Your hosts
Mike Seghers (@mikeseghers)
Filip Maelbrancke (@fmaelbrancke)
Consultants at iDA MediaFoundry
(@iDAMediaFoundry)
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Why this talk?
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First off...
Why mobile architecture?
What is it?
How to implement?
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Architecture
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You = McGuyver
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Avoid problems
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Build up confidence
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! Nerdvana
“There are two ways of constructing a
software design: One way is to make it so
simple that there are obviously no
deficiencies and the other way is to make it
so complicated that there are no obvious
deficiencies.”
Tony Hoare
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Relation to enterprise
architecture?
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Layered architecture
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Dependency Injection
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Relation to rich client
architecture?
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MVC
View
Model
Controller
Data retrieval
Data changes
User
Gestures
View Selection
Events
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Mobile challenges
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Remoting
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Data handling
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Remoting
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Naive client
GUI thread
View
Remoting
logic
Transformation
logic
Storage
logic
Presentation
logic
CRUD operations Save data structure
Remote Local storage
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The problems with the naive
approach
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Naive approach = Let your users
wait
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A less naive approach
GUI thread
View
Presentation
logic
Background thread
Remote Local storage
CRUD operations Save data structure
Service
Remoting
logic
Transformation
logic
Storage
logic
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Working towards a layered
architecture
Communication with remote systems
Caching data in local storage
Translation of data
Keeping state of the cached data
Passing data to the view layer
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Remoting Services
Remoting Service Remote API
HTTP/JSON/XML
AMF
ProtocolBuffers
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Adaptors
Remoting Service Remote API
HTTP/JSON/XML
AMF
ProtocolBuffers
Adaptor
Entities
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Storage
Remoting Service Remote API
HTTP/JSON/XML
AMF
ProtocolBuffers
Adaptor
Data
Source
Entities
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Local Storage Service
Remoting Service Remote API
HTTP/JSON/XML
AMF
ProtocolBuffers
Adaptor
Data
Source
Entities
Local Service
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Data Synchronisation
What is still missing?
Something to tie the services together and
communicate with the GUI layer.
Something to keep track of the state of our
local data. Eg. when do we need to refresh
the data from the backend?
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Dataprovider
Remoting Service Remote API
HTTP/JSON/XML
AMF
ProtocolBuffers
Adaptor
Data
Source
Entities
Local Service
Data Provider
GUI Layer
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Statekeeper
Remoting Service Remote API
HTTP/JSON/XML
AMF
ProtocolBuffers
Adaptor
Data
Source
Entities
Local Service
Data Provider State Keeper
GUI Layer
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Non-blocking?
We now know that we will handle data using
the data provider, which encapsulates all
data handling logic.
However, we still didn’t tackle the “my-main-
thread-is-blocked-for-a-while” problem.
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Making things asynchronous
1. Using Events/Notifications
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Making things asynchronous:
Events
Pros:
Loose coupling
Easy to implement
Cons:
Hard to maintain
Hard to follow where all events end up
Event storms!
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Making things asynchronous
2. Callback system
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Making things asynchronous:
Callbacks
Pros:
Loose coupling
Easy to refactor
Easy to follow and to maintain
Cons:
Little more complex then eventing
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Making things asynchronous:
Implementing a callback system
Responders and Callhandles
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Responder explained
caller
callee
calls
• on X
• on Y
• on Z
immediately returns • on X
• on Y
• on Z
• on X
• on Y
• on Z
other actors
• on X
• on Y
• on Z
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Callhandles explained
callee
caller
calls
immediately returns
• on X
• on Y
• on Z
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Tying it up!
Remoting Service Remote API
HTTP/JSON/XML
AMF
ProtocolBuffers
Adaptor
Data
Source
Entities
Local Service
Data Provider State Keeper
GUI Layer
Responder/
Callhandle
Responder/
Callhandle
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Back-end communication
technologies
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Back-end communication?
SOAP
RMI
REST
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REST
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Backend
optimizations?
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Compress!
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DRY
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Data handling
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CRUD via REST
Method Operation Change? Idempotent?
GET GET / SELECT ✔ ✔
POST INSERT ✘ ✘
PUT UPDATE ✘ ✔
DELETE DELETE ✘ ✔
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POST
Data Provider + State Keeper Remote Service
Data Source
insert
set STATE_INSERTING
update
clear STATE_INSERTING
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PUT
update
set STATE_UPDATING
update
clear STATE_UPDATING
Data Provider + State Keeper Remote Service
Data Source
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DELETE
update
set STATE_DELETING
delete
Data Provider + State Keeper Remote Service
Data Source
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GET
insert new resources
Data Provider + State Keeper Remote Service
Data Source
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Data Provider
1 Responder
Callhandle
1
No local data
Front layer
Local Service
2
State Watcher
3
Remote Service
4
Responder
Callhandle 4
5
State Keeper
6
7
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Data up-to-date
Front layer
Data Provider
1
Responder
Callhandle
1
Local Service
2
State Watcher
3
State Keeper
4
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Data outdated
Front layer
Data Provider
1 Responder
Callhandle
1
Local Service
2
State Watcher
3
4
8
Up-to-
date data
Remote Service
5
Responder
Callhandle 5
6
State Keeper
7
Stale
data
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Conclusions
Do not call backend logic inside UI threads
Start long running operations from a
background service
Persist early and persist often
Minimize the network usage
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References
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Suggested reading
Design patterns: elements of reusable
object-oriented software
Gamma et al. (978-0201633610)
Patterns of enterprise application
architecture
Fowler et al. (978-0321127426)
The pragmatic programmer
Hunt, Thomas (978-0201616224)
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Suggested viewing
WWDC sessions
Google IO sessions
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Q + A
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Contact information
iDA MediaFoundry
info@ida-mediafoundry.be
@iDAMediaFoundry
Filip
filip.maelbrancke@ida-mediafoundry.be
@fmaelbrancke
Mike
michael.seghers@ida-mediafoundry.be
@mikeseghers