ABAP CHANNELS DEMOSa248.g.akamai.net/n/248/420835/ea1c12f07cd5a3f29c542a893...2016/06/22 · information and sale conditions to browser UI (SAPUI5, Web Dynpro ABAP, BSP) as soon as

ABAP CHANNELS DEMOS ABAP Channels in Developer Edition AS ABAP 7.5

December 2015 Olga Dolinskaja / SAP SE

ABAP Channels in Developer Edition AS ABAP 7.5

2

TABLE of Contents

TABLE of Contents .............................................................................................................................................. 2

A.INTRODUCTION ................................................................................................................................................... 3

GENERAL INFORMATION .................................................................................................................................... 3

MOTIVATION ...................................................................................................................................................... 3

B. DEMO ABAP PUSH CHANNEL (APC) ................................................................................................................... 4

INTRODUCTION .................................................................................................................................................. 4

DEMO ................................................................................................................................................................. 4

SUMMARY ........................................................................................................................................................ 11

C. DEMO ABAP MESSAGING CHANNEL (AMC) .................................................................................................... 12

INTRODUCTION ................................................................................................................................................ 12

DEMO ............................................................................................................................................................... 12

SUMMARY ........................................................................................................................................................ 15

D. DEMO COLLABORATION USING ABAP CHANNELS .......................................................................................... 16

INTRODUCTION ................................................................................................................................................ 16

DEMO ............................................................................................................................................................... 16

SUMMARY ........................................................................................................................................................ 19


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A.INTRODUCTION

General information

Welcome to the ABAP Channels demos in the Developer Edition of AS ABAP 7.5. In this document you will find descriptions about how to use: B. Demo ABAP Push Channel (APC) C. Demo ABAP Messaging Channel (AMC) D. Demo collaboration using ABAP Channels Before you start, here is some technical information on the prerequisites, demo packages, etc. that you will use: Integrated Development Environment (IDE)

Eclipse Mars 1(4.5.1)

ABAP Development Tools ABAP Development Tools 2.51

UI Development Kit for HTML5 UI Development Kit for HTML5 1.32

SAPUI5 ABAP Repository Team Provider

SAPUI5 ABAP Repository Team Provider 1.32

ABAP System A4H

ABAP Client 001

ABAP Username DEVELOPER

ABAP Channels Demo Package DEMO_CHANNELS

SAPUI5 application ZAPC_CHAT

Motivation

Most ABAP applications use polling techniques to achieve an event-driven communication. For pushing an event from an ABAP backend to a browser based user agent like SAPUI5, Web Dynpro ABAP, Business Server Pages (BSP) or WebGUI, the polling in multi-seconds interval is frequently used. This is a quite system resource consuming technique. The ABAP Channels technology targets to replace such inefficient eventing based on polling techniques through Web Sockets (ABAP Push Channel) and publish/subscribe mechanism (ABAP Messaging Channel).

Now, enjoy the demos!


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B. DEMO ABAP PUSH CHANNEL (APC)

Introduction

Immediate access on UI to the frequently changing business information and data in ABAP backend will support timely business insights, decision making and productivity. The examples for this can be for instance bringing the irregularly and often changing product information and sale conditions to browser UI (SAPUI5, Web Dynpro ABAP, BSP) as soon as data change takes place in the ABAP backend, pushing short-lived financial data relevant for trades to the browser UI, statistics, process information (sales figures in different areas, financial statistics, manufacturing process status). In all these cases the data presentation on UI (charts, diagrams, text and numbers) must be updated immediately accordingly to the modified data in the ABAP backend.

In such situations in order to present the latest up-to-date information from the ABAP backend in real-time on the browser based UI most ABAP applications used polling techniques with multi-seconds intervals or refresh button periodically to get newest updates to UI. These approaches are quite resource consuming result in insufficient performance and poor user experience. The availability of real-time data in ABAP backend is unpredictable and it is unnecessary effort to make requests and open and close HTTP connections.

The ABAP Push Channel (APC) technology replaces such inefficient polling approach through Web Sockets. ABAP Push Channel is bi-directional message based communication channel representing the Web Socket integration in ABAP, allowing e.g.to push notification to the UI as soon as data change in ABAP backend happens. This is a sign for a user to request the changed data from ABAP backend and update UI.

