HTTP response status codes
HTTP response status codes indicate whether a specific request has been successfully completed or not and many of us (mobile developers) are not aware about all the http status as we can’t judge which status should be received or what backend guys should provide us in API’s response.
Basically all the developers are aware about the 200 and 500 http status code but if a talk about others like 201,503 etc then often mobile developer are not aware about that so I would like to explain about some the the available http status code so that mobile developer can taken decision at what time and what should they received in API’s response.
Lets discuss in detail:
Responses are grouped in five classes:
- Informational responses (100 –199),
- Successful responses (200 — 299),
- Redirects (300 — 399),
- Client errors (400 – 499),
- and Server errors (500 — 599).
1. Information responses
100 (Continue): This interim response indicates that everything so far is OK and that the client should continue the request, or ignore the response if the request is already finished.
101 (Switching Protocol): This code is sent in response to an upgrade request header from the client, and indicates the protocol the server is switching to.
102 (Processing): This code indicates that the server has received and is processing the request, but no response is available yet.
103 (Early Hints): This status code is primarily intended to be used with the link header, letting the user agent start preloading resources while the server prepares a response.
2. Successful responses
200 (OK): The request has succeeded. The meaning of the success depends on the HTTP method:
- GET: The resource has been fetched and is transmitted in the message body.
- HEAD: The entity headers are in the message body.
- PUT or POST: The resource describing the result of the action is transmitted in the message body.
- TRACE: The message body contains the request message as received by the server
201 (Created): The request has succeeded and a new resource has been created as a result. This is typically the response sent after Post requests, or some Put requests.
204 (No Content): There is no content to send for this request, but the headers may be useful. The user-agent may update its cached headers for this resource with the new ones.
205 (Reset Content): Tells the user-agent to reset the document which sent this request.
3. Redirection messages
300 (Multiple Choice): The request has more than one possible response. The user-agent or user should choose one of them.
301 (Moved Permanently): The URL of the requested resource has been changed permanently. The new URL is given in the response.
302 (Found): This response code means that the URI (Uniform Resource Identifier) of requested resource has been changed temporarily. Further changes in the URI might be made in the future. Therefore, this same URI should be used by the client in future requests.
303 (See Others): The server sent this response to direct the client to get the requested resource at another URI with a GET request.
304 (Not Modified): This is used for caching purposes. It tells the client that the response has not been modified, so the client can continue to use the same cached version of the response.
4. Client error responses
400 (Bad Request): The server could not understand the request due to invalid syntax.
401 (Unauthorized): Although the HTTP standard specifies "unauthorized", semantically this response means "unauthenticated". That is, the client must authenticate itself to get the requested response.
402 (Payment Required): This response code is reserved for future use. The initial aim for creating this code was using it for digital payment systems, however this status code is used very rarely and no standard convention exists.
403 (Forbidden): The client does not have access rights to the content; that is, it is unauthorized, so the server is refusing to give the requested resource. Unlike 401, the client's identity is known to the server.
404 (Not Found): The server can not find the requested resource. In the browser, this means the URL is not recognized. In an API, this can also mean that the endpoint is valid but the resource itself does not exist. Servers may also send this response instead of 403 to hide the existence of a resource from an unauthorized client. This response code is probably the most famous one due to its frequent occurrence on the web.
405 (Method Not Allowed): The request method is known by the server but has been disabled and cannot be used. For example, an API may forbid DELETE-ing a resource. The two mandatory methods, GET and HEAD, must never be disabled and should not return this error code.
406 (Not Acceptable): This response is sent when the web server, after performing server-driven content negotiation, doesn't find any content that conforms to the criteria given by the user agent.
408 (Request Timeout): The server did not receive a complete request message within the time that it was prepared to wait.
5. Server error responses
500 (Internal Server Error): The server has encountered a situation it doesn't know how to handle.
501 (Not Implemented): The request method is not supported by the server and cannot be handled. The only methods that servers are required to support (and therefore that must not return this code) are GET and HEAD.
502 (Bad Gateway): This error response means that the server, while working as a gateway to get a response needed to handle the request, got an invalid response.
503 (Service Unavailable): The server is not ready to handle the request. Common causes are a server that is down for maintenance or that is overloaded.
504 (Gateway Timeout)This error response is given when the server is acting as a gateway and cannot get a response in time.
505 (HTTP Version Not Supported): The HTTP version used in the request is not supported by the server.
I hope now you guys are aware of available HTTP status code.
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