Building Composite Applications
Lots of ground to cover!
New concepts, code!
Look for code, samples and presentation downloads
- The whole is greater than the sum of its parts
- Composed of a number of discrete and independent pieces, aggregating this functionality through a software interface.
- Break free from “silo” issues
- Lower cost of development
- An encapsulated system providing its own self sufficiency
What’s enabled all this?
- Software over services
- Loosely coupled
- 3 tier architecture
- Result: Reuse of software!
Traps to watch for
- Maturity for integration
- Must be able to leverage services for direct integration for greatest benefit
- External Trust
- External data lives in the cloud
- Reliance on provider for business operations
Example: Exchange Server 2007 is used by
- Outlook Web Access
- Outlook Voice Access
- Outlook Mobile
- Lightweight build: 3 weeks
- Consumes resources from
- Also publishes services and data
- Presentation Layer = ASP.Net 2.0 & AJAX
- Business Layer = Content Service, controllers & Model
- Resource Layer = Service Proxies & LINQ to SQL Server
- Start with the problem e.g. Provide a community site to provide content for DreamScene
- Focus on the interface
- Work out who is already offering functionality
- Flickr works well for images
- Soapbox works well for videos
We already had great tools
- .NET 2.0 and .NET 3.0 Frameworks
- ASP.Net AJAX
- Composite Web Block
- Enterprise Library
- Don’t forget about 3rd party!
- RSS Toolkit
- 2 way data-binding
Some tips from the Background Motion build
Supervising Controller (MVP)
- View (GET http://site/pages.aspx)
- Presenter (View is based on the PageBase class which wires it up to the Presenter)
- Model (View can work with the Model but calls back to Presenter to perform process flow)
- “Factor the UI into a view and controller where the view handles simple mapping to the underlying model and the controller handles input response and complex view logic.” Martin Fowler – www.martinfowler.com
- Cleanly separates UI process form binding/event logic
- Improves testability
- Establish a level of abstraction via a public interface, and remove dependency on components by (for example) supplying a plug-in architecture – Wiki
- Allows for loose coupling
- Abstraction through interfaces
- Composite Web Block uses
- ServiceLocator approach
- I need an instance of IDataLayer class! (Consumer to Interface)
- I can ask the ServiceLocator to give me an instance of IDatalayer
- ServiceLocator holds an instance of Factory <IDataLayer>
- Factory <IDataLayer> assembles a Concrete class instance
- Concrete instance is returned to the Consumer
- Consumer always calls through the IDataLayer interface
- Solid foundation leads to flexibility – supports change!
- Lower development complexity – modularity!
- Testability of solution
- More effective integration
- Shorter cycles
- Always building working code!
· Create a separate library (project in the solution)
· NUnit – a free testing framework
· Define [Test] methods
o (do some work)
· Where might these be useful?
o When a field length changes, the Unit Test will fail the Validator.
o Helps save you a lot of time by capturing these types of failures
- Developer checks in to source control
- The BuildServer monitors the source control
- The BuildServer builds the application
- The BuildServer runs the unit tests
- The BuildServer notifies whether all tests passed
- External from this application
- Active Directory
- Web Services
- Legacy System
- Contract based consumption
- Loose coupling
- Flexibility in plug and play
- Windows Communication Foundation
- The Unified Framework for rapidly building service oriented applications
· Building block for building Connected Systems
· Designed around messages!
· Full standards/specifications support (WS-* oriented)
· Provide consistent API regardless of messaging requirement
· Part of .Net 3.0 Framework
Software + Services
· ASP.NET AJAX. The free framework for quickly creating a new generation of more efficient, more interactive and highly personalized Web experiences
· Building a mash-up using ASP.NET AJAX
AJAX with Services
- ASP.Net AJAX allows native call
- Too fast
Call to Action
- Read about Patterns
- Look at Unit Tests and CI http://ccnet.thoughtworks.com
- Download the Composite Web Block
- And the Validation Block
- And the Enterprise Library
- Publish services in your enterprise to allow composite applications to flourish!
Other related posts:
Teach Yourself Azure in 4 hours
Geek Post Monthly Newsletter Volume 2 Issue 10
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