1. CS 395-2 QoS-enabled Middleware Design & Application Dr. Douglas C. Schmidt d.schmidt@.vanderbilt.edu www.dre.vanderbilt.edu/~schmidt/cs395/ Professor of EECS Vanderbilt University Nashville, Tennessee

2. 2 CS 395 Course Philosophy Good design & programming is not learned by generalities, but by seeing how significant programs can be made clean, easy to read, easy to maintain & modify, human-engineered, efficient, & reliable, by the application of good design & programming practices. Careful study & imitation of good designs & programs significantly improves development skills. - Kernighan & Plauger

3. 3 Recommended reading CS 395 Course Information CS 395 class web page www.dre.vanderbilt.edu/ ~schmidt/cs395/ My office hours in Featheringill Hall 226 Mon 1:00 to 3:00pm Wed 1:00 to 3:00pm TA: Deepti Thopte deepti.s.thopte@Vanderbilt.Edu Deepti’s office hours will be announced shortly Please send all questions to d.schmidt@vanderbilt.edu d.schmidt@vanderbilt.edu I’ll send the answers to the class mailing list

4. The Need for QoS-enabled Technologies Scale Real-Timeliness Near Real-Time Fault- Tolerant Information PRocessing Throughput, Availability Real-Time Information Processing Determinism Systemic Signal Processing Data Processing Parallelism Complex Information Management Scalability, Persistence, Security Parallel SystemsDistributed Systems

5. Network Centric Architectures are emerging as a key trend for next generation military & civil system of systems Efficient, scalable & QoS-enabled technologies are an enabling technology for network-centric systems The Right Information => To the Right People => At the Right Time The Need for QoS-enabled Technologies

6. Common Requirements Shared Operational Picture ‣ Increasing need in real-time access to the common operational picture Increased Data Volumes ‣ Real-time dissemination of massive data volumes, often over large scale Loosely Coupled & Plug & Play ‣ Ability seamlessly support MANET, VANET, time, & space decoupling Interoperability ‣ Interoperability is a key enabler for achieving better performance & enabling new operational requirements

7. 7 The Solution is in the Middleware There are multiple COTS middleware layers & research/business opportunities Historically, mission-critical apps were built directly atop hardware Tedious, error-prone, & costly over lifecycles Standards-based COTS middleware helps: Control end-to-end resources & QoS Leverage hardware & software technology advances Evolve to new environments & requirements Provide a wide array of reusable, off- the-shelf developer-oriented services There are layers of middleware, just like there are layers of networking protocols Hardware Domain-Specific Services Common Middleware Services Distribution Middleware Host Infrastructure Middleware & OS Operating Systems & Protocols Applications

8. 8 Operating System & Protocols Operating systems & protocols provide mechanisms to manage endsystem resources, e.g., CPU scheduling & dispatching Virtual memory management Secondary storage, persistence, & file systems Local & remote interprocess communication (IPC) OS examples UNIX/Linux, Windows, VxWorks, QNX, etc. Protocol examples TCP, UDP, IP, SCTP, RTP, etc. RTP DNS HTTP UDPTCP IP TELNET EthernetATMFDDI Fibre Channel FTP INTERNETWORKING ARCH TFTP 20 th Century Win2KLinuxLynxOS Solaris VxWorks Middleware Services Middleware Applications MIDDLEWARE ARCH 21 st Century

9. 9 www.cs.wustl.edu/~schmidt/ACE.html Host Infrastructure Middleware Host infrastructure middleware encapsulates & enhances native OS mechanisms to create reusable network programming components These components abstract away many tedious & error-prone aspects of low-level OS APIs Domain-Specific Services Common Middleware Services Distribution Middleware Host Infrastructure Middleware Synchronization Memory Management Physical Memory Access Asynchronous Event Handling Scheduling Asynchronous Transfer of Control www.rtj.org Examples Java Virtual Machine (JVM), Common Language Runtime (CLR), ADAPTIVE Communication Environment (ACE)

10. 10 Distribution Middleware Distribution middleware defines higher-level distributed programming models whose reusable APIs & components automate & extend native OS capabilities Domain-Specific Services Common Middleware Services Distribution Middleware Host Infrastructure Middleware Distribution middleware avoids hard-coding client & server application dependencies on object location, language, OS, protocols, & hardware Examples OMG Real-time CORBA & DDS, Sun RMI, Microsoft DCOM, W3C SOAP en.wikipedia.org/wiki/Data_Distribution_Servicerealtime.omg.org/