For introduction to ABAP Channels please refer to http://scn.sap.com/community/abap/connectivity/blog/2014/11/27/introduction-to-abap-channels

More detailed information about how to use ABAP Push Channel: http://scn.sap.com/community/abap/connectivity/blog/2013/11/18/websocket-communication-using-abap-push-channels

Video Tutorials: http://scn.sap.com/community/abap/blog/2015/03/09/how-to-implement-and-use-abap-

channels--video-tutorials

Demo

In this demo you can investigate simple SAPUI5 application (Chat program) which uses ABAP Push Channel as Web Socket communication with ABAP backend system. It works as following. You put any text into the text field and press the arrow button. The text is sent to the ABAP backend system over the ABAP Push Channel (Web Socket). The ABAP System enriches the text with date, time and user and sends it back. The UI displays the text below the text field.

http://scn.sap.com/community/abap/connectivity/blog/2014/11/27/introduction-to-abap-channels

http://scn.sap.com/community/abap/connectivity/blog/2013/11/18/websocket-communication-using-abap-push-channels

http://scn.sap.com/community/abap/connectivity/blog/2013/11/18/websocket-communication-using-abap-push-channels

http://scn.sap.com/community/abap/blog/2015/03/09/how-to-implement-and-use-abap-channels--video-tutorials



5

In this demo you can see how

ABAP Push Channel (APC) is implemented

ABAP Push Channel is used in the SAPUI5 application

Explanation Screenshot

1. Start Eclipse, your Integrated Development Environment (IDE).

2. Switch to the ABAP perspective by clicking the Open Perspective button or using the Menu Window > Open Perspective > Other.

3. Create ABAP Project (using connection data to your ABAP backend system of the AS ABAP Developer Edition. File > New > ABAP Project… and follow then the suggested wizard steps.

4. Add DEMO_CHANNELS as

favorite package to your project (Favorite Packages > Add a Package)


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5. Now create SAPUI5 project for the UI application. File > New > Other > SAPUI5 Application Development > Application Project and click Next button

6. Enter as project name

ZAPC_CHAT and click Next

button


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7. Enter as View name Chat,

choose XML as development

paradigm and click Next button. On the last wizard screen print Finish button.

You have created the empty

SAPUI5 project ZAPC_CHAT.

8. Now retrieve the UI application sources from the SAPUI5 ABAP Repository. In the Project Explorer mark your

ZAPC_CHAT SAPUI5 Project

and select in the context menu Team > Share Project.

9. Choose SAPUI5 ABAP Repository from the list and click Next button.


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10. Select your system connection using Browse button, click Next button Enter your logon data, click Next button

Select the ZAPC_CHAT BSP

application from the SAPUI5 ABAP Repository and click Finish button

11. Now retrieve the sources of the

ZAPC_CHAT application from

the SAPUI5 ABAP Repository using the context menu Team > Retrieve.


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All resources must be selected. Click Finish button.

12. Now take a look at the ABAP Push Channel (APC)

ZAPC_CHAT by double-clicking

it or using SAPC transaction

(shortcut Alt+F8 to run ABAP

application in embedded

SAPGUI in Eclipse, type SAPC).

The associated service

/sap/bc/apc/sap/zapc_ch

at (you can find it in the

transaction SICF) and the

corresponding ABAP Push Channel application class were generated by Generate Class and Service button. The service gets activated automatically after generation.

The V10.PCP.SAP.COM value

stays for the SAP’s common message exchange protocol PCP to exchange messages in the PCP format.

13. Open the corresponding ABAP Push Channel class ZCL_APC_WSP_EXT_ZAPC_CH

AT in the editor and take a look

at the IF_APC_WSP_EXT_PCP~ON_M

ESSAGE method. The relevant

code lines are on the screenshot. The importing parameter of this

method i_message represents

the message which is delivered through APC. First, the text is


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collected from the i_message.

Then the message gets enriched with author and date and prepared for the UI display in the method prepare_message_for_ui(

). Then the message is sent

back with the

i_message_manager through

APC to the UI.

