Nowadays we can connect everything everywhere, but no software is "an island entire of itself": every software "is a piece of the continent, a part of the main". From mainframes to the IoT and the Cloud above, architectures and paradigms keep on changing: who is the client and who is the server? Which component can fail and which can not? Where is data? What is Fog Computing? This talk aims at sharing the experience we developed opening doors with Sofia (https://www.sofialocks.com/en/), as no smart-lock, smar-phone or smart-gateway is just a client: they are part of the Internet as we know it. Video: https://www.youtube.com/watch?v=RIhMJj7BCMI

1. Client and Server,
3 meters above the Cloud

2. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Ma/eo Ferroni
๏ Me
Passionate coder, so.ware architect, (Web) surfer and musician
๏ Educa)on
Ph.D., Politecnico di Milano
Visi;ng Researcher, University of California, Berkeley (UCB)
๏ Work
CTO & Co-Founder, Bo9ega52 Srl
Teaching, Politecnico di Milano & LIUC
๏ Web
maDeo@boDega52.it
@maHerroni

3. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Today’s talk:
Client and Server,
3 meters above the Cloud

4. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
IoT, the Cloud and all the Fog in between

5. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
BACK-END
DEVELOPERS
FRONT-END
DEVELOPERS

6. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Front-End vs. Back-End

7. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
A real world deployment

8. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Client-Server model
Client
Mobile
Client
Desktop
Remote
Server
Request
Response
Request
Response
“The client-server model is a distributed applica)on structure that par;;ons
tasks or workloads between the providers of a resource or service, called
servers, and service requesters, called clients.”
— "Distributed ApplicaMon Architecture", Sun Microsystem

9. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Server-side developers
“I tested the endpoints, they are working”
"You're sending me the wrong input"
"You have a bug in your frontend!"
A normal day in the office
Client-side developer
"The server’s endpoints are not working"
"The data you're sending back are wrong”
"You have a bug in your backend!"

10. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
The baPle is geQng worse: SOA
— hPp://daas.co.id/index.php?page=detail-service&id=S001
“A Service Oriented Architecture (SOA) is a flexible set of design principles
used in systems development and integra;on. SOA arose because [...] Clients
using legacy architectures typically found their solu;on increasingly difficult to
maintain as the number of systems increase above a cri;cal point.”

11. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
And worse: Microservices architecture
— Adrian CockcroZ, Cloud Architect at Ne[lix
“A Microservices architecture as a service-oriented architecture composed of
loosely coupled elements that have bounded contexts.”
— MarMn Fowler, Chief ScienMst at ThoughtWorks
“[…] a suite of small services, each running in its own process and
communica;ng with lightweight mechanisms, o.en an HTTP resource API.”

12. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Microservices: how they should look like

13. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Microservices: how yours actually look
— Brian Foote and Joseph Yoder, Big Ball of Mud. Fourth Conference on PaPerns
Languages of Programs (PLoP '97/EuroPLoP '97) MonMcello, Illinois, September 1997
“A Big Ball of Mud is a haphazardly structured, sprawling, sloppy, duct-tape-
and-baling-wire, spaghe^-code jungle. These systems show unmistakable signs
of unregulated growth, and repeated, expedient repair.”

14. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Why should I bother?
Server Architectures,
SOA/ESB,
Microservices, etc.
The
Cloud
Clients
“All that complexity
stays on your side!”
…What about the rise of Internet of Things
and Fog Compu)ng?

15. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Internet of Things and Fog CompuMng
— Infographic by The ConnecMvist, based on Cisco data
“The Internet of Things (IoT) comes a.er the Mobile App era, when a lot of
businesses have been enabled by digital and Internet-based services through
mobile devices. These two markets are now going to be merged in a unique
vision and ecosystem".

16. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Internet of Things and Fog CompuMng
— “IoT, from Cloud to Fog CompuMng”, Cisco Systems
Fog Compu)ng [...] extends Cloud compu;ng and services to the edge of the
network. […] Fog provides data, compute, storage, and applica)on services to
end-users. The dis;nguishing Fog characteris;cs are its proximity to end-users,
its dense geographical distribu;on, and its support for mobility.
Cloud
Fog node
Desktop Mobile
Fog node
Mobile
Embedded
device
Embedded
device
Sensor
Mobile
Sensor
Sensor
Embedded
device

17. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
If you think this is not your business, think again:
• What service are you talking with?
• Is it a Web service, a Fog node or an IoT device?
• Do you understand and support its language and data?
• Are you reading the most recent version of data you're interested in?
• Opportunis6c networks, anyone?
Why should I bother?

18. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
Access Control
System
ACS
HTTPS
Smart Lock
AC power
Remote control
WiFi ConnecBon

19. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
Access Control
System
ACS
HTTPS
Smart Lock
AC power
Remote control
WiFi ConnecBon
Open!
request
while(true)
if(open)
Open!
else
Sleep!
Client-Server
model
BUSY-WAITING

20. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
Access Control
System
ACS
MQTT
Smart Lock
AC power
Remote control
WiFi ConnecBon
Open!
message
Open!
request
— hPp://mqP.org/
MQTT is a machine-to-
machine (M2M)/"Internet of
Things" connecSvity protocol.
It was designed as an
extremely lightweight publish/
s u b s c r i b e m e s s a g i n g
transport.
Publish-Subscribe
model

21. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
HTTPS
Request
credenSals!
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
Ba;ery powered
Bluetooth Connec6on
Very low power
Mobile app
Check remote creden7als
Login/Logout & basic features
Internet Connec7on
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Password
authen7ca7on
(secret sent to mobile)

22. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
HTTPS
Receive
credenSals!
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
Ba;ery powered
Bluetooth Connec6on
Very low power
Mobile app
Check remote creden7als
Login/Logout & basic features
Internet Connec7on
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Password
authen7ca7on
(secret sent to mobile)

23. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
HTTPS
Receive
credenSals!
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
Ba;ery powered
Bluetooth Connec6on
Very low power
Mobile app
Check remote creden7als
Login/Logout & basic features
Internet Connec7on
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Open! with
credenSals
Password
authen7ca7on
(secret sent to mobile)

24. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
HTTPS
Receive
credenSals!
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
Ba;ery powered
Bluetooth Connec6on
Very low power
Mobile app
Check remote creden7als
Login/Logout & basic features
Internet Connec7on
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Open! with
credenSals
TRUSTED?
Password
authen7ca7on
(secret sent to mobile)

25. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Challenge!
request
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
Ba;ery powered
Bluetooth Connec6on
Very low power
Mobile app
Check remote creden7als
Login/Logout & basic features
Internet Connec7on
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)HTTPS
Access Control
System
ACS
Challenge–response
authen7ca7on
(secret NOT sent to mobile)

26. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Challenge!
request
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
Ba;ery powered
Bluetooth Connec6on
Very low power
Mobile app
Check remote creden7als
Login/Logout & basic features
Internet Connec7on
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)HTTPS
Access Control
System
ACS
Solve the challenge!
request
Challenge–response
authen7ca7on
(secret NOT sent to mobile)

27. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
Ba;ery powered
Bluetooth Connec6on
Very low power
Mobile app
Check remote creden7als
Login/Logout & basic features
Internet Connec7on
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)HTTPS
Access Control
System
ACS
Response
soluSon!
Challenge–response
authen7ca7on
(secret NOT sent to mobile)

28. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Open!
with solu;on
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
Ba;ery powered
Bluetooth Connec6on
Very low power
Mobile app
Check remote creden7als
Login/Logout & basic features
Internet Connec7on
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)HTTPS
Access Control
System
ACS
Response
soluSon!
Challenge–response
authen7ca7on
(secret NOT sent to mobile)

29. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)HTTPS
Access Control
System
ACS
OFFLINEOpen! with
OFFLINE
credenSals
cached/offline
credenSals
Cache-Aside
pa>ern
TRUSTED?

30. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
HTTPS
MQTT
HTTPS
MQTT
Introducing
Fog Compu7ng

31. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
HTTPS
MQTT
HTTPS
MQTT
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Introducing
Fog Compu7ng
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
<virtualconnecSon>

32. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
HTTPS
MQTT
HTTPS
MQTT
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Introducing
Fog Compu7ng
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
<virtual connecSon>
<virtual connecSon>
HTTPS

33. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
HTTPS
HTTPS
MQTT
HTTPS
MQTT
UNRELIABLE
Cache-Aside
pa>ern
TRUSTED
cached/offline
credenSals

34. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
Access Control
System
ACS
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
HTTPS
HTTPS
MQTT
HTTPS
MQTT
OFFLINE

35. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
HTTPS
HTTPS
MQTT
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
Opportunity to connect
1. cache new credenMals
2. remove expired ones
3. send access logs
<virtual connecSon>
Access Control
System
ACS
Opportunis7c
Networks
“[…] a form of mobile ad hoc
networks that exploit the
human social characterisScs,
such as similariSes, daily
rouSnes, mobility pa9erns,
and interests to perform the
message rou)ng and data
sharing.”
— Nikolaos Vastardis and Kun Yang,
"Mobile Social Networks: Architectures,
Social ProperMes, and Key Research
Challenges," IEEE CommunicaMons
Surveys and Tutorials, vol. 15, no. 3,
2013, pp. 1355

36. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
HTTPS
HTTPS
MQTT
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
<virtual connecSon>
Opportunis7c
Networks
DELAYED
Mobile app
HTTPS
Access Control
System
ACS
<virtual connecSon>…when the
connec7on
is available
a.k.a.
“piggybacking”
Opportunity to connect
1. cache new credenMals
2. remove expired ones
3. send access logs

37. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
When IoT Comes Knocking at Your Door... or Locks it
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
HTTPS
HTTPS
MQTT
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
<virtual connecSon>
Access Control
System
ACS
Opportunis7c
Networks
“[…] a form of mobile ad hoc
networks that exploit the
human social characterisScs,
such as similariSes, daily
rouSnes, mobility pa9erns,
and interests to perform the
message rou)ng and data
sharing.”
— Nikolaos Vastardis and Kun Yang,
"Mobile Social Networks: Architectures,
Social ProperMes, and Key Research
Challenges," IEEE CommunicaMons
Surveys and Tutorials, vol. 15, no. 3,
2013, pp. 1355

38. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
When IoT Comes Knocking at Your Door... or Locks it
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
HTTPS
HTTPS
MQTT
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
<virtual connecSon>
Access Control
System
ACS
Opportunis7c
Networks
“[…] a form of mobile ad hoc
networks that exploit the
human social characterisBcs,
such as similariBes, daily
rouBnes, mobility paIerns, and
interests to perform the
message rou)ng and data
sharing.”
— Nikolaos Vastardis and Kun Yang,
"Mobile Social Networks: Architectures,
Social ProperMes, and Key Research
Challenges," IEEE CommunicaMons
Surveys and Tutorials, vol. 15, no. 3,
2013, pp. 1355

39. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
When IoT Comes Knocking at Your Door... or Locks it
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
HTTPS
HTTPS
MQTT
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
<virtual connecSon>
Access Control
System
ACS
Opportunis7c
Networks
“[…] a form of mobile ad hoc
networks that exploit the
human social characterisBcs,
such as similariBes, daily
rouBnes, mobility paIerns, and
interests to perform the
message rou)ng and data
sharing.”
— Nikolaos Vastardis and Kun Yang,
"Mobile Social Networks: Architectures,
Social ProperMes, and Key Research
Challenges," IEEE CommunicaMons
Surveys and Tutorials, vol. 15, no. 3,
2013, pp. 1355

40. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
When IoT Comes Knocking at Your Door... or Locks it
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
HTTPS
MQTT
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
Access Control
System
ACS
HTTPS
MQTT
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)
HTTPS
Mobile app
…when the
connec7on
is available
Main
Storage
cached/offline
credenSals
HTTPS OUTDATED
credenSals
Cache
coherency
problem

41. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
SMll a Client-Server model?
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
Just a simple
Client-Server interac;on?

42. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
You are a part of something bigger
“No man is an island enBre of itself;
every man is a piece of the conBnent,
a part of the main.”
— John Donne
SOFTWARE
DISTRIBUTED SYSTEM

43. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
IntegraMon is everything
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
Mobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)HTTPS
Access Control
System
ACS
Customer
External System
IntegraCon
ERP, CMR, Legacy code
Management soVware
HTTPS
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
HTTPS
HTTPS
HTTPS
MQTT
HTTPS
MQTT
HTTPS
MQTT
OFFLINE
UNRELIABLE

44. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
IntegraMon is everything
Let's assume we want to open a door with a Smartphone
Smart Lock
No cable
Remote control
BaIery powered
Bluetooth ConnecBon
Very low power
HTTPS
Front-end
Grant & Revoke permissions
Login/Logout & basic features
Manage Users
Access Control Lists (ACL)HTTPS
Customer
External System
IntegraCon
ERP, CMR, Legacy code
Management soVware
HTTPS
Local Gateway
AC power plug
Bluetooth ConnecBon
WiFi/LAN ConnecBon
HTTPS
HTTPS
HTTPS
MQTT
HTTPS
MQTT
HTTPS
MQTT
OFFLINE
UNRELIABLEMobile app
Check remote credenBals
Login/Logout & basic features
Internet ConnecBon
Fingerprint reader
(Asynchronous)
Idempotent Retry
pa>ern
Access Control
System
ACS

45. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Introducing Sofia
• Corpo livello uno
• Corpo livello due
• Corpo livello tre
• Corpo livello quaDro
• Corpo livello cinque
Smartphone Based and
Cloud Access Control Systems
Industries
• AccomodaSon
• USliSes
• Smart Working
• LogisSc
Partners

46. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Some takeaways:
• Apply Design PaSerns and avoid An)-PaSerns
• So.ware should be cynical (a.k.a., bad things will happen)
• Be conserva)ve in what you send, be liberal in what you accept
(“Robustness principle")
• Every integra)on point will eventually fail in some way
• It’s not just you and your code, you are part of something bigger
Why should I bother?

47. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
You are building something bigger
“No man is an island enBre of itself;
every man is a piece of the conBnent,
a part of the main.”
— John Donne
SOFTWARE
DISTRIBUTED SYSTEM
DEVELOPER
TEAM

48. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Server-side developers
“I tested the endpoints, they are working”
"You're sending me the wrong input"
"You have a bug in your frontend!"
Please, stop fighMng
Client-side developer
"The server’s endpoints are not working"
"The data you're sending back are wrong”
"You have a bug in your backend!"

49. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Please, stop fighMng
THERE’S
ONE
JUST
ENEMY

50. END USERS

51. @ma$erroni | www.bo/ega52.itClient and Server, 3 meters above the Cloud
Thank
you
Client and Server,
3 meters above
the Cloud