Spring/spring-net
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Initial import!

Browse Source
This commit is contained in:
markpollack
2008-05-30 22:55:02 +00:00
commit c478a783c0
2978 changed files with 510966 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

464
doc/reference/src/dbprovider.xml Normal file
View File

@@ -0,0 +1,464 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter id="dbprovider">
<title>DbProvider</title>
<section id="dbprovider-introduction">
<title>Introduction</title>
<para>Spring provides a generic factory for creating ADO.NET API artifacts
such as <code><classname>IDbConnection</classname></code> and
<code><classname>IDbCommand</classname></code>. The factory API is very
similar to the one introduced in .NET 2.0 but adds extra metadata needed
by Spring to support features provided by its DAO/ADO.NET framework such
as error code translation to a DAO exception hierarchy. The factory itself
is configured by using a standard Spring XML based configuration file
though it is unlikely you will need to modify those settings yourself, you
only need be concerned with using the factory. Out of the box several
popular databases are supported and an extension mechanism is available
for defining new database providers or modifying existing ones. A custom
database namespace for configuration aids in making terse XML based
declarations of Spring's database objects you wish to use.</para>
<para>The downside of Spring's factory as compared to the one in .NET 2.0
is that the types returned are lower level interfaces and not the abstract
base classes in System.Data.Common. However, there are still 'holes' in
the current .NET 2.0 provider classes that are 'plugged' with Spring's
provider implementation. One of the most prominent is the that the top
level DbException exposes the HRESULT of the remote procedure call, which
is not what you are commonly looking for when things go wrong. As such
Spring's provider factory exposes the vendor sql error code and also maps
that error code onto a consistent data access exception hierarchy. This
makes writing portable exception handlers much easier. In addition, the
DbParameter class doesn't provide the most common convenient methods you
would expect as when using say the SqlServer provider. If you need to
access the BCL provider abstraction, you still can through Spring's
provider class. Furthermore, a small wrapper around the standard BCL
provider abstraction allows for integration with Spring's transaction
management facilities, allowing you to create a DbCommand with its
connection and transaction properties already set based on the transaction
calling context.</para>
</section>
<section id="dbprovider-dbprovider">
<title>IDbProvider and DbProviderFactory</title>
<para>The <code><interfacename>IDbProvider</interfacename></code> API is
shown below and should look familiar to anyone using .NET 2.0 data
providers. Note that Spring's DbProvider abstraction can be used on .NET
1.1 in addition to .NET 2.0</para>
<programlisting> public interface IDbProvider
{
IDbCommand CreateCommand();
object CreateCommandBuilder();
IDbConnection CreateConnection();
IDbDataAdapter CreateDataAdapter();
IDbDataParameter CreateParameter();
string CreateParameterName(string name);
string CreateParameterNameForCollection(string name);
IDbMetadata DbMetadata
{
get;
}
string ConnectionString
{
set;
get;
}
string ExtractError(Exception e);
bool IsDataAccessException(Exception e);
}</programlisting>
<para>ExtractError is used to return an error string for translation into
a DAO exception. On .NET 1.1 the method IsDataAccessException is used to
determine if the thrown exception is related to data access since in .NET
1.1 there isn't a common base class for database exceptions.
