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MICROSERVICES BOUNDED CONTEXTS AND EVERYTHING IN BETWEEN vladikk

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@vladikk vladikk.com

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”95% of the words are spent extolling the benefits of “modularity” and that little, if anything, is said about how to achieve it” Glenford J. Myers Composite / Structured Design, 1974

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“MICROSERVICES FTW!!!!!!!!1” Me @ Internovus

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“MICROSERVICES FTW!!!!!!!!1” Me @ Internovus

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”95% of the words are spent extolling the benefits of “modularity” and that little, if anything, is said about how to achieve it” Glenford J. Myers Composite / Structured Design, 1974

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Decomposi/on Strategies Microservices Design Heuris/cs

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vladikk NAXEX / INTERNOVUS 01 BUSINESS DOMAIN

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Your Product Marketing
 Strategy Creatives Campaigns Sales
 Agents Optimization Profits

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vladikk DECOMPOSITION 02 STRATEGIES

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Bounded Contexts

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Business Domain Expert Software Developer ??? !!! Ubiquitous Language

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Campaigns Sales
 Agents Your Product Marketing
 Strategy Creatives Optimization Profits

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Campaigns Sales
 Agents Your Product Marketing
 Strategy Creatives Optimization Profits

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Sales Agent Campaign Manager ??? !!! LEAD?

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Conflicting models Different contexts Dividing the language/model Bounded Context

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MarkeCng Sales Lead Lead Funnel Campaign Placement Landing Page Agency Insertion Order Message Campaign Proposition Desk Conversion Contact CDR Bounded Contexts

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MarkeCng Service Sales Service DecomposiCon Strategy #1: Bounded Contexts

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MarkeCng

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MarkeCng Creative Catalog Contracts Billing Campaign Management Identity & Access Ads Optimization

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MarkeCng Sales Creative Catalog Contracts Billing Campaign Management Identity & Access Ads Optimization

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MarkeCng Sales Commissions Desks Sales
 Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ads Optimization Identity & Access

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Business (Sub)Domains

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Business Domain: Customer Acquisi/on Bounded Context: Marke/ng Bounded Context: Sales Subdomain: Crea/ve Catalog Subdomain: Campaigns Mngmt Subdomain: Ads Op/miza/on Subdomain: Contracts Mngmt Subdomain: CRM Subdomain: Sales Op/miza/on Subdomain: Commissions Subdomain: Desks Mngmt

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DecomposiCon Strategy #2: Subomains Campaign Management Service Content Catalog Service Desks Management Service CRM Service Users Service Billing Service

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Business EnCCes and Processes

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MarkeCng Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization

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MarkeCng Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Campaign Management Campaign Placement Funnel Banner Landing Page Website Zone Asset Publisher Target Market

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DecomposiCon Strategy #3: EnCCes Website Asset Target Market Broker Distribu/on Customer

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DecomposiCon Strategies Bounded Contexts Subdomains Business Entities and Processes

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SHOW ME THE MICROSERVICES!

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Bounded Contexts == Microservices ?

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Sales Agent Campaign Manager ??? !!! LEAD?

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MarkeCng Sales Lead Lead Funnel Campaign Placement Landing Page Agency Insertion Order Message Campaign Proposition Desk Conversion Contact CDR

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MarkeCng Sales Lead Lead Funnel Campaign Placement Landing Page Agency Insertion Order Message Campaign Proposition Desk Conversion Contact CDR

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MarkeCng Sales Lead Lead Funnel Campaign Placement Landing Page Agency Insertion Order Message Campaign Proposition Desk Conversion Contact CDR

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Lead Lead

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Lead Lead

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MarkeCng Creative Catalog Campaign Management Optimization Lead Sales Commissions Optimization CRM Lead Desks Telephony Support Contracts Billing Identity & Access

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Bounded Contexts Decomposi/on #1 Bounded Contexts Decomposi/on #2 Bounded Contexts Decomposi/on #3

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Bounded Context Consistency boundary of the language / model Define the biggest valid monoliths Required decomposition boundary

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Bounded Contexts == Microservices? No

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Campaign Management Campaign Placement Funnel Banner Landing Page Website Zone Asset Publisher Target Market Campaign Website Placement Funnel MarkeCng Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Bounded Contexts? No Subdomains? EnCCes?

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Campaign Management Campaign Placement Funnel Banner Landing Page Website Zone Asset Publisher Target Market Campaign Website Placement Funnel MarkeCng Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Bounded Contexts? No Subdomains? EnCCes?

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vladikk MICROSERVICES 03

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Service “A service is a unit of functionality exposed to the world” - Juval Lowy “A mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface” - OASIS

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“A service is a unit of functionality exposed to the world” - Juval Lowy “A mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface” - OASIS Service

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Service Interface “Any mechanism for getting data in or out of the service” - Randy Shoup

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Service Interface Synchronous: • Request / Réponse • Bulk ETL

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Service Interface Asynchronous: • Producing events • Consuming events Synchronous: • Request / Réponse • Bulk ETL

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Service Interface “Any mechanism for getting data in or out of the service” - Randy Shoup

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Service Interface

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Services ➜ Microservice

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A microservice is a service with a micro interface

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A microservice is a service with a micro interface

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Microservice = Microinterface Reducing coupling between services Limits reasons for change Easier to understand Better fault isolation More autonomy between services

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Microservice & Databases Microservices should own its database No external access Access through Microservice’s API only Database = infinite interface!

