HP OpenVMS Systems Documentation

The new branch should have been previously authorized. Authorization is provided either by a matching call to $JOIN_RM with the DDTM$M_COORDINATOR flag set or by a matching call to $ADD_BRANCH. Two calls, one to $ADD_BRANCH and one to $START_BRANCH or one to $JOIN_RM and one to $START_BRANCH, are said to be matching when the following conditions are true:

• The same TID values are passed to both calls.
• The BID returned by the call to $ADD_BRANCH or $JOIN_RM is the same as that passed to the call to $START_BRANCH.
• The call to $START_BRANCH is made on the node identified by the tm_name argument passed to the call to $ADD_BRANCH or on the node on which the call to $JOIN_RM was made.
• The call to $ADD_BRANCH or $JOIN_RM is made on the node identified by the tm_name argument passed to the call to $START_BRANCH.

$START_BRANCH does not check that there has been a matching call to $ADD_BRANCH or $JOIN_RM unless the tm_name argument passed to $START_BRANCH specifies the local node.

Preconditions for the successful completion of $START_BRANCH are:

• The local node must have a DECdtm transaction log.
• The TP_SERVER process must be running on the local node.
• There must not have been a successful call to $START_BRANCH on the local node that passed the specified BID.
• If the tm_name argument specifies the local node, there must have been a matching call to $ADD_BRANCH or $JOIN_RM on the local node.
• If the DDTM$M_NONDEFAULT flag is clear, the calling process must not have an unended default transaction.
• If this process already contains a branch of this transaction, then the access mode of the caller must be the same as or more privileged than the access mode of that branch.

$START_BRANCH may fail because:

• Preconditions were not met.
• An abort event occurred for the transaction.
• A call to $END_TRANS to end the transaction is in progress and it is too late to add a new branch to the transaction.
• The DDTM$M_NONDEFAULT flag was clear and a call to $SET_DEFAULT_TRANS by the calling process is in progress.

When $START_BRANCH completes successfully:

• A new branch running in the calling process has been added to the transaction.
• All Transaction Started events reported to RMIs in the calling process have been acknowledged.
• If the DDTM$M_NONDEFAULT flag was clear, the transaction is the default transaction of the calling process.

A branch may:

• Invoke resource manager operations, explicitly passing the TID.
• Invoke resource manager operations without specifying the TID, if the transaction is the default transaction of the calling process, and the resource manager supports default transactions.
• Call $ADD_BRANCH to authorize another branch to be added to the transaction.

(The way to invoke a resource manager operation is defined by the interfaces provided by the resource manager; see the resource manager documentation.)

A synchronized branch is removed from the transaction by calling $END_BRANCH, specifying the appropriate BID and TID. An unsynchronized branch is removed from the transaction by DECdtm during commit or abort processing.

The branch is also removed from the transaction (and the transaction aborted):

• On termination of the current image or process.
• On successful completion of a call to $ABORT_TRANS in the calling process that passes the appropriate TID and BID.

There is also a wait form of the service, $START_BRANCHW.

Required Privileges

None

Required Quotas

BYTLM, ASTLM

Related Services

$ABORT_TRANS, $ABORT_TRANSW, $ACK_EVENT, $ADD_BRANCH, $ADD_BRANCHW, $CREATE_UID, $DECLARE_RM, $DECLARE_RMW, $END_BRANCH, $END_BRANCHW, $END_TRANS, $END_TRANSW, $FORGET_RM, $FORGET_RMW, $GETDTI, $GETDTIW, $GET_DEFAULT_TRANS, $JOIN_RM, $JOIN_RMW, $SETDTI, $SETDTIW, $SET_DEFAULT_TRANS, $SET_DEFAULT_TRANSW, $START_BRANCHW, $START_TRANS, $START_TRANSW, $TRANS_EVENT, $TRANS_EVENTW

