Interacting with data in a transaction for .NET applications

The API for WebSphere® eXtreme Scale Client requires each thread to have a separate IGridMapPessimisticTx or IGridMapPessimisticAutoTx object. With the IGridMapPessimisticTx object, the Transaction property is used to explicitly begin, commit or roll back the transaction. With the IGridMapPessimisticAutoTx object, the transaction begin, commit and rollback operations occur automatically. Use sessions to interact with data, including Add, Put, and Replace operations.

About this task

The IGridMapPessimisticTx and IGridMapPessimisticAutoTx interfaces provide operations such as Add, Get, Put, Replace, and Remove to manipulate the data. The IGridMapPessimisticTx interface provides additional operations such as Lock and GetAndLock to control concurrent access to the data.

• Add data.

  The following code fragment demonstrates how to use the IGridMapPessimisticTx interface to begin a new transaction, create an item for the data grid, and then commit the entire transaction.

  IGridMapPessimisticTx<String,Person> ptmap; 
  ptmap = grid.GetGridMapPessimisticTx<String,Person>("PERSON"); 
  ptmap.Transaction.Begin(); 
  Person p = new Person(); 
  p.name = "John Doe"; 
  ptmap.Add(p.name, p); 
  ptmap.Transaction.Commit();

  The pattern is designed to obtain references to the maps for the thread, start a transaction, work with the data, then commit the transaction.

• Replace data.

  The following code fragment demonstrates how to use the IGridMapPessimisticTx interface to begin a new transaction, lock an item in the data grid and obtain its value, replace the item value, and commit the transaction.

  IGridMapPessimisticTx<String,Person> ptmap;
  ptmap = grid.GetGridMapPessimisticTx<String,Person>("PERSON"); 
  ptmap.Transaction.Begin(); 
  Person p = ptmap.GetAndLock("John Doe", LockMode.Upgradable);
  p.age = 30; 
  ptmap.Replace(p.name, p); 
  ptmap.Transaction.Commit();

  The application normally uses the GetAndLock method rather than a simple get to lock the record. The method must be called to provide the updated value to the map. If the Replace method is not called, then the map is not changed.