RFC problem with TransactionalEventStore and ArangoDB

[sandrokeil]

I see some problems with TransactionalEventStore interface and ArangoDB or other event store implementations who handles transactions in another way. ArangoDB has no beginTransaction, commit, rollback or isInTransaction see docs.

Can we achieve more interoperability by simply using a function e.g. executeTransaction which gets a list of streams? But we have to differ between create and appendTo. Maybe instead of using create and appendTo methods, we introduce a stream type which can be create or appendTo, so the provided stream list can be executed in order.

/cc @prolic @codeliner

[codeliner]

Can't we handle the logic behind the TransactionalEventStore interface?
ArangoDB handles transactions in one go but IMHO this is implementation detail. From a user POV it makes no difference:

$arangoDbES->beginTransaction();
//$this->inTransaction = true;
$arangoDbES->create($stream);
//$this->transactionOperations[] = new ArangoCreateStreamOperation($stream);
$arangoDbES->appendTo($streamName, $streamEvents);
//$this->transactionOperations[] = new ArangoAppendToStreamOperation($streamName, $streamEvents);
$arangoDbES->commit();
//$this->executeTransaction();
//foreach($this->transactionOperations as $op) {/*map to transaction description*/}
//$this->arangoConnection->transaction($transactionDescription); 

//or in case of a userland error before $arangoDbES->commit() is called
try {
//do something that causes an error
} catch (\Throwable $error) {
  if ($arangoDbES->isInTransaction()) { //return $this->inTransaction;
    $arangoDbES->rollback();
    //$this->transactionOperations = [];
    //$this->inTransaction = false;
  }
}

[sandrokeil]

Yes that should be possible. It's only confusing if you have to use these methods and read in the ArangoDB docs, transaction is handled in one go.

[prolic]

@sandrokeil can we close this now?