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Ado.net session04
The document discusses connected and disconnected environments in ADO.NET. A connected environment maintains a constant connection to the data source, while a disconnected environment does not directly connect. It also covers synchronous and asynchronous operations using command objects, and how asynchronous commands can improve performance by executing in parallel. Methods like BeginExecuteReader() and EndExecuteReader() are used for asynchronous retrieval and completion of data.
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Ado.net session04
- 1. Developing Database ApplicationsUsing ADO.NET and XML Objectives In this session, you will learn to: Identify the connected and disconnected environment in ADO.NET Working in a connected environment Ver. 1.0 Session 4 Slide 1 of 14
- 2. Developing Database ApplicationsUsing ADO.NET and XML Introducing Connected and Disconnected Environment A connected environment is one in which a user or an application is constantly connected to a data source. A connected environment provides the following advantages: Data concurrency issues are easier to control. Data is current and updated. A connected environment has the following disadvantages: A constant network connection may, sometimes, lead to network traffic logging. Scalability and performance issues in applications. Let us now discuss the disconnected environment. Ver. 1.0 Session 4 Slide 2 of 14
- 3. Developing Database ApplicationsUsing ADO.NET and XML Introducing Connected and Disconnected Environment (Contd.) In a disconnected environment is one in which a user or an application is not directly connected to a data source. A disconnected environment provides the following advantages: Allows multiple applications to simultaneously interact with the data source. Improves the scalability and performance of applications. A disconnected environment has the following disadvantages: Data is not always up to date as no proper connection is established with the data source. Data concurrency issues can occur when multiple users are updating the data to the data source. Ver. 1.0 Session 4 Slide 3 of 14
- 4. Developing Database ApplicationsUsing ADO.NET and XML Introducing Connected and Disconnected Environment (Contd.) The following figure shows the connected and disconnected environment in ADO.NET. XML Data Source Ver. 1.0 Session 4 Slide 4 of 14
- 5. Developing Database ApplicationsUsing ADO.NET and XML Working with Command Objects A Command object is a specific command that is used to manipulate data in a data source in a connected environment. A Command object represents a DML statement or a stored procedure that is used to retrieve, insert, delete, or modify data in a data source. The two types of operations performed by a command object to retrieve and modify data in a data source are: Synchronous operations Asynchronous operations Let us discuss these operations in detail. Ver. 1.0 Session 4 Slide 5 of 14
- 6. Developing Database ApplicationsUsing ADO.NET and XML Working with Command Objects (Contd.) During synchronous operations, the command objects are linked to each other. Executing command objects synchronously results in a sequential execution, where each database command must complete before the next command is executed. Synchronous operations are performed with the help of the following command objects: DbCommand object Executes a command in a data source against a valid open connection DbParameters object Assigns parameterized values to stored procedures DbDataReader object Retrieves a forward-only, read-only data from the data source Ver. 1.0 Session 4 Slide 6 of 14
- 7. Developing Database ApplicationsUsing ADO.NET and XML Just a minute • Which method of the DbCommand object executes a DML statement against a connection and returns the number of rows affected? 1. ExecuteReader() 2. CreateObjRef() 3. ExecureNonQuery() 4. ExecuteScalar() Answer: 3. ExecuteNonQuery() Ver. 1.0 Session 4 Slide 7 of 14
- 8. Developing Database ApplicationsUsing ADO.NET and XML Working with Command Objects (Contd.) • Asynchronous execution of commands enhances the overall performance and responsiveness of the client application. • ADO.NET supports asynchronous execution of commands to enable parallelism by allowing the client application to execute commands while waiting for the response from a previously issued command. • The asynchronous execution of commands is carried out in the SQLCommand class. Ver. 1.0 Session 4 Slide 8 of 14
