What does ASYMMETRICAL DATA MANIPULATION MEAN

Question

Dear all,

Im reading about Linq , and i came across this paragraph:

"In fact, when programming with .NET 3.5/C# 2008, you can (and will) certainly make direct use of ADO.NET, the XML namespaces, reflection services, and the various collection types. However, the basic problem is that each of these APIs is an island unto itself, which offers very little in the way of integration. True, it is possible (for example) to save an ADO.NET DataSet as XML, and then manipulate it viathe System.Xml namespaces, but nonetheless, data manipulation remains rather asymmetrical. The LINQ API is an attempt to provide a consistent, symmetrical manner in which programmers can obtain and manipulate “data” in the broad sense of the term. Using LINQ, we are able to create directly within the C# programming language entities called query expressions. These query expressions are based on numerous query operators that have been intentionally designed to look and feel very similar (but not quite identical) to a SQL expression.

Question1 :can anybody tell me what they mean by SYMMETRICAL DATA MANIPULATION?

Question2: can anybody explains this for me : Many developers find it very difficult to move from the strongly typed object oriented world of c# to the data tier where the objects are second class citizens ( this is also from an article of LINQ to SQL)

i know what strongly typed object oriented means but i have no idea what the second part of the sentence is !thank u :):)

Answer 1

I think that what the author is really just talking about consistency when he talks about symmetry.

He makes the point that the various pre-LINQ APIs for manipulating different kinds of data are all very different. LINQ is an attempt to provide a consistent programming model over different kinds of data. So LINQ introduces a kind of symmetry to data from a database, data from an XML document or from a .NET collection.

As for the second question, programmers are normally more comfortable working with data and logic in an object-oriented model. However that data is often stored in a relational database, which has a very different way of representing data based on set theory. So saving objects to a relational database and retrieving them again is not a smooth process, though there are tools that help, LINQ being one.