Hello World

Just copy the following class into your system:

CLASS zcl_app_hello_world DEFINITION PUBLIC.
  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.

  PROTECTED SECTION.
  PRIVATE SECTION.
ENDCLASS.

CLASS zcl_app_hello_world IMPLEMENTATION.
  METHOD z2ui5_if_app~main.
    client->message_box_display( `Hello World` ).
  ENDMETHOD.
ENDCLASS.

Open the abap2UI5 startup page in your browser — the page the Quickstart ends on — enter the class name ZCL_APP_HELLO_WORLD in the input field, and launch it.

That is a complete abap2UI5 app: one class, one method, no frontend project and no OData service.

Starting an App by URL

The startup page is a convenience around a URL parameter you will use from now on. ?app_start=<class> appended to your service URL starts that app directly:

https://<host>:<port>/sap/bc/<your_service>?app_start=zcl_app_hello_world

That is the form a browser bookmark, a Launchpad tile and every sample catalogue use — the sample pages all say "start it with ?app_start=<class>" and mean exactly this.

If launching reports The app 'ZCL_APP_HELLO_WORLD' does not exist in the system., the framework could not instantiate the class: a typo in the name, or the class is not activated yet. Anything that goes wrong after this point — an app that renders empty, a binding that does not update, an error view on a roundtrip — is catalogued with symptom, cause and fix in Common Failures.

Naming

Name your own apps in your customer namespace (Z.../Y...). The Z2UI5_ prefix is reserved for the framework and its samples.

A Real Screen, an Event and Data Exchange

A message box is not an app. This second class is still one class, and it has everything a real one has — a view, data travelling both ways, and an event:

CLASS zcl_app_hello_screen DEFINITION PUBLIC.
  PUBLIC SECTION.
    INTERFACES z2ui5_if_app.
    DATA name TYPE string.

  PROTECTED SECTION.
  PRIVATE SECTION.
ENDCLASS.

CLASS zcl_app_hello_screen IMPLEMENTATION.
  METHOD z2ui5_if_app~main.

    IF client->check_on_navigated( ).

      name = `World`.

      DATA(view) = z2ui5_cl_ui5_view_builder=>factory(
          )->ele( n = `View` ns = `mvc`
              )->a( n = `xmlns`     v = `sap.m`
              )->a( n = `xmlns:mvc` v = `sap.ui.core.mvc`

              )->ele( `Shell`
                  )->ele( `Page`
                      )->a( n = `title` v = `abap2UI5 - Hello World`

                      )->tag( `Input`
                          )->a( n = `value` v = client->_bind( name )
                      )->tag( `Button`
                          )->a( n = `text`  v = `Say Hello`
                          )->a( n = `press` v = client->_event( `SAY_HELLO` ) ).

      client->view_display( view->stringify( ) ).

    ELSEIF client->check_on_event( `SAY_HELLO` ).

      client->message_toast_display( |Hello { name }!| ).

    ENDIF.

  ENDMETHOD.
ENDCLASS.

Type a name, press the button, and the toast greets it. Three things are happening, and none of them needed any code you had to write yourself:

• the view is a UI5 XML view, built in ABAP with z2ui5_cl_ui5_view_builder
• client->_bind( name ) ties the input to the public attribute, so what the user types is in name on the next roundtrip
• client->_event( ) sends the button press back to main, and check_on_event( ) catches it

Jump into the Code

Press Ctrl+F12 in any running app to open the Developer Tools — tabs for the app's source code, the rendered view XML, the model data, the request/response pair and the error log. It is the first place to look when something does not render the way you expected:

Next: Build Something

Want all of that explained rather than just shown? The Walkthrough takes these two classes apart and grows them into a complete app, one concept per step — views, events, binding, lists, tables, a selection screen and popups. Every step is a complete class you can run in the browser.

Working Samples

Complete apps from the sample catalogue that use what this page describes. Each is a single class — pull the repository with abapGit and start it with ?app_start=<class>.

Sample	Class
Basics I — Hello World, the Smallest App	Z2UI5_CL_SMP_APP_493