When configuring a data source using existing data, which of the following source types can you utilize?

When configuring a data source using existing data, using a database as a source type is appropriate because databases are foundational structures that store large volumes of data efficiently and are designed for interaction by applications such as Appian. They support structured queries and allow for data manipulation through SQL, which is essential for retrieving and managing data within Appian applications.

Databases also enable robust connections that can leverage existing data management practices, security protocols, and optimized performance characteristics. Moreover, Appian provides connectors and integration capabilities specifically tailored for various database types, enhancing data access and manipulation.

The other choices, while they represent different methods of accessing or interacting with data, are more specialized. Process models focus on the workflow and business logic rather than the direct querying of data. Salesforce objects pertain specifically to Salesforce's ecosystem and require additional integration considerations. Web services offer data exchange capabilities across different systems but may involve more complexity for managing existing data structures compared to a direct database connection.

Thus, utilizing a database is the most fitting choice for setting up a data source with existing data in Appian.