Add MXL domain ID retrieval and auto resolution for transport parameters in node implementation

Author: jonathan-r-thorpe

Development/nmos-cpp-node/node_implementation.cpp

@@ -138,6 +138,11 @@ namespace impl
 
     nmos::interlace_mode get_interlace_mode(const nmos::settings& settings);
 
+    // Effective MXL domain id from settings, or a repeatable default when omitted (used by resolve_auto)
+    nmos::id get_mxl_domain_id(const nmos::settings& settings);
+
+    web::json::value resolve_mxl_auto_value(const web::json::value& constraint, const nmos::id& fallback);
+
     // the different kinds of 'port' (standing for the format/media type/event type) implemented by the example node
     // each 'port' of the example node has a source, flow, sender and/or compatible receiver
     DEFINE_STRING_ENUM(port)
@@ -2073,10 +2078,11 @@ nmos::connection_resource_auto_resolver make_node_implementation_auto_resolver(c
     const auto ws_receiver_ids = impl::make_ids(seed_id, nmos::types::receiver, ws_receiver_ports, how_many);
     const auto mxl_receiver_ports = boost::copy_range<std::vector<impl::port>>(receiver_ports | boost::adaptors::filtered(impl::is_mxl_port));
     const auto mxl_receiver_ids = impl::make_ids(seed_id, nmos::types::receiver, mxl_receiver_ports, how_many);
+    const auto mxl_domain_id = impl::get_mxl_domain_id(settings);
 
     // although which properties may need to be defaulted depends on the resource type,
     // the default value will almost always be different for each resource
-    return [rtp_sender_ids, rtp_receiver_ids, ws_sender_ids, ws_sender_uri, ws_receiver_ids, mxl_sender_ids, mxl_receiver_ids](const nmos::resource& resource, const nmos::resource& connection_resource, value& transport_params)
+    return [rtp_sender_ids, rtp_receiver_ids, ws_sender_ids, ws_sender_uri, ws_receiver_ids, mxl_sender_ids, mxl_receiver_ids, mxl_domain_id](const nmos::resource& resource, const nmos::resource& connection_resource, value& transport_params)
     {
         const std::pair<nmos::id, nmos::type> id_type{ connection_resource.id, connection_resource.type };
         // this code relies on the specific constraints added by node_implementation_thread
@@ -2113,13 +2119,22 @@ nmos::connection_resource_auto_resolver make_node_implementation_auto_resolver(c
         }
         else if (mxl_sender_ids.end() != boost::range::find(mxl_sender_ids, id_type.first))
         {
-            nmos::details::resolve_auto(transport_params[0], nmos::fields::mxl_domain_id, [&] { return web::json::front(nmos::fields::constraint_enum(constraints.at(0).at(nmos::fields::mxl_domain_id))); });
-            nmos::details::resolve_auto(transport_params[0], nmos::fields::mxl_flow_id, [&] { return web::json::front(nmos::fields::constraint_enum(constraints.at(0).at(nmos::fields::mxl_flow_id))); });
+            nmos::details::resolve_auto(transport_params[0], nmos::fields::mxl_domain_id, [&]
+            {
+                return impl::resolve_mxl_auto_value(constraints.at(0).at(nmos::fields::mxl_domain_id), mxl_domain_id);
+            });
+            nmos::details::resolve_auto(transport_params[0], nmos::fields::mxl_flow_id, [&]
+            {
+                return impl::resolve_mxl_auto_value(constraints.at(0).at(nmos::fields::mxl_flow_id), nmos::fields::flow_id(resource.data).as_string());
+            });
         }
         else if (mxl_receiver_ids.end() != boost::range::find(mxl_receiver_ids, id_type.first))
         {
             // BCP-007-03: mxl_flow_id does not use "auto" on receivers (UUID or null only).
-            nmos::details::resolve_auto(transport_params[0], nmos::fields::mxl_domain_id, [&] { return web::json::front(nmos::fields::constraint_enum(constraints.at(0).at(nmos::fields::mxl_domain_id))); });
+            nmos::details::resolve_auto(transport_params[0], nmos::fields::mxl_domain_id, [&]
+            {
+                return impl::resolve_mxl_auto_value(constraints.at(0).at(nmos::fields::mxl_domain_id), mxl_domain_id);
+            });
         }
     };
 }
@@ -2427,6 +2442,28 @@ nmos::create_device_model_object_handler make_create_device_model_object_handler
 
 namespace impl
 {
+    nmos::id get_mxl_domain_id(const nmos::settings& settings)
+    {
+        const auto seed_id = nmos::experimental::fields::seed_id(settings);
+        return fields::mxl_domain_id(settings).empty()
+            ? nmos::make_repeatable_id(seed_id, U("/x-nmos/mxl/domain"))
+            : fields::mxl_domain_id(settings);
+    }
+
+    web::json::value resolve_mxl_auto_value(const web::json::value& constraint, const nmos::id& fallback)
+    {
+        using web::json::value;
+        if (constraint.has_field(nmos::fields::constraint_enum))
+        {
+            const auto& en = nmos::fields::constraint_enum(constraint);
+            if (en.is_array() && 0 != en.as_array().size())
+            {
+                return web::json::front(en);
+            }
+        }
+        return value::string(fallback);
+    }
+
     nmos::interlace_mode get_interlace_mode(const nmos::settings& settings)
     {
         if (settings.has_field(impl::fields::interlace_mode))