Mondrian作为一个OLAP引擎自然也提供了发布XMLA服务的功能，下面的实例将介绍如何利用Mondrian发布一个XMLA服务，以及客户端如何利用XMLA服务访问元数据和执行MDX查询。
数据我们还是采用上一个实例用到的销售模型，详见http://blog.csdn.net/chch87/article/details/23953731
首先是服务端，Mondrian并没有用WebService的实现，而是通过servlet来发布服务。Mondrian一共提供了三个servlet：MondrianXmlaServlet，基于mondrian引擎的实现。DynamicDatasourceXmlaServlet，在MondrianXmlaServlet的基础上增加了动态加载数据源的能力。Olap4jXmlaServlet，基于Olap4j的实现。这里就介绍一下MondrianXmlaServlet和Olap4jXmlaServlet。
MondrianXmlaServlet
首先是数据源的配置，WEB-INF下建立一个datasources.xml文件如下（我是在官方demo上改的）：
<?xml version="1.0"?>
<DataSources>
<DataSource>
<DataSourceName>Sample</DataSourceName>
<DataSourceDescription>Mondrian Sample</DataSourceDescription>
<URL>http://127.0.0.1:8080/XmlaServer/xmla</URL>
<DataSourceInfo>Provider=mondrian;Jdbc='jdbc:derby:classpath:/sample';JdbcDrivers=org.apache.derby.jdbc.EmbeddedDriver;JdbcUser=sa;JdbcPassword=sa;Catalog=http://127.0.0.1:8080/XmlaServer/sample.xml;PoolNeeded=false;
</DataSourceInfo>
<!-- Provider name must be 'Mondrian'. -->
<ProviderName>Mondrian</ProviderName>
<!-- Provider type must be 'MDP'. -->
<ProviderType>MDP</ProviderType>
<!-- Authentication mode. Allowable values are 'Unauthenticated', 'Authenticated',
'Integrated'. -->
<AuthenticationMode>Unauthenticated</AuthenticationMode>
<!-- A data source contains one or more catalogs. -->
<Catalogs>
<Catalog name="sample">
<!-- Mondrian connect string for the data source. This element is optional;
if specified, it overrides the data source's <DataSourceInfo> element. Typically,
you would use this element if the catalogs have different JDBC data sources. -->
<!-- <DataSourceInfo>Provider=mondrian;Jdbc=jdbc:odbc:MondrianFoodMart;JdbcDrivers=sun.jdbc.odbc.JdbcOdbcDriver</DataSourceInfo> -->
<!-- URI of the schema definition file. -->
<Definition>http://127.0.0.1:8080/XmlaServer/sample.xml</Definition>
</Catalog>
</Catalogs>
</DataSource>
</DataSources>
每个属性的意义官方注释里写的很清楚了，这里就注意两点
一个是DataSourceInfo里的PoolNeeded=false，如果不设置这个属性的话，会出现Could not create a validated object, cause: A read-only user or a user in a read-only database is not permitted to disable read-only mode on a connection.这个错误，原因可能是我采用的derby数据库不支持dbcp的连接池，把PoolNeeded=false;设上不缓存数据库连接就行了。
还有一个就是Catalogs结点的设置，Catalogs是用来对应多Catalog的，但是如果你只有一个Catalog，也不能将Catalogs省略，也就是说同样的Catalog要分别在DataSourceInfo和Catalogs定义两遍。
然后是servlet的配置：
<servlet>
<servlet-name>MondrianXmlaServlet</servlet-name>
<servlet-class>mondrian.xmla.impl.MondrianXmlaServlet</servlet-class>
<init-param>
<param-name>CharacterEncoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>MondrianXmlaServlet</servlet-name>
<url-pattern>/xmla</url-pattern>
</servlet-mapping>这里有个CharacterEncoding的设置，主要是为了防止SOAP请求中包含中文。但仅仅是这样并不能解决所有的中文问题，前一篇文章中就提到了引擎内部对模式中的中文解析有bug，解决办法只能是修改源码了，这里我向它妥协，把模式定义（sample.xml）全修改成了英文。至此MondrianXmlaServlet的配置就完成了。
Olap4jXmlaServlet
官方并没有给出Olap4jXmlaServlet的demo，实际用起来也确实有些问题，看来不推荐使用。跟上面不一样，没有datasources的设置，看样子也不支持多数据源。直接就是servlet的配置了：
