[wip] feat: openTelemetry integration design in client_design.md

src/guide/develop/client_design.md

@@ -411,3 +411,59 @@ $operation failed, error: $error_details
 # example:
 writePoint failed, unmarshall response body error: json: cannot unmarshal number ...
 ```
+# OpenTelemetry integration design
+To enhance the observability of the OpenGemini Go client and facilitate tracking of performance metrics, errors, and other information related to query and write operations, this solution adopts the interceptor pattern to integrate OpenTelemetry, enabling full-link tracing. The design supports non-intrusive extensions, allowing coexistence with other interceptors (such as logging and authentication interceptors) while minimizing modifications to the original client.
+
+## Define the interceptor interface 
+
+```mermaid
+interface Interceptor {
++ context.Context QueryBefore(context.Context, string)
++ void QueryAfter(context.Context, string, error)
++ context.Context WriteBefore(context.Context, []byte)
++ void WriteAfter(context.Context, []byte, error)
+}
+```
+
+## Define the base client class,associated with the Interceptor interface
+
+```mermaid
+class Client {
+- []Interceptor interceptors
++ Client(interceptors ...Interceptor)
++ AddInterceptor(interceptors ...Interceptor)
++ context.Context doQueryBefore(context.Context, string)
++ void doQueryAfter(context.Context, string, error)
++ context.Context doWriteBefore(context.Context, []byte)
++ void doWriteAfter(context.Context, []byte, error)
+}
+```
+
+## Define the interceptor implementation class integrating OpenTelemetry,implementing the Interceptor interface
+
+```mermaid
+class OtelClient {
+- trace.Tracer tracer
++ OtelClient()
++ context.Context QueryBefore(context.Context, string)
++ void QueryAfter(context.Context, string, error)
++ context.Context WriteBefore(context.Context, []byte)
++ void WriteAfter(context.Context, []byte, error)
+}
+```
+
+## Define processes related to main function usage examples (simplified to show invocation relationships)
+
+```mermaid
+class Main {
++ static func initOtel() func()
++ static func main()
++ static func performQuery(context.Context, string) error
+}
+
+The implementation and association relationships between interfaces and classes
+Client --> Interceptor : contains multiple
+OtelClient --> Interceptor : implement
+Main --> Client : use
+Main --> OtelClient : initialize and add to client
+```