Complete Guide to Server-Side Scripting in ServiceNow.

[Tushar8649]

🔷 1. Introduction to Server-Side Scripting

Server-side scripting in ServiceNow refers to JavaScript code executed on the server, responsible for handling business logic, database operations, automation, and backend processing.

• Executes on the ServiceNow instance (server)

• Not visible to end users (secure & tamper-proof)

• Handles data integrity, automation, and integrations

📌 Common Use Cases:

• Auto-updating fields

• Data validation

• Triggering notifications/events

• Processing large datasets

• Integration with external systems (ServiceNow)

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🔷 2. Client vs Server-Side (Foundation You MUST Understand)

Aspect Client-Side Server-Side

Runs On	Browser	Server
Purpose	UI interaction	Business logic
APIs	g_form, g_user	GlideRecord, gs
Security	Less secure	Highly secure

👉 Key Insight:
Server-side scripting is mandatory for enforcing business rules and maintaining data consistency. (infocenter.io)

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🔷 3. Core Server-Side Script Types

These are the building blocks:

✅ 3.1 Business Rules (Most Important)

A Business Rule is a server-side script that runs when a record is:

• Inserted

• Updated

• Deleted

• Queried (ServiceNow)

🔹 Types of Business Rules

Type When it Runs Use Case

Before	Before DB save	Modify current record
After	After save	Update related records
Async	Background after save	Performance-heavy tasks
Display	Before form load	Pass data to client

📌 Example (Before Business Rule):

if (current.priority == 1) {
    current.urgency = 1;
}

📌 Key Rule:

• Never use current.update() in before rules

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✅ 3.2 Script Includes (Reusable Logic)

Script Includes are reusable server-side classes/functions.

• Centralized logic

• Called from Business Rules, Client Scripts, APIs

• Improve maintainability

📌 Definition:
Reusable server-side logic that executes only when called (ServiceNow)

📌 Example:

var IncidentUtils = Class.create();
IncidentUtils.prototype = {
    initialize: function() {},

    getActiveIncidents: function() {
        var gr = new GlideRecord('incident');
        gr.addActiveQuery();
        gr.query();
        return gr.getRowCount();
    }
};

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✅ 3.3 GlideRecord (Most Critical API)

GlideRecord is the backbone of server-side scripting.

👉 Used for:

• Query

• Insert

• Update

• Delete records

📌 Example:

var gr = new GlideRecord('incident');
gr.addQuery('active', true);
gr.query();

while (gr.next()) {
    gs.info(gr.number);
}

📌 Key Insight:
GlideRecord is used in almost every server-side implementation. (ServiceNow Guru)

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✅ 3.4 GlideSystem (gs Object)

Used for:

• Logging

• User info

• System operations

📌 Example:

gs.info("Incident created successfully");

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✅ 3.5 Scheduled Jobs (Background Automation)

• Run at defined intervals

• Used for batch processing

📌 Example Use Cases:

• Cleanup scripts

• Data archiving

• Reports generation

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✅ 3.6 Background Scripts

• Used for testing and quick execution

• Runs immediately

📌 Important:

• Powerful but risky (direct DB impact)

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🔷 4. Execution Flow (Critical Concept)

Understanding execution order is key for debugging:

1. Query Business Rules

2. Display Business Rules

3. Before Business Rules

4. Database Operation

5. After Business Rules

6. Async Business Rules

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🔷 5. Advanced Concepts

🔶 5.1 Query Business Rules

• Modify queries before execution

• Affect all GlideRecord queries

⚠️ Use carefully → can impact performance and debugging (ServiceNow)

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🔶 5.2 GlideAggregate

Used for:

• Count

• Sum

• Avg

📌 Example:

var agg = new GlideAggregate('incident');
agg.addAggregate('COUNT');
agg.query();

if (agg.next()) {
    gs.info(agg.getAggregate('COUNT'));
}

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🔶 5.3 Event-Driven Architecture

• Use gs.eventQueue() to trigger notifications

📌 Example:

gs.eventQueue('incident.created', current, current.sys_id, gs.getUserID());

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🔶 5.4 Script Includes + GlideAjax

• Bridge client → server

• Fetch data asynchronously

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🔶 5.5 Security in Server Scripts

• Use GlideRecordSecure

• Respect ACLs

• Avoid exposing sensitive logic

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🔷 6. Best Practices (Highly Important)

✅ Coding Standards

• Avoid hardcoding values (ServiceNow)

• Use Script Includes for reuse

• Keep scripts modular

✅ Performance

• Use conditions in Business Rules

• Avoid unnecessary queries

• Prefer async for heavy operations

✅ Maintainability

• Proper naming conventions

• Avoid duplicate logic

• Use logging (gs.info)

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🔷 7. Common Mistakes to Avoid

❌ Using GlideRecord in loops inefficiently
❌ Writing logic in Client Script instead of server
❌ No conditions in Business Rules
❌ Overusing synchronous Business Rules
❌ Not using Script Includes

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🔷 8. Real-World Use Case (End-to-End)

👉 Scenario: Auto-update related incidents

var gr = new GlideRecord('incident');
gr.addQuery('short_description', current.short_description);
gr.addQuery('active', true);
gr.query();

while (gr.next()) {
    gr.work_notes = "Similar incident updated";
    gr.update();
}

✅ Conclusion

If you want to become a strong ServiceNow Developer, server-side scripting is non-negotiable.

It is not just about writing scripts — it is about:

• Designing efficient logic

• Maintaining data integrity

• Building scalable solutions