I've read quite a few documentations and other stackoverflow questions regarding this matter but I can't seem to get my code working.
So essentially I have a WebClient making a POST request.
IF the response status is 200, then I make another call to another endpoint using a different WebClient. After second webclient call, return a string.
ELSE I just return a String from the method e.g. "failed to create order.".
Simple enough. (this is all done in a seperate thread fyi, not the main thread.)
But I've noticed that if i do get back a 500 error code, WebClient throws an exception. What I want to do is capture the exception and handle that gracefully and return a String like "Error calling first endpoint etc."
This is what I have so far:
private String generateOrder(ImportedOrderDetails importedOrderDetails)
{
Order requestBody = generateRequestBody(importedOrderDetails);
OrderResponse responseForCreatingOrder = orderWebClient()
.post()
.body(Mono.just(requestBody), Order.class)
.retrieve()
.bodyToMono(OrderResponse.class)
.block();
if (responseForCreatingOrder.getResponseStatus().equals(SUCCESS))
{...other call using different webclient}
else{ return "Error creating order."}
This works fine when the response status is 200 but when its 500 it blows up.
OrderResponse is a custom object. orderWebClient() is just a method that returns a prebuilt WebClient containing the baseUrl and headers etc.
I came across this:
Spring WebClient - How to handle error scenarios I did try implementing it but couldn't figure out where to put the block method since I kept on getting the following:
reactor.core.Exceptions$ReactiveException: java.lang.Exception
at reactor.core.Exceptions.propagate(Exceptions.java:393)
at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:97)
at reactor.core.publisher.Mono.block(Mono.java:1680)
I had to edit my code a bit to try and implement the answer to that question:
private Mono<? extends Throwable> handleError(String message) {
log.error("====---"+message);
return Mono.error(Exception::new);
}
private String generateOrder(ImportedOrderDetails importedOrderDetails)
{
Order requestBody = generateRequestBody(importedOrderDetails);
Mono<OrderResponse> responseForCreatingDemo = orderWebClient()
.post()
.body(Mono.just(requestBody), Order.class)
.retrieve()
.onStatus(
(HttpStatus::is5xxServerError),
(it -> handleError(it.statusCode().getReasonPhrase()))
)
.bodyToMono(OrderResponse.class);
System.out.println("-=-"+responseForCreatingDemo);
if (responseForCreatingOrder != null && responseForCreatingOrder.block().getHeader().getResponseStatus().equals(SUCCESS)){...}
The error was coming from the .block part in the if condition. I believe this is something pretty trivial and missing the big picture.
Any suggestions?
It seems you have two kinds of statuses:
Http status, defined by the protocol itself (see HTTP response status codes)
Something specific to the application you're working on, encapsulated into the OrderResponse class.
So you have to handle two "errors" instead of one, one of the possible solutions might look like
.retrieve()
.bodyToMono(OrderResponse.class)
// 4xx, 5xx errors and return "Unable to create order" String instead
.onErrorContinue(WebClientResponseException.class, (ex, v) ->
Mono.just("Unable to create order"))
// if application specific status is not "ok" return "Unable to create order"
.map(it -> it.ok ? "Ok response" : "Unable to create order")
.block();
Please note that this code sample ignores exception and does not even log it
I'm new to camel and writing a small POC to implement in an existing application. Application takes a xml request as input which contains the requested services and relevant data. It then calls those services one by one.
When a service is called successfully then I retrieve the http response code in a processor like below and do further logic:
Object code = exchange.getIn().getHeader(Exchange.HTTP_RESPONSE_CODE);
if(null!=code && code instanceof Integer)
{
responseCode = (Integer) code;
}
In success case, responseCode received = 201
Based on the responseCode, I know if the service call is successful and then proceed with the next one.
However, I tried to produce the negative scenario by making the service url incorrect and can't see the http response code anymore:
Original service url - http://xxx:0000/.../.../.../.../...
Modified service url - http://xxx:0000/.../.../.../.../abc/...
In failure case, responseCode received = null
In postman, I get the below error:
org.apache.camel.http.common.HttpOperationFailedException: HTTP
operation failed invoking http://xxx:0000/.../.../.../.../abc/...
with statusCode: 404 at
org.apache.camel.component.http.HttpProducer.populateHttpOperationFailedException(HttpProducer.java:274)
at
org.apache.camel.component.http.HttpProducer.process(HttpProducer.java:183)
I don't know why exchange doesn't contain the http response code when it's present in the error message in the postman.
