Servicenow Custom Application Development Mastery

Beyond the Basics: Mastering ServiceNow Custom Application Development

ServiceNow is renowned for its robust ITSM capabilities, but its true power lies in its platform-as-a-service (PaaS) capabilities, enabling the development of custom applications to address unique business needs. Moving beyond simple configuration and into custom application development unlocks immense potential for automation, process optimization, and digital transformation. This post delves into advanced techniques and best practices for mastering ServiceNow custom application development.

1. Understanding the ServiceNow Application Development Lifecycle

Before diving into code, it’s crucial to understand the lifecycle of a ServiceNow application:

Planning & Requirements Gathering: Define the application’s purpose, target audience, scope, and functional/non-functional requirements.
Design: Design the data model (tables, fields, relationships), user interface (forms, lists, UI actions), workflow, and security model.
Development: Build the application using ServiceNow’s development tools (Studio, Script Editor, Flow Designer).
Testing: Thoroughly test the application for functionality, performance, security, and usability. Unit tests, integration tests, and user acceptance testing (UAT) are essential.
Deployment: Deploy the application to the production environment.
Maintenance: Monitor the application’s performance, address bugs, and implement enhancements as needed.

2. Advanced Scripting Techniques

ServiceNow scripting relies heavily on JavaScript, both client-side (browser) and server-side. Mastering advanced scripting techniques is crucial for building robust and efficient applications.

GlideRecord Advanced Queries: Go beyond simple queries with addQuery and addEncodedQuery.

addEncodedQuery: Enables complex filtering using encoded query strings.


var gr = new GlideRecord('incident');
gr.addEncodedQuery('category=network^priority=1^active=true');
gr.query();
while (gr.next()) {
    // Process incident records
}

addJoinQuery: Allows joining tables without creating database views. (Requires the Database Views plugin to be enabled, which is deprecated).


var gr = new GlideRecord('incident');
var join = gr.addJoinQuery('task', 'task_number'); // Deprecated
join.addCondition('sys_class_name', 'problem'); // Deprecated
gr.query();
while (gr.next()) {
// Process incident records
}

Asynchronous Scripting (GlideAjax, Queued Transactions): Offload long-running tasks to prevent blocking the user interface.

GlideAjax: Allows client-side scripts to call server-side scripts asynchronously.


// Client-side script
var ga = new GlideAjax('MyScriptInclude');
ga.addParam('sysparm_name', 'myFunction');
ga.addParam('sysparm_value', 'someValue');
ga.getXMLAnswer(function(answer) {
    // Process the answer from the server
    alert(answer);
});
 
// Server-side script include (MyScriptInclude)
var MyScriptInclude = Class.create();
MyScriptInclude.prototype = Object.extendsObject(AbstractAjaxProcessor, {
    myFunction: function() {
        var value = this.getParameter('sysparm_value');
        return 'Hello ' + value;
    },
    type: 'MyScriptInclude'
});

Queued Transactions (Event Queue): Schedule scripts to run in the background using events. This is the preferred approach for asynchronous server-side processing.


// Fire an event
gs.eventQueue('my.custom.event', current, gs.getUserID(), gs.getUserName());
 
// Create a System Event [sysevent] record for 'my.custom.event'
 
// Create a script action that listens for 'my.custom.event' and executes your server-side script.

Business Rules Considerations: Understand when to use before, after, async, and display business rules. Choose the appropriate type based on the application’s requirements. Async business rules are generally preferred for non-realtime updates
Script Includes Best Practices:
- Use classes instead of functions to provide structure
- Extend AbstractAjaxProcessor to enable client-side scripting
- Use the “type” property to define the script include’s purpose.

3. Data Model Design: Beyond Simple Tables

A well-designed data model is crucial for application performance and scalability.

Table Extension vs. Table Rotation: Understand when to extend an existing table (e.g., extending task for a custom request type) vs. creating a new, independent table. Table rotation is useful for archiving data.
Database Indexing: Optimize query performance by creating indexes on frequently queried fields. Use caution, as too many indexes can degrade write performance. Use the db.index.stats to find the list of the used index. Reference: ServiceNow Index Recommendation
Choice Lists vs. Reference Fields: Choose the appropriate field type based on the data being stored. Use choice lists for a predefined set of values and reference fields to link to existing records in other tables.
Auditing: Configure auditing on important tables to track changes to data.

4. Mastering the User Interface

A user-friendly interface is essential for application adoption.

Service Portal Widget Development: Create custom widgets to provide a tailored user experience in the Service Portal. Use AngularJS (still supported but deprecated) and consider moving to web components as you build new widgets. React is also gaining popularity for Servicenow.
UI Policies and Client Scripts: Use UI policies to dynamically control form behavior (e.g., making fields read-only, mandatory, or visible/hidden) based on certain conditions. Client scripts can be used for more complex UI interactions.
UI Actions: Create UI actions to perform custom actions on records (e.g., creating a related record, sending an email, or triggering a workflow).
Accessibility (WCAG Compliance): Design your application with accessibility in mind, following WCAG guidelines to ensure it is usable by people with disabilities. Reference: ServiceNow Accessibility
Mobile App Configuration: Configure your application for use on the ServiceNow mobile app.

5. Workflow and Automation with Flow Designer

Flow Designer provides a no-code/low-code environment for automating tasks and processes.

Custom Actions: Create custom actions to encapsulate reusable logic.
Subflows: Break down complex flows into smaller, more manageable subflows.
Error Handling: Implement robust error handling to gracefully handle unexpected events.
Integration with External Systems: Use IntegrationHub to connect to external systems and integrate data into your flows.

Example: A Custom Change Management Application

Let’s consider building a custom Change Management application.

Data Model: Create a custom table extending task called u_change_request. Add fields like u_business_justification, u_rollback_plan, and u_implementation_start_date. A related table u_change_task could extend task and reference u_change_request.
Workflow: Design a workflow using Flow Designer to manage the change approval process. This workflow could involve multiple approval stages, automated task creation, and notifications.
User Interface: Create a custom form for the u_change_request table with UI policies to control the visibility and mandatory status of fields based on the change type and status. A Service Portal widget could be created to allow users to submit change requests.
Integration: Integrate with a CMDB system to automatically update configuration items affected by the change.

6. Security Considerations

Security is paramount in ServiceNow application development.

Access Control Lists (ACLs): Define ACLs to control who can access and modify data. Follow the principle of least privilege.
Application Scoping: Develop your application within a dedicated application scope to prevent naming conflicts and ensure proper isolation.
Data Encryption: Encrypt sensitive data at rest and in transit.
Vulnerability Scanning: Regularly scan your application for vulnerabilities using tools like the ServiceNow Vulnerability Response application.

7. Testing and Debugging

Thorough testing is crucial for ensuring application quality.

Automated Testing: Use the Automated Test Framework (ATF) to create automated tests for your application.
Debugging Tools: Use the ServiceNow script debugger to identify and fix errors in your scripts.
Logging: Implement robust logging to track application behavior and identify potential issues.

Visualizing Application Development Stages

Conclusion

Mastering ServiceNow custom application development requires a deep understanding of the platform’s capabilities, advanced scripting techniques, and best practices for data model design, user interface development, workflow automation, and security. By following the principles outlined in this post, you can build robust, scalable, and user-friendly applications that address unique business needs and unlock the full potential of the ServiceNow platform. Continuously learning and exploring new features and functionalities is the key to staying ahead in the ever-evolving world of ServiceNow development.