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Apache-Camel: How to control the scope of the exchange headers?

I'm using the exchange headers to store any variables in the route. But, looks like these headers will be carried on to the other routes which are called from this route.
In the below sample, I'm calling a getContact route which will call a http endpoint. But, it will also send the headers, variable1 & variable2, it got from the initial route, direct:start.
from("direct:start")
.setHeader("variable1", constant("value1"))
.setHeader("variable2", constant("value2"))
.to("direct:getContact");
from("direct:getContact")
.setHeader("Content-Type", constant("application/json"))
.setHeader("Accept", constant("application/json"))
.setHeader(Exchange.HTTP_METHOD, constant("GET"))
.to("http://<host>:<port>/contact/3")
.unmarshal().json(JsonLibrary.Jackson);
Is there a way to avoid this? In contrast, a method call in java will hide all the existing variables by context switch.

I've run into the problem before when sending a webservice call using http4. Tt's rather annoying that Camel seems to send send the entire exchange when you're using the http4/http endpoint. I got around this by using a content enricher. I placed the actual call using http4 in the enrich route and had an simple aggregation strategy combine the two messages afterwards.
Alternatively, you can make the call in a bean. This way you lose some of the benefits of camel but you have complete control over the call body.

There is no direct way to avoid this. If you are setting the headers to a hard-coded value then you might be able to move the header to a URI property on your endpoint. If not then you only really have 2 other options. The first option is to remove all of the headers using a remove header call after your HTTP call so they don't go downstream. The second is to set all of the headers in the same route as the http call and have a different route call that endpoint with an enrich statement and in the aggregation back to the main route you can customize the returned exchange.
Here is an camel http reference page for all of the allowed headers to see if you can put it in the URI http://camel.apache.org/http4.html
Sample of a route removing headers
from("direct:start")
.setHeader("variable1", constant("value1"))
.setHeader("variable2", constant("value2"))
.setHeader("Content-Type", constant("application/json"))
.setHeader("Accept", constant("application/json"))
.setHeader(Exchange.HTTP_METHOD, constant("GET"))
.to("http://<host>:<port>/contact/3")
.unmarshal().json(JsonLibrary.Jackson)
.removeHeaders("variable*")
.to("Anything I call now won't have the variable headers");
enrichment call
AggregationStrategy aggregationStrategy = new ExampleAggregationStrategy();
from("direct:start")
.enrich("direct:getContact", aggregationStrategy)
.to("You can have no additional headers here");
public class ExampleAggregationStrategy implements AggregationStrategy {
public Exchange aggregate(Exchange original, Exchange resource) {
Object originalBody = original.getIn().getBody();
Object resourceResponse = resource.getIn().getBody();
Object mergeResult = //TODO implement this however you want. You can remove any headers here you like
if (original.getPattern().isOutCapable()) {
original.getOut().setBody(mergeResult);
} else {
original.getIn().setBody(mergeResult);
}
return original;
}
}
Actually 1 more option came to mind when going through the camel documentation I found an interesting property. Disclaimer I have never tried this property myself since I am still running camel 2.15 atm, but feel free to test it really quick it might just be what you need.
copyHeaders
default: true
Camel 2.16: If this option is true then IN exchange headers will be copied to OUT exchange headers according to copy strategy. Setting this to false, allows to only include the headers from the HTTP response (not propagating IN headers).

Just use:
.removeHeaders("variable*")
to remove headers of any pattern.

How can i preserve the request headers in error response prepared through JAX-RS ( Apache-CXF implementation) ExceptionMapper

I am implementing JAX-RS using apache CXF. I have created an ExceptionMapper to handle bad requests like this:
public class ClientErrorExceptionMapper implements ExceptionMapper<ClientErrorException> {
#Override
public Response toResponse(final ClientErrorException exception) {
return Response.status(Response.Status.BAD_REQUEST).entity("Invalid request: Invalid URI.").build();
}
}
I am not sure how this works internally but i suppose that framework would throw an exception in case user is making an invalid request and this handler will prepare an error message to be send back. My problem is that i wish to preserve some custom headers that user sends in the request, so that i send that back with the response. But using this exception mapper, i cant see any option to get the original request headers. I can set any new header in the response, but i wish to preserve the request headers - like i do in a normal request.
So is there any way in JAX-RS where i can preserve or efficiently refer to the custom headers in current request ?

What we have resorted to is using a thread local variable to save the RequestContext when the request arrives and then in the ExceptionMapper we can obtain request specific information.
Ugly but it works. I think we have a generic filter in the filter list that catches all requests before dispatch.

