Architecture Without an End State

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The Typical Enterprise Architecture Proposal

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1. Start with a caricature

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2. Show the promise

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3. Pitch the plan Call Now 011 45 72 84 26

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1. Start with a caricature Current State

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2. Show the promise End State

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3. Pitch the plan Year 1 Year 2 Year 3 Vendor Selection & Pilot Legacy Conversion Converged Applications

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4. Start a new cycle Year 1 Year 2 Year 3 Year 1 Year 2 Year 3 Year 1 Year 2 Year 3 Year 1 Year 2 Year 3 Year 1 Year 2 Year 3 Current CIO’s vision Previous CIO’s boondoggle Legacy crap Legacy crap Legacy crap

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The “steady state” is a superposition of ongoing wavefronts of change.

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Complex Systems • No “grand narrative”, no privileged vantage point. • Only locally contextualized views • Many local optimizations • Global optimization not possible

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Complex Systems One person cannot know the complete ramiﬁcations of a decision.

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8 Rules 1. Embrace Plurality

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Single System Of Record TRUTH

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Like world peace, it exists only brieﬂy and is so very fragile. Like world peace, it exists only brieﬂy and is so very fragile.

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• Mergers & acquisitions • Partnerships • Divestitures • Entering new markets Obvious Challenges To SSoR

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• “We can only know what we can record.” • SSoR must choose one representation • “What is a customer?” • Any model enables some thoughts, disallows others. Epistemological Challenges

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Example: Getting SKUd • What is a Stock Keeping Unit (SKU)? • Can be sold • Must be shipped • Takes up shelf space • Has a price & cost • One SKU exists per “kind of thing” that can be sold • Does not track the individual inventory item

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Getting SKUd: Changes In One Year New Market Rendered Irrelevant Added Digital Downloads Shelf space, shipping, ﬁxed cost Tracking individual purchases Partner sales Controlled ID space Multiple prices & shippers per item Home Installation & Renovation 16,000,000 add’l SKUs

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COGS Distribution Stocking Presentation Pricing Delivery Inventory COGS Distribution Stocking Presentation Pricing Delivery Inventory Entitlements COGS Distribution Stocking Pricing Delivery Inventory Presentation Competing Deconstructions

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COGS Distribution Stocking Presentation Pricing Delivery Inventory All SKUs Competing Extents

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All SKUs Competing Extents Dark Matter

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Hardgoods Software Subscriptions Partners Services Packages Federated Extents

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Hardgoods Software Subscriptions Partners Services Packages Multiple Systems Of Record

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Focus on • Local authorities and spans • System of identiﬁers: URNs & URIs • Representations for interchange • Enable copies instead of eliminating them • Representations identify their contributors Multiple Systems Of Record

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Enablers • DNS • HTTP • XML Multiple Systems Of Record

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Consumers must assume open world • Cannot embed rules from all sources • Use service URLs to identify mechanics • E.g., “price me by posting to this URL” Multiple Systems Of Record

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8 Rules 1. Embrace Plurality 2. Contextualize Downstream

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Business Rules Are Contextual How much information is required? What is the lifecycle of the entity? What can it be used for in the current state? Answers will vary across business units.

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Example: Comparing Desk Sizes Equity Fixed-income HFT Frequency Size Execution Ratio per minute per day per microsecond 105 – 106 106 – 107 104 – 106 ~ 1:1 1:1 1:105

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Example: Auto Financing How many rules are the same between personal auto ﬁnancing and ﬂeet vehicle leasing?

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Upstream & Downstream

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Upstream & Downstream

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Upstream & Downstream

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Upstream & Downstream Augment Contextualize

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Apply policies in systems nearest the users. Those will change most often.

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Corollary: Minimize the entities that all systems need to know about.

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8 Rules 1. Embrace Plurality 2. Contextualize Downstream 3. Beware Grandiosity

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! Enterprise Data Dictionary

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! Enterprise Data Architecture

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! Global Object Model

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! “One World”

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Prerequisites For An Enterprise Modeling Project • Global perspective • Agreement across all business units • Talent for abstraction • Concrete experience in all contexts • Small enough team to make decisions

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How are industry standards different?

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Compromise

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The Modeling Fallacy All models are wrong. Some are useful.

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1. Seek compromises 2. Assume an open world 3. Begin small, incrementalize 4. Allow lengthy comment periods

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8 Rules 1. Embrace Plurality 2. Contextualize Downstream 3. Beware Grandiosity 4. Decentralize

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Decentralization Explore market space Explore market space Explore solution space

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Chaos? What about standards? What about duplication?

