Reducing technical debt in php

WPS - Workplace Solutions GmbH //// Hans-Henny-Jahnn-Weg 29 //// 22085 HAMBURG
Reducing technical debts in PHP
Dr. Carola Lilienthal
Carola.Lilienthal@wps.de, @cairolali
www.wps.de
Wolfgang Strunk
Wolfgang.Strunk@sixt.com
Sixt Leasing AG

2
Mobility services provider with highly attractive and
customer centric product offering
Mid-sized and large corporates Private and business customersCustomer focus
Full Service Leasing Fleet Management
Leasing / Vario Financing
+ Services
Key products
~50k(2) ~31k ~16k(2)# of contracts 2014
Total: ~97k(1)
Value proposition
One-Stop-Online-Shop for >30 OEMs
• Price
• Transparency
• Convenience
OEM independent optimization of Total Cost of Ownership (TCO)
• Know-how
• Buying power
• Outsourcing
Sixt Leasing AG
(1) Each Sixt Leasing vehicle is linked to one contract. However, not all contracts refer to a Sixt Leasing vehicle (e.g. Fleet Management). Hence, the total number
of vehicles (~54k in 2014) is typically lower than the total number of contracts
(2) The contracts include new contracts (order book) for which the leased vehicle has not yet been delivered to the customer and pure service contracts
Contract CAGR
2012-2014
2% 111% 54%
Fleet Leasing Fleet Management Online Retail

26.04.2016 //// Seite 3WPS - Workplace Solutions GmbH
Software
Architecture
Requirement
Engineering
Control Room
and Interaction
Software
Development
Business software,
for joyfull work!
WPS – Workplace Solutions GmbH

4
Proprietary data and software development across the
value chain as key competitive advantage
Quote Procurement Contract Length ReturnProcess Level 1
Process Level 2
Tender &
Implementation
Vehicle
Order
Vehicle
Logistics
Vehicle
Handover
Final
Invoices
Quotes
Vehicle
Return
Invoices
Vehicle
Disposal
Customer Service
User
Service
Order configuration Vehicle transport
Delivery station
Registration Fuel invoicing
Lease- & full service invoiceParking ticket management
Driver license check
Contract adjustment
Early return
Order management Handover to the station
Validity check
Customer/ User change
Delivery date coordination
Order changes
Reference calculation Cancellation
Incoming invoices (Check & enter, debit)
Pricing
Quotation negotiations
Breakdown service Return to retailer
Self-marketingAppraisalHandover to the retailer
Delivery
Collective invoicing
Return logistics
Return damage invoice
Final invoicing
Vehicle invoices
Fuel card service
Contract changes
Maintenance& attrition
Damage processing
Tire change & replacement
Residual value factors Order checks Work shop routing
Preliminary rental vehicle
Implementation
Damage invoicingActivation of contract
Return letter
Leasing request & contract check
Web portal & parameter keeping Reports & analyses (Customer demands)
Resignation from contract Cancellation by customerPurchasing
Software Modules
Customer facing
Internal
Source: Company information

Technical Debts ≠ Long-living

Measures against technical debts
Regular architecture discussions
Qualification for developers and architects
Automated tests and continuously refactoring
Regular architecture analysis and renovation

Architektur analysis: What is this?

Architecture renovation: how do we do that?
Refactorings
Analysis
+
Discussion
Determination
f measures
Implemented
Architecture
Reconstruction
Source-
Code
Planned
Architecture
Architecture
Alternatives
Violations

Sotograph
Plattform for Architecture
Renovation
Commercial product since 2002
Many customers, e.g.
Siemens, Lufthansa, HHLA,
Kühne&Nagel, Daimler,
Infineon
Analyses Java, C++, C#, ABAP,
PHP and offers an open
interface for other parsers
www.hello2morrow.de

Components of sotograph
Java
Parser
Soto
Reposi-
tory
C#
Parser
Code-
Checker
C/C++
Parser
Sotoweb
Sotoarc
Sotograph
Sotoreport
ABAP
Parser
PHP
Parser

Two goals for long-livingness
1) Maintainability
• Finding bugs quickly
• Make quick changes
• Understand and analyses quickly
• Reduction of complexity
2) Flexibility
• Variants of business processes
• Changing requirements
• Service orientation and scalability
• Modularity (Baukastenprinzip)

70%
20%
10%
Code verstehen
Problem lösen
Code schreiben
How do we spend our time when programming?
Code comprehension
Problem solving
Writing code

Well-formed complex structures = saving time!
Cognitive Mechanisms
HierarchiesChunking Schemata

@ naturfotographen-forum.de
Marion Meixner

Zusammenhängende Einheiten
@ www.fotocommunity.de
Jan Schwensweger

Well-formed
architecture
Modularity

Modularity
High Cohesion and lose Coupling
Responsibility Driven Design
Separation of Concerns
Single Responsibility Principle

Well-formed
architecture
Modularity

Hierarchies

Well-formed
architecture
Modularity
Hierarchical
Layerng

Well-formed
architecture
Modularity
Hierarchical
Layerng
Pattern
Consistency

30
Hierarchies on the architectural level: layers and modules
TechnicalLayering
Domain Layering
Presentation
BP & Activity
Domain
Data

Two dimensions in on architecture
Technical layering Domain layering
Tree violations
that are easy to
resolve
Difficult
violations
One component
cuasing several
problems
One component
causing a
problem

Domain layering is missing
Technical layering No domain layering
Some violations
of the technical
layering
Allmost all
domain
components
need each other

Hierarchies on class level
Influences:
maintainability
reusability
testability
modularisation
Pattern conformity

119 classes from 4 components
+ 28 other classes

327 classes from 8 components
That all need each other

Well-formed
architecture
Modularity
Hierarchical
Layerng
Pattern
Consistency

Uneven Modules
One big Monolith with several little satellites
950.860 LOC
84.808 LOC

Uneven Modules
9 Components = 17 Subsystems

Well-formed
architecture
Modularity
Hierarchical
Layerng
Pattern
Consistency

Pattern on the architectural level: four modules
Module
green
Module
purple
Module
orange
Module
blue

Pattern conformity: Bad example

Pattern conformity: Good example

Pattern on class level: design pattern and pattern languages
User Interface
Domain
Application
Domain ModuleDomain Module
Window
GUI
Model
View
C
o
n
t
r
o
l
ValueObject
Service
BusinessObject
SchichtungdurchMuster

Pattern conformity: Good example
☺ 90% of the source code can be assigned to pattern
☺ 0,1% violations between the pattern

Pattern conformity: the discovery of a pattern language
☺ 80% of the source code can be assigned to 23 pattern
☺ 4% violations between the pattern

Modularity
Hierarchical
Layerng
Pattern
Consistency
Consistent and
integrated pattern
Use a pattern
language
No cycles neither
on architectural
level nor on class
level
responsibility
coupling
size
interfaces

Process of analyses and renovation of architecture

Thank you for your attention!
www.langlebige-softwarearchitektur.de
Dr. Carola Lilienthal
Mitglied der
Geschäftsleitung
cl@wps.de
www.wps.de
+49 170 184 77 11
Diplom-Informatikerin
@cairolali

Reducing technical debt in php

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