SOA was meant to reduce complexity in IT systems. But the concept itself got entangled with complexities and lost its soul to a string of acronyms. Don Fornes has made a laudable attempt to demystify SOA by explaining it in laymen terms.

...SOA is the IT-equivalent of managing a large, diverse workforce. It cataloguess the systems in place and figures out what they can do. It specifies a common language that they can all use to communicate...

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