Condition Values Returned

SS$_NORMAL	If returned in R0, the request was successfully queued. If returned in the I/O status block, the service completed successfully.
SS$_SYNCH	The service completed successfully and synchronously (returned only if the DDTM$M_SYNC flag is set).
SS$_ACCVIO	An argument was not accessible to the caller.
SS$_ALRCURTID	Either: An attempt was made to make the transaction specified by the tid argument the default transaction (the DDTM$M_NONDEFAULT flag was clear) when the calling process had an unended default transaction. The DDTM$M_NONDEFAULT flag was clear and a call to $SET_DEFAULT_TRANS by the calling process was in progress.
SS$_BADPARAM	Either the options flags were invalid or the tid argument was omitted but the bid argument was not zero.
SS$_BRANCHSTARTED	There has already been a call to $START_BRANCH on the local node specifying that TID and BID (returned only if the node specified by the tm_name argument was the local node).
SS$_CONNECFAIL	The node specified by the tm_name argument was not the local node, and there was no communications link between the DECdtm transaction managers on the local node and the specified node.
SS$_EXASTLM	The process AST limit (ASTLM) was exceeded.
SS$_EXQUOTA	The job buffered I/O byte limit quota (BYTLM) was exceeded.
SS$_ILLEFC	The event flag number was invalid.
SS$_INSFARGS	A required argument was missing.
SS$_INSFMEM	There was insufficient system dynamic memory for the operation.
SS$_INVBUFLEN	The string passed in the tx_class argument was longer than 31 characters, or the string passed in the tm_name argument was longer than 256 characters.
SS$_NOLOG	The local node did not have a transaction log.
SS$_NOSUCHBID	Either: The specified BID was not returned by any call to $ADD_BRANCH or $JOIN_RM on the local node (returned only if the node specified by the tm_name argument was the local node). An BID of zero was supplied.
SS$_NOSUCHTID	The local node did not have any branches in the specified transaction (returned only if the node specified by the tm_name argument was the local node).
SS$_TPDISABLED	The TP_SERVER process was not running on the local node.
SS$_WRONGSTATE	The transaction was in the wrong state for the attempted operation because either: An abort event has occurred for the transaction. A call to $END_TRANS to end the transaction is in progress and it is now too late to add a new branch to the transaction.

Adds a new branch to a transaction.

$START_BRANCHW always waits for the request to complete before returning to the caller. Other than this, it is identical to $START_BRANCH.

Format

SYS$START_BRANCHW [efn] ,[flags] ,iosb ,[astadr] ,[astprm] ,tid ,tm_name ,bid [,[timout] ,[acmode], [tx_class]]

C Prototype

int sys$start_branchw (unsigned int efn, unsigned int flags, struct _iosb *iosb, void (*astadr)(__unknown_params), int astprm, unsigned int tid [4], void *tm_name, unsigned int bid [4],...);

Starts a new transaction.

Format

SYS$START_TRANS [efn] ,[flags] ,iosb [,[astadr] ,[astprm] ,[tid] ,[timout] ,[acmode] ,[tx_class]]

C Prototype

int sys$start_trans (unsigned int efn, unsigned int flags, struct _iosb *iosb,...);

Arguments

efn

OpenVMS usage:	ef_number
type:	longword (unsigned)
access:	read only
mechanism:	by value

Number of the event flag that is set when the service completes. If this argument is omitted, event flag 0 is used.

flags

OpenVMS usage:	mask_longword
type:	longword (unsigned)
access:	read only
mechanism:	by value

Flags specifying options for the service. The flags argument is a longword bit mask in which each bit corresponds to an option flag. The $DDTMDEF macro defines symbolic names for these option flags, which are described in Table SYS-57. All undefined bits must be 0. If this argument is omitted, no flags are used.