I'm using onException to handle any exceptions and then calling a processor to process the flow further:
<camel:onException>
<camel:exception>java.lang.Exception</camel:exception>
<camel:process ref="xxxProcessor" />
</camel:onException>
I think I can consider responseCode=null as failure and proceed with my logic but want to understand why response code is being returned as null.
Thanks in advance!
I figured it out. It seems that in case of service exception, an instance of org.apache.camel.http.common.HttpOperationFailedException is thrown and the http status code is present in it. It can be retrieved in the processor like below:
Exception e = exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class);
if(null!=e && e instanceof HttpOperationFailedException)
{
HttpOperationFailedException httpOperationFailedException = (HttpOperationFailedException)e;
responseCode=httpOperationFailedException.getStatusCode();
}
The accepted answer helped me and it might have been valid! In the camel version I'm usin (2.20.1), getting the exception via the property does not seem to work. The following does
HttpOperationFailedException httpOperationFailedException = exchange.getException(HttpOperationFailedException.class);
if(null!=e) {
responseCode = httpOperationFailedException.getStatusCode());
}
I'm building a Rest Client using jersey-client 2.19:
public ReleaseEntity createRelease(ReleaseEntity newRelease, int workspaceId) {
Releases wrapper = new Releases();
wrapper.setData(Arrays.asList(newRelease));
WebTarget target = client.target(urlPrefix)
.path(AgmUrls.getReleasesUrl(workspaceId));
wrapper = target
.request()
.accept(MediaType.APPLICATION_JSON)
.post(Entity.entity(wrapper, MediaType.APPLICATION_JSON))
.readEntity(Releases.class);
return wrapper.getData().get(0);
}
The client is initialized in the constructor
this.client = ClientBuilder.newClient();
The problem is that, in case of bad response the post call does not throw an exception, neither explicit nor runtime.
Should I do this manually, or am I missing something?
This question is quite dated, but better prevent others to repeat the same mistake...
Instead of
result = target
.request()
.accept(MediaType.APPLICATION_JSON)
.post(Entity.entity(input, MediaType.APPLICATION_JSON))
.readEntity(Releases.class);
which has post(entity) return a Response on which readEntity is called, better use overloaded post(entity, responseType) which will throw WebApplicationException on Error-Statuscodes.
// throws runtime exception derived from WebApplicationException
// on error-statuscodes
result = target
.request()
.accept(MediaType.APPLICATION_JSON)
.post(Entity.entity(input, MediaType.APPLICATION_JSON), Releases.class);
Every http method in JAX-RS has such overloaded methods for reading either Responses or representation objects. Reading representation objects is highly advised to consume potential response bodies in any case.
// consumes response as string and guarantees to close the http call.
// A no-arg delete(); would be a potential leak!
target.request().delete(String.class);
Unfortunately, when response-headers must be read, it is still required to read Response instead of the representation objects.
The framework should not throw an exception. The user should handle the response however they see fit. This is the same with any client. The Response object will contain all the context you need to handle the response however you see fit.
So what you should do is get the Response first
Response response = target
.request()
.accept(MediaType.APPLICATION_JSON)
.post(Entity.entity(wrapper, MediaType.APPLICATION_JSON));
Then you can check the status
int status = response.getStatus();
Then handle the status
if (status == 200) {
wrapper = response.readEntity(Releases.class);
...
} else {
handleOtherStatus();
}
If you do not get the Response first, then you have no idea what the actual problem is, as readEntity(...) will fail (as there it's not the body you are expecting), and throw a different exception. With the Response at least you have some context if you want to tell the user what actual problem is.
I want to have two interceptors for every request I do on a webservice. One for the outgoing communication, and one for the response.
I am using ClientHttpRequestInterceptor which is working for the outgoing. I am setting it as follows:
//Rest template
RestTemplate tpl = api.getRestTemplate();
List<ClientHttpRequestInterceptor> interceptors = new ArrayList<ClientHttpRequestInterceptor>();
interceptors.add( new OutgoingRequestInterceptor() );
tpl.setInterceptors( interceptors );
However, I want something like this interceptor for the incoming (response). I checked Spring Framework sourcecode and I couldn't find anything for this.
