CS 395-2 QoS-enabled Middleware Design & Application

CS 395-2CS 395-2QoS-enabled Middleware Design & QoS-enabled Middleware Design &

ApplicationApplication

Dr. Douglas C. [email protected]

www.dre.vanderbilt.edu/~schmidt/cs395/

Professor of EECS Vanderbilt University Nashville, Tennessee

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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

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•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

•[email protected]

•Deepti’s office hours will be announced shortly

•Please send all questions to [email protected]

• I’ll send the answers to the class mailing list

The Need for QoS-enabled Technologies

ScaleReal-Timeliness

Near Real-Time Fault-Tolerant Information

PRocessing

Near Real-Time Fault-Tolerant Information

PRocessing

Throughput, Availability

Real-Time Information Processing

Real-Time Information Processing

Determinism

Systemic Signal

Processing

Systemic Signal

Processing

Data Processing

Data Processing

Parallelism

Complex Information Management

Complex Information Management

Scalability, Persistence, Security

Parallel Systems Distributed Systems

• 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

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

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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-SpecificServices

CommonMiddleware Services

DistributionMiddleware

Host InfrastructureMiddleware

& OS

Operating Systems & Protocols

Applications

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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

UDP TCP

IP

TELNET

Ethernet ATM FDDI

Fibre Channel

FTP

INTERNETWORKING ARCH

TFTP

20th Century

Win2K Linux LynxOS

Solaris VxWorks

Middleware

MiddlewareServices

MiddlewareApplications

MIDDLEWARE ARCH

21st Century

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-SpecificServices

CommonMiddleware Services

DistributionMiddleware

Host InfrastructureMiddleware

Synchronization

MemoryManagement

PhysicalMemoryAccess

AsynchronousEvent Handling

Scheduling

AsynchronousTransfer of

Control

www.rtj.org

•Examples•Java Virtual Machine (JVM), Common Language Runtime (CLR), ADAPTIVE Communication Environment (ACE)

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Distribution Middleware•Distribution middleware defines higher-level distributed programming models whose reusable APIs & components automate & extend native OS capabilities

Domain-SpecificServices

CommonMiddleware Services

DistributionMiddleware

Host InfrastructureMiddleware

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

ClientOBJREF

Object(Servant)

in argsoperation()

out args + return

IDLSTUBS

IDLSKEL

Object Adapter

ORB CORE GIOP

Protocol Properties

End-to-End PriorityPropagation

ThreadPools

StandardSynchronizersExplicit

Binding

Portable Priorities

SchedulingService

en.wikipedia.org/wiki/Data_Distribution_Servicerealtime.omg.org/

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Common Middleware Services•Common middleware services augment distribution middleware by defining higher-level domain-independent services that focus on programming “business logic”

Domain-SpecificServices

CommonMiddleware Services

DistributionMiddleware

Host InfrastructureMiddleware

•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

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Domain-Specific Middleware

Modalitiese.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-SpecificServices

CommonMiddleware Services

DistributionMiddleware

Host InfrastructureMiddleware

Boeing Bold Stroke • Common software

platform for Boeing avionics mission computing systems

•Examples

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Overview of CORBA

InterfaceRepository

IDLCompiler

ImplementationRepository

ClientOBJREF

Object(Servant)

in argsoperation()out args +

return

DIIIDL

STUBSORB

INTERFACE

IDLSKEL

DSI

Object Adapter

ORB CORE GIOP/IIOP/ESIOPS

•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

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Overview of Real-time CORBA 1.0

ClientOBJREF

Object(Servant)

in argsoperation()

out args + return

IDLSTUBS

IDLSKEL

Object Adapter

ORB CORE GIOP

Protocol Properties

End-to-End PriorityPropagation

ThreadPools

StandardSynchronizersExplicit

Binding

Portable Priorities

SchedulingService

• 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

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

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

Comparing CORBA & DDS

ServerServer

ClientClient

ServerServer

ClientClient

ServerServer

ClientClient

ServerServer

ClientClient

CORBA Characteristics

• Distributed object model

• Remote method calls

• Connection-oriented transport

Best forRemote command processing

• File transfer

• Synchronous & asynchronous transactions

CORBA Characteristics

• Distributed object model

• Remote method calls

• Connection-oriented transport

Best forRemote 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

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

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Application

CORBA

DDS

CORBA

DDS