Table SYS-57 $START_TRANS Option Flags

Flag	Description
DDTM$M_NONDEFAULT	Set this flag if you do not want the new transaction to be the default transaction of the calling process. An error is returned if this flag is set and the tid argument is zero or omitted. If this flag is clear, the new transaction becomes the default transaction of the calling process. An error is returned if this flag is clear and the calling process already has a default transaction.
DDTM$M_SYNC	Set this flag to specify that successful synchronous completion is to be indicated by returning SS$_SYNCH. When SS$_SYNCH is returned, the AST routine is not called, the event flag is not set, and the I/O status block is not filled in.

iosb

OpenVMS usage:	io_status_block
type:	quadword (unsigned)
access:	write only
mechanism:	by reference

I/O status block in which the completion status of the service is returned as a condition value. See the Condition Values Returned section.

The following diagram shows the structure of the I/O status block:

astadr

astprm

tid

No other call to $START_TRANS on any node ever returns the same TID value.

The default value of this argument is zero. An error is returned if the DDTM$M_NONDEFAULT flag is set and this argument is either omitted or zero.

timout

A positive time value specifies an absolute time. The absolute value of a negative time specifies an offset (delta time) from the current time.

The transaction is aborted at the next timer interval if you specify either a zero time value or any time in the past. If this argument is omitted, the new transaction has no timeout.

acmode

An access mode is maintained for each transaction per process. All branches in a transaction in a process have the same access mode. Subsequent operations do not alter it. The access mode of a branch is the least privileged mode in which a successful call to $END_TRANS may be made.

Note that the transaction may be aborted by a call to $ABORT_TRANS from any access mode.

The access mode of the branch is the least privileged of the following:

• The access mode of the caller
• The access mode specified by the acmode argument

If the acmode argument is omitted, the access mode of the new branch is the same as that of the caller.

tx_class

This string must be no longer than 31 characters. If this argument is omitted or the string is of length zero, the new transaction has no transaction class on the local node. In this case, the class of the transaction on the local node can be specified by a subsequent call to $START_BRANCH on that node.

Description

The $START_TRANS system service starts a new transaction whose commit or abort processing is to be coordinated by the local DECdtm transaction manager. The service:

• Adds a branch running in the calling process to the new transaction. The identifier (BID) of the new branch is 0.
• Sets the default transaction of the calling process to the new transaction, if the DDTM$M_NONDEFAULT flag is clear and the process does not have a default transaction.
• Delivers an event of type Transaction Started to each RMI in the calling process that requested Transaction Started events and has an access mode that is the same as or more privileged than that specified in this call to $START_TRANS. See the description of the acmode argument.

The event delivered to all such RMIs is either a default transaction-started event or a nondefault transaction-started event, depending on whether the DDTM$M_NONDEFAULT flag is clear or not.

Preconditions for the successful completion of $START_TRANS are:

• The local node must have a DECdtm transaction log.
• The TP_SERVER process must be running on the local node.
• If the DDTM$M_NONDEFAULT flag is clear, the calling process must not have an unended default transaction.

$START_TRANS may fail for various reasons including:

• Preconditions were not met.
• The DDTM$M_NONDEFAULT flag was clear and a call to $SET_DEFAULT_TRANS by the calling process is in progress.

When $START_TRANS completes successfully:

• A new transaction has started, with a unique identifier.
• The transaction has a single branch, with a BID of 0.
• All Transaction Started events reported to RMIs in the calling process have been acknowledged.
• If the DDTM$M_NONDEFAULT flag was clear, the transaction is the default transaction of the calling process.

A branch may:

• Invoke resource manager operations, explicitly passing the TID.
• Invoke resource manager operations without specifying the TID, if the transaction is the default transaction of the calling process, and the resource manager supports default transactions.
• Call $ADD_BRANCH to authorize another branch to be added to the transaction.

(The way to invoke a resource manager operation is defined by the interfaces provided by the resource manager. For additional information, see the resource manager documentation.)

DECdtm cannot commit the transaction until the process calls $END_TRANS.

