The correct answer is: B. ESB
An ESB (Enterprise Service Bus) is a software solution that enables the integration of different applications and services. It provides a communication layer that allows applications to communicate with each other regardless of their underlying technology.
XML (Extensible Markup Language) is a markup language that is used to define data structures and to represent data in a human-readable format. It is not a middleware layer.
UDDI (Universal Description, Discovery and Integration) is a platform-independent, open framework for describing services. It is not a middleware layer.
The following figure shows an example of an ESB architecture:
The ESB in this architecture provides a communication layer between the different applications and services. It also provides a number of features that make it easier to integrate applications, such as message routing, transformation, and mediation.
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