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ServiceNow Scripted REST API Interview Questions 2024

What are Custom Web Services in ServiceNow?

  • Custom Web Services in ServiceNow allow developers to create custom inbound REST or SOAP web services for integrating with external systems.

What is a Scripted REST API in ServiceNow?

  • A Scripted REST API is a custom API defined using JavaScript to create endpoints that handle HTTP requests within the ServiceNow platform.

What are the key components of a Scripted REST API?

  • The key components include the API definition, resources, and the associated scripts that handle requests and responses.

How do you create a new Scripted REST API in ServiceNow?

  • Navigate to System Web Services > Scripted REST APIs, click ‘New,’ provide a name, base path, and version, then define resources and methods.

What is a resource in a Scripted REST API?

  • A resource is an endpoint within the API that maps to a specific path and HTTP method to handle requests.

How do you define a resource in a Scripted REST API?

  • Within the Scripted REST API, add a new resource, specify the HTTP method, the relative path, and write the script to handle the request.

How can you secure a Scripted REST API?

  • Secure a Scripted REST API using authentication methods such as OAuth 2.0, Basic Auth, or API keys, and enforce role-based access control through ACLs.

What are ACLs and how are they used in Scripted REST APIs?

  • ACLs (Access Control Lists) are used to control access to resources based on user roles, ensuring that only authorized users can access certain API endpoints.

How do you access query parameters in a Scripted REST API?

  • Query parameters can be accessed using request.queryParams['parameterName'].

How do you process the request body in a Scripted REST API?

  • The request body is accessed through request.body.data for JSON data and can be parsed and processed within the script.

How can you set the HTTP response status in a Scripted REST API?

  • Use response.setStatus(statusCode) to set the desired HTTP status code in the response.

How do you implement error handling in a Scripted REST API?

  • Use try-catch blocks to catch exceptions, log errors using gs.error(), and set appropriate HTTP status codes and error messages in the response.

What is the importance of logging in Scripted REST APIs?

  • Logging helps in troubleshooting, monitoring, and auditing API usage and errors, making it easier to maintain and support the API.

How do you return complex JSON objects in a Scripted REST API response?

  • Create a JavaScript object or array, populate it with data, and use JSON.stringify() to convert it to a JSON string to be sent in the response body.

What is the use of GlideRecord in Scripted REST APIs?

  • GlideRecord is used to interact with the ServiceNow database, allowing CRUD operations on records within the API scripts.

How would you implement pagination in a Scripted REST API?

  • Implement pagination by accepting limit and offset query parameters, and use these values to limit and skip records in a GlideRecord query.

How do you manage versioning for a Scripted REST API?

  • Include the version number in the base path of the API, such as /api/namespace/v1/resource, and create new versions for significant changes.

What are the best practices for naming endpoints in Scripted REST APIs?

  • Use clear, consistent, and descriptive names for endpoints, typically using nouns for resources (e.g., /api/namespace/v1/users).

How can you test Scripted REST APIs in ServiceNow?

  • Use the REST API Explorer, Postman, or any HTTP client to send requests to the API endpoints and validate the responses.

What should be considered when deploying Scripted REST APIs in a production environment?

  • Ensure thorough testing, implement proper error handling and security, and monitor performance and usage.

How can you optimize the performance of a Scripted REST API?

  • Minimize database queries, use caching strategies, and ensure efficient use of GlideRecord operations.

What tools can be used to monitor the performance of Scripted REST APIs?

  • Use ServiceNow’s built-in monitoring tools, external APM tools, and analyze logs and metrics.

Give an example of a use case for a Scripted REST API in ServiceNow.

  • Integrating ServiceNow with an external incident management system to automatically create incidents based on external triggers.

How would you handle authentication for external systems calling your Scripted REST API?

  • Use OAuth 2.0 for secure token-based authentication, or API keys for simpler integrations, ensuring secure transmission over HTTPS.

How can you extend the functionality of a Scripted REST API without breaking existing clients?

  • Introduce new endpoints or optional parameters, and ensure backward compatibility with existing endpoints.

What are the benefits of using Scripted REST APIs over out-of-the-box REST APIs in ServiceNow?

