developing a 21 st century point of service using the latest openedge tools brian preece business...

Developing a 21st Century Point of Service using the latest OpenEdge tools

Brian Preece

Business Computer Projects

Using the Advanced GUI, Structured Error Handling and SonicMQ to build a Semi-Disconnected Point of Sale

Session Objectives

• To describe how we used OpenEdge features both old and new to create an Operationally Responsive Point of Service

2Developing a 21st Century Point of Service using the latest OpenEdge tools


Who are BCP?• Major supplier in Europe of Food Wholesale,

Retail and Cash and Carry systems • Users: Spar, NISA, Pets at Home, BWG,

Musgrave, ADM, Morrisons, etc…• Area: currently UK and EU, keen to expand!• 1st “Extranet” - Late 1970s Telspar

• 1st Scanning in convenience stores in UK• Early adopter of SonicMQ with our AIMS

wholesale/ retail messaging hub• Continuous innovators



Agenda

• Business Acceleration and Operational Responsiveness

• The PoS Dilemma• Solving the dilemma using the latest

OpenEdge tools• Demo• A closer look at the tools• Moving to an Object Oriented world• Conclusions



Agenda






Business velocity is increasing

Typical Business SLAs 106 105 104 103 100 10 1 0 Seconds

Source: Gartner, Inc.

Automated share trading100 ms 20 ms

Supply chain updates1 day 15 min

Phone activation1 min3 days

1 week 0.5 hour Refresh data warehouse

Track financial position5 min1 day

Airline operations20 min 30 sec

Trade settlement5 days 2 hrs.

mail express fax e-mail real time Business Process

same-day service



Supply Chain Operational Responsiveness


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GS1Cost effective

Product information

EPOSReal time links

Essential demand tracking

Demand ForecastingSophisticated buying

Voice Deliver stock cheaply

Through Accuracy


Agenda






The Retail Challenge

• Many stores and no IT expertise in the stores• Fixes and new features need to be rolled out as

fast as possible• But visiting each store is very expensive• This implies a thin client solution

BUT• MUST BE RESILIENT - the store must continue

to trade as long as one till still works– Even if: no back office

no AppServer™

no comms9Developing a 21st Century Point of Service using the latest OpenEdge

tools


Changes to Business Model

• Independent stores coalescing into chains• Wholesalers buying retail stores and running as

multiple chain• Hence desire for

– Centralised control

– Centralised data management

– Centralised data analysis



Agenda






“Classic” WebClient Architecture



Semi-disconnected Architecture



• 9.0 WebClient• 10.1 Sonic Integration features• 10.1 XML features• 10.2 GUI for .NET• 10.1/ 10.2 OO ABL

Tools we used


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Agenda





Using the Advanced GUI, Structured Error Handling and SonicMQ to build a Semi-Disconnected Point of Sale 16

Demo



Demo setup


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Host laptop

“PoS” laptop

LAN

BackOffice

VM

SonicBroker

BODB

CentralManagement

VM

SonicBroker

CMDB

Software Download Site


Agenda






• WebClient for easy deployment– Use temp-tables to store product/ price data, deals, etc.

• Sonic for real time messaging– Transactions are sent to the AppServer in real time

• Sonic Local Persistence to handle disconnection– Connection/ Disconnection handled in the background

• XML to ProDataSet/ Temp-table– Very fast transformation to and fro

– Also give loose coupling between PoS and Back Office

The Basics


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Old PoS


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Using the Advanced GUI, Structured Error Handling and SonicMQ to build a Semi-Disconnected Point of SaleDEV-32: Using the Advanced GUI, Structured Error Handling and SonicMQ to build a Semi-Disconnected Point of Sale 21

GUI for .NET Transformation

Dynamically coloured buttons

Much cleaner

overall look

Gradient fill spans across

group of objects

Object Oriented

GUI

Bitmap embedded

within button object


Style sheets


• Can use UML to design• More robust since more checking is done at

compile time• Easier to unit test because of small objects with

well defined interfaces• Easier to customise• Defined API• Facilitates continuous integration and other

Agile techniques

OO ABL


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Agenda






• Total rewrite from the ground up• Thin OO wrapper round existing procedural

code• In between solution

We chose the latter on a case by case basis

• Only possible because Progress allow mixing of OO and procedural code!

Three approaches


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• Essential where code interacts with GUI for .NET

• Highly desirable for main program structure• Highly desirable for code that has either been

badly written or much amended• New code needs to be audited against the

original code• Our example: Scanning

– Core part of the system

– Existing logic must be reused in business entities

OO Redesign


25


• LibPoSService.p

– Structured procedure

– Reads and Writes to the database

– Contains code for locating product information, creating transaction records, adding items to a transaction, etc

Scanning – Starting Point


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• First, the domain level classes are identified

Scanning – Class Model


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• Next, internal procedures that can be moved to the domain level classes are selected

• In LibPoSService.p we have:

– GetItemDetails:

• Finds a product based on a scanned code

• Outputs product details as a temp-table parameter

– AddItemToBasket:

• Receives product details as a temp-table parameter

• Adds scanned product details to the current basket

Scanning – Code Refactoring


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• Procedural code is changed to:

– run from temp-tables instead of database tables

– use data access objects to read / write data within the functional code

• Procedures are transformed into class methods in associated domain level classes



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==


• Finally, any remaining “control” code is translated to use the domain level objects.

