welcome to. introduction to data access with spring.net mark pollack principal codestreet llc
TRANSCRIPT
Welcome to
Introduction to Data Access with Spring.NET
Mark Pollack
PrincipalCodeStreet LLC
Overall Presentation Goal
Learn about Spring.NET's support for ADO.NET, O/R Mappers, and
transaction management abstraction
Speaker’s Qualifications
Mark Pollack is a founding partner at CodeStreet LLC, a software and consulting firm in the financial services industry.
.NET and J2EE architect and developer specializing in front office solutions, EAI, and message based middleware
Spring Developer (2003)• JmsTemplate
Founder of Spring.NET (2004)
Co-lead of Spring.NET with Aleks Seovic
Outline
Quick overview of Spring.NET
.NET Data Access Landscape
ADO.NET Framework
NHibernate integration
Transaction management
Spring.NET Overview
Concepts in Spring are not platform specificWant to build .NET apps in a similar way• Need for an application framework
Not a blind port of SpringVersion 1.0 released September 2005
Spring.NET subsystems
Core
AOPServices
(Exporters)Data Access
Web Desktop3rd Party
Integration
Data Access Landscape
Wide range of data access strategies and technologiesDeveloper toolbox has matured• PEAA – Fowler• Know how to ‘codify’ best practice patterns
Technologies• ADO.NET, O/R Mappers
Transaction Management• Local
– ADO.NET– System.Transactions (.NET 2.0)
• Distributed - MS-DTC/COM+Services– EnterpriseServices (.NET 1.1)
– System.Transactions (.NET 2.0)
– .NET 3.0 (WinFX)
Spring Data Access
Provide uniform best practice approach across data access technologies.IoC integrationTransaction management • Programmatic and declarative
Resource management• ‘Template’/callback APIs
Exception TranslationAdded value• Make ‘native’ APIs easier to use – ADO.NET • Higher level encapsulation of Data Access
– DAO support classes, “AdoOperation” objects
Spring.NET Data Access
“Spring.Java” users should feel right at home• ADO.NET, to first order• Java ported O/R Mappers, to second order.
ADO.NET framework
NHibernate support• iBatis.NET under development.
Early Adopter stage• Well hedged by “Spring.Java” design• A small feature set used in production now.
– Daily P/L calculations and reporting for a major hedge fund.
ADO.NET API overview
Uniform API between “Text SQL” and Stored procedures• IDbCommand property: CommandType
IDbParameters used extensively• In, Out, InOut, Return
Few easy methods on Command class• ExecuteScalar, ExecuteNonQuery, ExecuteReader• DataSets – DataAdapter + CRUD IDbCommands
Parameter binding• By name is prevalent in API • Generally, no fallback to generic placeholder if provider supports
named parameters
Transaction object• Can assign to a command object.
Motivations for ADO.NET framework
Provide usable provider independent API• No factory in BCL (.NET 1.1)
• Simplistic and at times incomplete interfaces
IoC integration• Connection String management
Easier parameter management• BCL interfaces leads to verbose code
Exception Handling• Not singly rooted (.NET 1.1)
• Base exception + error code (.NET 2.0)
• No portable “DAO” exception hierarchy
Motivations for ADO.NET framework II
Centralize resource management• Connection, Command, DataReader• ‘using’ is A Good Thing.
– Does reduce try/finally verbosity but ‘no catch’
Transaction management• Ad-hoc passing around of Transaction object
API Quirks• Exception reading a null from IDataReader
AdoTemplate
Execute()• ICommandCallback, CommandDelegate• Use of delegates – i.e. stateless callbacks.• Use of variable length arguments, boxing
ExecuteScalar(), ExecuteNonQuery(), Query()• IRowCallback, IRowMapper, IResultSetExtractor
Variations with• IDbCommandSetter, IDbCommandCreator• One “inline” parameter
– string name, Enum dbType, int size, object parameterValue
Factory Method for creating IDbParameters
Callback Interface
Central method of AdoTemplate• Resource Management• Transaction Aware
public interface IAdoOperations { . . . public Object Execute(ICommandCallback action);
public Object Execute(CommandDelegate del);}
public interface ICommandCallback { Object DoInCommand(IDbCommand command);}
public delegate Object CommandDelegate(IDbCommand command);
Standard ADO.NET
public class NativeAdoTestObjectDao : ITestObjectDao {
// Connection String Property ...
