In ASP.NET, you separate concerns with Controllers, Services, and Repositories.

The Intent Behind This Question

This tests whether you can map ServiceNow's server-client architecture to the layered patterns you've built in .NET. The key insight: ServiceNow's UI is server-rendered (think classic ASP.NET Web Forms / Razor Pages), not a detached SPA. The client-server boundary is explicit and enforced.

The Architecture Map

// ASP.NET MVC Architecture (what you know)
//
// View (.cshtml)          → Client Scripts + UI Policies
// Controller              → Business Rules (server triggers)
// Service Layer           → Script Includes (reusable classes)
// Repository / DbContext  → GlideRecord (data access)
// AJAX calls (fetch/axios) → GlideAjax (client-to-server bridge)
// ViewComponents          → UI Scripts, Widgets (Service Portal)
// [Authorize] attribute   → ACLs (access control lists)
// Startup.cs middleware   → System Properties + Before Query BRs

Script Includes — Your Service Layer

// This is like a C# class in your Services/ folder
var IncidentHelper = Class.create();
IncidentHelper.prototype = Object.extendsObject(
  AbstractAjaxProcessor, { // Extend this to expose via GlideAjax
  
  // Server-only method (like a private service method)
  calculateSLA: function(incidentGR) {
    var priority = incidentGR.getValue('priority');
    var slaHours = {1: 4, 2: 8, 3: 24, 4: 72};
    return slaHours[priority] || 72;
  },
  
  // Client-callable method (like a [HttpGet] API endpoint)
  getIncidentSLA: function() {
    var incId = this.getParameter('sysparm_incident_id');
    var gr = new GlideRecord('incident');
    if (gr.get(incId)) {
      return this.calculateSLA(gr);
    }
    return -1;
  },
  
  type: 'IncidentHelper'
});

GlideAjax — Your AJAX Calls

// Client Script calling GlideAjax
// This is like: fetch('/api/incident/getSLA?id=123')
var ga = new GlideAjax('IncidentHelper'); // The Script Include name
ga.addParam('sysparm_name', 'getIncidentSLA'); // Method to call
ga.addParam('sysparm_incident_id', g_form.getUniqueValue());
ga.getXMLAnswer(function(answer) {
  // 'answer' is the return value from the server method
  g_form.setValue('u_sla_hours', answer);
});

The Critical Boundary

• Client-side (runs in browser): Client Scripts, UI Policies, UI Scripts, GlideAjax calls. You have g_form (form manipulation API — like jQuery for ServiceNow forms) and g_user (current user context).
• Server-side (runs on instance): Business Rules, Script Includes, Scheduled Jobs, Flow Designer. You have GlideRecord, GlideSystem (gs), and full database access.
• You cannot call GlideRecord from a Client Script. This is the #1 mistake .NET devs make — assuming they can query the DB from the browser like they would with Entity Framework in a Blazor Server app. The bridge is always GlideAjax.