Comparison of Event Choreography and Orchestration Techniques in Microservice Architecture

Microservice Architecture (MSA) is an architectural design pattern which was introduced to solve the challenges involved in achieving the horizontal scalability, high availability, modularity and infrastructure agility for the traditional monolithic applications. Though MSA comes with a large set of benefits, it is challenging to design isolated services using independent Database per Service pattern. We observed that with each micro service having its own database, when transactions span across multiple services, it becomes challenging to ensure data consistency across databases, particularly in case of roll backs. In case of monolithic applications using RDBMS databases, these distributed transactions and roll backs can be handled efficiently using 2 phase commit techniques. These techniques cannot be applied for isolated No-SQL databases in micro services. This research paper aims to address three things: 1) elucidate the challenges with distributed transactions and rollbacks in isolated No-SQL databases with dependent collections in MSA, 2) examine the application of event choreography and orchestration techniques for the Saga pattern implementation, and 3) present the fact-based recommendations on the saga pattern implementations for the use cases.