tech stuff

1. There are only 3
operations in a web
application
(or maybe 2)

2. History
Worked on lots of web applications
Seems to be lots of attempts at the same
problems
Typically non-SOLID solutions

3. History
Without SOLID web applications are
Difficult to maintain
Buggy
Difficult to scale

4. Back to basics
As any other application
Identify the entities
Identify the operations these entities execute

5. Back to basics
Web applications have lots of entities
Customer … Order … Hotel … Basket … Page
… Section … SubSection … etc.

6. Back to basics
However the stateless nature of the web
plus user expectations lead to …..

7. The big idea.
… A limited number of operations
1. Find 0 or more entities
2. Add a new entity
3. Change an entity

8. The big idea.
… A limited number of operations
1. Find 0 or more entities
2. Add a new entity
3. Change an entity
Sometimes combined into a ‘Crupdate’

9. The big idea.
Sign up? Add item to basket? Log error?
Add new entity
Login? Get Hotel Details? View sale items ?
Find 0 or more entities
Update password?
Change an entity

10. The big idea
So … can we make a framework that
abstracts away all the common parts of
these operations, allowing us to produce
SOLID software with the minimum of
changes?

11. The big idea
So … can we make a framework that
abstracts away all the common parts of
these operations, allowing us to produce
SOLID software with the minimum of
changes? ….. MAYBE?

12. The big idea.
How about creating a suite of “Micro
services” for each entity.
The service contains all the (validation)
business logic for the entity, returning the
results in a consistent way. ….

13. The big idea.
These micro services can only be reached
through a message, making them fully
decoupled from the consuming application.

14. The Message
A POCO class whose single responsibility is
to transmit information between the
provider and the producer

17. The Message Processor
A POCO class whose sole responsibility is to
update the state of the message.
Simple to test.
Simple to read.
Only place for business logic.

20. Consuming with MVC
Can be consumed by any .net framework.
As there is no business logic consuming is
simple.
Every message is consumed in the same
way, so consuming code follows a similar,
simple pattern.

22. Epilogue
● Normalising code to its common
components reduces repeated code.
● Normalising code to its common
components reduces the amount of code
needed.
● Normalising code to its common
components encourages SOLID software.

23. Questions...