[Notes from Pinal]: SSIS is very well explored subject, however, there are so many interesting elements when we read, we learn something new. A similar concept has been Using Project Connections in SSIS.
In SQL Server Integration Services, connection managers are used as gateways for most any external read and write operation. Connection managers are type- and format-specific, and in the case of relational database connection managers, they are usually specific to vendor (Oracle, DB2, etc.) as well.
In most use cases, the same connection will be used across multiple packages in the same project. In pre-2012 versions of SSIS, each package would have its own connection manager for every connection used in that package. Creating and maintaining all those connection managers could be time-consuming as the number of packages grows. In SQL Server 2012, Microsoft added project connections to SSIS, allowing for the creation of connections that were accessible across all packages in a project. Instead of having to create a copy of each connection manager in every package, developers can now simply create the connection at the project level. Project connections will automatically show up in the connection manager tray for all packages in that project.
As shown, any project connection automatically has the designation (project) prepended to the name to clearly indicate that it is a project connection. Those without this designation are package connections, and are only accessible from within that package.
Project connections will also appear in the Solution Explorer window, under the Connection Managers tab.
You can create a new project connection by right-clicking on the Connection Managers node shown above, and walking through the steps to build the connection. Similarly, you can edit or delete an existing project-level connection manager from this same window.
You can also promote an existing package connection to a project connection by right-clicking on the package connection and selecting Convert to Project Connection.
Coincidentally, you can also convert back to a package connection through a similar process. Right-clicking on a project connection will expose an option to Convert to Package Connection. However, you have to be careful when choosing this option. If you convert a project connection to a package connection, that connection will then be visible only in the package in which you are currently working. If you have used the connection in any other packages in that project, those operations will fail because the connection is no longer visible at the project level. You will get a warning message when you attempt to convert a project connection to a package connection.
Finally, if you are using project connections, you can still use dynamic properties such as expressions and parameters. Do be aware that, if you use parameters to configure a project connection, you must use project parameters rather than package parameters. The latter is not accessible beyond the scope of a single package, and therefore would not always be accessible for project connections. Fortunately, the UI for the expression builder limits you to only project parameters when configuring project connections.
In conclusion, the project connection in SSIS is an excellent tool for configuring connections at the project level to minimize the extra work required for sharing connections across multiple packages in a project.
Reference: Pinal Dave (https://blog.sqlauthority.com)