CreateParameterName is used to create the string for parameters used in a
CommandText object while CreateParameterNameForCollection is used to
create the string for a IDataParameter.ParameterName, typically contained
inside a IDataParameterCollection.</para>
<para>The class <classname>DbProviderFactory</classname> creates
IDbProvider instances given a provider name. The connection string
property will be used to set the IDbConnection returned by the factory if
present. The provider names, and corresponding database, currently
configured are listed below.</para>
<itemizedlist>
<listitem>
<para><code>SqlServer-1.1</code> - Microsoft SQL Server, provider
V1.0.5000.0 in framework .NET V1.1</para>
</listitem>
<listitem>
<para><code>SqlServer-2.0</code> (aliased to
<code>System.Data.SqlClient</code>) - Microsoft SQL Server, provider
V2.0.0.0 in framework .NET V2.0</para>
</listitem>
<listitem>
<para><literal>SqlServerCe-3.1</literal> (aliased to
<literal>System.Data.SqlServerCe</literal>) - Microsoft SQL Server
Compact Edition, provider V9.0.242.0</para>
</listitem>
<listitem>
<para><code>OleDb-1.1</code> - OleDb, provider V1.0.5000.0 in
framework .NET V1.1</para>
</listitem>
<listitem>
<para><code>OleDb-2.0</code> (aliased to
<code>System.Data.OleDb</code>) - OleDb, provider V2.0.0.0 in
framework .NET V2.0</para>
</listitem>
<listitem>
<para><code>OracleClient-2.0</code> (aliased to
<code>System.Data.OracleClient</code>) - Oracle, Microsoft provider
V2.0.0.0</para>
</listitem>
<listitem>
<para><code>OracleODP-2.0</code> (aliased to
<code>System.DataAccess.Client</code>) - Oracle, Oracle provider
V2.102.2.20</para>
</listitem>
<listitem>
<para><code>MySql</code> - MySQL, MySQL provider 1.0.10.1</para>
</listitem>
<listitem>
<para><literal>MySql-1.0.9</literal> - MySQL, MySQL provider
1.0.9</para>
</listitem>
<listitem>
<para><literal>MySql-5.0</literal> - MySQL, MySQL provider
5.0.7.0</para>
</listitem>
<listitem>
<para><literal>MySql-5.0.8.1</literal> - MySQL, MySQL provider
5.0.8.1</para>
</listitem>
<listitem>
<para><literal>MySql-5.1 </literal>- MySQL, MySQL provider
5.1.2.2</para>
</listitem>
<listitem>
<para><literal>MySql-5.1.4</literal> - (aliased to
<literal>MySql.Data.MySqlClient</literal>) MySQL, MySQL provider
5.1.2.2</para>
</listitem>
<listitem>
<para><literal>Npgsql-1.0</literal> - Postgresql provider 1.0.0.0 (and
1.0.0.1 - were build with same version info)</para>
</listitem>
<listitem>
<para><literal>Npgsql-2.0-beta1</literal> - Postgresql provider
1.98.1.0 beta 1</para>
</listitem>
<listitem>
<para><literal>DB2-9.0.0-1.1</literal> - IBM DB2 Data Provider 9.0.0
for .NET Framework 1.1</para>
</listitem>
<listitem>
<para><literal>DB2-9.0.0-2.0 </literal>- (aliased to
<literal>IBM.Data.DB2</literal>) - IBM DB2 Data Provider 9.0.0 for
.NET Framework 2.0</para>
</listitem>
<listitem>
<para><literal>DB2-9.1.0-1.1</literal> - IBM DB2 Data Provider 9.1.0
for .NET Framework 1.1</para>
</listitem>
<listitem>
<para><literal>DB2-9.1.0.2</literal> - (aliased to
<literal>IBM.Data.DB2.9.1.0</literal>) - IBM DB2 Data Provider 9.1.0
for .NET Framework 2.0</para>
</listitem>
<listitem>
<para><literal>SQLite-1.0.43 </literal>SQLite provider 1.0.43 for .NET
Framework 2.0</para>
</listitem>
<listitem>
<para><literal>SQLite-1.0.47 </literal>- (aliased to
System.Data.SQLite) - SQLite provider 1.0.43 for .NET Framework
2.0</para>
</listitem>
<listitem>
<para><literal>SybaseAse-12</literal> - Sybase ASE provider for ASE
12.x</para>
</listitem>
<listitem>
<para><literal>SybaseAse-15</literal> - Sybase ASE provider for ASE
15.x</para>
</listitem>
<listitem>
<para><literal>Odbc-1.1</literal> - ODBC provider V1.0.5000.0 in
framework .NET V1.1</para>
</listitem>
<listitem>
<para><literal>Odbc-2.0</literal> - ODBC provider V2.0.0.0 in
framework .NET V2</para>
</listitem>
</itemizedlist>
<para>An example using DbProviderFactory is shown below</para>
<programlisting>IDbProvider dbProvider = DbProviderFactory.GetDbProvider("System.Data.SqlClient");</programlisting>
<para>The default definitions of the providers are contained in the
assembly resource
<code>assembly://Spring.Data/Spring.Data.Common/dbproviders.xml</code>.
Future additions to round out the database coverage are forthcoming. The
current crude mechanism to add additional providers, or to apply any
standard Spring <interfacename>IApplicationContext</interfacename>
functionality, such as applying AOP advice, is to set the public static
property DBPROVIDER_ADDITIONAL_RESOURCE_NAME in
<classname>DbProviderFactory</classname> to a Spring resource location.
