Prepare XA (QxdaXAPrepare) API

A transaction manager calls QxdaXAPrepare() to request that a resource manager prepare for commitment any work performed on behalf of the transaction branch identifier. The resource manager places all resources used in the transaction branch in a state that the changes can be made permanently when it later receives the QxdaXACommit() request. The connection does not have to be associated with the transaction in any way.

Authorities and Locks

None.

Required Parameter Group

Connection handle

INPUT; BINARY(4)

The handle number of the connection on which to perform the XA operation. The connection handle must have been generated by the QxdaConnectEDRS API in the current job and activation group.

Transaction branch identifier

INPUT; CHAR(*)

The transaction branch identifier. This identifier is generated by the transaction manager when it starts the transaction branch. The max length is 140 bytes.

Offset		Type	Field
Dec	Hex
0	0	BINARY(4)	Format identifier
4	4	BINARY(4)	Length of global transaction identifier
8	8	BINARY(4)	Length of branch qualifier
12	C	CHAR(128)	Transaction branch identifier

Format identifier:	Identifies the naming format being used. If OSI CCR naming is used, the format identifier should be set to 0. If some other format is used, a the value should be greater than 0. A value of -1 means the transaction branch identifier is null.
Length of global transaction identifier:	Identifies the first of at most two contiguous components comprised by the data field. This specifies the number of bytes (1-64) starting at the first byte of the data element. This is not null-terminated.
Length of branch qualifier:	Identifies the second of at most two contiguous components comprised by the data field. This specifies the number of bytes (1-64) starting at the first byte after the global transaction identifier. This is not null-terminated.
Transaction branch identifier:	Contains the data of the transaction branch identifier.

Return value

OUTPUT; BINARY(4)

The return value of the XA operation. The following return codes indicate that the resource manager has rolled back the work done on this transaction branch.

100	[XA_RBROLLBACK]	The transaction branch was rolled back for an unspecified reason.
101	[XA_RBCOMMFAIL]	The transaction was rolled back because a communications failure occurred within the resource manager.
102	[XA_RBDEADLOCK]	The transaction was rolled back because a deadlock condition was detected within the resource manager.
103	[XA_RBINTEGRITY]	The transaction was rolled back because the resource manager detected a violation of the integrity of its resources.
104	[XA_RBOTHER]	The resource manager rolled back the transaction branch for a reason not on this list.
105	[XA_RBPROTO]	The transaction was rolled back because a protocol error occurred in the resource manager.
106	[XA_RBTIMEOUT]	The transaction was rolled back because a timeout occurred in the resource manager.
107	[XA_RBTRANSIENT]	The transaction was rolled back because a transient error was detected in the resource manager.

All other return codes:

-7	[XAER_RMFAIL]	An error occurred that makes the resource manager unavailable.
-6	[XAER_PROTO]	xa_prepare() was not successful. Function was called in an improper context.
-5	[XAER_INVAL]	xa_prepare() was not successful. Incorrect arguments were specified.
-4	[XAER_NOTA]	The specified xid is not known by the resource manager.
-3	[XAER_RMERR]	xa_prepare() was not successful. The resource manager detected an error when preparing the transaction branch.
-2	[XAER_ASYNC]	xa_prepare() was not successful. The resource manager does not support asynchronous operations.
0	[XA_OK]	xa_prepare() was successful.
3	[XA_RDONLY]	The transaction branch was read-only and has been committed.

Flags

INPUT; BINARY(4)

Indicator of how to perform the XA operation. The following are valid settings of flags:

TMNOFLAGS:

x00000000

Perform the prepare operation normally.

Error code

I/O; CHAR(*)

The structure in which to return error information. For the format of the structure, see Error Code Parameter.

Usage Notes

This function may be called from the initial thread of a job only.

Error Messages

Related Information

The QxdaXA APIs follow the NTS (transactions with transaction scoped locks) model. For more information regarding the NTS model, see XA APIs.

Example

See Code disclaimer information for information pertaining to code examples.

#include qxdaedrs.h 

main()
{ 
err_t     err; 
Qxda_CDBI0100_t *istr = (Qxda_CDBI0100_t *) instruct;
Qxda_CDBO0100_t  ostr;
int ostrsize;
XID inxid;
char gtrid[8] = "TestXA";
char bqual[6] = "Test"; 
inxid.formatID = 0;  
inxid.gtrid_length = 6; 
inxid.bqual_length = 4; 
int create = XDA_SQL_TXN_CREATE;
int end = XDA_SQL_TXN_END;
int timeoutval = 60;
Qsq_sqlca_t      myca;
int   stmt1len = 21;
int flags = 0;
int ret_val; 
_CPYBYTES(dtaara, gtrid, inxid.gtrid_length); 
_CPYBYTES(dtaara + inxid.gtrid_length, bqual, inxid.bqual_length);   
_CPYBYTES(inxid.data, dtaara, inxid.gtrid_length + inxid.bqual_length); 
XID *xid = &inxid;




 memset(istr, '\0', sizeof(Qxda_CDBI0100_t));       


 istr->Connection_Type = 'U';                                                        
 memset(istr->Server_Name, ' ', 256);                  
 istr->Commitment_Control = 'S';                          
 _CPYBYTES(istr->Commit_Scope, "*XA                      ", 10);         
 istr->Allow_Suspend = 'Y';
 memset(istr->RDB_Specified, '0', 1);
 istr->SQLDA_Cache_Size = 10;                             
 istr->Offset_Job_Data = sizeof(Qxda_CDBI0100_t);         
 istr->Length_Job_Data = 7;                               
 _CPYBYTES((char *)istr + istr->Offset_Job_Data, "CONNECT", 7);   
 istr->Offset_Suspend_Data = istr->Offset_Job_Data + istr->Length_Job_Data; 
 istr->Length_Suspend_Data = 7;   
 memset(istr->RDB_Name, ' ', 18);
 _CPYBYTES(istr->TM_Info, "TM_Name         ", 10); 
 istr->LockTimeoutVal = 10;  
 ostrsize = sizeof(Qxda_CDBO0100_t);                                        


 QxdaConnectEDRS(istr, "CDBI0100", &ostr, &ostrsize,
                  "CDBO0100", &err);


 QxdaSetXaConnection(&ostr.Connection_Handle, xid, &ret_val, &create, &timeoutval, &err);

QxdaProcessImmediateEDRS(&ostr.Connection_Handle,
              "SELECT * FROM MYTABLE", &stmt1len, &myca, &err); 

 QxdaSetXaConnection(&ostr.Connection_Handle, xid, &ret_val, &end, &timeoutval, &err);


 QxdaXAPrepare(&ostr.Connection_Handle, xid, &ret_val, &flags, &err);

}