11. 11 Common Middleware Services Common middleware services augment distribution middleware by defining higher-level domain-independent services that focus on programming “business logic” Domain-Specific Services Common Middleware Services Distribution Middleware Host Infrastructure Middleware Common middleware services support many recurring distributed system capabilities, e.g., Transactional behavior Authentication & authorization, Database connection pooling & concurrency control Active replication Dynamic resource management Examples CORBA Component Model & Object Services, Sun’s J2EE, Microsoft’s.NET, W3C Web Services

12. 12 Domain-Specific Middleware Modalities e.g., MRI, CT, CR, Ultrasound, etc. Siemens MED Syngo Common software platform for distributed electronic medical systems Used by all ~13 Siemens MED business units worldwide Domain-specific middleware services are tailored to the requirements of particular domains, such as telecom, e- commerce, health care, process automation, or aerospace Domain-Specific Services Common Middleware Services Distribution Middleware Host Infrastructure Middleware Boeing Bold Stroke Common software platform for Boeing avionics mission computing systems Examples

13. 13 Overview of CORBA CORBA shields applications from heterogeneous platform dependencies e.g., languages, operating systems, networking protocols, hardware Common Object Request Broker Architecture (CORBA) A family of specifications OMG is the standards body Over 800 companies CORBA defines interfaces, not implementations It simplifies development of distributed applications by automating/encapsulating Object location Connection & memory mgmt. Parameter (de)marshaling Event & request demultiplexing Error handling & fault tolerance Object/server activation Concurrency Security

14. 14 Overview of Real-time CORBA 1.0 Real-time CORBA adds QoS control to regular CORBA to improve application predictability, e.g., Bounding priority inversions & Managing resources end-to-end Policies & mechanisms for resource configuration/control in Real-time CORBA include: Processor Resources Thread pools Priority models Portable priorities Synchronization Communication Resources Protocol policies Explicit binding Memory Resources Request buffering These capabilities address some (but by no means all) important real-time application development challenges

15. Overview of the Data Distribution Service (DDS) High Performance real-time data-centric publish/subscribe middleware The right data, at the right place, at the right time—all the time Fully distributed, multicast-enabled, high performance, highly scalable, & high availability, hot-swap/hot-hot architecture Blends data-centric & real-time publish/subscribe technologies Content-based subscriptions, (continuous) queries, & filters Fine-grained, policy-based tuning of resource usage, data delivery, availability QoS Optimal networking & computing resources usage Global Data Space Loosely coupled Plug & play architecture with dynamic discovery Time & space decoupling Open standard OMG DDS v1.2 latest version www.omg.org/dds

16. DDS: Foundational Abstractions Information Model. Defines the structure, relations, & QoS, of the information exchanged by the applications, & supports flat, relational, & object-oriented modeling Typed Global Data Space. A logical data space in which applications read & write data anonymously & asynchronously, decoupled in space & time Publisher/Subscriber. Produce/Consume information into/from the Global Data Space QoS. Regulates the non-functional properties of information in the Global Data Space, e.g., reliability, availability, & timeliness, etc. Global Data Space

17. Comparing CORBA & DDS Server Client Server Client Server Client Server Client CORBA Characteristics Distributed object model Remote method calls Connection-oriented transport Best for  Remote command processing File transfer Synchronous & asynchronous transactions CORBA Characteristics Distributed object model Remote method calls Connection-oriented transport Best for  Remote command processing File transfer Synchronous & asynchronous transactions DDS Characteristics Data distribution model Relational collaborations Multicast transport Best for Quick dissemination to many nodes Dynamic networks Flexible QoS & delivery requirements DDS Characteristics Data distribution model Relational collaborations Multicast transport Best for Quick dissemination to many nodes Dynamic networks Flexible QoS & delivery requirements CORBA & DDS address different needs: Complex systems often need both

18. Distributed Application Planes Data Plane Ubiquitous, asynchronous, & real-time data access One-to-many & many-to-many distribution patterns Integration with Enterprise Data Layer, i.e., DBMS Control Plane Synchronous Command/Control interactions, often to actuate commands Mostly one-to-one interactions Management Plane A combination of asynchronous real-time access of data & command/control interactions One-to-one, one-to-many Control Plane Data Plane Management Plane Application CORBA DDS CORBA DDS