Preliminary high-level comparison

TR-0076-Integrating_NGSI-LD_API_in_oneM2M.md

@@ -964,6 +964,17 @@ Figure 7.3.3-1 shows an IPE with mapping information, where the information in t
 
 A possible issue with this approach is the number of Mca requests that the IPE needs to execute in order to answer a request. This can range from a few (e.g. retrieval of a single entity with few attributes) to a very large query (e.g. graph query with many entities).
 
+## 7.4 High-level comparison of approaches (preliminary)
+
+In clauses 7.2 a mapping-based approach is described that proposes to integrate the NGSI-LD functionality directly into a oneM2M system, whereas Clause 7.3 describes different interworking-based approaches, where NGSI-LD related functionality is implemented by an Interworking Proxy Entity.
+
+The general aspects that have to be taken into account for the comparison is efficiency and avoidance of information duplication on the one side and the complexity of the implementation on the other side.
+
+The integrated approach described in clause 7.2 generally enables more efficient access as many of the steps are internal and do not have to go via the external binding. Also, internally, more implementation optimizaions are possible, e.g. indexing, pre-fetching of information and pre-processing.
+Furthermore, there is no need to duplicate information. However, there is a significant complexity of implementation that has to be handled by the implementor of the oneM2M system.
+
+The synchronization based interworking approaches all duplicate information, so the respective applications can efficiently access the information. The efficiency of the information access by the Interworking Proxy is worse than in the integrated approach as there is the overhead of the binding for each request and there are less optimization possibilities as in the internal case.
+The request-based interworking approach avoids the duplication of information, but possibly, at the expense of access efficiency and the resulting delay suffered by the reuqesting application.
 
 # 8 Mapping between the information stored in oneM2M resources and the NGSI-LD information model