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Posted to dev@qpid.apache.org by Colin Crist <co...@messageforge.org> on 2006/09/05 18:36:03 UTC
Bug: BytesMessage.reset() throws MessageNotWriteableException
Hi,
BytesMessage.reset() can be called on a read only message, its purpose
is to "reset" the message so it can be read again from the start, it
does not affect the message content.
2006-09-05 17:25:34,436 [AWT-EventQueue-0] ERROR
hermes.renderers.HexMessageRenderer - exception converting message to
byte[]:
javax.jms.MessageNotWriteableException: You need to call clearBody() to
make the message writable
at
org.apache.qpid.client.message.JMSBytesMessage.checkWritable(JMSBytesMes
sage.java:148)
at
org.apache.qpid.client.message.JMSBytesMessage.reset(JMSBytesMessage.jav
a:342)
Regards,
Colin
http://hermesjms.com
Re: Bug: BytesMessage.reset() throws MessageNotWriteableException
Posted by Gordon Sim <gs...@redhat.com>.
Colin,
Thanks for pointing that out. Someone will get around to fixing that soon.
--Gordon.
Colin Crist wrote:
>
> Hi,
>
> BytesMessage.reset() can be called on a read only message, its purpose
> is to "reset" the message so it can be read again from the start, it
> does not affect the message content.
>
> 2006-09-05 17:25:34,436 [AWT-EventQueue-0] ERROR
> hermes.renderers.HexMessageRenderer - exception converting message to
> byte[]:
> javax.jms.MessageNotWriteableException: You need to call clearBody() to
> make the message writable
> at
> org.apache.qpid.client.message.JMSBytesMessage.checkWritable(JMSBytesMes
> sage.java:148)
> at
> org.apache.qpid.client.message.JMSBytesMessage.reset(JMSBytesMessage.jav
> a:342)
>
> Regards,
>
> Colin
> http://hermesjms.com
>
>
>
RE: [java] Re: Bug: BytesMessage.reset() throws MessageNotWriteableException
Posted by Colin Crist <co...@hermesjms.com>.
Hi,
The suggested fix works with at least some limited testing in HermesJMS.
Regards,
Colin.
http://hermesjms.com
-----Original Message-----
From: Gordon Sim [mailto:gsim@redhat.com]
Sent: 11 September 2006 08:43
To: qpid-dev@incubator.apache.org
Subject: [java] Re: Bug: BytesMessage.reset() throws
MessageNotWriteableException
Apologies for slow reply, was out of the office for a couple of days...
Martin Ritchie wrote:
> I'm sure flip() is correct and all that need be done is remove the
> checkWritable() call. It would be good if someone (I guess Robert or
> Gordon) more familiar with this bit of code could OK this change.
I believe the idea behind the current code is that reset() gets called to
make a writable message readable. Whether this is required or not I can't
say for sure, but as pointed out at the start of this thread it should allow
users to invoke it multiple times once the message is readable though.
> public void reset() throws JMSException
> {
> //checkWritable();
> _data.flip();
> _readable = true;
> }
I think we still want to check whether the message is writable, and if it is
call _data.flip(), if it isn't call _data.rewind(). i.e. along the lines of:
if(_readable){
_data.rewind();
}else{
_data.flip();
_readable = true;
}
[java] Re: Bug: BytesMessage.reset() throws MessageNotWriteableException
Posted by Gordon Sim <gs...@redhat.com>.
Apologies for slow reply, was out of the office for a couple of days...
Martin Ritchie wrote:
> I'm sure flip() is correct and all that need be done is remove the
> checkWritable() call. It would be good if someone (I guess Robert or
> Gordon) more familiar with this bit of code could OK this change.
I believe the idea behind the current code is that reset() gets called
to make a writable message readable. Whether this is required or not I
can't say for sure, but as pointed out at the start of this thread it
should allow users to invoke it multiple times once the message is
readable though.
> public void reset() throws JMSException
> {
> //checkWritable();
> _data.flip();
> _readable = true;
> }
I think we still want to check whether the message is writable, and if
it is call _data.flip(), if it isn't call _data.rewind(). i.e. along the
lines of:
if(_readable){
_data.rewind();
}else{
_data.flip();
_readable = true;
}
Re: Bug: BytesMessage.reset() throws MessageNotWriteableException
Posted by Martin Ritchie <ma...@jpmorgan.com>.
I've had a look at the rest code and I would suggest the checkWritable();
is not required. Removing this as below would prevent the exception from
occurring.
The problem is I don't understand the difference in mina between flip()
and rewind().
from the mina spec.
flip() makes a buffer ready for a new sequence of channel-write or
relative get operations: It sets the limit to the current position and
then sets the position to zero.
rewind() makes a buffer ready for re-reading the data that it already
contains: It leaves the limit unchanged and sets the position to zero.
I seems to me that rewind() would be what we want for a JMS reset() [Puts
the message body in read-only mode and repositions the stream of bytes to
the beginning. ]
However the BytesMessageTest fails when using rewind() as the size of the
read bytes is not known. Which suggests that the code uses the limit value
in the mina buffer to determine the size of the ByteMessage and as it
isn't set with a rewind() it returns the size of the Mina buffer (1024).
I'm sure flip() is correct and all that need be done is remove the
checkWritable() call. It would be good if someone (I guess Robert or
Gordon) more familiar with this bit of code could OK this change.
public void reset() throws JMSException
{
//checkWritable();
_data.flip();
_readable = true;
}
Cheers
--
Martin
"Colin Crist" <co...@messageforge.org>
2006-09-05 17:36
Please respond to qpid-dev
To: <qp...@incubator.apache.org>
cc:
Subject: Bug: BytesMessage.reset() throws
MessageNotWriteableException
Hi,
BytesMessage.reset() can be called on a read only message, its purpose
is to "reset" the message so it can be read again from the start, it
does not affect the message content.
2006-09-05 17:25:34,436 [AWT-EventQueue-0] ERROR
hermes.renderers.HexMessageRenderer - exception converting message to
byte[]:
javax.jms.MessageNotWriteableException: You need to call clearBody() to
make the message writable
at
org.apache.qpid.client.message.JMSBytesMessage.checkWritable(JMSBytesMes
sage.java:148)
at
org.apache.qpid.client.message.JMSBytesMessage.reset(JMSBytesMessage.jav
a:342)
Regards,
Colin
http://hermesjms.com
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