What is Nucleus? in ATG
Ans.Nucleus is ATG`s open Object Application Framework. ATG 7 is said to be a component-centric development platform. The ATG 7 Web applications are nothing but individual JavaBean components assembled together. These JavaBean components are configured and linked together by .properties files within Nucleus.
In Nucleus, each service is packaged as a JavaBean or set of JavaBeans. These JavaBeans are configured individually and mounted into a namespace. The beans then interconnect with the beans representing other services. Nucleus is responsible for interpreting the component configurations and the management of the component namespace.
Dynamo uses the Nucleus framework to organize components into a hierarchical structure (similar to a directory structure). Each Nucleus service has a unique Nucleus name. For example, the default javax.sql.DataSource component is located at /atg/dynamo/service/jdbc/JTDataSource
Nucleus is the core of the entire ATG system. It creates and configures Nucleus components (also called beans and JavaBeans) and organizes them into a hierarchical namespace, essentially giving them a place to live so they can be referenced by other components. By reading the .properties files associated with each component, Its Nucleus which figures out that which components are to be used in an application ,initializes them to their default values and how decides about how they connect to each other. This model makes it easier for the developers to build ATG applications by configuring and using the pre-built components instead of writing a lot of Java code from scratch.