When you are working with an Analysis Services database in project mode, SQL Server Data Tools (SSDT) creates an XML definition for each object within the project folder. You can view the contents of the XML file for each object within SQL Server Data Tools (SSDT). You can also edit the XML file directly; however, this is not recommended in most circumstances as you may make changes that make the XML unreadable by SQL Server Data Tools (SSDT).
You cannot view the xml code for an entire project, but rather you view the code for each object because a separate file exists for each object. The only way to view the code for an entire project is to build the project and view the ASSL code in the <project name>.asdatabase file.
To view the XML code for an object
Open the Analysis Services project in SQL Server Data Tools (SSDT).
Right-click the object in Solution Explorer and then click View Code.
The XML code for the object appears in SQL Server Data Tools (SSDT).