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Message
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| PeterPotkay |
 Posted: Thu Nov 18, 2004 3:51 pm Post subject: MQGET works, but the read throws a 2195 |
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Poobah
Joined: 15 May 2001
Posts: 7722
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5.3.0.8
Windows XP SP1
In the below VB.NET code, the MQGET returns a 2033, but the read of the message into the buffer throws a 2195. What am I doing wrong. I am trying to follow the example in the .NET manual on how to read an MQ message into the buffer.
The message is being taken off of the queue, and I can read its attributes, like Persistence. But if I try and stick it in the buffer, I get a 2195 MQRC_UNEXPECTED_ERROR.
| Code: |
Try
myQM = New MQQueueManager(QMName, myHashTable)
'**************************************************
' Open the Queue
'**************************************************
openOptions = 0
openOptions = openOptions + MQC.MQOO_INPUT_SHARED + MQC.MQOO_INQUIRE + MQC.MQOO_FAIL_IF_QUIESCING
myQ = myQM.AccessQueue(screenQueueName, openOptions)
gmo = New MQGetMessageOptions
getOptions = 0
getOptions = getOptions + MQC.MQGMO_FAIL_IF_QUIESCING + MQC.MQGMO_WAIT
gmo.Options = getOptions
gmo.WaitInterval = 10000
myMsg = New MQMessage 'create a buffer to hold the incoming message
Do 'Until EndOfLoop
'**************************************************
' Start issuing MQGETs in a loop
'**************************************************
Try
With myMsg
.MessageId = MQC.MQMI_NONE
.CorrelationId = MQC.MQCI_NONE
.ClearMessage()
End With
myQ.Get(myMsg, gmo) <<<<THIS WORKS
Dim MyPersistence As String
MyPersistence = myMsg.Persistence <<<THIS WORKS
Dim myMsgTxt As String
myMsgTxt = myMsg.ReadUTF <<<THIS THROWS A 2195
If myMsg.Feedback = MQC.MQFB_QUIT Then
EndOfLoop = True
End If
Catch mqError As MQException
Select Case mqError.ReasonCode
Case MQC.MQRC_NO_MSG_AVAILABLE
'continue
Case Else
EndOfLoop = True
End Select
End Try
Loop Until EndOfLoop
Catch mqError As MQException
'MQCONN or MQOPEN failed. Add error logic here.
End Try
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Peter Potkay
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| fjb_saper |
| Posted: Thu Nov 18, 2004 5:08 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Peter,
I trust that your message has been written to as writeUTF and is not just a plain and simple text message.
Remember that UTF message vs Text message has 2 more bytes at the beginning...
Hope it helps
F.J.  |
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| PeterPotkay |
| Posted: Thu Nov 18, 2004 5:27 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Ughhhhh....?
I put the message in the queue using MQExplorer. I can browse it using other tools. Is ReadUTF not the correct thing to do here?
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Peter Potkay
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| jefflowrey |
| Posted: Thu Nov 18, 2004 5:35 pm Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| PeterPotkay wrote: |
| I put the message in the queue using MQExplorer. |
Couldn't you at least have used that overpriced "developer" tool you have lying around?
Likely MQExplorer wrote the data in Windows standard CCSID, rather than Unicode.
Try using the .NET sample put program instead.
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| fjb_saper |
| Posted: Thu Nov 18, 2004 5:36 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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No readUTF is not the correct thing to do there.
Try any of the other read methods and you should be fine.
Remember UTF has specific characteristics....
Enjoy  |
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| kirani |
| Posted: Thu Nov 18, 2004 5:48 pm Post subject: |
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Jedi Knight
Joined: 05 Sep 2001
Posts: 3779
Location: Torrance, CA, USA
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Try using ReadString method.
_________________
Kiran
IBM Cert. Solution Designer & System Administrator - WBIMB V5
IBM Cert. Solutions Expert - WMQI
IBM Cert. Specialist - WMQI, MQSeries
IBM Cert. Developer - MQSeries
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| PeterPotkay |
| Posted: Thu Nov 18, 2004 8:39 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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I was looking at that ReadString method, but it takes an int length parameter.
| Quote: |
public String ReadString(int length) Throws IOException, EndOfStreamException.
Reads a string in the codeset identified by the characterSet member variable, and convert it into Unicode.
Parameters:
length: The number of characters to read (which may differ from the number of bytes according to the codeset, because some codesets use more than one byte per character).
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What I don't understand here is what value would I pass in as int? 100 MEG, just to be sure I can take the largest message MQ can provide? Or pick a smaller number, and risk not reading the entire buffer?
I want to be able to read the message regardless of where it came from, or whether it was UTF or not. So I guess readString is the correct read method with that in mind?
Why would you want to use ReadUTF? Only if you were 100% sure the sending program was sending UTF? Seems a bit constraining if so.....
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Peter Potkay
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| kirani |
| Posted: Thu Nov 18, 2004 11:32 pm Post subject: |
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Jedi Knight
Joined: 05 Sep 2001
Posts: 3779
Location: Torrance, CA, USA
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| PeterPotkay wrote: |
What I don't understand here is what value would I pass in as int? 100 MEG, just to be sure I can take the largest message MQ can provide? Or pick a smaller number, and risk not reading the entire buffer?
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I'd specify maximun size for the message.
| PeterPotkay wrote: |
I want to be able to read the message regardless of where it came from, or whether it was UTF or not. So I guess readString is the correct read method with that in mind?
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Yes.
_________________
Kiran
IBM Cert. Solution Designer & System Administrator - WBIMB V5
IBM Cert. Solutions Expert - WMQI
IBM Cert. Specialist - WMQI, MQSeries
IBM Cert. Developer - MQSeries
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| fjb_saper |
| Posted: Fri Nov 19, 2004 1:54 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Peter,
Isn't there a method on the message that allows you to get the payload length? If you call that one up first and only then the read method you can determine how big your buffer needs to be before reading the message.
Enjoy  |
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| PeterPotkay |
| Posted: Fri Nov 19, 2004 2:03 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Yes, I fingered that out! Thanks for your help guys.
My Frankenstein program is breathing.......now to get it to do something useful.
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Peter Potkay
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| kirani |
| Posted: Fri Nov 19, 2004 3:02 pm Post subject: |
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Jedi Knight
Joined: 05 Sep 2001
Posts: 3779
Location: Torrance, CA, USA
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Peter,
There are two attributes (DataLength and MessageLength), which gets populated after MQGET call. Does that help you?
_________________
Kiran
IBM Cert. Solution Designer & System Administrator - WBIMB V5
IBM Cert. Solutions Expert - WMQI
IBM Cert. Specialist - WMQI, MQSeries
IBM Cert. Developer - MQSeries
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| PeterPotkay |
| Posted: Fri Nov 19, 2004 3:07 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Yes, that is what I am using. I am familiar with the MQ API because I wrote our COBOL MQ wrapper programs. Its translating this knowledge into an object oriented language that is tough. Basically I am trying to learn VB.NET at the same time I am writing this.
The pure MQ stuff I am cool with. Its the VB.NET stuff like reading strings that confooooses me!
My little app will be like sausages :you don't want to see it being made, but the end product is oh so good! 
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Peter Potkay
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