Ultra-Large-Scale (ULS) Ultra-Large-Scale (ULS) Systems & Systems & Their Impact on Technology & Their Impact on Technology & Society Society Friday, December 31, 2021 Friday, December 31, 2021 Dr. Douglas C. Schmidt [email protected]www.dre.vanderbilt.edu/~schmidt Vanderbilt University Nashville, Tennessee Institute for Software Integrated Systems
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Ultra-Large-Scale (ULS) Systems & Their Impact on Technology & Society Friday, September 11, 2015Friday, September 11, 2015Friday, September 11, 2015Friday,
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Ultra-Large-Scale (ULS) Systems Ultra-Large-Scale (ULS) Systems & Their Impact on & Their Impact on
CPU & network performance has increased by orders of magnitude in past decades
1,200 bits/sec to 10+ Gigabits/sec
The Road Ahead
Extrapolating these trends another decade or so yields• ~10 Gigahertz desktops• ~100 Gigabits/sec LANs• ~100 Megabits/sec wireless• ~10 Terabits/sec Internet backbone
10 Megahertz to 4+ Gigahertz
Unfortunately, software quality & productivity hasn’t improved as
rapidly or predictably as hardware – especially for mission- & safety-
critical systems
Example Mission- & Safety-Critical Systems
Why Hardware Improves So Consistently
Advances in hardware & networks stem largely from R&D on standardized & reusable APIs & protocols
x86 & Power PC chipsets TCP/IP
ApplicationSoftware
ApplicationSoftware
ApplicationSoftware
ApplicationSoftware
Why Software Fails to Improve as ConsistentlyIn general, software has not been as standardized or reusable as hardware, especially for DRE systems
New Challenges: Ultra-Large-Scale (ULS) SystemsA ULS System has unprecedented scale in some of these dimensions:
• Lines of code
• Amount of data stored, accessed, manipulated, & refined
• Number of connections & interdependencies
• Number of hardware elements
• Number of computational elements
• Number of system purposes & user perception of these purposes
• Number of routine processes, interactions, & “emergent behaviors”
• Number of (overlapping) policy domains & enforceable mechanisms
• Number of people involved in some way
• …
ULS systems are socio-economic ecosystems comprised of software-intensive systems, people, policies, cultures, & economics
ULS systems report is available from www.sei.cmu.edu/uls
Example Emerging ULS SystemsULS systems are systems of systems at Internet scale
ULS system examples from Linda Northrop’s OOPSLA 2006 keynote talk
Characteristics of ULS systems that arise because of their scale include
• Decentralization
• Inherently conflicting, unknowable, & diverse requirements
• Continuous evolution & deployment
• Heterogeneous, inconsistent, & changing elements
• Erosion of the people/system boundary
• “Normal” failures
• New paradigms for acquisition & policy
Scale Changes Everything
• These characteristics appear in some of today’s systems, but in ULS systems they dominate
• These characteristics undermine the assumptions that underlie today’s technology approaches, rendering incremental solutions inadequate
Serialized Phasing is Common in ULS Systems
Application components developed after
infrastructure is sufficiently mature
Software Lifecycle Timeline
Level of
Ab
stra
ctio
n
System infrastructure components developed
first
Software Lifecycle Timeline
Level of
Ab
stra
ctio
n
System integration & testing is performed after application development
is finished
Serialized Phasing is Common in ULS Systems
Integration Surprises!!!
Complexities of Serialized Phasing
Development Timeline
Level of
Ab
stra
ctio
n
Still in development
Ready for testingComplexities
• System infrastructure cannot be tested adequately until applications are done
Complexities of Serialized Phasing
Development Timeline
Level of
Ab
stra
ctio
n
End-to-end performance of
critical path?
System bottleneck?
Complexities
• System infrastructure cannot be tested adequately until applications are done
• Entire system must be deployed & configured (D&C) properly to meet end-to-end QoS requirements
• Existing tools & platforms have poor support for realistic “what if” evaluation
QoS needs of components in ULS systems often unknown until late in lifecycle
Promising Approach for ULS System Challenges:
System Execution Modeling (SEM) Tools
EnsureDesign
Conformance
Express &ValidateDesignRules
Conduct “What If”Analysis
Tools to express & validate design rules
• Help applications & developers adhere to system specifications at design-time
Tools to ensure design rule conformance
• Help properly deploy & configure applications to enforce design rules throughout system lifecycle
Tools to conduct “what if” analysis
• Help analyze QoS concerns prior to completing the entire system, i.e., before system integration phase
SEM tools should be applied continuously when developing software elements
SEM Tool Approach for Planning AspectApproach
• Develop Component Workload Emulator (CoWorkEr) Utilization Test Suite (CUTS) so architects & systems engineers can conduct “what if” analysis on evolving systems by
CUTS integrates nicely with continuous integration servers & test-driven development
3. Tools synthesize emulation code & configuration metadata to deploy system in target environment
4. Metrics are collected & analyzed to explore how design alternatives from multiple computational & valuation perspectives affect system QoS
1. Software architects, developers, & systems engineers specify structure of an enterprise DRE system
2. They associate necessary QoS characteristics with individual components (e.g., CPU utilization) or system as a whole
• Application components are represented as Component Workload Emulators (CoWorkErs)
• CoWorkErs can be interconnected by the PICML tool to form operational strings
• CoWorkErs are programmed using the Component Behavior Modeling Language (CBML)