14. Now examine how the UI part establishes the WebSocket connection. In the Project Explorer navigate to the

onInit()method of the Chat

controller (Chat.controller.js) and double click it to open in the editor window. On the screenshot you see the source code line, which establishes the Web Socket connection.

Remark: In the onInit()

method the Web Socket connection is established to the registered service /sap/bc/apc/sap/zapc_ch

at (ABAP Push Channel) with

SAP’s common message exchange protocol PCP. Furthermore the callback function is registered on Web Socket events and the UI model is set. If a message arrives, its data get parsed, formatted and added as a new entry to the UI model. By using

unshift() the newest entry

gets displayed on the top of the

list. The method refresh ()

updates the UI model on the screen.


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15. Run ZAPC_CHAT application:

select index.html and execute it on the ABAP Server: Run As > Run on ABAP Server.

16. After entering your user and password you can use the Chat program. Type text into the text field and press the ‘arrow’ button. The text gets displayed on top of the list below the text field.

Summary

This demo creates the ABAP Push Channel (Web Socket) using the SAPC transaction and uses it in the SAPUI5 application (Chat program) to exchange the messages through the ABAP Push Channel between the SAPUI5 application and the ABAP system.


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C. DEMO ABAP MESSAGING CHANNEL (AMC)

Introduction

Event-driven communication between ABAP sessions across the boundaries of ABAP application servers will streamline the business process workflow, speed up performance and reduce the rate of consumption of database resources. An ABAP application might need to identify and react to certain events in the other ABAP session as soon as they occur. Moreover an ABAP application might involve data processing in order to provide some output to be delivered to another application, running in another ABAP session and therefore has to send notification. Traditionally to realize such real-time event-driven behavior ABAP applications often poll periodically for the state information on the database. Bottleneck problems on the database may occur with numerous active polling from many ABAP applications simultaneously.

Instead of using periodically polling technique, a publish/subscribe mechanism can be used for prompt notification which can eliminate unnecessary database load. ABAP Messaging Channel (AMC) infrastructure replaces the polling through publish/subscribe mechanism and acts as a broker for the message exchange between different ABAP sessions, which can reside on different ABAP application servers. After ABAP sessions act as publisher and subscribers respectively, as soon as an ABAP session publishes notification to AMC, all subscriber ABAP sessions get notified.


More detailed information about how to use ABAP Messaging Channel: http://scn.sap.com/community/abap/connectivity/blog/2014/03/26/abap-channels-part-2-publish-subscribe-messaging-using-abap-messaging-channels

Video Tutorials: http://scn.sap.com/community/abap/blog/2015/03/09/how-to-implement-and-use-abap-

channels--video-tutorials

Demo

This demo implements communication with the ABAP Messaging Channel (AMC) between two simple ABAP programs AMC sender and AMC receiver which are executed in two parallel ABAP

sessions. While the AMC receiver program subscribes to the AMC channel /ping and waits for

incoming messages, the AMC sender program sends messages to the AMC channel /ping and the

AMC receiver program receives them.


http://scn.sap.com/community/abap/connectivity/blog/2014/03/26/abap-channels-part-2-publish-subscribe-messaging-using-abap-messaging-channels

http://scn.sap.com/community/abap/connectivity/blog/2014/03/26/abap-channels-part-2-publish-subscribe-messaging-using-abap-messaging-channels




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After executing the AMC message receiver program it shows sand glass and is in the waiting state. After executing the AMC sender program, the message ‘Hi there!’ is sent through the AMC channel

/ping and the AMC message receiver receives and displays the message on the UI.


ABAP Messaging Channel is implemented

ABAP Messaging Channel is used for the communication between two ABAP sessions


1. Switch in the Eclipse to the ABAP Perspective. Under Connectivity of

the package ZDEMO_CHANNELS

you will find within ABAP Messaging Channels the AMC

application ZAMC_CHAT. Double

click to open it in the embedded SAPGUI in Eclipse (or use shortcut

Alt+F8 to run ABAP application in

the SAPGUI, type SAMC).

