ESB is fundamentally an architecture. It is a set of rules and principles for integration numerous applications together over a bus-like infrastructure. The core concept of the ESB is that you integrate different applications by putting a communication bus between them and then enable each application to talk to the bus. This decouples systems from each other, allowing them to communicate without dependency on or knowledge of other systems on the bus.
The ESB performs transformations of data models, handles connectivity, performs message routing, converts communication protocols and potentially manages the composition of multiple requests.
An ESB is an essential component of SOA, or Service Oriented Architecture, a software architecture emerged in the late 1990s. SOA defines a way to make software components reusable via service interfaces.
In theory, an ESB simplifies communication, messaging, and integration between services across the enterprise. Software application can simply connect to the ESB and leave it to the ESB to transform the protocols, route the messages, and transform into the data formats as required providing the interoperability to get the transactions executed.
While ESBs were deployed successfully in many organizations, in many other organizations the ESB came to be seen as the bottleneck. Making changes or enhancements to ine integration could destabilize others who used that same integration. Updates to the ESB middleware often impacted existing integrations. Because the ESB was centrally managed, application teams soon found themselves waiting in line for their integrations.
For a deeper dive, read this article.
Microservices architecture enables the internals of a single application to be broken up into small pieces that can be independently changed, scaled, and administered. Microservices emerged and gained steam with the rise of virtualization, cloud computing, Agile development practices, and DevOps.
Microservices offers the following:
- Improved developer agility and productivity
- Simpler, more cost effective scalability
- Greater resilience
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