<servlet>
<servlet-name>Olap4jXmlaServlet</servlet-name>
<servlet-class>mondrian.xmla.impl.Olap4jXmlaServlet</servlet-class>
<init-param>
<param-name>OlapDriverClassName</param-name>
<param-value>mondrian.olap4j.MondrianOlap4jDriver</param-value>
</init-param>
<init-param>
<param-name>OlapDriverConnectionString</param-name>
<param-value>jdbc:mondrian:Jdbc='jdbc:derby:classpath:/sample';JdbcDrivers=org.apache.derby.jdbc.EmbeddedDriver;JdbcUser=sa;JdbcPassword=sa;Catalog=http://127.0.0.1:8080/XmlaServer/sample.xml;PoolNeeded=false;</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>Olap4jXmlaServlet</servlet-name>
<url-pattern>/olap4jXmla</url-pattern>
</servlet-mapping>如上所示，指定了Olap4j的驱动和url就行了，本来这样应该就可以了的，可实际调用的时候，出现了下面的错误：
Caused by: java.lang.UnsupportedOperationException
at mondrian.olap4j.MondrianOlap4jConnection.rollback(MondrianOlap4jConnection.java:272)
at org.apache.commons.dbcp.DelegatingConnection.rollback(DelegatingConnection.java:265)
at org.apache.commons.dbcp.PoolableConnectionFactory.passivateObject(PoolableConnectionFactory.java:352)
at org.apache.commons.pool.impl.GenericObjectPool.addObjectToPool(GenericObjectPool.java:1430)
at org.apache.commons.pool.impl.GenericObjectPool.addObject(GenericObjectPool.java:1694)
at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:865)
... 31 moredebug跟到dbcp的代码，会发现BasicDataSource初始化连接的时候会检查新创建的连接，当连接不能自动提交的时候会尝试rollback，这里的数据连接并不是关系数据库的连接而是Olap4j连接，尽管Olap4j连接也符合JDBC标准，但也并不是实现了JDBC的每一个接口，比如这个rollback就没实现，那自然就会报错了。这又是一个BUG了，而且不改不行，应该是Olap4j数据连接与BasicDataSource不兼容。下面就是我的修改，NewOlap4jXmlaServlet继承了Olap4jXmlaServlet，重新简单的实现了createConnectionFactory方法。（这里插句题外话，Mondrian采用的开源协议是EPL，也就是意味着基于它的非独立模块也必须开源，比如BUG修正之类的，所以拿来做商用的要忘开了小心侵权哦。。）
package xmlaserver;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Map;
import java.util.Properties;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import mondrian.xmla.XmlaHandler;
import mondrian.xmla.impl.Olap4jXmlaServlet;
import org.olap4j.OlapConnection;
@SuppressWarnings("serial")
public class NewOlap4jXmlaServlet extends Olap4jXmlaServlet {
@Override
protected XmlaHandler.ConnectionFactory createConnectionFactory(ServletConfig servletConfig)
throws ServletException {
final String olap4jDriverClassName = servletConfig.getInitParameter("OlapDriverClassName");
final String olap4jDriverConnectionString = servletConfig
.getInitParameter("OlapDriverConnectionString");
return new XmlaHandler.ConnectionFactory() {
@Override
public OlapConnection getConnection(String catalog, String schema, String roleName,
Properties props) throws SQLException {
try {
Class.forName(olap4jDriverClassName);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
Connection olap4jConn = DriverManager.getConnection(olap4jDriverConnectionString);
return olap4jConn.unwrap(OlapConnection.class);
}
@Override
