MSMQ transaction management

Provides StartMQTransaction and EndMQTransaction so a caller can batch multiple Distribute a document calls into a single transactional unit of work against the MSMQ transactional queue, rather than committing a transaction per message.

Field	Value
Operation ID	OP-05
Trigger	StartMQTransaction / EndMQTransaction invoked directly by a caller
Inputs	None (StartMQTransaction); inAction As Boolean commit/abort flag (EndMQTransaction)
Outputs	A committed or aborted MessageQueueTransaction
Primary components	clsPrint.StartMQTransaction, clsPrint.EndMQTransaction
Entry point	SAIF.Services.Printing/clsPrint.vb

Steps

1. StartMQTransaction: if a transaction is not already started (m_TxnStarted = False), creates a new MessageQueueTransaction, begins it, and sets m_TxnStarted = True.
2. If a transaction is already started, this call is a no-op — calling it twice in a row silently keeps the first transaction rather than starting a second one or raising an error. This idempotent-restart behavior underlies the "if the caller did not start one" framing in BR-PRT-004.
3. EndMQTransaction(inAction): if m_TxnStarted is True, commits the transaction when inAction = True, or aborts it when inAction = False.
4. On any exception during commit or abort, the Finally block described in step 3 still executes.
5. Finally (always runs): resets m_TxnStarted = False and disposes/nulls m_Txn, regardless of whether a transaction was actually started or whether the commit/abort succeeded.
6. If EndMQTransaction is called when m_TxnStarted = False, the commit/abort branch in step 2 is skipped entirely, but this Finally cleanup still runs harmlessly.

Process flow

flowchart TD
    subgraph Start_flow["StartMQTransaction"]
        S1(["StartMQTransaction called"]) --> S2{"m_TxnStarted?"}
        S2 -->|No| S3["New MessageQueueTransaction,<br>Begin, set flag True"]
        S2 -->|Yes| S4(["No-op"])
    end
    subgraph End_flow["EndMQTransaction(inAction)"]
        E1(["EndMQTransaction called"]) --> E2{"m_TxnStarted?"}
        E2 -->|Yes| E3{"inAction?"}
        E3 -->|True| E4["Commit"]
        E3 -->|False| E5["Abort"]
        E4 --> E6["Finally: reset flag,<br>dispose/null txn"]
        E5 --> E6
        E2 -->|No| E6
    end

Failure and edge-case behavior

• There is no exception handling around Commit()/Abort() beyond the Finally cleanup — an exception raised from Commit() propagates to the caller after the Finally block has already reset state.
• Calling StartMQTransaction twice without an intervening EndMQTransaction silently reuses the existing transaction rather than erroring or starting a second one.
• Distribute a document relies on this same start/commit/rollback mechanic internally when the caller has not started a transaction of their own, per BR-PRT-004 and BR-PRT-005.

Related documentation

• Index
• Overview
• Architecture
• Dependencies
• Operations and processes
• Business rules
• Configuration
• API reference

Sources

• SAIF.Services.Printing/clsPrint.vb