Event Bus as Backbone for Decoupled Microservice Choreography (JFall 2017)

Editor's Notes

• #2: Microservices are independent, encapsulated entities that produce meaningful results and business functionality in tentative collaboration. Events and pub/sub are great for allowing such decoupled interaction. Using Apache Kafka as robust, distributed, real-time, high volume event bus, this session demonstrates how microservices implemented in Java, Node, Python and SQL collaborate unknowingly. The microservices respond to social (media) events - courtesy of IFTTT - and publish results to multiple channels. The event bus operates across cloud services and on premises platforms: both the bus and the microservices can run anywhere. presentation summary - intro microservices objectives, focus on decoupled collaboration - demo four mservices in different technologies; no direct dependencies - outline desired choreography, use of events and need of event bus - intro Kafka - demo pub and sub from each mservice to Kafka - link IFTTT to Kafka (for demo: use ngrok to expose local Kafka to IFTTT cloud) - demo end-to-end Social event=>IFTTT=>Kafka=>choreographed mservices=> final result - discuss cloud deployment of event bus + mservices
• #20: https://www.martinfowler.com/bliki/StranglerApplication.html https://dzone.com/articles/why-springboot
• #23: http://microservices.io/patterns/data/event-driven-architecture.html http://eventuate.io/whyeventdriven.html http://www.kennybastani.com/2017/01/building-event-driven-microservices.html
• #24: http://www.dreweaster.com/blog/2016/05/08/the-art-of-microservices-integration-using-service-choreography/ End-to-end autonomy (each microservice leverages event sourcing to maintain the state it needs (even though it does not own it) https://www.slideshare.net/CAinc/hypermediadriven-orchestration-in-microservices-55985377
• #34: Workflow initiator responds to NewTweetEvent Workflow Initiator - When tweet is for hashtag oraclecode then create routingslip document with tweet data, store in cache under key and publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload Validate Tweet – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if ValidateTweet should act; if so, validate tweet, update routing slip, retrieve and store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload Enrich Tweet – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if EnrichTweet should act; if so, enrich tweet, update routing slip, retrieve and store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload TweetBoard – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if TweetBoard should act; if so, add tweet to tweet list, update routing slip, retrieve-and-store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload All microservices publish logging about their actions with the conversation identifier as part of the logging
• #37: Workflow initiator responds to NewTweetEvent Workflow Initiator - When tweet is for hashtag oraclecode then create routingslip document with tweet data, store in cache under key and publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload Validate Tweet – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if ValidateTweet should act; if so, validate tweet, update routing slip, retrieve and store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload Enrich Tweet – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if EnrichTweet should act; if so, enrich tweet, update routing slip, retrieve and store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload TweetBoard – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if TweetBoard should act; if so, add tweet to tweet list, update routing slip, retrieve-and-store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload All microservices publish logging about their actions with the conversation identifier as part of the logging
• #40: Workflow initiator responds to NewTweetEvent Workflow Initiator - When tweet is for hashtag oraclecode then create routingslip document with tweet data, store in cache under key and publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload Validate Tweet – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if ValidateTweet should act; if so, validate tweet, update routing slip, retrieve and store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload Enrich Tweet – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if EnrichTweet should act; if so, enrich tweet, update routing slip, retrieve and store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload TweetBoard – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if TweetBoard should act; if so, add tweet to tweet list, update routing slip, retrieve-and-store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload All microservices publish logging about their actions with the conversation identifier as part of the logging
• #46: Workflow initiator responds to NewTweetEvent Workflow Initiator - When tweet is for hashtag oraclecode then create routingslip document with tweet data, store in cache under key and publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload Validate Tweet – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if ValidateTweet should act; if so, validate tweet, update routing slip, retrieve and store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload Enrich Tweet – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if EnrichTweet should act; if so, enrich tweet, update routing slip, retrieve and store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload TweetBoard – when OracleCodeTwitterWorkflow event – fetch workflow state from cache based on event payload, check routingslip to see if TweetBoard should act; if so, add tweet to tweet list, update routing slip, retrieve-and-store in cache; publish workflow event for OracleCodeTwitterWorkflow with cache key for workflow state in payload All microservices publish logging about their actions with the conversation identifier as part of the logging