public Map<String, Object> getPreConfiguredDiscoverDatasourcesResponse() {
return null;
}
};
}
}
servlet的配置也稍作修改
<servlet>
<servlet-name>Olap4jXmlaServlet</servlet-name>
<!-- <servlet-class>mondrian.xmla.impl.Olap4jXmlaServlet</servlet-class> -->
<servlet-class>xmlaserver.NewOlap4jXmlaServlet</servlet-class>
<init-param>
<param-name>OlapDriverClassName</param-name>
<param-value>mondrian.olap4j.MondrianOlap4jDriver</param-value>
</init-param>
<init-param>
<param-name>OlapDriverConnectionString</param-name>
<param-value>jdbc:mondrian:Jdbc='jdbc:derby:classpath:/sample';JdbcDrivers=org.apache.derby.jdbc.EmbeddedDriver;JdbcUser=sa;JdbcPassword=sa;Catalog=http://127.0.0.1:8080/XmlaServer/sample.xml;PoolNeeded=false;</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>Olap4jXmlaServlet</servlet-name>
<url-pattern>/olap4jXmla</url-pattern>
</servlet-mapping>
至此服务端的介绍就结束了，下面开始介绍客户端的用法。
Olap4j已经实现一个XMLA客户端，所以客户端只要引入Olap4j相关jar包就可以了。下面是一个具体实例
package xmlaclient;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import org.olap4j.CellSet;
import org.olap4j.OlapConnection;
import org.olap4j.OlapDatabaseMetaData;
import org.olap4j.OlapStatement;
import org.olap4j.layout.CellSetFormatter;
import org.olap4j.layout.RectangularCellSetFormatter;
public class TestXmla {
public static void main(String[] args) throws Exception {
String url = "http://127.0.0.1:8080/XmlaServer/xmla";
String userName = "sa";
String password = "sa";
// 加载驱动
Class.forName("org.olap4j.driver.xmla.XmlaOlap4jDriver");
// 建立连接
String strUrl = "jdbc:xmla:Server=" + url;
strUrl += ";JdbcUser=" + userName;
strUrl += ";JdbcPassword=" + password;
Connection olap4jConn = DriverManager.getConnection(strUrl);
OlapConnection olapConn = olap4jConn.unwrap(OlapConnection.class);
OlapDatabaseMetaData databaseMetaData = olapConn.getMetaData();
// 获取数据立方体信息
ResultSet resultSet = databaseMetaData.getCubes(null, null, null);
while (resultSet.next()) {
System.out.println("CUBE_NAME:" + resultSet.getString("CUBE_NAME"));
}
// 获取维度信息
resultSet = databaseMetaData.getHierarchies(null, null, "Sales", null, null);
while (resultSet.next()) {
System.out.println("HIERARCHY_NAME:" + resultSet.getString("HIERARCHY_NAME"));
}
// 执行查询
// String mdxStr = "select {[Stores].Members} on columns,"
// + "{[Time].Members} ON rows"
// + " from Sales ";
String mdxStr = "select {[Measures].[Sales],[Measures].[Profit]} on columns,"
+ "{[Quarter].Members} ON rows"
+ " from Sales "
+ "where [Store].[支店01]";
OlapStatement statement = olapConn.createStatement();
CellSet cellSet = statement.executeOlapQuery(mdxStr);
// 输出结果
CellSetFormatter formatter = new RectangularCellSetFormatter(false);
formatter.format(cellSet, new PrintWriter(System.out, true));
}
}当服务端的web程序启动后，客户端就可以通过xmla服务url（http://127.0.0.1:8080/XmlaServer/xmla）来访问多维数据的元数据和执行mdx查询了，非常简单。
最后，给出该实例的完整代码：http://download.csdn.net/detail/chch87/7216471