ADF transactions are defined by the business service
implementation used in the application (Application Modules). Application Modules
provides the connections and transaction to commit the data into the DB. The AM
are exposed to the ViewController layer through an abstraction called Data Control.
By default AM provides transaction for the application to
commit the data into the DB. But the developer has the ability to change the
transaction flow. Each bounded task flow provides its own transaction and data
control scopes, example each bounded task flow can commit data separately or
use the default transaction.
In the below image you can see simple bounded taskflow with
transaction options.
For a given btf (Bounded Task Flow) there are 4 transaction
options.
I)
No Controller Transaction (btf use the existing
default transaction)
II)
Always Begin New Transaction (btf creates new transaction)
III)
Always Use the Existing Transaction (btf uses
the existing transaction)
IV)
Use the Existing Transaction If Possible.
Each btf data control scopes provides option to share the
transaction with the other btf or not. It provides 2 options
i)
Shared
ii)
Isolated
“Shared”: will try to
share any instance of a data control with the task flow's caller if the data
controls have the same definition, rather than creating a new instance.
“Isolated”: Even if both
task flows use the same design time data control definition, at runtime
each task flow will have their own instance of
the data control.
There is something called Data Control Frame which handles
all the data control scopes. Each task flow has its own data control frame and
containing list of data control scopes.
A data control frame is
created at run-time for the application’s unbounded task flow and for each
isolated data control scoped bounded task flow. When bounded task flow
specified the shared data control
scope and the current task flow uses the data control frame and the instances
attached to it.
Alternatively if the
bounded task flow specifies an isolated
data control scope, a new
frame will be created
and a new instance of any data controls used by the bounded task flow will
be attached to this new
frame.
The below image shows
when the new Data Control Frame is created
As you can see in the
above diagram there are three Data
Control Frame gets created. The red arrow shows that when the data control
scope of the BTF is selected as isolated
new Data Control Frame gets
created. And when the BTF is Shared,
the called BTF uses the dame Data
Control Frame and instances attached the same.
