DISTRIBUTED TRANSACTIONS IN .NET

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DISTRIBUTED TRANSACTIONS IN .NET

• Presented By Divya Josyala.

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Contents

• 1.Overview
• - Transaction
• - Local Transaction
• - Distributed Transaction
• - Acid Properties
• 2. Distributed transactions in .Net
• - Windows Application
• System.Transactions namespace -
  Demo
• - Web Services
• System.EnterpriseService
  namespaces - Demo
• - File Transaction Demo
• 3. References

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Overview

• What is a transaction?
• A transaction is a unit of work .
• Example bank transfer operation.
• The application transfers funds from one
  --account to another by debiting money from one
  account and crediting it to another.

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Overview

• Local Transaction transactions are performed on
  a single database

Transfer()
Charge()
Credit()
database
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Overview

• Distributed Transaction
• - Transactions that span two or more
  databases.
• - Incorporates several distinct operations
  occurring on different systems into an atomic
  action that succeeds or fails completely.

Transfer()
Credit()
Charge()
Database1
Database2
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Overview ACID Properties

• ACID properties of a transaction
• Atomicity
• Either all the operations in a transaction
  should complete or none of them should.
• Consistency
• A transaction should preserve the
  consistency of data
• Isolation
• Requires that each transaction appears to
  be the only transaction manipulating the data
  source irrespective of other transactions
  running concurrently.
• Durability
• If a transaction succeeds the system should
  guarantee that its updates will persist , even if
  the computer crashes immediately after the
  application performs a commit operation

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Distributed Transactions in .Net

• .Net framework provides support for
  distributed transactions
• in two ways
• TransactionScope class in System.Transactions
  namespace
• - Used in windows and web applications.
• ContextUtil class in System.EnterpriseServices
  namespace
• - Used in web services.

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Distributed Transactions in .Net

• Method 1
• System. Transactions namespace defines the
  TransactionScope class which enables you to
  create and manage distributed transactions.
• A Transaction scope defines a block of code that
  participates in a transaction.
• The first connection to a database within the
  transaction scope
• enlists it as a local transaction
• Subsequent connections to databases within the
  transaction scope promotes the local transaction
  to a distributed transaction.

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TransactionOptions

• // Create the TransactionOptions object
• TransactionOptions TranOpt new
  TransactionOptions()
• // Set the Isolation Level
• TranOpt.IsolationLevel
• System.Transactions.IsolationLevel.ReadCommitt
  ed
• // Set the timeout to be 2 minutes
• // Uses the (hours, minutes, seconds)
  constructor
• TimeSpan Time new TimeSpan(0, 2, 0)
• TranOpt.Timeout Time

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TransactionScopeOptions
TransactionScopeOptions Description
Required If within a currently active transaction scope, this transaction scope will join it. Otherwise it will create its own transaction scope.
RequiresNew This transaction will create its own transaction scope.
Supports If within a currently active transaction scope, this transaction scope will join it. Otherwise no transaction scope will be created.
NotSupported No transaction scope will be created.
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Transaction Scope - Code

• //Create a transaction scope object
• using (TransactionScope oTranScope new
  TransactionScope())
• using (SqlConnection oCn1 new
  SqlConnection(this.sCn1))
• SqlCommand oCmd new
  SqlCommand(this.sSQL, oCn1)
• oCn1.Open()
• oCmd.ExecuteNonQuery()
• oCn1.Close()
• // Tells the transaction scope
  that the transaction is in a
• // consistent state and can be
  committed
• oTranScope.Complete()
• // The following bracket
  completes, commits, and disposes
• // the transaction

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Distributed Transactions in .Net

• METHOD 2
• Systems.EnterpriseServices namespace defines
  the
• contextutil class .
• Methods in the contextutil class used for
  distributed transactions are
• 1.SetComplete() Indicates that the current
  transaction is committed and the object
  deactivated
• 2.SetAbort() Indicates that the current
  transaction has to be rolled back and the object
  deactivated.
• AutoComplete attribute calls the
  SetComplete method if no exceptions occur or
  SetAbort method if an exception is thrown.
• WebMethod(false, TransactionOption.Required)
• AutoComplete

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WebService - DEPT

• WebMethod(false, TransactionOption.Required)
• public int AddDept(string deptName,
  string location)
• try
• string connString
  System.Configuration.ConfigurationManager.Connect
  ionStrings "ConnectionString".ConnectionString
  
• int deptNo
• //Create the connection object
  passing to it the connection string
• SqlConnection connection new
  SqlConnection(connString)
• connection.Open()
• //Create and set the SqlCommand
  object and pass it the name of the
• // stored procedure to be executed
• SqlCommand command new
  SqlCommand("AddDept", connection)
• //Indicates that you want to
  execute a stored procedure
• command.CommandType
  CommandType.StoredProcedure

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WebService - DEPT

• //Add the DeptName parameter
• SqlParameter paramDeptName new
• SqlParameter("_at_DeptName",
  SqlDbType.VarChar, 50)
• paramDeptName.Value deptName
• paramDeptName.Direction
  ParameterDirection.Input
• command.Parameters.Add(paramDeptNa
  me)
• //Add the Location parameter
• SqlParameter paramLocation new
• SqlParameter("_at_Location",
  SqlDbType.VarChar, 50)
• paramLocation.Value location
• paramLocation.Direction
  ParameterDirection.Input
• command.Parameters.Add(paramLocati
  on)
• //Add the DeptNo parameter as the
  Output parameter
• SqlParameter paramDeptNo new
• SqlParameter("_at_DeptNo",
  SqlDbType.Int, 4)
• paramDeptNo.Direction
  ParameterDirection.Output
• command.Parameters.Add(paramDeptNo
  )

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WebService - DEPT

• // Execute the Command
• command.ExecuteNonQuery()
• //you can retrieve the output
  parameter from the parameters collection of
• //the SQL Command object
• deptNo (int)command.Parameters"
  _at_DeptNo".Value
• //commiting the transaction using
  the SetComplete method of the
• //ContextUtil Class
• ContextUtil.SetComplete()
• return deptNo
• catch (Exception ex)
• //rollback all the database
  operations if exceptions occur
• ContextUtil.SetAbort()
• throw ex

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Calling Webservice - CODE

• WebMethod(false, TransactionOption.Required)
• public bool AddDeptEmployees(string
  deptName, string deptLocation,
• string empName, string empAddres)
• try
• int deptNo
• //Create instances of the
  Department() and Employee() classes
• Department dept new
  Department()
• Employee emp new Employee()
• //Add the Dept details to the
  Dept table
• deptNo dept.AddDept(deptName,
  deptLocation)
• //Add the Employee details to the
  Emp table
• //int empNo emp.AddEmp(empName,e
  mpAddres,deptNo)
• int empNo emp.AddEmp(empName,
  empAddres, 200)
• return true

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REFERENCES

• MSDN - DATA POINTS By John Papa
• Url http//msdn.microsoft.com/msdnmag/issues/05/0
  2/DataPoints/
• Develop Transactional .Net Web Services By
  Thiru Thangarathinam
• Url http//www.developer.com/net/asp/article.php/
  3385631

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Comments / Questions ??

• THE END