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22 messages in org.postgresql.pgsql-jdbcRe: java & endianness [Re: Binary tx ...| From | Sent On | Attachments |
|---|---|---|
| Michael Guyver | Jun 21, 2006 10:26 am | |
| Dave Cramer | Jun 21, 2006 12:55 pm | |
| Mark Lewis | Jun 21, 2006 1:31 pm | |
| Tom Lane | Jun 21, 2006 3:40 pm | |
| Michael Guyver | Jun 22, 2006 1:16 am | |
| Tom Lane | Jun 22, 2006 9:54 am | |
| Mark Lewis | Jun 22, 2006 12:15 pm | |
| Michael Guyver | Jun 23, 2006 1:22 am | |
| Dave Cramer | Jun 23, 2006 4:43 am | |
| Markus Schaber | Jun 23, 2006 4:59 am | |
| Michael Guyver | Jun 23, 2006 5:46 am | |
| Dave Cramer | Jun 23, 2006 5:56 am | |
| Dave Cramer | Jun 23, 2006 6:16 am | |
| Tom Lane | Jun 23, 2006 9:18 am | |
| Mark Lewis | Jun 23, 2006 1:31 pm | |
| Dave Cramer | Jun 23, 2006 1:39 pm | |
| Kris Jurka | Jun 23, 2006 1:46 pm | |
| Mark Lewis | Jun 23, 2006 1:59 pm | |
| Marc Herbert | Jul 10, 2006 2:19 am | |
| Mark Lewis | Jul 10, 2006 9:18 am | |
| Marc Herbert | Jul 10, 2006 10:53 am | |
| Mark Lewis | Jul 10, 2006 11:59 am |
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| Subject: | Re: java & endianness [Re: Binary tx format for an array?] | Actions... |
|---|---|---|
| From: | Marc Herbert (Marc...@continuent.com) | |
| Date: | Jul 10, 2006 10:53:57 am | |
| List: | org.postgresql.pgsql-jdbc | |
Mark Lewis <mark...@mir3.com> writes:
public void SendInteger4(int val) throws IOException { SendChar((val >> 24)&255); SendChar((val >> 16)&255); SendChar((val >> 8)&255); SendChar(val&255); }
This code is like copied/pasted from the JDK:
* @since JDK1.0 DataOutputStream#writeInt()
Any reason for duplicating it in the driver?
Well, in the general case you can only use DataOutputStream's writeInt() method if everything is in big-endian byte order, which is true in this case but not universally so.
My point is that it IS universally true in the Java universe AND in the networking universe. There simply cannot be two opposed networking universes... that would mean we'd have two Internets for instance?
So I think the whole point of Java is that everything is big-endian, so you do not need to know about endianness anymore. IMHO this is a success.
Here it IS big-endian, so the choice is between duplicating one method a few lines long, or wrapping the main OutputStream in an extra DataOutputStream which would only be used when writing big-endian integers. Not sure if one solution is better than the other.
OK you can bypass/copy-paste some JDK code for performance reasons. But then you can not honestly complain Java does a poor job of hiding endianness when you fiddled with the machine internals instead of safely staying outside.
Moreover you don't really need to think about endianness when simply copy/pasting this code.
It's in the java.nio stuff, look at the javadoc for ByteBuffer.order() for a starting point.
Interesting. Looks like you need this only when dealing with badly-behaved applications that do not use the network order, right? Should be very seldom, don't you think?
Thanks for answering.