Setting a field to read-only in which object would make the field read-only in all applications of the RESTful Application Programming model?

In the context of the RESTful Application Programming model, setting a field to read-only in the behavior definition ensures that this restriction is propagated across all applications utilizing that behavior. Behavior definitions serve as the central point for defining how data entities interact, including their attributes and their modes of access—read, update, or delete.

When a field is marked as read-only in the behavior definition, it specifies that the field cannot be altered through any application using that behavior, thus protecting the integrity of the data. This read-only status is effectively enforced across all service calls that involve that behavior, ensuring a consistent application of business rules.

Other options, such as projection views and service definitions, define how data is structured and accessed but do not enforce business rules regarding data modification. While metadata extensions can enhance the information available through the model, they do not control the access mode of specific fields across all applications. Thus, setting the field to read-only in the behavior definition is the most effective way to achieve the desired outcome within the RESTful framework.