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| Browse Msg by MSGID; Problem storing MsgId in MQMD |
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| ScottieMQ |
 Posted: Mon Aug 15, 2005 11:27 am Post subject: Browse Msg by MSGID; Problem storing MsgId in MQMD |
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Newbie
Joined: 15 Nov 2004
Posts: 3
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Hello All,
I know that a knowledgeable C programmer will look at this problem and think it is trivial. Unfortunately, I am not a C programmer.
This is my problem.
I am modifying the IBM Sample browse program (amqsbcg0.c) on an AIX server running MQSeries v5.3.0.7. I am compiling and linking it as a client application using the VisualAge C Compiler for AIX. I have messages that are written to a local queue, which I am browsing, whose Message ID's are created by MQSeries (e.g. AMQ..servername..sequence number for uniqueness).
A sample Message ID in Hex as I see it displayed by the browse application is:
414D512051503054314131535620202042FB79A920000202
Since there is that null character (e.g. 00) in byte 22, it seems like coding:
printf("\n MsgId : X'");
for (i = 0 ; i < MQ_MSG_ID_LENGTH ; i++)
printf("%02X",MDin->MsgId[i] );
printf("'");
to produce the 24 byte hex string is the only way to capture the entire MsgId from what I have discovered is stored in some kind of Array data structure (e.g. MsgId[x]). Any other "flavor" of printf that I have tried truncates the last three bytes since I guess that it is treating the null character as end of string. Without those 3 bytes it is not possible to browse a specific message.
If I want to call the modified browse application and pass it 3 parameters
(Queue Name, Queue Manager Name, the above 24 byte haxadecimal MsgId string) so that I can read 1 specific message by MsgId:
1. GetMsgOpts.MatchOptions = MQMO_MATCH_MSG_ID;
2. memcpy(MsgDesc.MsgId, argv[3], sizeof(MQBYTE24) );
then is there a way of coding the memcpy command above or some other command that I can code that will store the third parameter (e.g the 24 byte hex MsgId string) properly in the MQMD MsgId field so that I browse the proper message?
Thanking you in advance for your support. |
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| RogerLacroix |
| Posted: Mon Aug 15, 2005 11:53 am Post subject: |
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Jedi Knight
Joined: 15 May 2001
Posts: 3264
Location: London, ON Canada
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Hi,
| Quote: |
| 24 byte haxadecimal MsgId string |
That is exactly your problem, MsgID, CorrelID, GroupID, etc.. are byte arrays and not string arrays.
As you noted, the MsgID contains nulls, therefore, there is no way to pass it on the command line. You need to pass the 48-bye 'hexadecimal' representation of the MsgID as a parameter to the program.
i.e. 414D512051503054314131535620202042FB79A920000202
Then in your program it will convert the 48-byte hexedecimal number to the proper 24-byte MsgID.
Other than a programming exercise, what are you trying to accomplish because the wheel (i.e. your tool) may have already been invented.
Regards,
Roger Lacroix
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Capitalware: Transforming tomorrow into today.
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| ScottieMQ |
| Posted: Mon Aug 15, 2005 12:30 pm Post subject: memcpy command failure |
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Newbie
Joined: 15 Nov 2004
Posts: 3
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Hello Roger,
Thanks for your response. No, I do not make it a habit of re-inventing the wheel as I have downloaded many an IBM Support Pac for MQSeries and made other little discoveries poking around on the web.
It is just that I have only been working in the distributed environment for 4 years and am thus wanting to improve my skill set such as learning shell scripting, c, and any other bits and pieces that I feel would leverage my ability to support the applications developers and my customers.
The problem that I have is that the memcpy command as I have coded it is taking the 48 character string that is the hex MsgId which I am passing as the third argument and is stripping off the first 24 characters and storing them in the MQMD MsgId which is not going to produce the results that I am looking for.
Hence, I am just looking for a "flavor" of memcpy or some other comparable command that will store the entire 48 character string that I supply as input properly into the MQMD MSgId field so that I can retrieve the message whose message ID is equal to what I am passing the program.
Regards.
ScottieMQ |
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| jefflowrey |
| Posted: Mon Aug 15, 2005 12:36 pm Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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You will have to reconvert the hex characters to byte values.
If you look at the code that converts it from bytes to hex, it may help you convert back.
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I am *not* the model of the modern major general. |
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| fjb_saper |
| Posted: Mon Aug 15, 2005 12:40 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Check if there is such a function as the java "decode" method
like Integer.decode("0x0fa5...")
or else use simple logic
get array position {0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f} for first char
multiply by 16 and add array position second char.
Set value to byte.
Enjoy |
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| tkane |
| Posted: Tue Aug 16, 2005 8:52 am Post subject: |
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Voyager
Joined: 23 Dec 2002
Posts: 82
Location: Kansas City
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I think what you want is something similar to:
| Code: |
/*****************************************************************/
/* MsgId is not null terminated, so print one char at a time (if */
/* the char is printable). Similarly for other strings below. */
/*****************************************************************/
for(i=0;i<24;i++) printf("%c",(isprint(md->MsgId[i]) \
? md->MsgId[i] : '.') );
printf("\n");
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This is a paste from a program called mget.c that's buried in a support PAC MA1C.
http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg24000080&loc=en_US&cs=utf-8&lang=en
It's one of my favorite MQ programs. I probably run it most days on Unix or Linux or MVS.
Note that on HP-UX where the default for a "char" is signed char you'll get odd results when the high order bit is on. The fix for that is to cast the char to MQBYTE
| Code: |
| pbuff = (MQBYTE *)pbuffer; |
Good Luck on this. I've learned C slowly over the years and am not the best.
Tom |
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