Has anyone encountered this behaviour before ? I have a script task

paulc919 over 9 years ago

Has anyone encountered this behaviour before ?

I have a script task that calls an web service via an expression rule.

We've also added an exception timer event that kicks in 59 seconds after the Script Task node is executed (to prevent automatic retry as the service creates a document).

When the expression rule is called on the input data tab, if the service call fails to respond, the exception timer is not kicking in and instead the node has a red line through it.

When I move the expression rule to the output data tab, the exception timer does kick in and the exception flow is executed accordingly.

Is this expected behaviour ?

The reason why we are using expression rules for our services is to enable a fast failover to our secondary VPN tunnel, so we're moving away from the Call Web Service Smart Service.

Many thanks

Paul

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Eduardo Fuentes over 9 years ago +1
Appian Employee

Per the documentation forum.appian.com/.../Exception_Flows.html: - On an unattended activity, the activity and the exception triggers are started at the same time. It is not possible to determine which…

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0 Eduardo Fuentes
Appian Employee
over 9 years ago

Per the documentation forum.appian.com/.../Exception_Flows.html:

- On an unattended activity, the activity and the exception triggers are started at the same time. It is not possible to determine which one completes first. This applies to Rule Events (as well as any Timer Events that have met their schedule conditions prior to node activation).

Depending on what error alert you were getting when the node was showing up the red line this documented constraint could explain the behavior.

Putting the expression in the output tab might work as you have seen because the expressions there get evaluated after the inputs but I'd still think this is prone to race conditions.

The documentation suggests the following:

- Configuring the Exception Flow on the subsequent node in your process ensures that an exception rule is evaluated in proper sequence for an unattended node.
- Configure a roll back of any actions taken by the previous activity, if you evaluate exception rules within a subsequent node.
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0 Eduardo Fuentes
Appian Employee
over 9 years ago

Per the documentation forum.appian.com/.../Exception_Flows.html:

- On an unattended activity, the activity and the exception triggers are started at the same time. It is not possible to determine which one completes first. This applies to Rule Events (as well as any Timer Events that have met their schedule conditions prior to node activation).

Depending on what error alert you were getting when the node was showing up the red line this documented constraint could explain the behavior.

Putting the expression in the output tab might work as you have seen because the expressions there get evaluated after the inputs but I'd still think this is prone to race conditions.

The documentation suggests the following:

- Configuring the Exception Flow on the subsequent node in your process ensures that an exception rule is evaluated in proper sequence for an unattended node.
- Configure a roll back of any actions taken by the previous activity, if you evaluate exception rules within a subsequent node.
Cancel
Vote Up +1 Vote Down

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