The document discusses the evolution of the first public API in the hospitality industry by Mews, outlining its purpose, design, and encountered issues such as polling inefficiencies and security concerns. It emphasizes the importance of simplicity, documentation, and maintainability while providing advice on change management and the evolution of APIs. Key takeaways include the need for performance improvements and effective monitoring to enhance user experience and API reliability.

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Make it remarkable.
24.11.2022
Evolution of the first
public API in the
hospitality industry
Peter Vitéz

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Agenda
﹢What is Mews?
﹢Why public API?
﹢Design API
﹢EncounteredProblems
﹢Polling is a problem
﹢Missing categorization
﹢Fetchingrelated entities
﹢Frequent outages
﹢General advices / best practices
﹢Change management
﹢Documentation
﹢Quality assurance
﹢Summary

3. What is Mews?
﹢Not only hotel software
﹢3100 hotels around the globe
﹢650 employees – HQ Prague
﹢80.000 daily bookings
Tech:
﹢.NET + React
﹢Azure
﹢Stateless Monolith
﹢Single multi-tenant SQL Database

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Why public API?
• Expand current functionality
• Domain expertise outside Mews
• Engineers' shortages
• Process automation
• Speed up companygrowth

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Design API
• Simplicityand convenience
• Inspired by JSON Pure
• Everything in body
• POSTonly
• Avoid using headers
• Flat API structure
• Marketplace

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Encountered issues

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Polling is a problem
Encountered issues
• Data synchronizationin external systems
• Polling mechanism
• Increased traffic on our API
• Not scalable& inefficient

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Addressing polling issue
Encountered issues
• Websocket
• Server holds the connection
• Webhook v1
• Serialize only changed entities
• Clients swamped with data
• Webhook v2
• Serialize only IDs of changed entities
• On-demand data consumption

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Poor security &
discoverability
Encountered issues
• Increasing amount of integrationpartners
• Variousdomainsavailablethrough API
• Security threat
• Poor categorizationand discoverability

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Adding permissions
Encountered issues
• Each entity RO/RW/None permissions
• Introduce certificationprocess
• Better categorization
• Better control

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Fetching related entities
Encountered issues
• Too many “get” calls
• Subsequent callsto retrieve relatedand
nested entities
• Not idealuser experience

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Introducing “extent”s
Encountered issues
• Define whatyou wantto receive
• Simplicity and convenience
• Logic similar to SQL and GraphQL
• Clients love this addition
• Problems with Extents
• Limit 1:M relationshipsin API
• Performance issues
• Difficultto paginaterelated entities

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Frequent outages
Encountered issues
• Cloud resources are expensive
• Clients misusing our API
• Overprovisionedinfrastructure
• Outages or system slowness

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Rate Limiting
Encountered issues
• Throttling & Quotas
• Async cancellation
• Reward early adopters
• Lesson learned: Cut before reaching our code
• Ideally consider using API management tools
• Azure
• Gravitee

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General advices

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Change management
Generaladvices
• API mustevolve
• How to communicatechanges
• Newsletter
• Distributionlist
• Monitor usages
• Establish the process with peers
• Lesson learned: deprecated codefor 5+ years

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Documentation
Generaladvices
• Documentation
• Describes the API
• Documentation as Code
• Technical writer
• Open API Specification (Swagger)
• Automatic SDK generation

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Maintainability
Generaladvices
• Monitoring & Observability
• Log every request
• Dashboards & alerts
• Traces & metrics
• Anonymization

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Summary
﹢Sometimes less is more– don’t reinventthe wheel
﹢Hard to do systematic changes – evolution is a must
﹢Performance–polling is bad, outages hinder reputation
﹢If you wantto improvesomething, measureit
Mews Open API documentation