Package net.morimekta.providence.server

Class ProvidenceHttpServlet<RequestType extends PMessage<RequestType>,​ResponseType extends PMessage<ResponseType>>

  • Type Parameters:
    RequestType - The request type.
    ResponseType - The response type.
    All Implemented Interfaces:
    java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig
    public abstract class ProvidenceHttpServlet<RequestType extends PMessage<RequestType>,​ResponseType extends PMessage<ResponseType>>
extends javax.servlet.http.HttpServlet
    A simple HTTP POST servlet that simply deserializes the POST body as a providence message, and serializes the response message using the requested content type or accept type.

    Note that the ProvidenceHttpServlet is NOT usable for thrift services, but is meant to be used to make simple POST based HTTP servlets. 

    
 public class MyServlet extends ProvidenceHttpServlet<
         MyRequest, MyRequest._Field,
         MyResponse, MyResponse._Field> {
     {@literal@}Override
     protected MyResponse handle(HttpServletRequest httpRequest,
                                 MyRequest request)
              throws MyException, InternalFailureException {
         // ... do stuff with request, or throw MyException or IFE.
         return MyResponse.builder()
                          .setFieldOut("yes")
                          .build();
     }

     {@literal@}Override
     protected int statusCodeForException({@literal@}Nonnull Throwable exception) {
         if (exception instanceof MyException) {
             return HttpStatus.BAD_REQUEST_400;
         }
         return super.statusCodeForException(ex);
     }
 }
    This will result in a simple HTTP servlet that can be queries with CURL e.g. like this: 
    
 # Simple success
 $ curl -sS -X POST -d "{\"field_in\": \"value\"}" \
 >     -H "Content-Type: application/json" \
 >     localhost:8080/my/servlet
 {\"field_out\":\"yes\"}

 # Simple Error
 $ curl -sSv -X POST -d "{\"field_in\": \"not valid\"}" \
 >     -H "Content-Type: application/json" \
 >     localhost:8080/my/servlet
 ...
 > Content-Type: application/json
 > Accept: *{@literal/}*
 ...
 < HTTP/1.1 400 Bad Request
 < Content-Type: application/json
 ...
 {\"text\":\"not valid value\"}
    Alternatively you can hijack the whole exception / error response handling, which might be needed where custom headers etc are needed, e.g. with Unauthorized (401): 
    
 public class MyServlet extends ProvidenceHttpServlet&lt;
         MyRequest, MyRequest._Field,
         MyResponse, MyResponse._Field&gt; {
     public MyServlet() {
         super(MyRequest.kDescriptor, new MyExceptionHandler(), DefaultSerializerProvider.INSTANCE);
     }

     {@literal@}Override
     protected MyResponse handle(HttpServletRequest httpRequest,
                                 MyRequest request)
              throws MyException, InternalFailureException {
         // ... do stuff with request, or throw MyException or IFE.
         return MyResponse.builder()
                          .setFieldOut("yes")
                          .build();
     }
 }
 
    
 public class MyExceptionHandler extends ExceptionHandler {
     {@literal@}Override
     protected void writeErrorResponse(
             {@literal@}Nonnull Throwable exception,
             {@literal@}Nonnull Serializer responseSerializer,
             {@literal@}Nonnull HttpServletRequest httpRequest,
             {@literal@}Nonnull HttpServletResponse httpResponse)
             throws IOException {
         if (exception instanceof MyException) {
             httpResponse.setStatus(HttpStatus.UNAUTHORIZED_401);
             httpResponse.setHeader(HttpHeaders.WWW_AUTHENTICATE, "www.my-domain.com");
             responseSerializer.serialize(httpResponse.getOutputStream(), (MyException) exception);
             return;
         }
         super.writeErrorResponse(exception);
     }
 }

    Overridable Methods

    Since:
    1.6.0
    See Also:
    Serialized Form

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      protected void doPost​(javax.servlet.http.HttpServletRequest httpRequest, javax.servlet.http.HttpServletResponse httpResponse)  
      protected abstract ResponseType handle​(javax.servlet.http.HttpServletRequest httpRequest, RequestType request)
      Handle the request itself as a simple called method.

      • Methods inherited from class javax.servlet.http.HttpServlet

        doDelete, doGet, doHead, doOptions, doPut, doTrace, getLastModified, service, service

      • Methods inherited from class javax.servlet.GenericServlet

        destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • handle

        @Nonnull
protected abstract ResponseType handle​(@Nonnull
                                       javax.servlet.http.HttpServletRequest httpRequest,
                                       @Nonnull
                                       RequestType request)
                                throws java.lang.Exception
        Handle the request itself as a simple called method.
        Parameters:
        httpRequest - The HTTP request.
        request - The parsed providence request.
        Returns:
        The response object.
        Throws:
        java.lang.Exception - On any internal exception.

      • doPost

        protected final void doPost​(javax.servlet.http.HttpServletRequest httpRequest,
                            javax.servlet.http.HttpServletResponse httpResponse)
                     throws java.io.IOException
        Overrides:
        doPost in class javax.servlet.http.HttpServlet
        Throws:
        java.io.IOException