DDS in a Nutshell
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DDS in a Nutshell

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This presentation gives a brief, semi-technical introduction to Data Distribution Service (DDS) technology from the Object Management Group. The focus is on the business benefits of the technology ...

This presentation gives a brief, semi-technical introduction to Data Distribution Service (DDS) technology from the Object Management Group. The focus is on the business benefits of the technology generally, not on RTI's implementation in particular.

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DDS in a Nutshell DDS in a Nutshell Presentation Transcript

  • DDS in a Nutshell Data-Centric Architecture and the Data Distribution Service The Global Leader Rick Warren rick.warren@rti.com in DDS Director of Technical Solutions© 2011 Real-Time Innovations, Inc.
  • Stuff You Will Learn DDS is data-centric messaging. 1.  What is “data-centricity” anyway? 2.  Why is it a good way to build and integrate systems? 3.  What’s special about DDS?© 2011 Real-Time Innovations, Inc. 2
  • Data-Centricity by Example: Calendaring Alternative Process #1: 1.  Email: “Meeting Monday at 10:00.” 2.  Email: “Meeting moved to Tuesday.” 3.  Email: “Here’s dial-in info for meeting…” 4.  You: “Where do I have to be? When?” 5.  You: (sifting through email…)© 2011 Real-Time Innovations, Inc. 3
  • Data-Centricity by Example: Calendaring Alternative Process #2: 1.  Calendar: (add meeting Monday at 10:00) 2.  Calendar: (move meeting to Tuesday) 3.  Calendar: (add dial-in info) 4.  You: “Where do I have to be? When?” 5.  You: (check calendar)© 2011 Real-Time Innovations, Inc. 4
  • Data-Centricity by Example: FaceBook Alternative Process #1:   Use the FaceBook web site. Alternative Process #2:   The web site doesn’t exist.   Deduce your friends’ information based on the notifications FaceBook sends you.© 2011 Real-Time Innovations, Inc. 5
  • What’s the Difference? State.   Things have attributes and characteristics “State” (“data”) is a –  The meeting will run 1:00–2:00 snapshot of those in the conference room. –  My friend’s phone number is attributes and 555-1234 and he’s currently characteristics. grooming his cat. –  The car is blue and is traveling north from Sunnyvale at 65 mph.   …whether they exist in the Best Practice: real world, in the computer, or both operate on state   …whether or not we observe directly, not dialogs or acknowledge them about state.© 2011 Real-Time Innovations, Inc. 6
  • Data-Centric = the part of you care about Describing the world as it is at a certain point in time Implication: State of the world can be maintained by infrastructure, not each app© 2011 Real-Time Innovations, Inc. 7
  • Not Data-Centric = Saying anything else   “Hey you: go do this.”   “The thing changed in this way.” Implication: State must be inferred, reconstructed, managed by each app (Sometimes called “message-centricity”: focus on what’s said vs. what is)© 2011 Real-Time Innovations, Inc. 8
  • Why is it better to just describe the world?   Reconstructing the state of the world is hard. –  Must infer based on all previous messages –  Maintaining all these messages is expensive –  Each app makes these inferences => duplicate effort   People make mistakes. –  Many copies of state => may be different => bugs vs. –  Uniform operations on state => fewer bugs© 2011 Real-Time Innovations, Inc. 9
  • Why is it better (over time) to just describe the world? Consider integrating based on Function vs. Stateful Data …© 2011 Real-Time Innovations, Inc. 10
  • Why is it better (over time) to just describe the world?   Computers are   Integration effort stupid. doesn’t scale. –  Integrate based on what –  Integrate at level of to do function => must know => everything integrates everything you might do with everything else => future extension => effort scales with hard square of number of –  Integrate based on what apps exists –  Integrate at level of => do whatever you stateful data like; no one else cares => everything integrates => future extension with common model easy => effort scales with number of apps© 2011 Real-Time Innovations, Inc. 11
  • So it’s “better.” Who cares?   Faster to implement => Save time and money   Easier to integrate and update => Protect your investment   More reliable systems => Protect your business© 2011 Real-Time Innovations, Inc. 12
  • Before We Forget: the Definition For example, data structures in XSD A data-centric architecture: or IDL file. 1.  …is based on a data model that is: Calendar Event = •  Start Time –  Appropriately documented— •  Duration i.e. understandable by humans •  Location –  Formally defined— •  Organizer i.e. understandable by machines –  Discoverable—i.e. can be found during execution 2.  The data model is independent of any domain-specific functionality / application. –  i.e. made of nouns, not verbs 3.  The (instantiated) data model is the only authoritative source of state in the system.© 2011 Real-Time Innovations, Inc. 13
  • DDS: Observe & Respond to a Changing World Other technologies that support data-centricity: –  Databases: SQL –  Web: HTTP (mostly)   …assume the world changes slowly Not scalable   …use network resources inefficiently 100 apps => 100x load   …are highly centralized Slow A few updates/sec App App Server App App State App App UnreliableFailure here kills many apps 14
  • DDS: Observe & Respond to a Changing World DDS:   …allows you to observe frequent changes   …uses network resources efficiently   …is decentralized Fast Scalable Managed Reliable 100,000’s updates/sec Load indep. # apps with QoS No single pt. failure App App App App App App State: Data Bus© 2011 Real-Time Innovations, Inc. 15
  • DDS: Observe & Respond to a Changing World Army JBC-P replaced home-grown messaging w/ DDS:   Tracks 20x more objects with fewer failures   …with 90+% less code   …with 90+% lower CPU resources Fast Scalable Managed Reliable 100,000’s updates/sec Load indep. # apps with QoS No single pt. failure App App App App App App State: Data Bus© 2011 Real-Time Innovations, Inc. 16
  • How DDS Works DDS is data-centric messaging. That is,   Messaging as a technique   for distributing, accessing, and modifying stateful data App App App App App App Data Data in Motion at Rest e.g. DDS complements e.g. database© 2011 Real-Time Innovations, Inc. 17
  • How DDS Works: Concepts & Terminology   Domain: world you’re talking about   Topic: group of similar things Domain –  Similar structure (“type”) what (e.g. medical devices) –  Similar way they change how over time (“QoS”) when   Instance: individual (changing) thing Topic (e.g. EKG readings)   Sample: snapshot of an instance at a point in time Instance (e.g.   DataWriter: source of information readings from about part of the world (topic) EKG #42)   DataReader: observer of part of the world (topic)© 2011 Real-Time Innovations, Inc. 18
  • Conclusion   Data-centric architecture brings significant business benefits –  Save time and money during initial development –  Leverage existing investments as solutions evolve –  Protect mission-critical functions with resilient, highly available implementations   DDS supports data-centricity for dynamic systems –  Develop event-driven systems based on open standards –  Communicate more efficiently: •  Deliver existing capability with fewer hardware resources •  Deliver greater capability with the same hardware resources –  Avoid single points of failure with distributed P2P topology –  Monitor and govern data delivery quality of service© 2011 Real-Time Innovations, Inc. 19
  • Download a free evaluation of RTI Data Distribution Service, Thank You Professional Edition from www.rti.com/downloads© 2011 Real-Time Innovations, Inc. 20