Custom filter-Scalable Open Financial Architecture(SOFAStack)-阿里云帮助中心

SOFARPC provides robust scalability and offers Service Provider Interface (SPI) capabilities for each module.

SOFARPC processes request and response filter chains as follows:

It uses multiple filters to intercept and process requests and responses.
It lets you create custom filter extensions. Custom filters run after the built-in filters.

This topic describes how to create and activate a custom filter class.

Custom filter class

A custom filter class must inherit the com.alipay.sofa.rpc.filter.Filter class. The following example shows how to do this:

package com.alipay.sofa.rpc.customfilter;

import com.alipay.sofa.rpc.core.exception.SofaRpcException;
import com.alipay.sofa.rpc.core.request.SofaRequest;
import com.alipay.sofa.rpc.core.response.SofaResponse;
import com.alipay.sofa.rpc.filter.Filter;
import com.alipay.sofa.rpc.filter.FilterInvoker;
import com.alipay.sofa.rpc.log.Logger;
import com.alipay.sofa.rpc.log.LoggerFactory;

public class CustomEchoFilter extends Filter{

/**
     * Logger for CustomEchoFilter
     **/
private static final Logger LOGGER =LoggerFactory.getLogger(CustomEchoFilter.class);

@Override
public boolean needToLoad(FilterInvoker invoker){
  // Decide whether to load this filter based on specific conditions.
  return true;
}

@Override
public SofaResponse invoke(FilterInvoker invoker,SofaRequest request) throws SofaRpcException{
        // Print the request before the call.
        LOGGER.info("echo request : {}, {}", request.getInterfaceName()+"."+ request.getMethod(),
        request.getMethodArgs());

        // Continue the call.
       SofaResponse response = invoker.invoke(request);

       // Print the return value after the call.
       if(response ==null){
            return response;
       }else if(response.isError()){
            LOGGER.info("server rpc error: {}", response.getErrorMsg());
       }else{
            Object ret = response.getAppResponse();
            if(ret instanceof Throwable){
                LOGGER.error("server biz error: {}",(Throwable) ret);
            }else{
                LOGGER.info("echo response : {}", response.getAppResponse());
            }
       }
       return response;
    }
}

Activating a custom filter class

A custom filter class can be activated in the following ways:

Using the API

This method lets you specify the provider or consumer where the filter takes effect. The following example shows how to do this:

// Service provider
providerConfig.setFilterRef(Arrays.asList(new CustomFilter()));
// Service consumer
consumerConfig.setFilterRef(Arrays.asList(new CustomFilter()));

Using the @Extension annotation, an extension file, and code injection

Follow these steps:

Process the custom filter class.

@Extension("customer")
public class CustomFilter extends Filter{
     @Override
     public boolean needToLoad(FilterInvoker invoker){
          return true;
     }
    @Override
    public SofaResponse invoke(FilterInvoker invoker,SofaRequest request) throws SofaRpcException{
         SofaResponse response = invoker.invoke(request);
         return response;
    }
}

Create an extension file.
- File name: The file name must end with `Filter`. For example, com.alipay.sofa.rpc.filter.Filter.
- File path: The file must be in the fixed path META-INF/services/sofa-rpc/.
For example, the full path is META-INF/services/sofa-rpc/com.alipay.sofa.rpc.filter.Filter. The content of the extension file is as follows:
```
customer=com.alipay.sofa.rpc.custom.CustomFilter
```

Inject the code.

// Service provider
providerConfig.setFilter(Arrays.asList(“customer”));
// Service consumer
consumerConfig.setFilter(Arrays.asList(“customer”));

Using the @Extension annotation, an extension file, and the @AutoActive annotation
Follow these steps:
1. Process the custom filter class.
```
@Extension(“customer”)
@AutoActive(providerSide =true, consumerSide =true)
public class customerFilter extends Filter{
     @Override
     public boolean needToLoad(FilterInvoker invoker){
        return true;
     }
     @Override
     public SofaResponse invoke(FilterInvoker invoker,SofaRequest request) throws SofaRpcException{
         SofaResponse response = invoker.invoke(request);
         return response;
     }
}
```
  Note
  Using the @Extension and @AutoActive annotations for the filter class eliminates the need for code injection. This applies the filter to all providers and consumers. The providerSide parameter specifies whether the filter is active on the server-side. The consumerSide parameter specifies whether the filter is active on the client.
2. Create an extension file.
  - File name: The file name must end with `Filter`. For example, com.alipay.sofa.rpc.filter.Filter.
  - File path: The file must be in the fixed path META-INF/services/sofa-rpc/.
  For example, the full path is META-INF/services/sofa-rpc/com.alipay.sofa.rpc.filter.Filter. The content of the extension file is as follows:
```
customer=com.alipay.sofa.rpc.custom.CustomFilter
```