Any tips?
Edit:
Maybe I am confused or something is wrong in my head. Im a bit ill today.
I've the following code in my interceptor class:
#Override
public ClientHttpResponse intercept( HttpRequest request, byte[] bytes, ClientHttpRequestExecution requestExecution ) throws IOException
{
SLog.d( "intercepted!!"+request.getURI()+". Bytes: "+bytes );
try
{
Thread.sleep( 5000 );
}
catch ( InterruptedException e )
{
e.printStackTrace();
}
ClientHttpResponse response = requestExecution.execute( request, bytes );
SLog.d( "Response Headers: " + response.getHeaders());
return response;
}
Question: Is this code working for outgoing, incoming, or both?
Because the log:request.getUri() is returning the destination URL.
Then, on the Response object, I get the headers sent by WebService.
So what I am sure of, is that response is actually the server response. But... How about getUri() thingy? Is it triggered before actually sending the request, or after?
Okay. After some tricky debugging, I got it.
Even though the interceptor class is called ClientHttpRequestInterceptor, it's intercepting both. Request from client, and respose from Server.
This interceptor class is something like a wrapper.
So...
This method is the wrapper of the whole request. From BEFORE request and after the request is done.
This part of the code is triggered BEFORE request is sent to webservice
This part of the code ACTUALLY CONTACTS WEBSERVICE, so it "pauses" there until it gets the response from the web service.
We return the response generated. Notice that if you use method response.getBody() which is an InputStream, you will consume it, so it will be null afterwards. I say that because you CAN'T directly log it. You've to mirror it first.
I'm building a REST API, but I've encountered a problem.
It seems that accepted practice in designing a REST API is that if the resource requested doesn't exist, a 404 is returned.
However, to me, this adds unnecessary ambiguity. HTTP 404 is more traditionally associated with a bad URI. So in effect we're saying "Either you got to the right place, but that specific record does not exist, or there's no such location on the Internets! I'm really not sure which one..."
Consider the following URI:
http://mywebsite/api/user/13
If I get a 404 back, is that because User 13 does not exist? Or is it because my URL should have been:
http://mywebsite/restapi/user/13
In the past, I've just returned a NULL result with an HTTP 200 OK response code if the record doesn't exist. It's simple, and in my opinion very clean, even if it's not necessarily accepted practice. But is there a better way to do this?
404 is just the HTTP response code. On top of that, you can provide a response body and/or other headers with a more meaningful error message that developers will see.
Use 404 if the resource does not exist. Don't return 200 with an empty body.
This is akin to undefined vs empty string (e.g. "") in programming. While very similar, there is definitely a difference.
404 means that nothing exists at that URI (like an undefined variable in programming). Returning 200 with an empty body means that something does exist there and that something is just empty right now (like an empty string in programming).
404 doesn't mean it was a "bad URI". There are special HTTP codes that are intended for URI errors (e.g. 414 Request-URI Too Long).
As with most things, "it depends". But to me, your practice is not bad and is not going against the HTTP spec per se. However, let's clear some things up.
First, URI's should be opaque. Even if they're not opaque to people, they are opaque to machines. In other words, the difference between http://mywebsite/api/user/13, http://mywebsite/restapi/user/13 is the same as the difference between http://mywebsite/api/user/13 and http://mywebsite/api/user/14 i.e. not the same is not the same period. So a 404 would be completely appropriate for http://mywebsite/api/user/14 (if there is no such user) but not necessarily the only appropriate response.
You could also return an empty 200 response or more explicitly a 204 (No Content) response. This would convey something else to the client. It would imply that the resource identified by http://mywebsite/api/user/14 has no content or is essentially nothing. It does mean that there is such a resource. However, it does not necessarily mean that you are claiming there is some user persisted in a data store with id 14. That's your private concern, not the concern of the client making the request. So, if it makes sense to model your resources that way, go ahead.
There are some security implications to giving your clients information that would make it easier for them to guess legitimate URI's. Returning a 200 on misses instead of a 404 may give the client a clue that at least the http://mywebsite/api/user part is correct. A malicious client could just keep trying different integers. But to me, a malicious client would be able to guess the http://mywebsite/api/user part anyway. A better remedy would be to use UUID's. i.e. http://mywebsite/api/user/3dd5b770-79ea-11e1-b0c4-0800200c9a66 is better than http://mywebsite/api/user/14. Doing that, you could use your technique of returning 200's without giving much away.
