Update 101-domain-driven-design.md (#1336)

* Update 101-domain-driven-design.md

* Update content/roadmaps/101-backend/content/114-design-and-development-principles/101-domain-driven-design.md

Co-authored-by: Kamran Ahmed <kamranahmed.se@gmail.com>

content/roadmaps/101-backend/content/114-design-and-development-principles/101-domain-driven-design.md

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-# Domain driven design
+# Domain-Driven Design
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+Domain-driven design (DDD) is a software design approach focusing on modeling software to match a domain according to input from that domain's experts.
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+In terms of object-oriented programming, it means that the structure and language of software code (class names, class methods, class variables) should match the business domain. For example, if a software processes loan applications, it might have classes like LoanApplication and Customer, and methods such as AcceptOffer and Withdraw.
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+DDD connects the implementation to an evolving model and it is predicated on the following goals:
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+- Placing the project's primary focus on the core domain and domain logic;
+- Basing complex designs on a model of the domain;
+- Initiating a creative collaboration between technical and domain experts to iteratively refine a conceptual model that addresses particular domain problems.
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+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
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+<BadgeLink colorScheme='blue' badgeText='Original Paper' href='https://matfrs2.github.io/RS2/predavanja/literatura/Avram%20A,%20Marinescu%20F.%20-%20Domain%20Driven%20Design%20Quickly.pdf'>Domain Driven Design Quickly</BadgeLink>