For example:
from("direct:test")
.multicast()
.to("direct:req1","direct:req2");
from("direct:req1")
.to(cxf:bean:endpoint1)
.process("response1");
from("direct:req2")
.process("requestProcessor2")
.to(cxf:bean:endpoint2)
.process(response2);
I am new to apache camel, i just wanna know is there any way to use the response which i get from the endpoint1 in "requestProcessor2" .
You could do something like this
from("direct:test")
.setProperty("test.body", body())
.to(cxf:bean:endpoint1)
.setProperty("endpoint1.body", body())
.process("response1")
.setBody(exchangeProperty("test.body"))
.to("direct:req2")
from("direct:req2")
.process("requestProcessor2")
.to(cxf:bean:endpoint2)
.process(response2);
You save the original body in an property and also the body from endpoint1. You then send the exchange to direct:req2 with the original body in the exhcnage body and the body form endpoint1 in a property which you then can access (in you processor or else where).
To access the the property in your processor:
public void process(final Exchange exchange) throws Exception {
Object body = exchange.getProperty("endpoint1.body");
}
You question already has the answer , use and you can get the property from the exchange whichever route you want. Also consider removing the property at the final route.
Related
Requisite disclaimer about being new to Camel--and, frankly, new to developing generally. I'd like to have a string generated as the output of some function be the source of my camel route which then gets written to some file. It's the first part that seems challenging: I have a string, how do I turn it into a message? I can't write it into a file nor can I use JMS. I feel like it should be easy and obvious, but I'm having a hard time finding a simple guide to help.
Some pseudo-code using the Java DSL:
def DesiredString() {return "MyString";}
// A camel route to be implemented elsewhere; I want something like:
class MyRoute() extends RouteBuilder {
source(DesiredString())
.to("file://C:/out/?fileName=MyFileFromString.txt");
}
I vaguely understand using the bean component, but I'm not sure that solves the problem: I can execute my method that generates the string, but how do I turn that into a message? The "vague" is doing a lot of work there: I could be missing something there.
Thanks!
Not sure if I understand your problem. There is a bit of confusion about what the String should be become: the route source or the message body.
However, I guess that you want to write the String returned by your method into a File through a Camel route.
If this is correct, I have to clarify first the route source. A Camel Route normally starts with
from(component:address)
So if you want to receive requests from remote via HTTP it could be
from("http4:localhost:8080")
This creates an HTTP server that listens on port 8080 for messages.
In your case I don't know if the method that returns the String is in the same application as the Camel route. If it is, you can use the Direct component for "method-like" calls in the same process.
from(direct:input)
.to("file:...");
input is a name you can freely choose. You can then route messages to this route from another Camel route or with a ProducerTemplate
ProducerTemplate template = camelContext.createProducerTemplate();
template.sendBody("direct:input", "This is my string");
The sendBody method takes the endpoint where to send the message and the message body. But there are much more variants of sendBody with different signatures depending on what you want to send it (headers etc).
If you want to dive into Camel get a copy of Camel in Action 2nd edition. It contains everything you need to know about Camel.
Example:Sending String(as a body content)to store in file using camel Java DSL:
CamelContext context = new DefaultCamelContext();
context.addRoutes(new RouteBuilder() {
public void configure() {
from("timer:StringSentToFile?period=2000")
.setBody(simple(DesiredString()))
.to("file:file://C:/out/?fileName=MyFileFromString.txt&noop=true")
.log("completed route");
}
});
ProducerTemplate template = context.createProducerTemplate();
context.start();
I currently have a process that needs to do some routing based on a message's exchange pattern. If a message is InOut, then the route ends and whatever the message contains gets sent back to the callback location. If the message is InOnly then the message gets routed somewhere else. The code is below:
...
.process(new Processor(){
public void process(Exchange e) throws Exception {
e.getIn().setHeader("ExchangePattern", e.getPattern().name());
}
})
.choice()
.when(header("ExchangePattern").isEqualTo("InOnly"))
.to(DESTINATION);
I know that in Camel 2.16 you can get the exchange pattern via the simple expression (exchange.getPattern.getName) but that's not available in 2.15. Is there a more elegant want do doing the routing or am I stuck with the ugly routing logic above?
Here is the route:
from("aws-sqs://myQueue?accessKey=RAW(xxx)&secretKey=RAW(yyy)&deleteAfterRead=false")
.log("Attributes: ${header.CamelAwsSqsAttributes}")
.process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
Map<String, String> messageAttributes = (Map<String, String>) exchange.getIn().getHeader("CamelAwsSqsAttributes");
...
}
});
The .log() shows an empty map as well as if I print messageAttributes from the processor.
I also tried with the header "CamelAwsSqsMessageAttributes" instead of "CamelAwsSqsAttributes" but still nothing.
