HTTP Status Code

1. 1xx Informational.

2. 2xx Success.

3. 3xx Redirection.

4. 4xx Client Error.

5. 5xx Server Error.

6. Unofficial codes. 6.1 Internet Information Services. 6.2 nginx. 6.3 CloudFlare

Default Response Codes:

The default response codes that JAX-RS uses are pretty straightforward. There is pretty much a one-to-one relationship to the behaviour described in the HTTP 1.1 Method Definition specification. Let’s examine what the response codes would be for both success and error conditions for the following JAX-RS resource class.

@Path("/customers")

class CustomerResource {

  @GET

  @Path("{id}")

  @Produces("application/xml")

  public Customer getCustomer(@PathParam("id") int id) {

    ...

  }

  @POST

  @Produces("application/xml")

  @Consumes("application/xml")

  public Customer create(Customer newCust) {

    ...

  }

  @PUT

  @Path("{id}")

  @Consumes("application/xml")

  public void update(@PathParam("id") int id, Customer cust) {

    ...

  }

  @Path("{id}")

  @DELETE

  public void delete(@PathParam("id") int id) {

    ...

  }

}

Successful Responses:

Successful HTTP response code numbers range from 200 to 399.

In the above of our CustomerResource class for the create() and getCustomer() methods 

(i) They will return a response code of 200, "OK" if the Customer object they are returning is not null. 

(ii) If the return value is null, a successful response code of 204, "No Content" is returned. 

The 204 response is not an error condition. It just tells the client that everything went OK, but that there is no message body to look for in the response. If the JAX-RS resource method’s return type is void, a response code of 204, "No Content" is returned. This is the case with our update() and delete() methods. IF the DELETE and PUT methods have return types then if response sent then 204 "OK" it will return.

The HTTP specification is pretty consistent for the PUT, POST, GET, and DELETE methods. If a successful HTTP response contains a message body, 200, "OK" is the response code. If the response doesn’t contain a message body, 204, "No Content" must be returned.

Error Responses:

In our CustomerResource example, error responses are mostly driven by application code throwing an exception. We will discuss this exception handling later in this chapter. 

There are some default error conditions are there and standard HTTP error response code numbers range from 400 to 599. 

In our example, if a client mistypes the request URI, for example, to customers, it will result in the server not finding a JAX-RS resource method that can service the request. In this case, a 404, "Not Found" response code will be sent back to the client.

For our getCustomer() and create() methods, if the client requests a text/html response, the JAX-RS implementation will automatically return a 406, "Not Acceptable" response code with no response body. This means that JAX-RS has a relative URI path that matches the request, but doesn’t have a JAX-RS resource method that can produce the client’s desired response media type.

If the client invokes an HTTP method on a valid URI to which no JAX-RS resource method is bound, the JAX-RS runtime will send an error code of 405, "Method Not Allowed", So in our example, if our client does a PUT, GET, or DELETE on the /customers URI, it will get a 405 response because POST is the only supported method for that URI. The JAX-RS implementation will also return an Allow response header back to the client that contains a list of HTTP methods the URI supports. So, if our client did a

GET /customers in our example, the server would send this response back: 

HTTP/1.1 405, Method Not Allowed

Allow: POST

The exceptional to this rule is the HTTP HEAD and OPTIONS methods. If a JAX-RS resource method isn’t available that can service HEAD requests for that particular URI, but there does exist a method that can handle GET, JAX-RS will invoke the JAX-RS resource method that handles GET and return the response from that minus the request body. If there is no existing method that can handle OPTIONS, the JAX-RS implementation is required to send back some meaningful, automatically generated response along with the Allow header set.

Summary:

Default Successful Response codes

Successful HTTP response code numbers range from 200 to 399.

200-"OK"

204-"No Content"

Default Error Response codes

HTTP error response code numbers range from 400 to 599. 

400-Bad Request-If input data syntax mistyped or if we ignore something to give req data.

For example if we have XSD representing the XML then we need to specify the XSD name space while sending the data, if we didn't specify the XSD in the XML data then also we will get 400-Bad Request.

404-Mistyping the URI "Not Found"

405-URI correct but req method is wrong: Method Not Allowed

406-"Not Acceptable" media type

415-Unsupported Media Type

For example if we have Resource method which can accept both appl/xml and appl/json format then 

(i) If we send content-type as appl/xml for json body format then we will get 400-Bad Request bcz content-type is matching but format is wrong for given req.

(ii) If we send content-type appl/json for XML body format then we will get 400-Bad Request bcz content-type is matching but format is wrong for given req.

(iii) If we send text/plain data then which will never matches to either appl/xml or appl/json hence it will send 415: Unsupported Media Type

401-Unathorized

500-Internal Server.

When conversion problems occurs etc and several environment related issues.