Integration middleware is software that is used to fill the gaps between applications and databases. That means it allows remote systems to communicate with one another and even do transformations between systems.
Integrations allow businesses to potentially save a lot of money by reducing duplicate data entry, reducing licensing costs, and allowing systems to interact end to end.
Understanding what Salesforce Integration Pattern to use is vital to a successful Salesforce implementation. Choosing the wrong pattern can result in a really weak architecture that fails regularly, or costs a lot.
An enterprise service bus (ESB) is a software architecture that allows for the integration of enterprise applications and services.
Since an enterprise service bus is a middle layer communication tool there are a number of great features that might exist.