net.morimekta.providence.server

Class ProvidenceHttpServlet<RequestType extends net.morimekta.providence.PMessage<RequestType>,ResponseType extends net.morimekta.providence.PMessage<ResponseType>>

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

net.morimekta.providence.server.ProvidenceHttpServlet<RequestType,ResponseType>

Type Parameters:

RequestType - The request type.

ResponseType - The response type.

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public abstract class ProvidenceHttpServlet<RequestType extends net.morimekta.providence.PMessage<RequestType>,ResponseType extends net.morimekta.providence.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<
         MyRequest, MyRequest._Field,
         MyResponse, MyResponse._Field> {
     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

• handle(HttpServletRequest, PMessage): The main handle method. This must be implemented.

Since:

1.6.0

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ProvidenceHttpServlet(net.morimekta.providence.descriptor.PMessageDescriptor<RequestType> requestDescriptor, ExceptionHandler exceptionHandler, net.morimekta.providence.serializer.SerializerProvider serializerProvider)

Method Summary

Modifier and Type	Method and 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

Constructor Detail

ProvidenceHttpServlet

public ProvidenceHttpServlet(@Nonnull
                             net.morimekta.providence.descriptor.PMessageDescriptor<RequestType> requestDescriptor,
                             @Nullable
                             ExceptionHandler exceptionHandler,
                             @Nullable
                             net.morimekta.providence.serializer.SerializerProvider serializerProvider)

Method Detail

handle

@Nonnull
protected abstract ResponseType handle(@Nonnull
                                                javax.servlet.http.HttpServletRequest httpRequest,
                                                @Nonnull
                                                RequestType request)
                                         throws 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:

Exception - On any internal exception.

doPost

protected final void doPost(javax.servlet.http.HttpServletRequest httpRequest,
                            javax.servlet.http.HttpServletResponse httpResponse)
                     throws IOException

Overrides:

doPost in class javax.servlet.http.HttpServlet

Throws:

IOException