These are my slides from the Bare-Bones Software Architecture course at XP Days Ukraine 2012. The workshop outlines a quick workshop-oriented process for initiating software projects

1. Agile Architecture
XP Days 2012
Johannes Brodwall, Chief scientist
Exilesoft Global

2. What is an architect?
From greek Arkhi-Tecton
Tecton: Builder
Arkhi: Chief.
Like “Arch angel”
Or “Arch villain”

3. What is an architect?
“Chief builder”

4. What is an architect?
(Exilesoft definition)

5. A solution architect is
someone who understands
the problem of the customer
and uncovers and
communicates
a feasible solution

6. A solution architect is someone who
understands the customer’s
problem (including
contraints, context, domain knowledge)
and uncovers (though a team effort)
and communicates (with credibility) a
feasible solution (primarily, but not
exclusively technical)

7. Uncover problem
vision, stakeholders, usage flow
Describe problem
context and domain model
Describe solution
deployment, implementation
model

8. • Describing architecture
• Simplifying architecture
• Delivering architecture
• Delivering software

9. Part I:

10. Describing
architecture

11. • Understanding problem
• Uncovering solution
• Communicating architecture

12. Understanding the
problem

13. (Tool time)

14. For some stakeholder
Who has a responsibility
The Bare-bones architecture workshop
Is a type of activity
Which gives a capability.
Unlike most relevant alternative
This has a distinguishing attribute.

15. For __________________
Who ________________
The _________________
Is a _________________
Which ________________.
Unlike ______________________
This _______________________.

16. Participant? ??? ???
Who are they? Description Description
What do they do? Duties Duties
Why do they care? Values Values

17. Example
«Smidig» conference application

19. Example vision
statement

20. For Agile practitioners
Who need to expand on their experience and network
The Smidig conference
Is a networking event
Which connects you with other Agile practitioners.
Unlike traditional conferences
This presents the experience of many people through
lightning talks.

21. For Conference organizers
Who want to organize a good conference
The Smidig conference app
Is a web application
Which eliminates unnecessary work.
Unlike commercial conference apps
This is optimized for the large number of talks
we have and allows us to make changes fast.

23. Example
stakeholders

24. Speaker Attendee Organizer
Description Description Description
• Experienced • Knows about agile • Volunteer
• New speaker • Works in project • Works in evenings
• Passionate • Norwegian • Has network
Duties Duties Duties
• Register talk • Pay for conference • Select talks
• Upload slide • Get approval to go • Follow up
• Give talk payments
Values Values
Values • Easy selection process
• Constructive
• Easy registration • Good information
feedback on talk overview
• Easy CfP • Never lose a participant
• Fast answer • Financial transparency

25. Sponsor
Description
• Busy
• Manager
• Not very interested
Duties
• Provide logo
• Pay sponsorship
Values
• Informal
communication
• Easy evaluation

26. Example usage flow

27. Attendance
1. Agile project practitioner wants to learn
2. Attendee goes to Smidig website
3. Attendee registers
4. Attendee pays using Paypal
5. Attendee receives confirmation mail
6. Organizer can see the registration
7. Organizer sends reminder email to attendee to
come
8. Organizer prints badges for attendees with Print
Company
9. Attendee shows up at Smidig and has an
excellent time

29. Speaker
1. Agile experts wants to share knowledge
2. Potential speaker goes to Smidig website
3. Potential speaker registers personal info
4. Potential speaker registers talk
5. Potential speaker receives registration confirmation
email
6. Organizer sees registered talk and can market
speaking opportunities
7. Organizer accepts talk for confence
8. Speaker receives acceptance email
– Alternative: Speaker withdraws talk – organizer updates
the talk and selects another
9. Organizer prints badges for speakers
10. Speaker shows up at Smidig and gives talk

30. /Understanding the
problem

31. Uncovering a
solution

32. Example context
model

33. Participant Speaker
Organizer
Paypal Smidig2011.no
Printing
company

34. Example domain
model

35. User
• Name Registration
• Email • Ticket type
• Price
• Company • Paid amount
• Phone • Paypal ref
• Password • Payment date
• Invoice address [optional]
• Accepts email?
*
Comment *
• Title Speaker
• Text
• Created date *
* Talk Period
• Title
• Description • Stage
• Tags[] * • Title
• Slide file • Time of day
• Status : • Day
{pending, accept, rejec
t}
• Email_sent
• Position

