C++ Network Programming with Patterns, Frameworks, and ACE

306 Pages·2004·3.82 MB·English

C++ Network Programming with Patterns,
Frameworks, and ACE
Douglas C. Schmidt
Professor Department of EECS
[e-mail] Vanderbilt University
www.cs.wustl.edu/ schmidt/ [phone]
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Sponsors
NSF, DARPA, ATD, BBN, Boeing, Cisco, Comverse, GDIS, Experian, Global MT,
Hughes, Kodak, Krones, Lockheed, Lucent, Microsoft, Mitre, Motorola, NASA, Nokia,
Nortel, OCI, Oresis, OTI, QNX, Raytheon, SAIC, Siemens SCR, Siemens MED,
Siemens ZT, Sprint, Telcordia, USENIX
Advanced ACE Tutorial Douglas C. Schmidt
Roadmap to Levels of Middleware
Observations
AAPPPPLLIICCAATTIIOONNSS
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– Historically, apps
HHUUDD AAVVIIOONNIICCSS
DDOOMMAAIINN--SSPPEECCIIFFIICC MMIIDDDDLLEEWWAARREE SSEERRVVIICCEESS WWTTSS RREEPPLLIICCAATTIIOONN
NNaavv SSEERRVVIICCEE built atop OS
CCoonnss – Today, apps built
EEVVEENNTT CCoonnss
CCOOMMMMOONN MMIIDDDDLLEEWWAARREE SSEERRVVIICCEESS
CCHHAANNNNEELL
CCoonnss atop middleware
– Middleware has
DDIISSTTRRIIBBUUTTIIOONN MMIIDDDDLLEEWWAARREE
multiple layers
HHOOSSTT IINNFFRRAASSTTRRUUCCTTUURREE MMIIDDDDLLEEWWAARREE Just like network
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protocol stacks
OOPPEERRAATTIINNGG SSYYSSTTEEMMSS && PPRROOTTOOCCOOLLSS
HHAARRDDWWAARREE DDEEVVIICCEESS
www.cs.wustl.edu/˜schmidt/PDF/
middleware-chapter.pdf
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Motivation for Concurrency
SERVER
Leveragehardware/software
maxfdp1
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read_fds
CLIENT
WORK – e.g., multi-processors and OS
REQUEST
thread support
WORK WORK WORK
CLIENT REQUEST REQUEST REQUEST
Increaseperformance
CLIENT CLIENT
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(1)
ITERATIVE SERVER – e.g., overlap computation and
communication
SERVER
Improveresponse-time
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CLIENT
WORK
– e.g., GUIs and network servers
REQUEST
WORK WORK WORK
CLIENT REQUEST REQUEST REQUEST Simplifyprogramstructure
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CLIENT CLIENT
– e.g., sync vs. async
(2)
CONCURRENT SERVER
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Motivation for Distribution
PRINTER
Collaboration connectivityand
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interworking
COMPUTER
FILE
Performance multi-processing
CD ROM SYSTEM
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and locality
(1) STAND-ALONE APPLICATION ARCHITECTURE
Reliability and availability
TIME (cid:15) !
NAME CYCLE replication
SERVICE
SERVICE SERVICE
DISPLAY Scalability and portability
SERVICE
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modularity
FI LE
NETWORK SERVICE
Extensibility dynamic
PRINT (cid:15) !
SERVICE configurationandreconfiguration
CD ROM
PRINTER FILE SYSTEM Cost effectiveness open
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(2) DISTRIBUTED APPLICATION ARCHITECTURE systemsand resourcesharing
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Challenges and Solutions
Developing efficient, robust, and extensibleconcurrent networking
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applications is hard
– e.g., must address complex topics that are less problematic or not
relevant for non-concurrent, stand-alone applications
OO techniques and OO language features help to enhance software
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quality factors
– Key OO techniques include patternsand frameworks
– Key OO language features include classes, inheritance, dynamic
binding, and parameterizedtypes
– Key software quality factors include modularity, extensibility,
portability, reusability, and correctness
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Caveats
OO is nota panacea
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– Though when used properly it helps minimize “accidental”
complexity and improve software quality factors
It’s also essential to understand advanced OS features to enhance
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functionality and performance, e.g.,
– Multi-threading
– Multi-processing
– Synchronization
– Sharedmemory
– Explicitdynamiclinking
– CommunicationprotocolsandIPCmechanisms
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Tutorial Outline
Brief overview of key OO networking and concurrency concepts and
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OS platform mechanisms
– Emphasis is on practicalsolutions
Examine a range of examples in detail
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– NetworkedLoggingService
– ConcurrentWebServer
– Application-levelTelecomGateway
– CallCenterManagerEventServer
Discuss general concurrent programming strategies
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Provide URLs for further reading on the topic
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Software Development Environment
The topics discussed here are largely independent of OS, network,
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and programming language
– Currently used successfully on UNIX/POSIX, Windows, and
RTOS platforms, running on TCP/IP networks using C++
Examples are illustrated using freely available ADAPTIVE
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Communication Environment (ACE) OO framework components
– Although ACE is written in C++, the principles covered in this
tutorial apply to other OO languages
– e.g., Java, Eiffel, Smalltalk, etc.
In addition, other networks and backplanes can be used, as well
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Sources of Complexity
PRINTER Inherent complexity
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COMPUTER – Latency
FILE – Reliability
CD ROM SYSTEM
– Synchronization
(1) STAND-ALONE APPLICATION ARCHITECTURE – Deadlock
TIME
NAME SERVICE CYCLE Accidental Complexity
SERVICE SERVICE
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DISPLAY
SERVICE – Low-level APIs
FI LE
– Poor debugging tools
NETWORK SERVICE
– Algorithmic
PRINT
SERVICE decomposition
CD ROM
– Continuous
PRINTER FILE SYSTEM
re-invention
(2) DISTRIBUTED APPLICATION ARCHITECTURE
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Sources of Inherent Complexity
Inherent complexity results from fundamental domain challenges,
e.g.:
Concurrent programming Distributed programming
Eliminating “race conditions” Addressing the impact of latency
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Deadlock avoidance Fault tolerance and high availability
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Fair scheduling Load balancing and service
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partitioning
Performance optimization
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and tuning Consistent ordering of distributed
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events
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