Logging Rest Assured's own headers

I'm trying to get access to the HTTP headers that are injected by Rest Assured. Spring's Mock MVC gives you access to pretty much everything via the MvcResult, and you can use this result to log pretty much anything you would like about the request and response. The only way I can see how to do this is in RestAssured is with a Filter. However, it gives you limited access to the request (you just get the RequestSpecification). I understand that it might be tricky to get access to headers that are added by the HttpClient, but it doesn't look like you can even get access to headers that are added by Rest Assured itself. For example, I can't see any OAuth related headers, nor content-type or content-length. The only headers that appear are those that were manually added using, for example, .contentType(ContentType.XML)
Is there any other way to get access to those headers? I don't need to modify the request, I just want to be able to log all of it and the headers that are injected by Rest Assured.

I found that it's possible to register your own HttpClientFactory with RestAssured:
RestAssured.config().httpClient(
HttpClientConfig.httpClientConfig().httpClientFactory(
new CustomHttpClientFactory())
So I created a new factory that returns an HTTP client into which I inject some request and response interceptors.
public class CustomHttpClientFactory extends HttpClientConfig.HttpClientFactory {
#Override
public HttpClient createHttpClient() {
DefaultHttpClient client = new DefaultHttpClient();
client.addRequestInterceptor((request, ctx) -> {
// do what you will
});
client.addResponseInterceptor((response, ctx) -> {
// do what you will
});
return client;
}
}
This gives you almost full access to manipulate the request and response. One thing to remember is that if you're going to read from the response's entity, you should first wrap it in a BufferedHttpEntity to make it re-readable:
if (response.getEntity() != null && !response.getEntity().isRepeatable()) {
response.setEntity(new BufferedHttpEntity(response.getEntity()));
}
Another problem I ran into is when trying to see the OAuth related information. When using RestAssured's OAuth functionality, it adds its own OAuthSigner interceptor to the HTTP client right before executing the request. This means that it will always be the last interceptor to be called and any interceptor you may have already injected will be called before the request ever gets signed. Because I don't really need to see the signature for now, I didn't investigate this further and I'm leaving it as an exercise for the reader. ;)

Dropwizard Multiple Rest API versions

Currently I am designing how to deal with routing in a versioned rest API where the version is not part of the url, but sent via a header variable.
I have considered/seen things like:
Re-writing the url based on the header variable i.e. the request /orders {X-Media-Type: v1} would rewrite to /v1/orders and then we could have a #Path("/v1/orders") OrderV1Resource {} and thus making v2 would be trivial #Path("/v2/orders") OrderV2Resource {}. (my first preference) How to use a servlet filter in Java to change an incoming servlet request url?
Having a Single #Path("/orders") OrderResource {} where each of it's methods have an injected HeaderParam and I could check the header variable and then decide which Order API implementation I wanted to use (which seems very messy to me)
// pseudo-java code
#Path("/orders")
OrderResource {
OrderV1Impl v1Impl;
OrderV2Impl v2Impl;
#GET
public List<Order> findAll(#HeaderParam header) {
version = header.get("accepts")
if(version.equals("v1")) { return v1Impl.findAll() }
else if(version.equals("v2")) { return v2Impl.findAll() }
return error
}
}
Or just bundling them up in seperated JARS and having a service look at the header and route to the correct version. (seems to make sense if the app grows to be really large)

I ended up passing the version in via a header then used this to route the desired resource via a javax.servlet.Filter.
Example Accept header:
Accept: application/vnd.datarank.v1+json

How to distinguish what format a client requests back to my REST webservice?

I have a Java WebService setup which consumes an xml file and want to be able to produce either xml or json based on what the client requests. I know that this is possible through reading up on Jersey REST methods but it does not show how to extract this information. I have also looked on google all over but can't seem to find any examples of this.
http://wikis.sun.com/display/Jersey/Overview+of+JAX-RS+1.0+Features is the site that I was initially referencing which shows that it is possible, I was just wondering if anyone would be able to help me find out how to actually distinguish the client's request. Is it in the html header? body? And if so what is the proper way to extract it?
This is what my method currently looks like, I do not have any issues with connection, just finding out what the client requests as a return type.
#POST
#Path("getStatisticData")
#Produces ({"application/xml","application/json"})
#Consumes ("application/xml")
public String getStatisticData(#FormParam("xmlCoords") String xmlFile) throws Exception{
Thanks in advance.

You can extract it using the #HeaderParam annotation:
...
public String getStatisticData(#HeaderParam("Accept") String accept,
#FormParam("xmlCoords") String xmlFile) throws Exception {
...
}

The Accept header in the request is used for the client to indicate to the server what methods it supports.

If the client can set HTTP headers, the proper way to do it is to use the Accept header:
http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
IF this is not possible, the type requested could be passed in as an argument.
Alternatively, expose two different web services: one that returns XML, one that returns JSON. Each web service would call the same code but with a parameter specifying which format to use.