update

Author: oblomov-dev

docs/development/navigation.md

@@ -3,11 +3,51 @@ outline: [2, 4]
 ---
 # Navigation
 
-### Backend 
+In abap2UI5, each application is represented by a single ABAP class. While you can embed all logic within a single class and call different views or popups within it, it is generally better practice to keep individual classes manageable in size. This can be achieved by creating multiple classes that interact with each other, allowing you to build reusable, generic applications and popups that can be called in various contexts.
 
+### Backend
+To call an ABAP class, use the following code:
+```abap
+METHOD z2ui5_if_app~main. root app
+    DATA(lo_app) = NEW z2ui5_cl_demo_app_025( ).
+    client->nav_app_call( lo_app ).
+ENDMETHOD.
+```
+The framework maintains a call stack. In the newly called class, you can return to the previous application using:
+```abap called app
+METHOD z2ui5_if_app~main.
+    client->nav_app_leave( ).
+ENDMETHOD.
+```
+If you need to access data from the previous application, use casting as follows:
+```abap root app
+METHOD z2ui5_if_app~main.
+    IF client->check_on_navigated( ).
+        DATA(lo_called_app) = CAST z2ui5_cl_demo_app_025( client->get_app_prev( ) ).
+        client->message_box_display( `Input made in the previous app:` && lo_called_app->mv_input ).
+    ENDIF.
+ENDMETHOD.
+```
+To navigate to an application without adding it to the call stack, use:
+```abap
+METHOD z2ui5_if_app~main. root app
+    DATA(lo_app) = NEW z2ui5_cl_demo_app_025( ).
+    client->nav_app_call( lo_app ).
+ENDMETHOD.
+```
+::: tipp
+Sound familiar? The abap2UI5 framework is designed to emulate the classic “call screen” and “leave to screen” logic.
+:::
 
 ### Launchpad
-
-
+It is recommended to use backend communication exclusively for view changes or popup calls. If you’re using a launchpad, consider navigating through the launchpad to utilize browser navigation and history. Here’s an example:
+```abap
+client->_event_client(
+    val = client->cs_event-cross_app_nav_to_ext
+        t_arg  = VALUE #( ( 
+            `{ semanticObject: "Z2UI5_CL_LP_SAMPLE_04",  action: "display" }` 
+    ) ) ).
+```
+To learn more about launchpads and routing, refer to the documentation (here.)[configuration/launchpad]
 ### Frontend
-In app
+Further frontend navigation features, including back button support with routing, are currently a work in progress. Track updates (here.)[https://github.com/abap2UI5/abap2UI5/issues/1420]