Hi,

Camel does support the concepts of streaming and stream caching. A stream cache 
will make a stream readable multiple times. For this purpose it stores the 
message payload either in memory or in a temporary file (and the whole concept 
is transparent for the camel components). 

See http://camel.apache.org/stream-caching.html for details. Finally you need 
your bean to support this by writing your output into a CachedOutputStream and 
then setting the StreamCache you get from it as message body.

Best regards
Stephan

-----Original Message-----
From: Goyal, Arpit [mailto:arpit.go...@sap.com] 
Sent: Samstag, 10. März 2018 06:48
To: users@camel.apache.org
Subject: Changing large in-memory data to file based operation

Hello Camel Experts,

Currently we have something of below route (as simplified version), where we 
keep reading records 1000 at a time and keep formatting and holding in memory.

Current Simplified Solution:

from("direct:processing")
.bean(<formatRecordsAndAddToBody>)
.choice()
.when(header(<isMoreRecords>).bean(<readMoreRecords>).to("direct:processing")
.otherwise().to("sftp:///";)

Generally the data is small and we kept in-memory, we want to improve the same 
now to safe-guard any in-memory problem. In our landscape we can use 'tmp' 
storage to hold the file. So we plan to change it like this

Possible Modified Solution:
from("direct:processing")
                .bean(<formatRecordsAndAddToTmpFile>)
                .choice()
                
.when(header(<isMoreRecords>).bean(<readMoreRecords>).to("direct:processing")
                .otherwise().bean(<readTmpFile&SetAsBody>).to("sftp:///";)

When locally tried the solution, we see it works - Camel understand 
'java.io.File' object & writes to SFTP.

Question 1 - Would camel load it in memory completely before writing to SFTP?
Question 2 - If yes, how can we solve this problem - does some way of streaming 
works?

Checked : 
http://www.catify.com/2012/07/09/parsing-large-files-with-apache-camel/ already 
but they are holding in memory.

Limitation: We don't want to write in chunks to sftp because of the complexity 
of some data have to written out-of-order.

Regards,
Arpit.


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