Skip to main content

How to set up an XMLA interceptor in an Atoti application

In this guide, we set up an XMLA interceptor, rewriting a MDX Select query when queried on a specific measure.
We implement the following rewriting logic: TradeID is a high-cardinality hierarchy. It must be filtered for measures heavy to compute. contributors.COUNT plays the role of such a measure.

caution

This part must be updated according to the hierarchies present in your project.

0. Prerequisites​

This guide assumes that the project is using Maven and Spring Boot and is already depending on the Atoti Server Starter.

1. Define the interceptor​

An XMLA interceptor is defined by implementing the interface com.activeviam.activepivot.xmla.intf.api.IXmlaInterceptor.

public class MyXmlaInterceptor implements IXmlaInterceptor {
  @Nullable
  @Override
  public RewrittenQuery rewriteSelect(
      final String mdx, final Collection<IContextValue> contextValues) {
    if (!mdx.contains("WHERE")
        && mdx.contains("[Measures].[contributors.COUNT]")
        && !mdx.contains("[TradeID].[TradeID]")) {
      return RewrittenQuery.builder()
          .mdx(mdx + " WHERE ([TradeID].[TradeID].[ALL].[AllMember].FirstChild)")
          .build();
    } else {
      return null;
    }
  }
}

In the code above, we inspect the MDX query to be executed. If the query contains the measure contributors.COUNT and no filter on TradeID, using a WHERE clause, not changing the shape of the MDX result.

2. Add the interceptor to the application​

The interceptor integrates into the application by returning it as a bean, in a configuration class loaded by the application.

@Configuration
class ExtraConfig {
  @Bean
  public MyXmlaInterceptor xmlaInterceptor() {
    return new MyXmlaInterceptor();
  }
}

3. See the interceptor in action​

Connecting your application to Excel - described here - you can see your queries being filtered on a single value trade value whenever the hierarchy TradeID is not expressed.

Going further​

See this section to deep dive into the capabilities of the interceptor.