public void Create(string name, int age) { using (SqlConnection connection =
new SqlConnection(connectionString)) { string sql = String.Format("insert into TestObjects(Age, Name) " +
"VALUES ({0}, '{1}')", age, name);
using (SqlCommand cmd = new SqlCommand(sql, connection) { connection.Open(); comm.ExecuteNonQuery(); } } }}
AdoTemplate Examplepublic class TestObjectDao : AdoDaoSupport, ITestObjectDao {
public void Create(string name, int age) {
AdoTemplate.ExecuteNonQuery( String.Format(CommandType.Text,
"insert into TestObjects(Age, Name) " + "VALUES ({0}, '{1}')", age, name));
}}
<object id="testObjectDao" type=“MyApp.DAL.TestObjectDao,MyApp.DAL"> <property name="ConnectionString" value="Data Source=(local);Database=Spring;
UserID=springqa;Password=springqa; Trusted_Connection=False"/>
</object>
Connection String Management
Custom Schema to set common connection string properties• XML’ized .NET 2.0 Connection String builders
<sqlServerConnection name="myConnectionString" dataSource="(local)" initialCatalog="Northwind" persistSecurityInfo="true" userID=“${userID}" password="${password}" />
Parameter Creation
Use any provider Sql Type Enumeration
Helper methods for parameter creation• AddOut, AddInOut, DataSet related
IDbParameters parameters = adoTemplate.NewDbParameters();
parameters.Add("Name", DbType.String, 12).Value = name;parameters.Add("Age", SqlDbType.Int).Value = age;
adoTemplate.ExecuteNonQuery(CommandType.Text, sql, parameters);
AdoOperations
OO model for DB operations• Preferred approach
AdoQuery - Result set mapping to objectsAdoNonQuery- Insert/Update/DeleteAdoScalar – Return single valueStoredProcedure • out parameters and multiple result sets
AdoDataSetQuery* – Return DataSetUse of ICommandCreater implementation for efficient parameter re-creation.
public class TestObjectQuery : MappingAdoQuery {
private static string sql = "select TestObjectNo, Age, Name from
TestObjects"; public TestObjectQuery(IDbProvider dbProvider) : base(dbProvider, sql) { CommandType = CommandType.Text; }
protected override object MapRow(IDataReader reader, int num) {
TestObject to = new TestObject(); to.ObjectNumber = reader.GetInt32(0); to.Age = reader.GetInt32(1); to.Name = reader.GetString(2); return to; }}
MappingAdoQuery
NullMappingDataReader
NullMappingDataReader
IDataReaderWrapper• NullMappingDataReader implementation• Specified in AdoTemplate• Say goodbye to code like this…
to.ObjectNumber = (!reader.IsDBNull(0)) ? reader.GetInt32(0) : -1;to.Age = (!reader.IsDBNull(1)) ? reader.GetInt32(1) : -1;to.Name = (!reader.IsDBNull(2)) ? reader.GetString(2) : String.Empty;
TestObjectQuery testObjectQuery = new TestObjectQuery(dbProvider);
IList testObjectList = testObjectQuery.Query();
AdoNonQuerypublic class CreateTestObjectNonQuery : AdoNonQuery {
private static string sql = "insert into TestObjects(Age,Name) values (@Age,@Name)";
public CreateTestObjectNonQuery(IDbProvider dbProvider)
: base(dbProvider, sql) {
DeclaredParameters.Add("Age", DbType.Int32); DeclaredParameters.Add("Name", SqlDbType.NVarChar, 16); Compile(); }
public void Create(string name, int age) { ExecuteNonQuery(name, age); }}
Variable length arguments
StoredProcedure
ADO.NET supports discovery of Stored Procedure parameters.