• As our PoS uses MVC, scanning control code was added to the controller for the main scanning screen

Scanning – Plugging it together


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• Performed after recoding is complete• Each line of the old code is checked to ensure

that it has been represented in the new code or is definitely not required

Scanning – Code Auditing


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...

run GetItemDetails in hLibPoSService (input dProductID, output table ttItemDetails).

...

run AddItemToBasket in hLibPoSService (input table ttItemDetails, input iQuantity).

...

/* Refresh transaction display */{&OPEN-QUERY-br_saleline}apply “ENTRY” to code-entry in frame f-main.apply “END” to browse br_saleline.

...

/* Recalculate total due and number of items */dTotal = 0.iNumItems = 0.

for each saleline where saleline.trans-id = iTransID no-lock: dTotal = dTotal + saleline.sales-value. iNumItems = iNumItems + saleline.quantity.end.

for each b-tendtran where b-tendtran.trans-id = iTransID no-lock:dTotal = dTotal - b-tendtran.amount.

end.

Scanning – Code Auditing


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Harvested for reuse in Product class

Harvested for reuse in Product class

Harvested for reuse in Transaction class

Harvested for reuse in Transaction class

Functional equivalent exists as a method in the

ScanningForm class

Functional equivalent exists as a method in the

ScanningForm class

These global variables are now properties of the Transaction class.

These global variables are now properties of the Transaction class.


• Requires well-structured code• Relies on interworking between OO and

procedural code• Normally achieved by wrapping procedural code

within an OO wrapper• Our example: Deals engine

– Self-contained

– Stateless

– Well defined interface

Re-using Procedural code


36


• 720 possible combinations! – which is best?

– 4 Cokes for £1

– 4 Soft drinks for £1.25

– Meal deal: drink, sandwich and snack for £2.50

– World Cup deal: 4 beers and 4 crisps for £3

– Bulk buy beer deal: 4 beers for £2.50, 8 beers for £4.50, 16 beers for £8.50

– Customer buys 4 Cokes, 2 Fantas, 6 packets of crisps, 2 sandwiches and 12 beers

• 5000 lines of stateless ABL code!• Must recalculate in real time when an item is scanned!• Development cost £200k 2 years ago

Deals Engine – The problem


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• DealsEngine.p

– Structured procedure with a single entry point

– Reads “static” data from the database

• e.g. the items that make up each deal

– Does not write to the database

• No functional changes required• But the PoS has no database access

Deals Engine – Starting Point


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/*------------------------------------------------------------------------ File : DealsEngine.p Purpose : Deals Procedure Library Syntax : Description : Author(s) : BCP Created : 15/12/2006 Notes : ---------------------------------------------------------------------*//* This .W file was created with the Progress AppBuilder. *//*----------------------------------------------------------------------*/{dsParameters.i}{dsDeal.i}

define buffer stparam for ttParameters.define buffer DealLiveMain for ttDealLiveMain.define buffer DealLiveList for ttDealLiveList.define buffer DealLiveItem for ttDealLiveItem.define buffer LinkedDeals for ttLinkedDeals.

DAParameters:Instance:FetchWhere("", output dataset dsParameters).DADeal:Instance:FetchWhere("", output dataset dsDeal).

...

Deals Engine – Code Changes


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Define the temp-tables and datasets that will be used in place of the database

tables

Define the temp-tables and datasets that will be used in place of the database

tables

These buffers have the same name as the

database tables in the old procedure

These buffers have the same name as the

database tables in the old procedure

Data access objects are used to populate the temp-

tables

Data access objects are used to populate the temp-

tables


class DealsEngine final:

define private variable hDealsEngine as handle no-undo.

constructor public DealsEngine (): super (). run DealsEngine.p persistent set hDealsEngine. end constructor.

destructor public DealsEngine ( ): if valid-handle(hDealsEngine) then delete procedure hDealsEngine. end destructor.

method public character ApplyDealsToBasket(input-output table tBasket, input iLineNumber as integer): run ApplyDealsToBasket in hDealsEngine (input-output table tBasket, input iLineNumber as integer).

end method.

end class.

Deals Engine – OOABL Wrapper


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Private handle for referencing the structured

procedure

Private handle for referencing the structured

procedure

Constructor loads the procedure persistenlyConstructor loads the procedure persistenly

Destructor deletes the procedure instance

Destructor deletes the procedure instance

Methods expose entry points to the structured

procedure

Methods expose entry points to the structured

procedure


Agenda






Conclusions

• Business logic is very hard-won – don’t throw it away

• By allowing OO and procedural code to co-exist, Progress have given us choices denied by other vendors when they introduced OO

• Strike a balance between retaining code and rewriting in OO

• Audit the code you rewrite



Questions



Thank you for your time!

[email protected] our Expo booth!


developing a 21 st century point of service using the latest openedge tools brian preece business...

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