I see the attributes from the AWS console though.
By the way I get the message body, and I use Camel 2.15
I figured it out, here is an example to get queue attributes and message attributes:
main.bind("sqsAttributeNames", Collections.singletonList("All"));
main.bind("sqsMessageAttributeNames", Collections.singletonList("All"));
Or add those objects to the registry if you don't use org.apache.camel.main.Main
Then:
from("aws-sqs://myQueue?accessKey=RAW(xxx)&secretKey=RAW(yyy)&deleteAfterRead=false&attributeNames=#sqsAttributeNames&messageAttributeNames=#sqsMessageAttributeNames")
Of course you can replace Collections.singletonList("All") with the list of attributes you need if you don't want all of them.
I faced the same issue. When I am using camel-aws 2.16.x and I have my endpoint configured as follow
from("aws-sqs://myQueue?...&messageAttributeNames=#sqsMsgAttributeNames")
.to(...)
Then I have defined a Collection of String in my spring configuration file
#Bean
public Collection<String> sqsMsgAttributeNames() {
return Arrays.asList("Attr1", "Attr2");
}
Above settings work fine but ever since I upgraded to camel-aws 2.17.3. It no longer works. As mentioned in Camel SQS Component, collection of string no longer will be supported for messageAttributeNames and it should be a String with attributes separated by comma.
Note: The string containing attributes should not contain any white
spaces otherwise camel-aws component will only read the first
attribute. I went through the pain to debug on this. Besides, setting the
attribute value to be "All" does not work for me, none of the message
attributes will be read.
Below is the changes I made that allowed camel-aws's SqsConsumer to work again:
#Bean
public String sqsMsgAttributeNames() {
return String.format("%s,%s", "Attr1", "Attr2");
}
It is not an issue of Camel. It can be the default behavior of SQS or aws-java-sdk-core library.
As a quick solution this aws-sqs URL can be used
aws-sqs://myQueue?<other attributes here>&attributeNames=All
Keep in mind that localstack can work well without attributeNames parameter, unlike SQS.
I have almost ready application in java that use jms with Camel. Pop up that we I have to add additional infomations in exchange/message. Lets say that those additional infomations are in fact new java object. What is the best way to add my new object to exchange?
I have a lot of Camel processors processing the message that look like this:
public class MyProcessor implements Processor {
#Override
public void process(Exchange exchange) throws Exception {
String s = exchange.getIn().getBody(String.class);
s = magicalTransform(s);
exchange.getIn().setBody(s, String.class);
//Now I have to add object of some Info.cass:
Info info = new Info( new Date() );
//Can I add it like this? :
exchange.getIn().setBody(info, Info.class);
}
}
The problem is that I can't find information if I can add many objects to Message. The Message method: setBody(Object body, Class type) suggest that it is possible, but there is also method: getBody() that sugesst that there is only one body class.
If I can't do it in this way, then what's the best way? I could try to wrap String that I transform and info in to one class, and put that new class in to message, but It will cause change the way obtaining String in every Processor. I want to avoid that.
The body of an Exchange is a single Object. If you want to add multiple objects to the body of your exchange you need to make the body of the exchange a map, list, or pojo with fields that you set all of your objects within.
I would like to process both request and response messages at the end of my route. However, I do not see a way how to access the original request message.
I have the terrible feeling I am struggling with some basic concept.
Here is a simple example route in DSL to outline my problem (streamCaching is enabled for the whole context):
from("activemq:queue:myQueue")
.to("log:" + getClass().getName() + "?showOut=true")
.to("http://localhost:8080/someBackend")
.log("Now in.Body returns this: ${in.body} and out.Body this: ${out.body}")
.to("log:" + getClass().getName() + "?showOut=true");
Here is an according excerpt from my logs (line-breaks edited for better reading). As one can see, the original SOAP message is lost once the http server replied, and the SOAP response object is stored in the inBody of the message.
2012-09-25 17:28:08,312 local.bar.foo.MyRouteBuilder INFO -
Exchange[ExchangePattern:InOut, BodyType:byte[],
Body:<?xml version="1.0" encoding="UTF-8"?><env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"><env:Header /><env:Body><urn:someRequest xmlns:urn="http://foo.bar.local/ns"></urn:someRequest></env:Body></env:Envelope>,
Out: null]
2012-09-25 17:28:08,398 org.apache.camel.component.http.HttpProducer DEBUG -
Executing http POST method: http://localhost:8080/someBackend
2012-09-25 17:28:09,389 org.apache.camel.component.http.HttpProducer DEBUG -
Http responseCode: 200
2012-09-25 17:28:09,392 route2 INFO -
Now in.Body returns this: <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><ns2:someResponse xmlns:ns2="http://foo.bar.local/ns"</ns2:someResponse></soap:Body></soap:Envelope>
and out.Body this:
2012-09-25 17:28:09,392 local.bar.foo.MyRouteBuilder INFO -
Exchange[ExchangePattern:InOut,
BodyType:org.apache.camel.converter.stream.InputStreamCache,
Body:[Body is instance of org.apache.camel.StreamCache],
Out: null]
I would have expected to have in.body and out.body be preserved across the whole route?
