Many business critical systems are built using SOA (Service Oriented Architecture). These days as the amount of data and users have increased exponentially, some of these SOA systems have resorted to desperate measures like stringing together dozens of *synchronous* API calls to fulfill simple operations like inventory look up. This not only results in high cost for performance but also high costs for maintaining these system. This talk attempts to show some of deficiencies of legacy architecture like SOA and how these are addressed in e-commerce by using modern techniques like Event Sourcing. We will heavily leverage the cloud in doing so. As a result, we will use some Serverless principles to handle the plumbing and coding.