- 9. Developing Database ApplicationsUsing ADO.NET and XML Working with Command Objects (Contd.) • The SQLCommand class provides the following methods for asynchronous execution of commands: BeginExecuteNonQuery() Starts the process of asynchronously executing a Transact-SQL statement or stored procedure that does not return rows BeginExecuteReader() Starts the process of asynchronously executing a Transact-SQL statement or stored procedure that returns rows BeginExecuteXmlReader() Initiates the asynchronous execution of the Transact-SQL statement or stored procedure that is described by the SqlCommand and returns the result as an XMLReader object Ver. 1.0 Session 4 Slide 9 of 14
- 10. Developing Database ApplicationsUsing ADO.NET and XML Working with Command Objects (Contd.) EndExecuteNonQuery() Completes the asynchronous execution of a Transact-SQL statement or stored procedure EndExecuteReader() Completes the asynchronous execution of a Transact-SQL statement or a stored procedure, thereby, returning the requested SqlDataReader EndExecuteXmlReader() Completes the asynchronous execution of a Transact-SQL statement or a stored procedure, thereby, returning XML data Ver. 1.0 Session 4 Slide 10 of 14
- 11. Developing Database ApplicationsUsing ADO.NET and XML Working with Command Objects (Contd.) Another way of retrieving data asynchronously is by using Multiple Active Result Sets (MARS). MARS allows the execution of multiple data readers on a single connection. By default, MARS feature is disabled in an application. You can enable MARS in the connection string, as shown in the following code snippet: String connectionString = "Data Source=SQLSERVER01;Initial Catalog=AdventureWorks;User id=sa;Password=niit#1234; MultipleActiveResultSets=True"; Enabling MARS property to True Ver. 1.0 Session 4 Slide 11 of 14
- 12. Developing Database ApplicationsUsing ADO.NET and XML Just a minute • What is the function of the EndExecuteReader() method of the SqlCommand class? 1. Asynchronously executes a stored procedure that returns rows 2. Executes the stored procedure and returns the result as an XmlReader object 3. Asynchronously executes a stored procedure that does not return rows 4. Executes the stored procedure and returns the result as an SqlDataReader object Answer: 4. Executes the stored procedure and returns the result as an SqlDataReader object Ver. 1.0 Session 4 Slide 12 of 14
- 13. Developing Database ApplicationsUsing ADO.NET and XML Summary In this session, you learned that: A connected environment is one in which a user or an application is constantly connected to a data source. A disconnected environment is one in which a user or an application is not directly connected to a data source. The two types of operations performed by a command object to retrieve and modify data in a data source are: Synchronous operations Asynchronous operations During synchronous operations, the command objects are linked to each other. Synchronous operations are performed with the help of the following command objects: DbCommand object DbParameters object DbDataReader object Ver. 1.0 Session 4 Slide 13 of 14
- 14. Developing Database ApplicationsUsing ADO.NET and XML Summary (Contd.) ADO.NET supports asynchronous execution of commands to enable parallelism by allowing the client application to execute commands while waiting for the response from a previously issued command. The SqlCommand class provides the following methods for asynchronous operations: BeginExecuteNonQuery() BeginExecuteReader() BeginExecuteXmlReader() EndExecuteNonQuery() EndExecuteReader() EndExecuteXmlReader() MARS allows the execution of multiple data readers on a single connection. Ver. 1.0 Session 4 Slide 14 of 14
Editor's Notes
- #2 Introduce the students to the course by asking them what they know about forensics. Next, ask the students what they know about system forensics and why is it required in organizations dependent on IT. This could be a brief discussion of about 5 minutes. Lead the discussion to the objectives of this chapter.
- #3 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #4 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #5 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #6 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #7 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #8 In this slide you need to show the calculation to determine the sum of an arithmetic progression for bubble sort algorithm. Refer to student guide.
- #9 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #10 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #11 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #12 Introduce the students to the different types of threats that systems face by: Asking the students to give examples of what they think are environmental and human threats. Asking the students to give instances of what they think are malicious and non-malicious threats. Conclude the discussion on the different types of threats by giving additional examples of malicious and non malicious threats.
- #13 In this slide you need to show the calculation to determine the sum of an arithmetic progression for bubble sort algorithm. Refer to student guide.