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But!

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1 Method = Perfect Microservice !!??

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STAFF ONLY STAFF ONLY

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The threshold upon which a system can be decomposed into microservices is defined by the use cases of the system that the microservices are a part of.

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Monolith Microservices Cost of Change

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Monolith Microservices Distributed
 Monolith Cost of Change

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Big Ball Of Mud Bounded Contexts Microservices Distributed Big Ball Of Mud Avg. Service Size

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Campaign Management Campaign Placement Funnel Banner Landing Page Website Zone Asset Publisher Target Market Campaign Website Placement Funnel Subdomains? EnCCes?

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”Global complexity … the complexity of the overall structure of a program or system. I.e., the degree of association or interdependence among the major pieces of a program” Glenford J. Myers Composite / Structured Design, 1974

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”Global complexity … the complexity of the overall structure of a program or system. I.e., the degree of association or interdependence among the major pieces of a program” Glenford J. Myers Composite / Structured Design, 1974

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”Global complexity … the complexity of the overall structure of a program or system. I.e., the degree of association or interdependence among the major pieces of a program” Glenford J. Myers Composite / Structured Design, 1974

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When you design a system…, then if the features can be broken into … loosely bound groups of rela>vely closely bound features, then that division is a good thing to be made a part of the design. This is just good engineering. Tim Berners-Lee Principles of design, 1998

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Services + Good Engineering = Microservices

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Its is not only necessary to make sure your own system is designed to be made of modular parts. It is also necessary to realize that your own system … should always be designed to be a part of another larger system. Tim Berners-Lee Principles of design, 1998

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A major part of this paper will be concerned with the ques>on of how good modularity can be achieved, that is, how modules can be chosen so as to minimize the connec5ons between them. Barbara Liskov A design methodology for reliable soIware systems, 1972

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A microservice is a service with a micro interface. The threshold upon which a system can be decomposed into microservices is defined by the use cases of the system that the microservices are a part of.

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A microservice is a service with a micro interface. The threshold upon which the system can be decomposed is defined by the use cases of the system that the microservices are a part of. …how to evaluate?

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vladikk DESIGN 04 HEURISTICS

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HeurisCc #1: Decompose to Bounded Contexts Do not implement conflicting models in the same service. 
 Always decompose to Bounded Contexts.

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HeurisCc #2: Don’t ”First Law of Distributed Object Design: 
 “Don’t distribute your objects” MarCn Fowler

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HeurisCc #2: Don’t Benefits Addi/onal
 Complexity

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Monolith: System design that undermines delivery of functional or non-functional requirements

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HeurisCc #2: Don’t Benefits Addi/onal
 Complexity

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HeurisCc #2: Don’t Benefits Addi/onal Complexity

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Core Supporting Generic

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Generic Subdomains No competitive advantage Everybody is implementing in the same way Complex business logic

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic

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MarkeCng Sales Commissions Desks Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Optimization Identity & Access Generic

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HeurisCc #3: Buy/Adopt Generic Subdomains Your System 3rd party product

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HeurisCc #3: Buy/Adopt Generic Subdomains Your System 3rd party product An/-Corrup/on Layer

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Core Subdomains Inventing something new Optimizing existing paractices Competitive advantage Complex business logic Change often

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MarkeCng Sales Commissions Desks Sales
 Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core

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MarkeCng Sales Commissions Desks Sales
 Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core

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Core Subdomains Inventing something new Optimizing existing paractices Competitive advantage Complex business logic Change often

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HeurisCc #4: Core Subdomains - Don’t Rush Adhere to subdomain’s boundaries. Decompose further only when you acquire domain knowledge.

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SupporCng Subdomains No competitive advantage Support the Core Subdomains Can’t be bought / adopted Simple business logic

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core Supporting

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core Supporting

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core Supporting

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core Supporting

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core Supporting

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MarkeCng Sales Commissions Desks Sales Optimization CRM Telephony Creative Catalog Contracts Billing Campaign Management Identity & Access Ad Optimization Identity & Access Generic Core Supporting

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SupporCng Subdomains No competitive advantage Support the Core Subdomains Can’t be bought / adopted Simple business logic

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HeurisCc #5: SupporCng Subdomains - Safe Safe to decompose beyond the subdomain’s boundaries.

