While designing the restful API, we need to make sure that API should always return the right and consistence HTTP status Code and without consistent HTTP status codes, customers will not know the difference between success or failure without parsing the response body.
References:
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HTTP standard provides almost 70 status codes to describe the response status and you can use below HTTP status code for restful API.
200 – OK
204 – OK – No Content
400 – Bad Request
401 – Unauthorized
500 – Internal Server Error
503 – Service is not available
HTTP – GET (Resource Inquiry):
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| HTTP GET Sequence Diagram |
The above sequence diagram explain how the HTTP request is being processed and returns the HTTP status code.
There are the possible scenarios for processing of the HTTP GET request.
1. Scenario : If request resource is found, Returns HTTP – 200 OK with Resource data
2. Scenario: If request resource is not found, Returns HTTP – 200 OK with NULL data.
3. Scenario: Any Validation Error/invalid input – returns HTTP – 400 Bad Request with validation or error message.
HTTP – POST (Resource Creation)
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| HTTP POST Sequence Diagram |
The above sequence diagram explain how the HTTP request is being processed and returns the right HTTP status code.
There are the possible scenarios for processing of the HTTP POST request.
1. Scenario: If requested resource is successfully created, Returns HTTP – 201 OK with Newly created Resource data
2. Scenario:
If request resource is already found or duplicate resource, returns – returns HTTP – 400 Bad Request with validation message
OR
· Any validation or invalid input error - returns HTTP – 400 Bad Request with validation message
HTTP – PUT (Resource Update)
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| HTTP PUT Sequence Diagram |
The above sequence diagram explain how the HTTP request is being processed and returns the right HTTP status code.
There are the possible scenarios for processing of the HTTP PUT request.
1. Scenario: Any validation or invalid input error - returns HTTP – 400 Bad Request with validation message
2. Scenario: If request resource is not available, return HTTP – 400 Bad Request – with message “Resource is not available”
In this scenario, if resource is not available, many architect prefer to create new resource and returns HTTP – 201 OK with newly created resource data
3. Scenario: If request resource is available and successfully updated, Returns HTTP – 200 OK with updated Resource data
HTTP – Patch (Partially Resource Update)
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| HTTP PATCH Sequence Diagram |
The above sequence diagram explain how the HTTP request is being processed and returns the right HTTP status code.
There are the possible scenarios for processing of the HTTP PATCH request.
1. Scenario : If request resource is available and successfully updated , Returns HTTP – 200 OK with updated Resource data
2. Scenario : Any validation or invalid input error - returns HTTP – 400 Bad Request with validation message
3. Scenario : If request resource is not available, return HTTP – 400 Bad Request – with message “Resource is not available”
HTTP – DELETE (Delete Resource)
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| HTTP DELETE Sequence Diagram |
The above sequence diagram explain how the HTTP request is being processed and returns the right HTTP status code.
There are the possible scenarios for processing of the HTTP DELETE request.
1. Scenario : If request resource is available and successfully deleted, Returns HTTP – 200 OK
2. Scenario : Any validation or invalid input error - returns HTTP – 400 Bad Request with validation message
3. Scenario : If request resource is not available, return HTTP – 400 Bad Request – with message “Resource is not available”
Note: In some scenario, requested URI is not matching with any API URI., then by default Web API/IIS returns HTTP – 404 - with message “HTTP resource was found that matches the request URI”
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