Order of operations (business rules, acls, data policies, ui policies, and client scripts)

Understanding when something runs is critical when building these systems. ServiceNow has a very simple and great image that captures that for business rules. However that doesn’t help with other scripts in the system. Bas @ Logicalis wrote something up about this on snc-blog but I thought I could improve on it. Also messing with things is a way I remember better.

I try to keep all the common diagrams I use on https://workflow.jace.pro/ but I realize I don’t really share when that changes.

Here I’ve been messing with this and I thought now is a great time to share this diagram I keep out there.

{{mermaid}} sequenceDiagram participant uxux as User Interactions participant csup as UI Policy participant cscs as Client Script participant ssss as Server Side participant eeee as Engines participant dbdb as Database uxux->>ssss: Form Request ssss->>dbdb: Query Business Rules dbdb->>ssss: Display Business Rules ssss->>cscs: OnLoad Client Scripts cscs->>csup: OnLoad UI Policies csup->>uxux: Form loaded loop Every Change uxux->>ssss: ref_qual_element field changes ssss->>cscs: OnChange Client Scripts cscs->>csup: OnChange UI Policies csup->>uxux: Form Updated end uxux->>csup: Form Submit(client) csup->>cscs: OnSubmit Client Scripts cscs->>ssss: Form Submit(server) ssss->>eeee: Before Business Rules <1000 eeee-->ssss: Approval engine eeee–>ssss: Assignment rules engine eeee–>ssss: Data policy engine eeee–>ssss: Escalation engine eeee–>ssss: Field normalization engine eeee–>ssss: Role engine eeee–>ssss: Execution plan engine eeee–>ssss: Update version engine eeee–>ssss: Workflow engine (for default workflows) eeee->>ssss: Before Business Rules >=1000 ssss->>dbdb: Database Update dbdb->>ssss: After Business Rules <1000 ssss-->eeee: Label engine ssss–>eeee: Listener engine ssss–>eeee: Table notifications engine Note right of eeee: This creates sysevents that process later ssss–>eeee: Role engine ssss–>eeee: Text indexing engine ssss–>eeee: Update sync engine ssss–>eeee: Data lookup engine inserts or updates ssss–>eeee: Workflow engine (for deferred workflows) ssss–>eeee: Trigger engine (for all Flow Designer flows) eeee->>ssss: After Business Rules >=1000 ssss->>ssss: Async Business Rules Note right of ssss: This creates sys_triggers that process later ssss->>dbdb: Query Business Rules dbdb->>ssss: Display Business Rules ssss->>uxux: Return UI

Note over uxux,dbdb: Thanks to http://www.snc-blog.com/2017/02/02/script-execution-flow/ {{mermaid}}

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Jace Benson
ServiceNow Developer

ServiceNow is my day job, JAMStack is my passion.