Which of the following is a capability in computer science that permits client software to converse
with database server software?

A.
Transaction object

B.
ScriptManager.Scripts

C.
Database connection

D.
ObjectDataSource

Explanation:
Database connection is a capability in computer science that permits client software to converse
with database server software. A connection is necessary to send commands and receive answers.
Connections are a key theory in data-centric programming. Some DBMS engines need considerable
time to connect to connection pooling to improve performance. No command can be performed
against a database without an “open and available” connection to it.
Connections are built by providing a primary driver or provider with a Connection String that is a way
of addressing a particular database or server and instance user authentication credentials. For
example, Server=sql_box;Database=Common;User ID=uid;Pwd=password. When a connection has
been built, it can be opened and closed and the properties can be set. The Connection String is
composed of a set of key/value pairs as specified by the data access interface and the data provider
being used. Some databases only permit one operation to be performed at a time on each
connection, others do not force this restriction. However, databases providing several operations
per connection acquire more overheads than those permitting only a single operation task at a time.
Answer B is incorrect. The ScriptManager.Services property gets a ServiceReferenceCollection
object that contains a ServiceReference object for each Web service that ASP.NET exposes on the
client for AJAX functionality. This property returns an object that is a collection of ServiceReference
objects, each of which represents a Web service that is registered with the ScriptManager control.
Answer D is incorrect. The ObjectDataSource class is used to represent a business object. The
business object gives data to data-bound controls in multi-tier Web applications. The
ObjectDataSource class allows users to use an ASP.NET data source control while retaining their
three-tier application architecture. The ObjectDataSource class makes use of reflection to construct
instances of business objects and to call methods on them to insert, update, retrieve, and delete
data. The ObjectDataSource class constructs and destroys an instance of the class for each method
call. However, it does not contain the object in memory for the lifetime of the Web request.
Answer A is incorrect. A transaction object is used for allowing multiple SQL statements to be
processed as a group. Each transaction object represents the DTC transaction. The transaction object
exists for the life of the transaction. It should be released when the transaction completes. It is used
to begin, commit, or roll back a transaction.