The default value is <code>file://dbProviders.xml</code>. (That isn't a
typo, there is a difference in case with the name of the embedded
resource). This crude mechanism will eventually be replaced with one based
on a custom configuration section in App.config/Web.config.</para>
<para>It may happen that the version number of an assembly you have
downloaded is different than the one listed above. If it is a point
release, i.e. the API hasn't changed in anyway that is material to your
application, you should add an assembly redirect of the form shown
below.</para>
<programlisting>&lt;dependentAssembly&gt;
&lt;assemblyIdentity name="MySql.Data"
publicKeyToken="c5687fc88969c44d"
culture="neutral"/&gt;
&lt;bindingRedirect oldVersion="0.0.0.0-65535.65535.65535.65535"
newVersion="1.0.10.1"/&gt;
&lt;/dependentAssembly&gt;</programlisting>
<para>This redirects any reference to an older version of the assembly
MySql.Data to the version 1.0.10.1.</para>
</section>
<section>
<title>XML based configuration</title>
<para>Creating a DbProvider in Spring's XML configuration file is shown
below in the typical case of using it to specify the DbProvider property
on an AdoTemplate.</para>
<programlisting>&lt;objects xmlns='http://www.springframework.net'
xmlns:db="http://www.springframework.net/database"&gt;
&lt;db:provider id="DbProvider"
provider="System.Data.SqlClient"
connectionString="Data Source=(local);Database=Spring;User ID=springqa;Password=springqa;Trusted_Connection=False"/&gt;
&lt;object id="adoTemplate" type="Spring.Data.AdoTemplate, Spring.Data"&gt;
&lt;property name="DbProvider" ref="DbProvider"/&gt;
&lt;/object&gt;
&lt;/objects&gt;</programlisting>
<para>A custom namespace should be registered in the main application
configuration file to use this syntax. This configuration, only for the
parsers, is shown below. Additional section handlers are needed to specify
the rest of the Spring configuration locations as described in previous
chapters.</para>
<programlisting>&lt;configuration&gt;
&lt;configSections&gt;
&lt;sectionGroup name="spring"&gt;
&lt;section name="parsers" type="Spring.Context.Support.NamespaceParsersSectionHandler, Spring.Core" /&gt;
&lt;/sectionGroup&gt;
&lt;/configSections&gt;
&lt;spring&gt;
&lt;parsers&gt;
&lt;parser type="Spring.Data.Config.DatabaseNamespaceParser, Spring.Data" /&gt;
&lt;/parsers&gt;
&lt;/spring&gt;
&lt;/configuration&gt;</programlisting>
</section>
<section>
<title>Connection String management</title>
<para>There are a few options available to help manage your connection
strings.</para>
<para>The first option is to leverage the Spring property replacement
functionality, as described in <xref
linkend="objects-factory-placeholderconfigurer" />. This lets you insert
variable names as placeholders for values in a Spring configuration file.
In the following example specific parts of a connection string have been
parameterized but you can also use a variable to set the entire connection
string.</para>
<para>An example of such a setting is shown below</para>
<programlisting>&lt;configuration&gt;
&lt;configSections&gt;
&lt;sectionGroup name="spring"&gt;
&lt;section name='context' type='Spring.Context.Support.ContextHandler, Spring.Core'/&gt;
&lt;/sectionGroup&gt;
&lt;section name="databaseSettings" type="System.Configuration.NameValueSectionHandler, System, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" /&gt;
&lt;/configSections&gt;
&lt;spring&gt;
&lt;context&gt;
&lt;resource uri="Aspects.xml" /&gt;
&lt;resource uri="Services.xml" /&gt;
&lt;resource uri="Dao.xml" /&gt;
&lt;/context&gt;
&lt;/spring&gt;
&lt;!-- These properties are referenced in Dao.xml --&gt;
&lt;databaseSettings&gt;
&lt;add key="db.datasource" value="(local)" /&gt;
&lt;add key="db.user" value="springqa" /&gt;
&lt;add key="db.password" value="springqa" /&gt;
&lt;add key="db.database" value="Northwind" /&gt;
&lt;/databaseSettings&gt;
&lt;/configuration&gt;</programlisting>
<para>Where <literal>Dao.xml</literal> has a connection string as shown
below</para>
<programlisting>&lt;objects xmlns='http://www.springframework.net'
xmlns:db="http://www.springframework.net/database"&gt;
&lt;db:provider id="DbProvider"
provider="System.Data.SqlClient"
connectionString="${db.datasource};Database=${db.database};User ID=${db.user};Password=${db.password};Trusted_Connection=False"/&gt;
&lt;object id="adoTemplate" type="Spring.Data.AdoTemplate, Spring.Data"&gt;
&lt;property name="DbProvider" ref="DbProvider"/&gt;
&lt;/object&gt;
&lt;!-- configuration of what values to substitute for ${ } variables listed above --&gt;