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Prerequisites • Transparency Methods, work, and results must be visible • Isolation One group’s failure cannot cause widespread damage • Economics Distributed economic decision-making

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Example: Boeing 777 Source: “Principles of Product Development Flow”, D. Reinertsen Aircraft Weight Cost 1 pound gross weight = $ 300 per plane

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Set Tradeoff Policies Centrally Deﬁne balancing forces globally. Allow local optimization.

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Misconception: Centralization == Leverage

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Leverage? Centralize IT ➞ Constant budget ﬁght, features vs. architecture. Playing “catch up” to business units.

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Leverage. Decentralize ➞ Slivers of other budgets, working toward shared beneﬁts.

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8 Rules 1. Embrace Plurality 2. Contextualize Downstream 3. Beware Grandiosity 4. Decentralize 5. Isolate Failure Domains

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Operational Failures

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Operational Failures

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Operational Failures

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Solution Space Failures Giant bet on a strategy? “Bet the company” means one shot.

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Value Of Modularity Splitting Substitution Augmenting Excluding Inversion Porting Source: “Design Rules: The Power of Modularity.”, Baldwin & Clark, 2000.

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Value Of Modularity Source: “Design Rules: The Power of Modularity.”, Baldwin & Clark, 2000. Options

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Value at exercise Proﬁt Negative Payoff (do not exercise) Positive Payoff Value Of An Option “long call”

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Value at exercise Proﬁt Negative Payoff (do not exercise) Positive Payoff Value Of An Option “long call”

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Negative Option Value Failed system or failed business unit == negative value option. Isolate the failure, use modularity options.

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Example: Trading Company Many small applications, integrated by messaging. Cheaper to rewrite than maintain individual apps.

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Example: Advertising Optimization Hundreds of auction/placement algos. “Developer anarchy.”

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Example: The Ultimate In Resilient Architecture CICS Transactions You can always ﬁt another screen in somewhere.

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Resilient architecture admits componentwise change.

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8 Rules 1. Embrace Plurality 2. Contextualize Downstream 3. Beware Grandiosity 4. Decentralize 5. Isolate Failure Domains 6. Data Outlives Applications 7. Applications Outlive Integrations

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Example: Mailing-list Vendor First list assembled: 1972 Still in operation: 2011 Data set is as old as I am.

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Database Technology ISAM VSAM Network Hierarchic Relational Graph KVS Document

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Integration Technology CICS FTP RPC Sockets RPC CD-ROM XML-HTTP RPC ESB

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Typical Layered Architecture UI Application Domain Persistence

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“Hexagonal Architecture” Or Ports & Adapters http://alistair.cockburn.us/Hexagonal+architecture System Boundary Admins Users Databases Feeds in ELinux: Disabled at runtime. SELinux: Unregistering netfilter hooks type=1404 audit(1316273329.901:2): selinux=0 auid=4294967295 ses=4294967295 input: PC Speaker as /class/input/input0 netfront: Initialising virtual ethernet driver. netfront: device eth0 has copying receive path. netfront: device eth1 has copying receive path. Floppy drive(s): fd0 is unknown type 15 (usb?), fd1 is unknown type 15 (usb?) Failed to obtain physical IRQ 6 floppy0: no floppy controllers found work still pending lp: driver loaded but no devices found md: Autodetecting RAID arrays. md: autorun ... Monitoring Metrics Feeds out Domain adapter adapter adapter adapter adapter adapter adapter

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Hexagonal Enterprise Architecture

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8 Rules 1. Embrace Plurality 2. Contextualize Downstream 3. Beware Grandiosity 4. Decentralize 5. Isolate Failure Domains 6. Data Outlives Applications 7. Applications Outlive Integrations 8. Increase Discoverability

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Omniscience is impossible. Facilitate coincidence instead.

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Improve by building on the work of others. It’s not eliminating duplication or reducing cost. But costs will come down as a result of being better.

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• Visible work: • Internal blogs • Open code repositories • Modern search engine (homegrown is ﬁne) Prerequisites

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• Contributions are disruptions • Inquiries are alarming. • They presage a budget annexation attack. Beware: Budget Culture

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• Default to open sharing • Every app should have links to: • Team blog • Bug submission • CI server Engineering Culture

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Foster engineering culture at the grass roots.

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You Probably Aren’t Either Of These Guys The Architect Vint Cerf

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Stop chasing the end state

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Abandon the 3 Year Plan Year 1 Year 2 Year 3 Vendor Selection & Pilot Legacy Conversion Converged Applications

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PHOTO CREDITS http://www.flickr.com/photos/geishaboy500 http://www.youtube.com/watch?v=08xQLGWTSag http://www.flickr.com/photos/vin60 http://www.flickr.com/photos/sergiu_bacioiu