How setHeader() works in Apache camel

Question

I was going through some documentation on Apache Camel and not able to understand what setHeader() does in Apache Camel. Does it add a header to the file specified within from. And also suggest some link where I can get tutorial on Apache Camel.

Answer 1

No, it does not add anything to a file. .setHeader() creates a header that exist within the current route. You can create a header like .setHeader("myHeader", "myHeaderValue"). Use headers to access dynamic properties during your route by .getHeader("myHeader") For more long lasting property use exchange properties.

Answer 2

setHeader to a file(message) consumed(from) does not set the header to the file.

Camel File2 check the Message Headers. This lists all the Message Headers supported for produce(to) and consume(from) of File endpoint. For a file consumed, you can access the (getHeader) supported headers in the message. But overwriting these values does not overwrite the meta data of the file though.

Headers and Properties in Apache Camel can be used interchangeably to pass values between processes in a single route, but when you want to carry across different routes the behaviors differs. Headers can be lost at endpoints basically as they usually represent some component specific things. Go through the document to understand further.

Best tutorials for Camel - Apache Camel Books and Apache Cammel Documentation