Union Station

Service Orchestration Layer

• Denver Union Station was built in 1868
• Facilitated 80 trains a day by 6 different railroads
• Recently evolved to serve FasTrack light rails and bus network

• Client-side apps
• Communicate w/ multiple BE services
  • Provsioning
  • Analytics
  • Curveball
  • Credstore
  • Atlas

• works ok for single application
• redundancy as multiple applications share services
• inconsistency as applications evolve
  • some may enforce validation, others may not

• Multiple applications reusing the same library 
• As more applications consume library, becomes harder to enforce current versions.
• Urgent bug fixes are harder to propogate/deploy across multiple applications
• Each application requires redundant configuration

3rd times a charm

dedicated service orchestration layer

• tailor-fit apis for your app
• smaller area of focus gets better results
• fast results - time from ideation to realization is low

• Communicate with various apis/services
• Normalize data/api for UI
• Separation of Responsibilities

• I/O fits well w/ javascript's asynchronous nature
• Lightweight, low overhead

• Local Mac development can be painful
  • yck, yca, ysecure, ostauth
  • dev proxy solutions

• Simplifies FE App Development
  • less dependencies
  • easier to follow for new team members
  • single client module for client/server
  • move quicker

• Leaner applications
• Less error prone
• Consistent error handling
• Move quicker

• UI can focus on UI
• Service Orchestration gets the attention it deserves
• Each become easier to test
• Each can scale independently

• Node.js
• Hapi.js by Walmart Labs
  • stable & reliable
  • eases api development
  • eases api testing
  • free api documentation
  • consistent i/o validation
  • plugin architecture
  • consistent error handling
    • status codes

Existing Infastructure

• Manhattan
• Replicatr

• Partially Integrated into recommends.yahoo.com
  • Full integration, UI will only communicate w/ union-station
• Plugin-based architecture allows for new FE consumers
• Currently we tunnel calls to union-station from FE server
  • Look at using Media V2 ATS to mount union-station on FE domain directly, i.e. /api/... and remove the need to manually proxy

References

• dshaw @ sfhtm5l talk
  • https://www.youtube.com/watch?v=PZyDPthMMK8&list=PLOU2XLYxmsIJdTqYYVrz1k3XivqXxY-uL#t=3301
• hapi.js
  • http://hapijs.com/
• ​union-station related repositories
  • https://git.corp.yahoo.com/tripleplay/union-station
  • https://git.corp.yahoo.com/tripleplay/union-station-data
  • https://git.corp.yahoo.com/tripleplay/union-station-client

Union-Station

Brad Harris - bharris@yahoo-inc.com