[Doc] add explanations for broker entry metadata (#13336)
* [Doc] add explanations for broker entry metadata
* update
* update
diff --git a/site2/docs/developing-binary-protocol.md b/site2/docs/developing-binary-protocol.md
index 1dbb0b8..4c4cc8b 100644
--- a/site2/docs/developing-binary-protocol.md
+++ b/site2/docs/developing-binary-protocol.md
@@ -63,6 +63,14 @@
| `broker_timestamp` | Optional | The timestamp when a message arrived at the broker (`id est` as the number of milliseconds since January 1st, 1970 in UTC) |
| `index` | Optional | The index of the message. It is assigned by the broker.
+If you want to use broker entry metadata for **brokers**, configure the [`brokerEntryMetadataInterceptors`](reference-configuration.md#broker) parameter in the `broker.conf` file.
+
+If you want to use broker entry metadata for **consumers**:
+
+1. Use the client protocol version [18 or later](https://github.com/apache/pulsar/blob/ca37e67211feda4f7e0984e6414e707f1c1dfd07/pulsar-common/src/main/proto/PulsarApi.proto#L259).
+
+2. Configure the [`brokerEntryMetadataInterceptors`](reference-configuration.md#broker) parameter and set the [`enableExposingBrokerEntryMetadataToClient`](reference-configuration.md#broker) parameter to `true` in the `broker.conf` file.
+
## Message metadata
Message metadata is stored alongside the application-specified payload as a serialized protobuf message. Metadata is created by the producer and passed without changes to the consumer.
diff --git a/site2/docs/reference-configuration.md b/site2/docs/reference-configuration.md
index 8bdbd59..cb2d181 100644
--- a/site2/docs/reference-configuration.md
+++ b/site2/docs/reference-configuration.md
@@ -354,6 +354,8 @@
| managedLedgerInfoCompressionType | Compression type of managed ledger information. <br><br>Available options are `NONE`, `LZ4`, `ZLIB`, `ZSTD`, and `SNAPPY`). <br><br>If this value is `NONE` or invalid, the `managedLedgerInfo` is not compressed. <br><br>**Note** that after enabling this configuration, if you want to degrade a broker, you need to change the value to `NONE` and make sure all ledger metadata is saved without compression. | None |
| additionalServlets | Additional servlet name. <br><br>If you have multiple additional servlets, separate them by commas. <br><br>For example, additionalServlet_1, additionalServlet_2 | N/A |
| additionalServletDirectory | Location of broker additional servlet NAR directory | ./brokerAdditionalServlet |
+| brokerEntryMetadataInterceptors | Set broker entry metadata interceptors.<br /><br />Multiple interceptors should be separated by commas. <br /><br />Available values:<li>org.apache.pulsar.common.intercept.AppendBrokerTimestampMetadataInterceptor</li><li>org.apache.pulsar.common.intercept.AppendIndexMetadataInterceptor</li> <br /><br />Example<br />brokerEntryMetadataInterceptors=org.apache.pulsar.common.intercept.AppendBrokerTimestampMetadataInterceptor, org.apache.pulsar.common.intercept.AppendIndexMetadataInterceptor|N/A |
+| enableExposingBrokerEntryMetadataToClient|Whether to expose broker entry metadata to client or not.<br /><br />Available values:<li>true</li><li>false</li><br />Example<br />enableExposingBrokerEntryMetadataToClient=true | false |
## Client
