Update important_interview_question.php

important_interview_question.php

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     27. State less means
     28. Ajax State...
     29. Soup and Rest API
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+    To create a REST API, you need to follow six architectural constraints:
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+Uniform interface – Requests from different clients should look the same, for example, the same resource shouldn’t have more than one URI.
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+Client-server separation – The client and the server should act independently. They should interact with each other only through requests and responses.
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+Statelessness – There shouldn’t be any server-side sessions. Each request should contain all the information the server needs to know.
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+Cacheable resources – Server responses should contain information about whether the data they send is cacheable or not. Cacheable resources should arrive with a version number so that the client can avoid requesting the same data more than once.
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+Layered system – There might be several layers of servers between the client and the server that returns the response. This shouldn’t affect either the request or the response.
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+Code on demand [optional] – When it’s necessary, the response can contain executable code (e.g., JavaScript within an HTML response) that the client can execute.