36. Example
deployment model

37. Web user
Developer html/http
git push git push
git pull
Smidig-
conference http
Paypal
github git.heroku (Rails)
smtp
Heroku
Smtp.dreamhost.com
smidigdb
PostgreSQL

38. Example
implementation
diagram

39. 1. Find controller
Router
2. Dispatch action
3. Find model
Controller Model class
4. Manipulate model Database
Model
5.? Save model
6. Render model with
view template
View template View template

40. POST /users/<id>
Router 1. Find UserController
2. update(id)
/app/controllers 3. find(id) /app/models 4. SELECT …
UsersController FROM users
User class
5. update_attr(params) Database
app/models
6. save User 7. UPDATE
8. Redirect /users/<id> users SET …

41. GET /users/<id>
Router 1. Find UsersController
2. show(id)
/app/controllers 3. find(id) /app/models 4. SELECT …
UsersController User class FROM users
Database
User
5. Render
/app/views/users
6. Get attributes
show.html.erb

42. Alternative

43. Browser Smidig2012.no Paypal.com
1. POST /users
Save user info
2. Redirect to paypal
with return_url and notify_url
3. Perform payment
4. POST /payment_notifications
Update user
info
5. Redirect to return_url
5. GET /user/<id>
Show user info

44. /Uncovering a
solution

45. Communicating a
solution

47. Vision
Stakeholders
Usage flow
Context
Domain model
Deployment
Implementation

48. Does the architect
have to do this
herself?

49. Team effort

51. /Communicating a
solution

52. /Describing
architecture

53. Part II:

54. Finding the
requirements

55. I need a volunteer

56. For some stakeholder
Who has a responsibilty
The system name
Is a type of system
Which gives a capability.
Unlike most relevant alternative
This has a distinguishing attribute.

57. Participant? ??? ???
Who are they? Description Description
What do they do? Duties Duties
What do they care Values Values
about?

58. ….
1. Something happens in the real world
2. The event is communicated to the system
3. The system does something
4. Someone does something with the system
5. …
6. …
7. …
8. …
9. …
10. Some goal is achieved

59. /Finding
requirements

60. Part III:

61. Describe
architecture

62. Frugalflights.com
1. A customer wants cheap vacations
2. The customer signs up for daily or weekly notifications of special
flight offers
3. Periodically the System checks which customers should get
notifications
4. The System checks for offers that matches the customer’s travel
preference by looking up flights with the travel provider system
5. The System notifies customer of any matching offers via SMS
• Variation: The System notifies customer of any matching offers via
email
6. The customer accepts the offer via SMS
1. Variation: The customer accepts the offer on the system website
7. The System books the tickets on behalf of the customer
8. The system confirms the booking by sending an SMS to the
customer
9. The customer can at any point see their active offers and accepted
offers on the system website
10. The customer enjoys a cheap vacation!

63. User User
Who are they Who are they
• … • …
What do they do? What do they do?
• … • …
What do they value? What do they value?
• … • …
User User
Who are they Who are they
• … • …
What do they do? What do they do?
• … • …
What do they value? What do they value?
• … • …

64. Example context
model

65. What actors did you
mention in scenario?

66. Context: Frugalflights.com
1. A customer wants cheap vacations
2. The customer signs up for daily or weekly notifications of special
flight offers (where?)
3. Periodically the System checks which customers should get
notifications
4. The System checks for offers that matches the customer’s travel
preference by looking up flights with the travel provider system
5. The System notifies customer of any matching offers via SMS
• Variation: The System notifies customer of any matching offers via
email
6. The customer accepts the offer via SMS
1. Variation: The customer accepts the offer on the system website
7. The System books the tickets on behalf of the customer (where?)
8. The system confirms the booking by sending an SMS to the
customer
9. The customer can at any point see their active offers and accepted
offers on the system website
10. The customer enjoys a cheap vacation!

