[GitHub] [apisix] tzssangglass commented on a diff in pull request #7059: docs: add pubsub develop example for kafka

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

tzssangglass commented on code in PR #7059:
URL: https://github.com/apache/apisix/pull/7059#discussion_r874795115


##########
docs/en/latest/pubsub.md:
##########
@@ -58,6 +58,85 @@ Apache APISIX implement an extensible pubsub module, which is responsible for st
 - Implement the required message system instruction processing functions
 - Optional: Create plugins to support advanced configurations of this messaging system
 
-### Example
+### Example of Apache Kafka
 
-TODO, an example will be added later to point out how to support other messaging systems.
+#### Add new commands and response body definitions to `pubsub.proto`
+
+The core of the protocol definition in `pubsub.proto` is the two parts `PubSubReq` and `PubSubResp`.
+
+First, create the `CmdKafkaFetch` command and add the required parameters. Then, register this command in the list of commands for `req` in `PubSubReq`, which is named `cmd_kafka_fetch`.
+
+Then create the corresponding response body `KafkaFetchResp` and register it in the `resp` of `PubSubResp`, named `kafka_fetch_resp`.
+
+The protocol definition [pubsub.proto](https://github.com/apache/apisix/blob/master/apisix/include/apisix/model/pubsub.proto).
+
+#### Add a new option to the `scheme` configuration item in upstream
+
+Add a new option `kafka` to the `scheme` field enumeration in the `upstream` of `apisix/schema_def.lua`.
+
+The schema definition [schema_def.lua](https://github.com/apache/apisix/blob/master/apisix/schema_def.lua).
+
+#### Add a new `scheme` judgment branch to `http_access_phase`
+
+Add a `scheme` judgment branch to the `http_access_phase` function in `apisix/init.lua` to support the processing of `kafka` type upstreams. Because of Apache Kafka has its own clustering and partition scheme, we do not need to use the Apache APISIX built-in load balancing algorithm, so we intercept and take over the processing flow before selecting the upstream node, here using the `kafka_access_phase` function.

Review Comment:
   ```suggestion
   Add a `scheme` judgment branch to the `http_access_phase` function in `apisix/init.lua` to support the processing of `kafka` type upstreams. Because Apache Kafka has its clustering and partition scheme, we do not need to use the Apache APISIX built-in load balancing algorithm, so we intercept and take over the processing flow before selecting the upstream node, using the `kafka_access_phase` function.
   ```



##########
docs/en/latest/pubsub.md:
##########
@@ -58,6 +58,85 @@ Apache APISIX implement an extensible pubsub module, which is responsible for st
 - Implement the required message system instruction processing functions
 - Optional: Create plugins to support advanced configurations of this messaging system
 
-### Example
+### Example of Apache Kafka
 
-TODO, an example will be added later to point out how to support other messaging systems.
+#### Add new commands and response body definitions to `pubsub.proto`
+
+The core of the protocol definition in `pubsub.proto` is the two parts `PubSubReq` and `PubSubResp`.
+
+First, create the `CmdKafkaFetch` command and add the required parameters. Then, register this command in the list of commands for `req` in `PubSubReq`, which is named `cmd_kafka_fetch`.
+
+Then create the corresponding response body `KafkaFetchResp` and register it in the `resp` of `PubSubResp`, named `kafka_fetch_resp`.
+
+The protocol definition [pubsub.proto](https://github.com/apache/apisix/blob/master/apisix/include/apisix/model/pubsub.proto).
+
+#### Add a new option to the `scheme` configuration item in upstream
+
+Add a new option `kafka` to the `scheme` field enumeration in the `upstream` of `apisix/schema_def.lua`.
+
+The schema definition [schema_def.lua](https://github.com/apache/apisix/blob/master/apisix/schema_def.lua).
+
+#### Add a new `scheme` judgment branch to `http_access_phase`
+
+Add a `scheme` judgment branch to the `http_access_phase` function in `apisix/init.lua` to support the processing of `kafka` type upstreams. Because of Apache Kafka has its own clustering and partition scheme, we do not need to use the Apache APISIX built-in load balancing algorithm, so we intercept and take over the processing flow before selecting the upstream node, here using the `kafka_access_phase` function.
+
+The APISIX init file [init.lua](https://github.com/apache/apisix/blob/master/apisix/init.lua).
+
+#### Implement the required message system commands processing functions
+
+First, create an instance of the `pubsub` module, which is provided in the `core` package.
+
+Then, an instance of the Apache Kafka client is created, and this code is omitted here.

Review Comment:
   ```suggestion
   Then, an instance of the Apache Kafka client is created and omitted code here.
   ```



##########
docs/en/latest/pubsub.md:
##########
@@ -58,6 +58,85 @@ Apache APISIX implement an extensible pubsub module, which is responsible for st
 - Implement the required message system instruction processing functions
 - Optional: Create plugins to support advanced configurations of this messaging system
 
-### Example
+### Example of Apache Kafka
 
-TODO, an example will be added later to point out how to support other messaging systems.
+#### Add new commands and response body definitions to `pubsub.proto`
+
+The core of the protocol definition in `pubsub.proto` is the two parts `PubSubReq` and `PubSubResp`.
+
+First, create the `CmdKafkaFetch` command and add the required parameters. Then, register this command in the list of commands for `req` in `PubSubReq`, which is named `cmd_kafka_fetch`.
+
+Then create the corresponding response body `KafkaFetchResp` and register it in the `resp` of `PubSubResp`, named `kafka_fetch_resp`.
+
+The protocol definition [pubsub.proto](https://github.com/apache/apisix/blob/master/apisix/include/apisix/model/pubsub.proto).
+
+#### Add a new option to the `scheme` configuration item in upstream
+
+Add a new option `kafka` to the `scheme` field enumeration in the `upstream` of `apisix/schema_def.lua`.
+
+The schema definition [schema_def.lua](https://github.com/apache/apisix/blob/master/apisix/schema_def.lua).
+
+#### Add a new `scheme` judgment branch to `http_access_phase`
+
+Add a `scheme` judgment branch to the `http_access_phase` function in `apisix/init.lua` to support the processing of `kafka` type upstreams. Because of Apache Kafka has its own clustering and partition scheme, we do not need to use the Apache APISIX built-in load balancing algorithm, so we intercept and take over the processing flow before selecting the upstream node, here using the `kafka_access_phase` function.
+
+The APISIX init file [init.lua](https://github.com/apache/apisix/blob/master/apisix/init.lua).
+
+#### Implement the required message system commands processing functions
+
+First, create an instance of the `pubsub` module, which is provided in the `core` package.
+
+Then, an instance of the Apache Kafka client is created, and this code is omitted here.
+
+Next, add the command registered in the protocol definition above to the `pubsub` instance, which will provide a callback function that provides the parameters parsed from the communication protocol, in which the developer needs to call the kafka client to get the data and return it to the `pubsub` module as the function return value.
+
+:::note Callback function prototype
+The `params` is the data in the protocol definition; the first return value is the data, which needs to contain the fields in the response body definition, and returns the `nil` value when there is an error; the second return value is the error, and returns the error string when there is an error
+:::
+
+Finally, it enters the loop to wait for client commands and when an error occurs it returns the error and stops the processing flow.

Review Comment:
   ```suggestion
   Finally, it enters the loop to wait for client commands, and when an error occurs, it returns the error and stops the processing flow.
   ```



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