Hi Santhosh,  We allow up to 8kB of HTTP headers in a request.  This is a pretty standard value to ensure we don't get DoS and ensures compatibility with Internet proxy servers.  This limit includes the standard headers like Authentication, Content-Type, Content-Length, etc.  For metadata be sure to include both the name and the value.  So, the limit depends a little on the length of the name as well since "name=Jason" would come across like:  x-amz-meta-name: Jason\r\n  So, 2kB is a pretty "safe" limit, but depending on the lengths of your names you can likely squeeze some more in there.
We are developing a solution where I need to enter nearly 40 information about an object (name, age, skill, etc). How I can enter these values while uploading an object? Is there any size limitation for user defined meta data? As per S3 documents it is 2KB. Is this applicable to ECS object?  Thanks, Santhosh Peter
How we can associate user defined meta data to an ECS object? Any size 
limitation?