67. Domain: Frugalflights.com
1. A customer wants cheap vacations
2. The customer signs up (?) for daily or weekly notifications of
special flight offers (=> “create a subscription”?)
3. Periodically the System checks which customers should get
notifications
4. The System checks for offers that matches the customer’s travel
preference by looking up flights with the travel provider system
5. The System notifies customer of any matching offers via SMS
(=> “sends notification”?)
• Variation: The System notifies customer of any matching offers via
email
6. The customer accepts the offer via SMS (=> “send acceptance”)
1. Variation: The customer accepts the offer on the system website
7. The System books the tickets on behalf of the customer
8. The system confirms the booking by sending an SMS to the
customer (=> “sends confirmation”?)
9. The customer can at any point see their active offers and
accepted offers on the system website
10. The customer enjoys a cheap vacation!

68. Example domain
model

69. What concepts did
you mention in
scenario?

70. Example
deployment model

71. Which servers are
involved in
production?

72. Example
implementation
diagram

73. How does the code
work?

74. Statnett electricity reserves
1. Grid operator want to maintain balance of electric production and consumption
2. Power producer sends unused capacity (reserves) per hour for each power plant to
LARM using EDIFACT via Sterling Integrator
– Detail: The capacity “line” has a price
– Detail: Each plant may have several capacities at different prices
– Detail: Capacity may be to increase or to decrease production
3. A spike occurs in the consumption or production
4. Grid operator sees list of available reserves per power plant
1. Alternative: Operator filters the list by grid market area
5. Grid operator selects a reserve to regulate for spike
6. Grid operator enters power usage on the regulation
1. Alternative: The system verifies that regulation is valid
7. Grid operator communicates the regulation to producer’s operation center using phone
1. Future: The system sends the regulation to the producer as XML/http
8. Balance is restored
9. At end of hour, system sends usage to pricing system (NOIS) (XML/http) via Sterling
Integrator
10. Some time later, pricing system sends price for usage via SI
11. System sends price capacity usage to accounting system via SI
12. Accounting system pays producer for usage

75. /Describe
architecture

76. What surprised you?
What did you learn?
Your plan to change
how you work?

77. Conclusion:

78. Tomorrow: Make your
system shine!

79. Thank you
jbr@exilesoft.com
http://johannesbrodwall.com
http://exilesoft.com
http://twitter.com/jhannes
• Vision
• Stakeholders
• Usage flows

80. • Lasagna architecture
• Feature oriented architecture
• Deployment constraints

81. Lasagna
architecture

82. Person- Person- Person-
PersonDao
Controller Service Repository
Person- Person-
Person- PersonDao
Controller- Repository
ServiceImpl Impl
Impl Impl
Session-
Factory

83. Controllers
Services
Managers
Workers
Repositories

84. Controllers
DTO
Services Mapping
Domain
Managers
Workers
Repositories

86. Customer
Invoice
Order
Product

87. Tidying up art (Ursus Wehrli)

89. Feature oriented
architecture

91. Coherence
• What changes together
lives together

93. Tolerance
• What should be different
can be different

95. Meaning
• What is central in domain
is central in code

97. Your thinking is
contrained by
technology fashion:

98. Controllers
DTO
Services Mapping
Domain
Managers
Workers
Repositories

99. Your solution is
constrained by
deployment

100. Web user
Browser
JSON/http
Controller DTO?
Web Application
Consumer DTO
SOAP
Service DTO
Web Service
Database

101. Web user
html/http
Controller
Web Application
DAO
Database

102. Web user
html/http
Reverse proxy
html/http
Controller
Web Application
DAO
Database

103. Web user
Browser
JSON/http
DTO?
Controller
Web Application
DAO
Database

104. Web user
Controller
Rich client
Consumer DTO
Web
service
Service DTO
Web Application
Database

105. Web user
Controller
Rich client
DTO
Objects
over http
DTO
Web Application
Database

106. Web user
External client Browser
JSON/http
Controller DTO?
Web Application
Consumer DTO
SOAP
Service DTO
Web Service
DAO
Database

107. Web user
External client Browser
JSON/http
Service Controller
DTO
Web Application
DAO
Database