TMF Operations and Recovery Guide (G06.24+)

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HP NonStop TMF Operations and Recovery Guide—522417-002

2-21

Normal Distributed Transaction Processing

Table 2-5 summarizes the usual progression of states that a homogeneous distributed

transaction goes through in the parent node and in a child node. Note that a

distributed transaction can involve not just one, but several child nodes. In such a

case, the transaction exists simultaneously in the parent node and in all involved child

nodes.

Under normal circumstances, homogeneous distributed transactions are started,

proceed through the various states, and disappear automatically. The TMPs in the

involved systems maintain contact with one another and cooperate in the creation and

management of the various portions of a homogeneous distributed transaction.

Heterogeneous distributed transactions, like homogeneous distributed transactions,

are also started, pass through various states, and disappear automatically. The

transaction managers that handle a heterogeneous distributed transaction cooperate in

its creation, management, and commitment. Details about heterogeneous transaction

processing are complex and involve considerations beyond the scope of this manual.

For further information about heterogeneous transaction processing, see the Open

Table 2-5. Homogeneous Distributed Transaction States

Transaction States in the…

Parent Node Child Node Activity

ACTIVE (does not yet

exist)

An application program starts a transaction in the parent

node by executing a BEGINTRANSACTION procedure

call. The transaction requires access to a table, file, or

server process on a child node.

ACTIVE ACTIVE The TMP in the parent node sends a message to the

TMP in the child node, which starts the transaction in the

child node.

ACTIVE PREPARED When the application executes an ENDTRANSACTION

procedure call, the parent-node TMP sends a message

to the child-node TMP, which then changes the state of

the transaction from active to prepared.

COMMITTED PREPARED After the transaction is in the prepared state in all

involved child nodes, the parent-node TMP changes the

transaction from active to committed and sends a

confirmation message to the child-node TMP.

COMMITTED (no longer

exists)

The child-node TMP commits the prepared transaction,

removes it from the list of transactions in progress, and

sends a confirmation message back to the parent-node

TMP.

(no longer

exists)

(no longer

exists)

After the transaction has been committed in all involved

child nodes, the parent-node TMP removes the

committed transaction from the list of transactions in

progress.