2. Double click the channel /ping.

The authorized programs to send and receive messages through the

AMC channel /ping are

ZAMC_SEND_MESSAGE_TEXT and ZAMC_RECEIVE_MESSAGE_TEXT

Remark: In this demo messages are exchanged in simple text

format (TEXT) within activity

scope client (Client).


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3. In the Source Code Library of the

package ZDEMO_CHANNELS you

will find the ABAP programs:

ZAMC_SEND_MESSAGE_TEXT as

AMC sender and ZAMC_RECEIVE_MESSAGE_TEXT

as AMC receiver.

4. Open the AMC sender program

ZAMC_SEND_MESSAGE_TEXT in

the editor window and take a look at its implementation. This program sends out the message

‘Hi there!’ through the AMC.

First the class factory cl_amc_channel_manager

creates AMC producer object for

the AMC application ZAMC_CHAT

and AMC channel /ping. Then

the message is published with the

provided interface method send()

to the AMC.

5. Open the AMC receiver program ZAMC_RECEIVE_MESSAGE_TEXT

in the editor window and take a look at its implementation. This program acts as a receiver of the text message sent with AMC. First the class factory cl_amc_channel_manager

creates the AMC receiver object for the AMC application

ZAMC_CHAT and AMC channel

/ping. Receiving messages can

be started with the provided interface method start_message_delivery().

To be able to receive messages the session has to be in an “interrupted” state and not busy. This can be achieved in two ways. Either explicitly with the new ABAP

statement WAIT FOR MESSAGING CHANNELS <expression> [UP

TO <time> SECONDS] or

implicitly by using e.g. list processing (PBO-PAI phases). To receive a message the callback object has to be provided which implements the interface receiver method if_amc_message_receiver_t

ext~receive(). After the

message arrives, it gets inserted into a table of the messages.


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6. Run ZAMC_SEND_MESSAGE_TEXT

and ZAMC_RECEIVE_MESSAGE_TEXT

in two Eclipse editor windows using context menu Run As > ABAP Application.

7. Split the editor windows to see both ABAP sessions in parallel and execute the programs as described above in the demo (first receiver and then sender).

Summary

This demo creates ABAP Messaging Channel using SAMC transaction and uses ABAP Messaging Channel to implement the message communication between two ABAP sessions. ABAP session must be in the ‘interrupted’ state to receive the messages. This can be achieved either explicitly by using

ABAP WAIT… statement or implicitly by using e.g. list processing. By the way in ABAP exists a number

of statements which provide an implicit interruption, e.g. Dynpro and List processing (PBO-PAI

phases) or COMMIT WORK, etc. and some statements which provide an explicit interruption, i.e. WAIT.

It depends on the logic of the application which kind of interruption should be used for processing of events.


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D. DEMO COLLABORATION USING ABAP CHANNELS

Introduction

Real-time collaboration scenarios allow multiple users in different locations to communicate instantly or work on the same business objects simultaneously sharing the same backend resources and even allowing collaborative real-time editing. In situations when multiple users work with the same data (e.g. customers or suppliers information) in the browser UI, and one user changes some data records, they must be updated immediately on all other user UIs.

Applying this to ABAP would mean for example SAPUI5 users in different ABAP sessions which reside on different ABAP application servers can communicate (send messages) and work together on the same ABAP data records.

For ABAP collaboration scenarios are ABAP Push and Messaging Channels the best choice. The publish/subscribe infrastructure of the ABAP Messaging Channels can be used with ABAP Push Channel to enable Web Socket UI clients to act as subscriber. This allows Web Socket UI clients to send and receive notifications about data changes.


