Run the 3 application classes as spring boot applications.

• ZuulGatewayApplication: runs zuul on port 8080
• FooApplication: hosts a /foo service on port 9080
• BarApplication: hosts a /foo service with a different implementation on port 7080

There are a number of filters are implemented:

• AddResponseHeaderFilter: adds a random X-Foo header to the response
• ModifyResponseBodyFilter: Adds a prefix to the response using RequestContext.setResponseBody(String). Only runs if service query parameter is NOT set.
• ModifyResponseDataStreamFilter: Adds a prefix to the response using RequestContext.setResponseDataStream(InputStream). Only runs if service query parameter is set.
• PrefixRequestEntityFilter: Adds a prefix to the request body by using a request wrapper and RequestContext.setRequest(). Only runs if service query parameter is set.
• QueryParamPortPreFilter: sets the port of the RequestContext.getRouteHost to the value of the port query parameter. Only runs if port query parameter is set.
• QueryParamServiceIdPreFilter: sets the serviceId to the value of the service query parameter.
• UppercaseRequestEntityFilter: Upper cases the request body by setting RequestContext.setRequest("requestEntity"). Only runs if service query parameter is NOT set.

All examples use HTTPie(A better curl replacement).

$ http :8080/foo 
HTTP/1.1 200 
Content-Type: text/plain;charset=UTF-8
Date: Wed, 22 Mar 2017 20:06:45 GMT
Transfer-Encoding: chunked
X-Application-Context: application
X-Foo: 41e04412-84e8-48ac-8d71-cec209eda9ca

Modified via setResponseBody(): foo from FooApplication$$EnhancerBySpringCGLIB$$82229332

The application is routed to FooApplication because the response contains foo from FooApplication.

The AddResponseHeaderFilter ran because of the X-Foo: 41e04412-84e8-48ac-8d71-cec209eda9ca header was added to the response.

The ModifyResponseBodyFilter was run because the body was prefixed with Modified via setResponseBody():.

$ http ":8080/foo?service=bar"
HTTP/1.1 200 
Content-Type: text/plain;charset=UTF-8
Date: Wed, 22 Mar 2017 20:09:23 GMT
Transfer-Encoding: chunked
X-Application-Context: application
X-Foo: 9dc2e5fa-a43f-445d-a289-d3e62319413a

Modified via setResponseDataStream(): bar from BarApplication$$EnhancerBySpringCGLIB$$a78c1598

The application is routed to BarApplication because the response contains bar from BarApplication.

The AddResponseHeaderFilter ran because of the X-Foo: 9dc2e5fa-a43f-445d-a289-d3e62319413a header was added to the response.

The ModifyResponseDataStreamFilter was run because the body was prefixed with Modified via setResponseDataStream():.

$ echo -n "hello" | http POST :8080/foo
HTTP/1.1 200 
Content-Type: application/json;charset=UTF-8
Date: Wed, 22 Mar 2017 21:48:46 GMT
Transfer-Encoding: chunked
X-Application-Context: application
X-Foo: 69866ea1-db9a-4275-a8f1-5e20d87e5065

Modified via setResponseBody(): foo recieved: HELLO

UppercaseRequestEntityFilter was run because foo recieved: HELLO was in the response body.

$ echo -n "hello" | http POST ":8080/foo?service=bar"
HTTP/1.1 200 
Content-Type: application/json;charset=UTF-8
Date: Wed, 22 Mar 2017 21:49:02 GMT
Transfer-Encoding: chunked
X-Application-Context: application
X-Foo: 97aebe27-6845-4dc3-9ef6-80ccdf14059d

Modified via setResponseDataStream(): bar recieved: request body modified via request wrapper: hello

PrefixRequestEntityFilter was run because foo recieved: HELLO was in the response body.

$ http :8080/hello
HTTP/1.1 500 
Connection: close
Content-Type: application/json;charset=UTF-8
Date: Fri, 24 Mar 2017 21:05:04 GMT
Transfer-Encoding: chunked
X-Application-Context: application

{
    "error": "Internal Server Error",
    "exception": "org.apache.http.conn.HttpHostConnectException",
    "message": "Connect to localhost:80 [localhost/127.0.0.1, localhost/0:0:0:0:0:0:0:1, localhost/fe80:0:0:0:0:0:0:1%1] failed: Connection refused",
    "status": 500,
    "timestamp": 1490389504014
}

Uses a bad port, QueryParamPortPreFilter not run.

$ http ":8080/hello?port=9080"
HTTP/1.1 200 
Content-Type: text/plain;charset=UTF-8
Date: Fri, 24 Mar 2017 21:07:07 GMT
Transfer-Encoding: chunked
X-Application-Context: application
X-Foo: 50774952-b947-47cd-902b-2889d02feece

Modified via setResponseBody(): hello from FooApplication$$EnhancerBySpringCGLIB$$82229332

QueryParamPortPreFilter was run because response contains hello from FooApplication.