Question

I have some confusion regarding “When should we use disributed architecture”.

I know concept behind the disributed architecture. When we want different component interact with each other then we should use disributed architecture.

What are the examples of application where we use the disributed architecture?

I always seen that when we develope shopping cart we use EJB. Is it that necessary?
We can design shopping cart without EJB too.

Hope this helps.

Answer 1

In distributed architecture different pieces of your application are located in different physical nodes as opposed to clustered architecture, where the same application (all components) are deployed on all nodes.

You may want to have a distributed architecture when:

• different parts of your system have different requirements on hardware
• you need greater SLA by distributing your application to multiple data centers
• you want to enforce better security constraints between layers (e.g. firewalls/DMZ between web servers and application servers)
• your system can work without some artifacts with some fall-back; real-life example: when Suggested products module is not working simply display best-sellers regardless of the customer

And yes, you can implement shopping cart with session EJB (e.g. using HTTP session). But in both cases this should rather be called clustering rather than distributing.