The transaction is aborted:

• On termination of the current image or process.
• On successful completion of a call to $ABORT_TRANS in the calling process, specifying a BID of 0.

There is also a wait form of the service, $START_TRANSW.

Required Access or Privileges

None

Required Quotas

ASTLM, BYTLM

Related Services

$ABORT_TRANS, $ABORT_TRANSW, $ACK_EVENT, $ADD_BRANCH, $ADD_BRANCHW, $CREATE_UID, $DECLARE_RM, $DECLARE_RMW, $END_BRANCH, $END_BRANCHW, $END_TRANS, $END_TRANSW, $FORGET_RM, $FORGET_RMW, $GETDTI, $GETDTIW, $GET_DEFAULT_TRANS, $JOIN_RM, $JOIN_RMW, $SETDTI, $SETDTIW, $SET_DEFAULT_TRANS, $SET_DEFAULT_TRANSW, $START_BRANCH, $START_BRANCHW, $START_TRANSW, $TRANS_EVENT, $TRANS_EVENTW

Condition Values Returned

SS$_NORMAL	If returned in R0, the request was successfully queued. If returned in the I/O status block, the service completed successfully.
SS$_SYNCH	The service completed successfully and synchronously (returned only if the DDTM$M_SYNC flag is set).
SS$_ACCVIO	An argument was not accessible to the caller.
SS$_ALCURTID	Either: An attempt was made to start a default transaction (the DDTM$M_NONDEFAULT flag was clear) when the calling process had an unended default transaction. The DDTM$M_NONDEFAULT flag was clear and a call to $SET_DEFAULT_TRANS by the calling process was in progress.
SS$_BADPARAM	Either the DDTM$M_NONDEFAULT flag was set and the tid argument was omitted, or the options flags were invalid.
SS$_CURTIDCHANGE	The DDTM$M_NONDEFAULT flag was clear and a call to change the default transaction of the calling process was in progress.
SS$_EXASTLM	The process AST limit (ASTLM) was exceeded.
SS$_EXQUOTA	The job buffered I/O byte limit quota (BYTLM) was exceeded.
SS$_ILLEFC	The event flag number was invalid.
SS$_INSFARGS	A required argument was missing.
SS$_INSFMEM	There was insufficient system dynamic memory for the operation.
SS$_INVBUFLEN	The string passed to the tx_class argument was longer than 31 characters.
SS$_NOLOG	The local node did not have a transaction log.
SS$_TPDISABLED	The TP_SERVER process was not running on the local node.

Starts a new transaction.

$START_TRANSW always waits for the request to complete before returning to the caller. Other than this, it is identical to $START_TRANS.

Format

SYS$START_TRANSW [efn] ,[flags] ,iosb [,[astadr] ,[astprm] ,[tid] ,[timout] ,[acmode]]

C Prototype

int sys$start_transw (unsigned int efn, unsigned int flags, struct _iosb *iosb,...);

On Alpha and Integrity server systems, disables user image alignment fault reporting.

Format

SYS$STOP_ALIGN_FAULT_REPORT

C Prototype

int sys$stop_align_fault_report (void);

Arguments

None.

Description

The Stop Alignment Fault Reporting service disables user image alignment fault reporting.

The service returns SS$_AFR_NOT_ENABLED if user image alignment fault reporting is not enabled; otherwise, it returns success.

Required Access or Privileges

None

Required Quota

None

Related Services

$GET_ALIGN_FAULT_DATA, $GET_SYS_ALIGN_FAULT_DATA, $INIT_SYS_ALIGN_FAULT_REPORT, $PERM_DIS_ALIGN_FAULT_REPORT, $PERM_REPORT_ALIGN_FAULT, $START_ALIGN_FAULT_REPORT, $STOP_SYS_ALIGN_FAULT_REPORT

Condition Values Returned

SS$_NORMAL	The service completed successfully.
SS$_AFR_NOT_ENABLED	The $START_ALIGN_FAULT_REPORT service has not been called.