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Core Supporting Generic

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HeurisCc #6: Evaluate Consistency Requirements Method A Method B

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HeurisCc #6: Evaluate Consistency Requirements Concurrency control? - Same service Method A Method B 
 Service A

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HeurisCc #6: Evaluate Consistency Requirements Read last write? - Two services, synchronous communication 
 Service A Method A 
 Service B Method B Sync call

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HeurisCc #6: Evaluate Consistency Requirements Eventual consistency? - Two services, asynchronous communication 
 Service A Method A 
 Service B Method B Asynchronous Communication

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HeurisCc #6: Evaluate Consistency Requirements Concurrency control? - Same service Read last write? - Two services, sync communication Eventual consistency? - Two services, async communication

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 Service A Method A 
 Service B Method B Asynchronous Communication

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HeurisCc #7: Public / Private Events Service Event Type 1 Event Type 2 Event Type 3 Event Type 4 Event Type 5 Event Type 6 Event Type 1000 …

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HeurisCc #7: Public / Private Events Service Event Type 1 Event Type 2 Event Type 3 Event Type 4 Event Type 5 Event Type 6 Event Type 1000 … Private event types (Implementation details) }

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HeurisCc #7: Public / Private Events Service Event Type 1 Event Type 2 Event Type 3 Event Type 4 Event Type 5 Event Type 6 Event Type 1000 … Private event types (Implementation details) }Public event types (Public interface) }

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Service HeurisCc #7: Public / Private Events

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Service EmailChanged PhoneNumberChanged AddressChanged HeurisCc #7: Public / Private Events

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Service EmailChanged PhoneNumberChanged AddressChanged HeurisCc #7: Public / Private Events

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Service EmailChanged PhoneNumberChanged AddressChanged ContactDetailsChanged HeurisCc #7: Public / Private Events

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Service EmailChanged PhoneNumberChanged AddressChanged ContactDetailsChanged Private event types (Implementation details) } Public event type (Public interface) } HeurisCc #7: Public / Private Events

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HeurisCc #7: Public / Private Events Events?

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HeurisCc #7: Public / Private Events Events? Domain Events

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HeurisCc #7: Public / Private Events Events? Domain Events State Change
 Events

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HeurisCc #7: Public / Private Events Events? Domain Events State Change
 Events Private Public

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HeurisCc #8: Make Events Explicit Eliminate ambiguity

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HeurisCc #8: Make Events Explicit Service AgentAssignedToLead

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HeurisCc #8: Make Events Explicit Service AgentAssignedToLead AgentAssignedToLead AgentAssignedToLead

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HeurisCc #8: Make Events Explicit Service AgentAssignedToLead AgentUnassignedToLead AgentAssignedToLead

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HeurisCc #8: Make Events Explicit Service AgentAssignedToLead AgentUnassignedToLead AgentAssignedToLead

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HeurisCc #9: Evaluate Reasons for Change Service A Service B

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Same reasons for change? Same rate of change? Can be decoupled? Should be the same service? HeurisCc #9: Evaluate Reasons for Change

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HeurisCc #10: Evaluate Services’ “Doors”

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HeurisCc #10: Evaluate Services’ “Doors” STAFF ONLY STAFF ONLY

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HeurisCc #10: Evaluate Services’ “Doors” STAFF ONLY STAFF ONLY

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vladikk WRAP UP 05

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1. A service is a unit of func/onality exposed to the world through its public interface. 2. A microservice is a service with micro interface 3. The “micro-interface” is rela/ve to the use cases of the system that the service is a part of

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Heuris/c #1: Always decompose to Bounded Contexts Heuris/c #2: Don’t go further, unless you have to Heuris/c #3: Buy/adopt generic subdomains Heuris/c #4: Core subdomains - don’t rush Heuris/c #5: Suppor/ng subdomains can be decomposed early

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Heuris/c #6: Evaluate Consistency Requirements Heuris/c #7: Private / Public Events Heuris/c #8: Explicitly Define Events Heuris/c #9: Evaluate Reasons for Change Heuris/c #10: Evaluate Services’ “Doors”

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Big Ball Of Mud Bounded Contexts Microservices Distributed Big Ball Of Mud Avg. Service Size

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Bibliography 1. A Design Methodology for Reliable Soeware Systems, Barbara Liskov 2. Composite/Structured Design, Glenford Myers 3. Domain-Driven Design: Tackling Complexity in the Heart of Soeware, Eric Evans 4. Emerging Boundaries, Mathias Veraes 5. Implemen/ng Domain-Driven Design, Vaughn Vernon 6. Enterprise Integra/on Paherns, Gregory Hohpe, at al 7. Long Sad Story of Microservices, Greg Young 8. Managing Data in Microservices, Randy Shoup 9. Microservices, At Last Some Boundaries, Eric Evans 10. On the Criteria to be Used in Decomposing Systems Into Modules, David Parnas 11. Paherns of Enterprise Applica/on Architecture, Mar/n Fowler, at al 12. Principles of Design, Tim Berners-Lee 13. Programming WCF Services, Juval Lowy 14. What Every Programmer Should Know About Object Oriented Design, Melir Page-Jones

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QUESTIONS? @vladikk vladikk.com

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THANK YOU! @vladikk vladikk.com