More detailed information about collaboration scenario: http://scn.sap.com/community/abap/connectivity/blog/2014/04/14/abap-channels-part-3-collaboration-scenario-using-abap-messaging-and-abap-push-channels

Video Tutorials: http://scn.sap.com/community/abap/blog/2015/03/09/how-to-implement-and-use-abap-channels--video-tutorials

Demo

In this demo the ABAP Push Channel SAPUI5 application from the first demo is changed to implement chat between users. The collaboration scenario works as following. One user enters the text into the field and presses the “arrow” button. The text will be sent to the ABAP backend system through ABAP Push Channel (Web Socket). For this the ABAP Messaging Channel is bound to the ABAP Push Channel (Web Socket). ABAP session checks the text for errors, enriches it with date, time and user and acts as a sender and sends it through the ABAP Messaging Channel to the subscribed ABAP Push Channels of other users and itself. The text is displayed below the field on all users UIs.


http://scn.sap.com/community/abap/connectivity/blog/2014/04/14/abap-channels-part-3-collaboration-scenario-using-abap-messaging-and-abap-push-channels

http://scn.sap.com/community/abap/connectivity/blog/2014/04/14/abap-channels-part-3-collaboration-scenario-using-abap-messaging-and-abap-push-channels




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Another ABAP Messaging Channel (AMC) is implemented in the AMC application

Collaboration is implemented by binding the AMC to your ABAP Push Channel from the first demo


1. Switch in the Eclipse to the ABAP Perspective. Under Connectivity of the package

ZDEMO_CHANNELS you will find

in ABAP Messaging Channels the AMC application

ZAMC_CHAT. Double click to

open it in the embedded SAPGUI in Eclipse (or use

shortcut Alt+F8 to run ABAP

application in SAPGUI, type

SAMC).

Double click the channel

/chat. This channel is used

for collaboration. The class ZCL_APC_WSP_EXT_ZAPC_CH

AT is authorized to send and

receive messages through the

/chat.

Remark: In this demo messages are exchanged in the PCP format (SAP Push Channel Protocol) within activity scope client (Client).

2. Now open the corresponding ABAP Push Channel class ZCL_APC_WSP_EXT_ZAPC_CH

AT in the editor and follow the

‘ATTENTION’ instructions in its

source code to adapt it for collaboration by commenting out and uncommenting the appropriate source code lines. Save and Activate the APC class.


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3. Now take a look at the implementation of the APC class ZCL_APC_WSP_EXT_ZAPC_CH

AT. For collaboration not only

on_message() but also

on_start() method needs to

be implemented. Navigate to

the on_start() method (e.g.

using Outline view of Eclipse).

4. The on_start() method is

executed as soon as the Web Socket connection setup phase is accomplished successfully. It is implemented to bind the APC Web Socket connection to the

AMC application ZAMC_CHAT

and channel /chat. The APC

Web Socket client is then able to act as a message receiver to get messages through AMC.

5. Navigate to the

on_message() method (e.g.

using Outline view) .The

on_message()method is

executed when the APC class receives a message. Here the same code as in the first demo is used with the only difference. The ABAP message channel manager is used to send the received messages from APC Web Socket client to the AMC

application ZAMC_CHAT and

channel /chat. The APC Web

Socket client acts as a message sender.


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6. Run ZAPC_CHAT application:

select index.html and execute it on the ABAP Server: Run As > Run on ABAP Server.

7. After entering your user and password you can use the chat program. Type text into the text field and press the “arrow” button. The text gets displayed on top of the list below the text field.

8. Start a browser of your choice (IE, Firefox, Chrome) and copy & paste the URL of the SAPUI5 application into its URL field. Run chat program. Any other user can logon to it. Whenever one user enters a message in one SAPUI5 application and press the “arrow” button, the message appears on top of the list under the text field in both chat programs of both users.

Summary

This demo implements chat program in ABAP as collaboration scenario using ABAP Push and ABAP Messaging Channels. For the collaboration scenario the Web Socket (ABAP Push Channel) connection must be bound to the AMC application and ABAP Messaging Channel in order to forward the AMC messages to Web Socket client. The APC Web Socket client acts as an AMC receiver after this binding action. The ABAP message channel manager is used to forward the received messages from Web Socket (ABAP Push Channel) client via the message sender to the AMC application and ABAP Messaging Channel. The APC Web Socket client acts as a sender in this case.


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Documents

ABAP CHANNELS DEMOSa248.g.akamai.net/n/248/420835/ea1c12f07cd5a3f29c542a893...2016/06/22 · information and sale conditions to browser UI (SAPUI5, Web Dynpro ABAP, BSP) as soon as