reserved. ☐ designed in such a way to Latency maximize time and space ☐ 15-20 usec Inter-Core Latency efficiency ☐ 75 usec over GBps Ethernet OpenSplice DDS ☐ OpenSplice DDS has been Throughput designed to minimize ☐ Up to 10+M msg/sec inter-core resource usage while maximizing performance and ☐ Up to 5M msg/sec inter node scalability
- 49. Back to the Space Traveller OpenSplice DDS
- 50. Example: Space Traveller [3/3] Copyright 2011, PrismTech – All Rights Reserved. FlyingObject FlyingObject IO pilot Dynamics animate Dynamics classify Classification Dynamics Dynamics OpenSplice DDS FlyingObject FlyingObject [FlyingObject] Dynamics IO fire [Dynamics] collide [Collision] display IO Dynamics Classification Collision
- 51. Space Traveller Topic Types //@Nested //@Nested enum Classifier { struct Bounds { struct Vector { UNKNOWN, Copyright 2011, PrismTech – All Rights Reserved. long width; long x; FRIEND, long height; long y; THREAT}; }; }; struct Classification { struct FlyingObject { struct Dynamics { long oid; // @key long oid; //@Key long oid; //@Key Classifier kind; OpenSplice DDS long kind; Vector pos; }; Bounds bounds; Vector speed; }; }; struct Collision { long oid; long coid; };
- 53. SESAR: The Single Sky Copyright 2011, PrismTech – All Rights Reserved. ☐ Adopted the DDS standard as the foundation of their DCA OpenSplice DDS ☐ Defined and standardized a domain specific Common Information Model concerning flights and their management
- 54. City Service -‐ Architecture Urbio&ca APPLICATIONS User, City agent Urbio2ca MESH network City Message BUS – Opensplice DDS Data warehouse Esper – Park systems Exis2ng Control
- 55. UK Generic Vehicle Architecture Copyright 2011, PrismTech – All Rights Reserved. ☐ Adopted the DDS standard as the technology at the foundation of next generation military vehicles OpenSplice DDS ☐ Defined a domain specific Common Information Model -- the GVA Information Model
- 56. OpenSplice DDS Summing Up
- 57. Concluding Remarks Copyright 2011, PrismTech – All Rights Reserved. ☐ Interoperability, Extensibility and Efficiency is key for an increasing number of applications ☐ Data Centric Architectures (DCAs) provide an architectural OpenSplice DDS framework that facilitates the design of systems that are interoperable, extensible and efficient ☐ DDS is the middleware infrastructure that most naturally supports DCAs
- 58. OpenSplice DDS
- 59. 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 ¥ Simple C++ API for DDS ¥ DDS-PSM-Java for OpenSplice DDS ¥ DDS-based Advanced Distributed ¥ Open Source ¥ Open Source Algorithms Toolkit ¥ github.com/kydos/simd-cxx ¥ github.com/kydos/simd-java ¥ Open Source ¥ github.com/kydos/dada
- 60. :: Connect with Us :: ¥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