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2015-01-26

Create an Agnostic Vendor Infrastructure in Ruby

Depending how the code was written adding new services to it can be difficult.
For instance, let's say we are building a rails application that gets integrated to cloud storage vendors.
A naive implementation would be to directly integrate to a cloud storage specific APIs.
In this case when new cloud storage vendors are added it is very probable that several nasty case... when ... end statements would be inserted in code.

When a new cloud storage service is added the developer must remember all places where those growing case-like statements are inserted. This makes the system more susceptible to errors due to  changes in several parts of the code. This problem is explained in detail by the shotgun surgery anti-pattern (http://en.wikipedia.org/wiki/Shotgun_surgery)

The rest of the system shouldn't be aware that a new cloudstorage service was added. That is where a combination of design patterns come in handy:
  • a facade to provide a simple interface for cloud storage operations 
  • a service locator to find the right cloud storage adapter
  • a cloud storage adapters that make each vendor API compliant to a single defined interface that can be understood by the facade


1) Cloud Storage Facade

2) Cloud Storage Adapter Locator

3) Cloud Storage Adapters

Note that this combination of patterns can be used to abstract many other types of services. Cloud storage service was just an example used here.

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