Some quick notes about software development

Cloud Architecture

Topic	Description
Web Services	Very small service which provides a single functionality with it’s own database or table and which were consumed by other services. Used in service oriented architecture.
Microservices	Small services which have there own database and but sharing tables by an ID. They are tied by the business domain. They are connected with an event bus.
SOA	Service Oriented Architecture was popular between 2003 and 2009. Reusabal web services with SOAP, REST or RPC was the key focus.
DDD	Domain Driven Design is currently very popular. It the design pattern which Microservices following.
Event Sourcing	It is used to store events in a database table which is more or less a state of a system. An event could be a set of change events of all microservices. It is possible to recreate a state from the past to reproduce or analyze bugs. EventStore is currently very popular tool and a key component of DDD.

RabbitMQ

Topic	Description
vhost	Used to separate tenants virtually so that they have their own RabbitMQ instance with queues, etc. . A physical alternative is to host multiple RabbitMQ instances.
Exchange	Used by the producer as single point where the events gets delivered to. An exchange can be connected between 1 or N receiver queueus.
Queue	Used by the receiver of events. After reading and acknowledging the reception the event will be purged from the queueu.