public class CallCreateTestObject : StoredProcedure {
public CallCreateTestObject(IDbProvider dbProvider) : base(dbProvider, "CreateTestObject") { DeriveParameters(); Compile(); }
public void Create(string name, int age) { ExecuteNonQuery(name, age); }}
StoredProcedure
Easy access to out parameterspublic class CallCreateTestObject : StoredProcedure {
public CallCreateTestObject(IDbProvider dbProvider) : base(dbProvider, "CreateTestObject") { DeriveParameters(); Compile(); }
public void Create(string name, int age) { IDictionary inParams = new Hashtable(); inParams["name"] = name; inParams["age"] = age; IDictionary outParams = ExecuteNonQuery(inParams); }}
O/R Mapping Support
Easy ‘porting’ code/concepts from .NET versions of Java O/R• NHibernate • IBatis.NET
Two levels of support• IoC helpers for central object injection/configuration• Template classes for resource/tx management.
Others as well….• DB40• WilsonORM• Gentle.NET• Neo• Microsoft - ADO.NET 3.0 LINQ for X.
NHibernate Examplepublic class NativeNHTestObjectDao : ITestObjectDao { // SessionFactory property ... public void Create(TestObject to) { ISession session = null; ITransaction transaction = null; try { session = SessionFactory.OpenSession(); transaction = session.BeginTransaction(); session.Save(to); transaction.Commit(); } catch { if(transaction != null) transaction.Rollback(); throw; } finally { if(session != null) session.Close(); } }}
NHibernateTemplate DAO Implementation
public class NHTestObjectDao : HibernateDaoSupport, ITestObjectDao { [Transaction()] public void Create(TestObject to) { HibernateTemplate.Save(to); }}
Support for declarative and programmatic transaction management for any data access technology
Microsoft Transaction Management
Local Distributed Declarative Programmatic
ADO.NET (1.1)
EnterpiseServices (1.1)
System.Transactions (2.0)
.NET 3.0 (WinFX)
The sweet spot• Declarative transaction management + local
transactions
ADO.NET Transactions
ADO.NET• Connection/Transaction pair.• Associate multiple DbCommands with the
same transaction• API
– Transaction.Begin(), Commit(), Rollback()
EnterpriseService Transactions
Access to COM+ services• MS-DTC for transaction management• Declarative transaction demarcation features
Cumbersome to deploy and develop• Declarative demarcation only at class level• NB: Spring.Services provides an EnterpriseServicesExporter
Originally required inheriting from ServicedComponentProviders are aware of transaction context of the thread• Similar to approach in Spring Template/TxMgr but part of
standard ADO.NET API.
Always uses MS-DTC to access databaseAPI• ServiceDomain.Enter(), Leave; ContextUtil.SetAbort()
.NET 2.0 Transactions
Easy to use programming model Providers are aware of transaction context of the threadUses most efficient means of db access• Local transactions can be promoted to distributed
– “Promotable Single Phase Enlistment” (PSPE)
• Only Microsoft providers for now– SqlServer 2005, MSMQ.
API• new TransactionScope(); .Complete(), Dispose(),• Transaction.Current.Rollback()
Transaction Managers
AdoPlatformTransactionManager
• Local transactionsServiceDomainPlatformTransactionManager
• Distributed transactionsTxScopePlatformTransactionManager
• Local or Distributed as needed.
Switching is just a small configuration change.Callback interfaces• ITransactionCallback
TODOs
Use ADO.NET and O/R Mappers within in same transaction
“KeyHolder” to easily access created keys
Custom schema for transaction mgmt
DataSet functionality
LOB support
Nested Transactions…
Summary
Spring’s approach to Data Access is very applicable to .NET development
ADO.NET framework will give you real productivity gains
Give it a whirl• Feedback more than welcome!• www.springframework.net
Q&A
DEMO