[GitHub] [pulsar] codelipenghui opened a new issue #4737: Producer can't produce messages with an old schema version.

[GitBox <gi...@apache.org>]

codelipenghui opened a new issue #4737: Producer can't produce messages with an old schema version.
URL: https://github.com/apache/pulsar/issues/4737
 
 
   **Describe the bug**
   
   Producer can't produce messages with an old schema version.
   
   **To Reproduce**
   Steps to reproduce the behavior:
   1. Use pulsar-admin to set-schema-autoupdate-strategy -c Backward public/default
   2. Run following test case:
   ```java
   
   import org.apache.pulsar.client.api.PulsarClient;
   import org.apache.pulsar.client.api.PulsarClientException;
   import org.apache.pulsar.client.api.Schema;
   
   public class SchemaTests {
   
       public static void main(String[] args) throws PulsarClientException {
   
           PulsarClient client = PulsarClient.builder().serviceUrl("pulsar://127.0.0.1:6650").build();
           client.newProducer(Schema.AVRO(UserV1.class)).topic("topic-1").create();
           client.newProducer(Schema.AVRO(UserV2.class)).topic("topic-1").create();
           client.newProducer(Schema.AVRO(UserV1.class)).topic("topic-1").create();
   
       }
   
   
       private static class UserV1 {
   
           private String username;
           private int age;
   
           public String getUsername() {
               return username;
           }
   
           public void setUsername(String username) {
               this.username = username;
           }
   
           public int getAge() {
               return age;
           }
   
           public void setAge(int age) {
               this.age = age;
           }
       }
   
       private static class UserV2 {
   
           public String getUsername() {
               return username;
           }
   
           public void setUsername(String username) {
               this.username = username;
           }
   
           private String username;
   
       }
   
   }
   ```
   
   Will produce the following error:
   
   ```
   Exception in thread "main" org.apache.pulsar.client.api.PulsarClientException$IncompatibleSchemaException: org.apache.pulsar.broker.service.schema.exceptions.IncompatibleSchemaException: Incompatible schema used
   	at org.apache.pulsar.client.api.PulsarClientException.unwrap(PulsarClientException.java:253)
   	at org.apache.pulsar.client.impl.ProducerBuilderImpl.create(ProducerBuilderImpl.java:88)
   	at org.apache.pulsar.issue.SchemaTests.main(SchemaTests.java:12)
   ```
   
   **Expected behavior**
   
   At producer side, producer can send messages using an old version schema.
   

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