2 files changed, 19 insertions, 8 deletions
diff --git a/src/core/lib/channel/channelz.cc b/src/core/lib/channel/channelz.cc
index 1ac7bd3976..9f54850002 100644
--- a/src/core/lib/channel/channelz.cc
+++ b/src/core/lib/channel/channelz.cc
@@ -117,6 +117,9 @@ grpc_json* ChannelNode::RenderJson() {
                                            GRPC_JSON_OBJECT, false);
   json = data;
   json_iterator = nullptr;
+  // template method. Child classes may override this to add their specific
+  // functionality.
+  PopulateConnectivityState(json);
   // populate the target.
   GPR_ASSERT(target_.get() != nullptr);
   grpc_json_create_child(nullptr, json, "target", target_.get(),
@@ -129,6 +132,10 @@ grpc_json* ChannelNode::RenderJson() {
   }
   // ask CallCountingHelper to populate trace and call count data.
   call_counter_.PopulateCallCounts(json);
+  json = top_level_json;
+  // template method. Child classes may override this to add their specific
+  // functionality.
+  PopulateChildRefs(json);
   return top_level_json;
 }
 
diff --git a/src/core/lib/channel/channelz.h b/src/core/lib/channel/channelz.h
index 14edc75123..e2cef233e6 100644
--- a/src/core/lib/channel/channelz.h
+++ b/src/core/lib/channel/channelz.h
@@ -124,6 +124,18 @@ class ChannelNode : public BaseNode {
 
   grpc_json* RenderJson() override;
 
+  // template methods. RenderJSON uses these methods to render its JSON
+  // representation. These are virtual so that children classes may provide
+  // their specific mechanism for populating these parts of the channelz
+  // object.
+  //
+  // ChannelNode does not have a notion of connectivity state or child refs,
+  // so it leaves these implementations blank.
+  //
+  // This is utilizing the template method design pattern.
+  virtual void PopulateConnectivityState(grpc_json* json) {}
+  virtual void PopulateChildRefs(grpc_json* json) {}
+
   void MarkChannelDestroyed() {
     GPR_ASSERT(channel_ != nullptr);
     channel_ = nullptr;
@@ -144,14 +156,6 @@ class ChannelNode : public BaseNode {
   void RecordCallFailed() { call_counter_.RecordCallFailed(); }
   void RecordCallSucceeded() { call_counter_.RecordCallSucceeded(); }
 
- protected:
-  // provides view of target for child.
-  char* target_view() { return target_.get(); }
-  // provides access to call_counter_ for child.
-  CallCountingHelper* call_counter() { return &call_counter_; }
-  // provides access to channel trace for child.
-  ChannelTrace* trace() { return &trace_; }
-
  private:
   // to allow the channel trace test to access trace();
   friend class testing::ChannelNodePeer;