&lt;object name="appConfigPropertyHolder"
type="Spring.Objects.Factory.Config.PropertyPlaceholderConfigurer, Spring.Core"&gt;
&lt;property name="configSections" value="DatabaseConfiguration"/&gt;
&lt;/object&gt;
&lt;/objects&gt;</programlisting>
<para>Please refer to the Section <xref
linkend="objects-factory-placeholderconfigurer" /> for more
information.</para>
</section>
<section id="dbprovider-additional">
<title>Additional IDbProvider implementations</title>
<para>Spring provides some convenient implementations of the IDbProvider
interface that add addtional behavior on top of the standard
implementation.</para>
<section id="dbprovider-usercredentials">
<title>UserCredentialsDbProvider</title>
<para>This <classname>UserCredentialsDbProvider</classname> will allow
you to change the username and password of a database connection at
runtime. The API contains the properties <literal>Username</literal> and
<literal>Password</literal> which are used as the default strings
representing the user and password in the connection string. You can
then change the value of these properties in the connection string by
calling the method <literal>SetCredentialsForCurrentThread</literal> and
fall back to the default values by calling the method
<literal>RemoveCredentialsFromCurrentThread</literal>. You call the
<literal>SetCredentialsForCurrentThread</literal> method at runtime,
before any data access occurs, to determine which database user should
be used for the current user-case. Which user to select is up to you.
You may retrieve the user information from an HTTP session for example.
Example configuration and usage is shown below</para>
<programlisting>&lt;object id="DbProvider" type="Spring.Data.Common.UserCredentialsDbProvider, Spring.Data"&gt;
&lt;property name="TargetDbProvider" ref="targetDbProvider"/&gt;
&lt;property name="Username" value="User ID=defaultName"/&gt;
&lt;property name="Password" value="Password=defaultPass"/&gt;
&lt;/object&gt;
&lt;db:provider id="targetDbProvider" provider="SqlServer-2.0"
connectionString="Data Source=MARKT60\SQL2005;Database=Spring;Trusted_Connection=False"/&gt;</programlisting>
<para>If you use dependency injection to configure a class with a
property of the type <literal>IDbProvider</literal>, you will need to
downcast to the subtype or you can change your class to have a property
of the type <literal>UserCredentialsDbProvider</literal> instead of
<literal>IDbProvider</literal>.</para>
<programlisting>userCredentialsDbProvider.SetCredentialsForCurrentThread("User ID=springqa", "Password=springqa");</programlisting>
<para><literal>UserCredentialsDbProvider's</literal> has a base class,
<literal>DelegatingDbProvider</literal>, and is intended for you to use
in your own implementations that delegate calls to a target
<literal>IDbProvider</literal> instance. This class in meant to be
subclassed with subclasses overriding only those methods, such as
<literal>CreateConnection()</literal>, that should not simply delegate
to the target <literal>IDbProvider</literal>.</para>
</section>
<section id="dbprovider-multidelegating">
<title>MultiDelegatingDbProvider</title>
<para>There are use-cases in which there will need to be a runtime
selection of the database to connect to among many possible candidates.
This is often the case where the same schema is installed in separate
databases for different clients. The
<classname>MultiDelegatingDbProvider</classname> implements the
<classname>IDbProvider</classname> interface and provides an abstraction
to the multiple databases and can be used in DAO layer such that the DAO
layer is unaware of the switching between databases.
<classname>MultiDelegatingDbProvider</classname> does its job by looking
into thread local storage under the key dbProviderName. This storage
location stores the name of the dbProvider that is to be used for
processing the request. <classname>MultiDelegatingDbProvider</classname>
is configured using the dictionary property
<literal>TargetDbProviders</literal>. The key of this dictionary
contains the name of a dbProvider and its value is a dbProvider object.
(You can also provide this dictionary as a constructor argument.) During
request processing, once you have determined which target dbProvider
should be use, in this example database1ProviderName, you should execute
the following code
<literal>LogicalThreadContext.SetData("dbProviderName",
"database1ProviderName")</literal> and then call the data access
layer.</para>
<para></para>
</section>
</section>
</chapter>