SSIS Package is a program that contains logic for ETL process. This logic may include workflow required to transfer data or perform data transformation. It is a collection on of atomic and distinct tasks required for the task at hand.
The SSIS Package can be compiled into a .DTSX file. This file is XML based file and contain all of the connections, properties required for execution of .DTSX file. This file can also be deployed to a SQL Server database.
.DTSX file format is shown below:
Notable features of this file are: connections, variables, executables and constraints all required by this particular SSIS Package.