Add documentation for StreamingUpdate

- Align figure
- Add architecture information
- Add section to top-level interface

Signed-off-by: Thomas Sedlmayer <tsedlmayer@pmsfit.de>

Author: thomassedlmayer

doc/architecture/architecture_overview.adoc

@@ -32,14 +32,16 @@ The following figure shows a more advanced use case for traffic participants.
 .Traffic participant with sensor models, AD function, and dynamic model
 image::{images_open_simulation_interface}/osi-traffic-participant-advanced.png[1100]
 
-[#fig-interface-streaming]
-.Interface for Streaming
-image::{images_open_simulation_interface}/osi-streaming-principle.png[1100]
-
 The `HostVehicleData` interface describes the measured internal states of a traffic participant.
 OSI currently provides only limited support for data structures that describe measured internal states of traffic participants.
 Actuator intentions are currently not covered by OSI and must be handled using a different data description format.
 
+The `StreamingUpdate` interface enables partial ground truth updates to modules that favor performance, especially latency, over data completeness/consistency (e.g. visualization applications) or that do not require complete data in the first place (e.g. logging applications).
+
+[#fig-interface-streaming]
+.Interface for partial ground truth updates
+image::{images_open_simulation_interface}/osi-streaming-principle.png[1100]
+
 NOTE: OSI uses singular instead of plural for `repeated` field names.
 
 NOTE: All fields in an interface are set to `optional`.

doc/architecture/streaming_update.adoc

@@ -0,0 +1,10 @@
+ifndef::include-only-once[]
+:root-path: ../
+include::{root-path}_config.adoc[]
+endif::[]
+= Streaming update
+
+The `StreamingUpdate` message provides an interface to transmit a subset of ground truth and/or vehicle internal data.
+This interface mainly addresses applications with low latency requirements and no need for highly consistent and complete data, e.g. visualization applications.
+Static and/or non-relevant objects can be omitted as required for the specific use case.
+Note that the receiver of partial updates can only rely on the most up-to-date information at the corresponding timestamp. E.g. omitting objects does not indicate static behaviour but it may be sufficient for the use case to update certain objects at a later point in time.

doc/images/osi-streaming-principle.PNG

@@ -27,6 +27,8 @@ include::./architecture/traffic_command.adoc[leveloffset=+3]
 
 include::./architecture/traffic_update.adoc[leveloffset=+3]
 
+include::./architecture/streaming_update.adoc[leveloffset=+3]
+
 === Model types
 
 include::./architecture/environmental_effect_model.adoc[leveloffset=+3]