Call Intercept Extension

Expansion Description

Service provider and service consumer call process interception. Most functions of Dubbo itself are implemented based on this extension point. Every time a remote method is executed, this interception will be executed. Please pay attention to the impact on performance.

agreement:

• User-defined filters are by default after built-in filters.
• The special value default, indicating where the default extension point is inserted. For example: filter="xxx,default,yyy", means xxx is before the default filter, and yyy is after the default filter.
• The special symbol - means culling. For example: filter="-foo1", exclude adding the default extension point foo1. For example: filter="-default", remove all default extension points.
• When the provider and service configure filters at the same time, all filters are accumulated instead of overwritten. For example: <dubbo:provider filter="xxx,yyy"/> and <dubbo:service filter="aaa,bbb" />, then xxx,yyy,aaa,bbb will take effect. If you want to overwrite, you need to configure: <dubbo:service filter="-xxx,-yyy,aaa,bbb" />

Extension ports

org.apache.dubbo.rpc.Filter

Extended configuration

<!-- Consumer call process interception -->
<dubbo:reference filter="xxx,yyy" />
<!-- The default interceptor of the consumer call process, which will intercept all references -->
<dubbo:consumer filter="xxx,yyy"/>
<!-- provider call process interception -->
<dubbo:service filter="xxx,yyy" />
<!-- Provider call process default interceptor, will intercept all services -->
<dubbo:provider filter="xxx,yyy"/>

Known extensions

• org.apache.dubbo.rpc.filter.EchoFilter
• org.apache.dubbo.rpc.filter.GenericFilter
• org.apache.dubbo.rpc.filter.GenericImplFilter
• org.apache.dubbo.rpc.filter.TokenFilter
• org.apache.dubbo.rpc.filter.AccessLogFilter
• org.apache.dubbo.rpc.filter.CountFilter
• org.apache.dubbo.rpc.filter.ActiveLimitFilter
• org.apache.dubbo.rpc.filter.ClassLoaderFilter
• org.apache.dubbo.rpc.filter.ContextFilter
• org.apache.dubbo.rpc.filter.ConsumerContextFilter
• org.apache.dubbo.rpc.filter.ExceptionFilter
• org.apache.dubbo.rpc.filter.ExecuteLimitFilter
• org.apache.dubbo.rpc.filter.DeprecatedFilter

Extended example

Maven project structure:

src
 |-main
    |-java
        |-com
            |-xxx
                |-XxxFilter.java (implement the Filter interface)
    |-resources
        |-META-INF
            |-dubbo
                |-org.apache.dubbo.rpc.Filter (plain text file, content: xxx=com.xxx.XxxFilter)

XxxFilter.java:

package com.xxx;
 
import org.apache.dubbo.rpc.Filter;
import org.apache.dubbo.rpc.Invoker;
import org.apache.dubbo.rpc.Invocation;
import org.apache.dubbo.rpc.Result;
import org.apache.dubbo.rpc.RpcException;
 
public class XxxFilter implements Filter {
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        // before filter...
        Result result = invoker.invoke(invocation);
        // after filter...
        return result;
    }
}

META-INF/dubbo/org.apache.dubbo.rpc.Filter:

xxx=com.xxx.XxxFilter