That is an very old post but I faced to a similar problem and I would like to share my experience with you guys.
I am building microservice architecture with rest APIs. I have some rest GET services, they collect data from back-end system based on the request parameters.
I followed the rest API design documents and I sent back HTTP 404 with a perfect JSON error message to client when there was no data which align to the query conditions (for example zero record was selected).
When there was no data to sent back to the client I prepared an perfect JSON message with internal error code, etc. to inform the client about the reason of the "Not Found" and it was sent back to the client with HTTP 404. That works fine.
Later I have created a rest API client class which is an easy helper to hide the HTTP communication related code and I used this helper all the time when I called my rest APIs from my code.
BUT I needed to write confusing extra code just because HTTP 404 had two different functions:
the real HTTP 404 when the rest API is not available in the given url, it is thrown by the application server or web-server where the rest API application runs
client get back HTTP 404 as well when there is no data in database based on the where condition of the query.
Important: My rest API error handler catches all the exceptions appears in the back-end service which means in case of any error my rest API always returns with a perfect JSON message with the message details.
This is the 1st version of my client helper method which handles the two different HTTP 404 response:
public static String getSomething(final String uuid) {
String serviceUrl = getServiceUrl();
String path = "user/" + , uuid);
String requestUrl = serviceUrl + path;
String httpMethod = "GET";
Response response = client
.target(serviceUrl)
.path(path)
.request(ExtendedMediaType.APPLICATION_UTF8)
.get();
if (response.getStatus() == Response.Status.OK.getStatusCode()) {
// HTTP 200
return response.readEntity(String.class);
} else {
// confusing code comes here just because
// I need to decide the type of HTTP 404...
// trying to parse response body
try {
String responseBody = response.readEntity(String.class);
ObjectMapper mapper = new ObjectMapper();
ErrorInfo errorInfo = mapper.readValue(responseBody, ErrorInfo.class);
// re-throw the original exception
throw new MyException(errorInfo);
} catch (IOException e) {
// this is a real HTTP 404
throw new ServiceUnavailableError(response, requestUrl, httpMethod);
}
// this exception will never be thrown
throw new Exception("UNEXPECTED ERRORS, BETTER IF YOU DO NOT SEE IT IN THE LOG");
}
BUT, because my Java or JavaScript client can receive two kind of HTTP 404 somehow I need to check the body of the response in case of HTTP 404. If I can parse the response body then I am sure I got back a response where there was no data to send back to the client.
If I am not able to parse the response that means I got back a real HTTP 404 from the web server (not from the rest API application).
It is so confusing and the client application always needs to do extra parsing to check the real reason of HTTP 404.
Honestly I do not like this solution. It is confusing, needs to add extra bullshit code to clients all the time.
So instead of using HTTP 404 in this two different scenarios I decided that I will do the following:
I am not using HTTP 404 as a response HTTP code in my rest application anymore.
I am going to use HTTP 204 (No Content) instead of HTTP 404.
In that case client code can be more elegant:
public static String getString(final String processId, final String key) {
String serviceUrl = getServiceUrl();
String path = String.format("key/%s", key);
String requestUrl = serviceUrl + path;
String httpMethod = "GET";
log(requestUrl);
Response response = client
.target(serviceUrl)
.path(path)
.request(ExtendedMediaType.APPLICATION_JSON_UTF8)
.header(CustomHttpHeader.PROCESS_ID, processId)
.get();
if (response.getStatus() == Response.Status.OK.getStatusCode()) {
return response.readEntity(String.class);
} else {
String body = response.readEntity(String.class);
ObjectMapper mapper = new ObjectMapper();
ErrorInfo errorInfo = mapper.readValue(body, ErrorInfo.class);
throw new MyException(errorInfo);
}
throw new AnyServerError(response, requestUrl, httpMethod);
}
I think this handles that issue better.
If you have any better solution please share it with us.
404 Not Found technically means that uri does not currently map to a resource. In your example, I interpret a request to http://mywebsite/api/user/13 that returns a 404 to imply that this url was never mapped to a resource. To the client, that should be the end of conversation.