Alternative solutions I am considering:
Make use of the Correlation Identifier pattern to correlate both request and reply. But would this preserve the message bodies as well? Also, my request/reply messages do not have unique identifiers for correlation.
Write a custom bean, which performs the call to the http backend, processing both request and reply objects (but this is basically a no-Camel solution, reinventing the wheel and hence not preferred)
Already failed approaches:
I tried to access the original request message using a Processor like this at the end of my route, with no success:
process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
Message originalInMessage = exchange.getUnitOfWork().getOriginalInMessage();
logger.debug(originalInMessage.getBody(String.class));
logger.debug(exchange.getIn().getBody(String.class));
}
});
Thanks for any help
Simply store the original body of the in message in a header or a property and retrieve it at the end:
from("activemq:queue:myQueue")
.setProperty("origInBody", body())
.to("http://localhost:8080/someBackend")
After the http call you can then access the property origInBody.
First, this article shows very well how in and out works in camel: http://camel.apache.org/using-getin-or-getout-methods-on-exchange.html
Typically, the out message is not always used, but rather copied from the in-message in each step.
In your case, where you want the original message to stay around til the end of the route, you could go ahead with the Enrichment EIP. http://camel.apache.org/content-enricher.html
Your route would be something like this:
public class MyAggregationStrategy implements AggregationStrategy {
public Exchange aggregate(Exchange orig, Exchange httpExchange){
// if you want to check something with the Http request, you better do that here
if( httpExchange is not correct in some way )
throw new RuntimeException("Something went wrong");
return orig;
}
}
AggregationStrategy aggStrategy = new MyAggregationStrategy();
from("activemq:queue:myQueue")
.enrich("http://localhost:8080/someBackend",aggStrategy)
.//keep processing the original request here if you like, in the "in" message
One of the biggest problem of camel, is the ease to misuse it. The best way to use it correctly is to think in terms of EIP : one of the main goals of camel, is to implement EIP in its DSL.
Here is a list of EIP
Now think about it. You want the request and the response at the end, for what use ? Logging, Aggregation, ... ? For logging, a correlationId should suffice, so I presume you need it to create a response, based on both request and the proxied-response. If that's what you want, you could do something like
from("direct:receiveRequest")
.enrich("direct:proxyResponse", new RequestAndResponseAggregationStrategy())
You will have the opportunity to merge your Request (in oldExchange) and your Response (in newExchange).
With all the due respect I have for Christian Schneider, I do think the idea of putting the request in a property that could be reused later is a bad design. By doing it, you create side-effect between your routes. If your route is a subroute for another, you'll maybe erase their property. If you store it to put it back later, maybe you should do something like
from("direct:receiveRequest")
.enrich("direct:subRouteToIgnoreResponse", AggregationStrategies.useOriginal())
A really really bad design that I have done too many time myself is to do :
from("direct:receiveRequest")
.to("direct:subroute")
from("direct:subroute")
.setProperty("originalBody", body())
.to("direct:handling")
.transform(property("originalBody")
This will lead to "properties/headers hell", and to routes that are just a successive call of processors.
And if you can't think of a solution of your problem with EIP, you should maybe use camel only to access their components. For example, something like :
from("http://api.com/services")
.to(new SomeNotTranslatableToEIPProcessor())
.to("ftp://destination")
But don't forget that those components has their own goals : creating a common abstraction between similar behaviour (e.g, time based polling consumer). If you have a very specific need, trying to bend a camel component to this specific need can lead to huge chunk of code not easily maintainable.
Don't let Camel become your Golden Hammer anti-pattern
I often use an aggregation strategy, which preserves the old exchange and puts the result of the enrich into a header:
import org.apache.camel.Exchange;
import org.apache.camel.processor.aggregate.AggregationStrategy;
public class SetBodyToHeaderAggregationStrategy implements AggregationStrategy {
private String headerName = "newBody";
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
oldExchange.getIn().setHeader(headerName, newExchange.getIn().getBody());
return oldExchange;
}
#SuppressWarnings("unused")
public void setHeaderName(String headerName) {
this.headerName = headerName;
}
}
Now you can use it like this:
<enrich strategyRef="setBodyToHeaderAggregationStrategy">
<constant>dosomething</constant>
</enrich>
<log loggingLevel="INFO" message="Result body from enrich: ${header.newBody}. Original body: ${body}" loggerRef="log"/>