To address concerns with ambiguity, you can enhance your API by providing other response codes. For example, suppose you want to allow clients to issue GET requests the url http://mywebsite/api/user/13, you want to communicate that clients should use the canonical url http://mywebsite/restapi/user/13. In that case, you may want to consider issuing a permanent redirect by returning a 301 Moved Permanently and supply the canonical url in the Location header of the response. This tells the client that for future requests they should use the canonical url.
So in essence, it sounds like the answer could depend on how the request is formed.
If the requested resource forms part of the URI as per a request to http://mywebsite/restapi/user/13 and user 13 does not exist, then a 404 is probably appropriate and intuitive because the URI is representative of a non-existent user/entity/document/etc. The same would hold for the more secure technique using a GUID http://mywebsite/api/user/3dd5b770-79ea-11e1-b0c4-0800200c9a66 and the api/restapi argument above.
However, if the requested resource ID was included in the request header [include your own example], or indeed, in the URI as a parameter, eg http://mywebsite/restapi/user/?UID=13 then the URI would still be correct (because the concept of a USER does exits at http://mywebsite/restapi/user/); and therefore the response could reasonable be expected to be a 200 (with an appropriately verbose message) because the specific user known as 13 does not exist but the URI does. This way we are saying the URI is good, but the request for data has no content.
Personally a 200 still doesn't feel right (though I have previously argued it does). A 200 response code (without a verbose response) could cause an issue not to be investigated when an incorrect ID is sent for example.
A better approach would be to send a 204 - No Contentresponse. This is compliant with w3c's description *The server has fulfilled the request but does not need to return an entity-body, and might want to return updated metainformation.*1 The confusion, in my opinion is caused by the Wikipedia entry stating 204 No Content - The server successfully processed the request, but is not returning any content. Usually used as a response to a successful delete request. The last sentence is highly debateable. Consider the situation without that sentence and the solution is easy - just send a 204 if the entity does not exist. There is even an argument for returning a 204 instead of a 404, the request has been processed and no content has been returned! Please be aware though, 204's do not allow content in the response body
Sources
http://en.wikipedia.org/wiki/List_of_HTTP_status_codes
1. http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
This old but excellent article... http://www.infoq.com/articles/webber-rest-workflow says this about it...
404 Not Found - The service is far too lazy (or secure) to give us a real reason why our request failed, but whatever the reason, we need to deal with it.
This recently came up with our team.
We use both 404 Not found with a message body and 204 No Content based on the following rational.
If the request URI indicates the location of a single resource, we use 404 Not found. When the request queries a URI, we use 204 No Content
http://mywebsite/api/user/13 would return 404 when user 13 does not exist
http://mywebsite/api/users?id=13 would return 204 no content
http://mywebsite/api/users?firstname=test would return 204 no content
The idea here being, 'query routes' are expected to be able to return 1, many or no content.
Whatever pattern you choose, the most important things is to be consistent - so get buy in from your team.
The Uniform Resource Identifier is a unique pointer to the resource. A poorly form URI doesn't point to the resource and therefore performing a GET on it will not return a resource. 404 means The server has not found anything matching the Request-URI. If you put in the wrong URI or bad URI that is your problem and the reason you didn't get to a resource whether a HTML page or IMG.
Since this discussion seems to be able to survive the end of time I'll throw in the JSON:API Specifications
404 Not Found
A server MUST respond with 404 Not Found when processing a request to fetch a single resource that does not exist, except when the request warrants a 200 OK response with null as the primary data (as described above).
HTTP/1.1 200 OK
Content-Type: application/vnd.api+json
{
"links": {
"self": "http://example.com/articles/1/author"
},
"data": null
}
Also please see this Stackoverflow question
For this scenario HTTP 404 is response code for the response from the REST API
Like 400, 401, 404 , 422 unprocessable entity
use the Exception handling to check the full exception message.
try{
// call the rest api
} catch(RestClientException e) {
//process exception
if(e instanceof HttpStatusCodeException){
String responseText=((HttpStatusCodeException)e).getResponseBodyAsString();
//now you have the response, construct json from it, and extract the errors
System.out.println("Exception :" +responseText);
}
}
This exception block give you the proper message thrown by the REST API