  • Scripted REST APIs offer greater flexibility and customization, allowing developers to define custom logic, handle complex data transformations, and meet specific business requirements.

What measures can you take to prevent SQL injection attacks in Scripted REST APIs?

  • Use parameterized queries with GlideRecord, validate and sanitize input data, and implement proper error handling.

How do you ensure compliance with data privacy regulations when developing Scripted REST APIs?

  • Ensure data is encrypted in transit and at rest, limit data exposure to necessary fields, and implement proper access controls.

What steps would you take to debug a failing Scripted REST API?

  • Check the logs for errors, use gs.debug() statements to trace the flow, verify the input data, and test the API using tools like Postman.

How do you handle timeouts and retries in Scripted REST APIs?

  • Implement timeout handling in the client-side logic, and use retry mechanisms with exponential backoff to manage transient failures.

What are the best practices for writing maintainable Scripted REST APIs?

  • Write clean, modular code, document the API and its endpoints, use version control, and follow coding standards and naming conventions.

How can you ensure scalability of Scripted REST APIs?

  • Design the API to handle concurrent requests efficiently, use asynchronous processing where possible, and monitor and optimize performance regularly.

What is the role of Script Includes in Scripted REST APIs?

  • Script Includes are reusable server-side scripts that can be called from other scripts, including Scripted REST API scripts, to promote code reuse and modularity.

How can you handle asynchronous processing in Scripted REST APIs?

  • Use GlideAjax or asynchronous GlideRecord operations to handle tasks that can be processed in the background, improving the responsiveness of the API.

How would you return a file from a Scripted REST API?

  • Set the appropriate content type in the response header and use the response stream to send the file data back to the client.

How do you manage API documentation for Scripted REST APIs?

  • Document the API endpoints, parameters, request and response formats, and example use cases using tools like Swagger or the ServiceNow REST API Explorer.

What should you do if a Scripted REST API needs to support multiple languages?

  • Implement localization by using language-specific resources and ensuring the API can handle language preferences passed in the request headers.

How can you handle rate limiting in Scripted REST APIs?

  • Implement rate limiting by tracking the number of requests from each client and enforcing limits based on predefined thresholds.

How do you update a Scripted REST API without causing downtime?

  • Use versioning to deploy new features, ensure backward compatibility, and use rolling updates or blue-green deployments to minimize downtime.

What strategies can be used for maintaining backward compatibility in Scripted REST APIs?

  • Ensure new changes do not break existing functionality, use feature toggles, and provide clear documentation for any deprecated features.

How would you integrate a third-party system with ServiceNow using Scripted REST APIs?

  • Create a Scripted REST API to receive data from the third-party system, process the data using GlideRecord, and update ServiceNow records accordingly.

Can you give an example of a Scripted REST API that performs data validation before processing?

  • Create a Scripted REST API that accepts user input, validates the data (e.g., checking for required fields or data types), and only processes the request if the validation passes.

How can you handle large data sets in Scripted REST APIs?

  • Implement pagination, use efficient queries, and consider asynchronous processing for operations that involve large data sets.

What are Custom Web Services in ServiceNow?

  • Custom Web Services in ServiceNow allow for creating custom inbound REST or SOAP web services to facilitate integration with external systems.

What is a Scripted REST API in ServiceNow?

  • A Scripted REST API in ServiceNow is a custom API created using JavaScript that allows developers to define custom endpoints and logic to handle HTTP requests within the platform.

What is the purpose of Scripted REST APIs?

  • Scripted REST APIs enable developers to extend ServiceNow’s functionality, customize data handling, and integrate with external systems in a highly flexible manner.

How do you create a new Scripted REST API in ServiceNow?

  • Navigate to System Web Services > Scripted REST APIs, click ‘New,’ provide a name, base path, and version, and then define resources and methods.

What is a resource in a Scripted REST API?

  • A resource is an endpoint within the API that handles specific HTTP methods (e.g., GET, POST) and is defined by a relative path and script.

What are the main components of a Scripted REST API resource?

  • The main components include the HTTP method, relative path, and the script that processes the request and generates a response.

How can you secure a Scripted REST API?

  • Secure a Scripted REST API using authentication methods such as OAuth 2.0, Basic Auth, or API keys, and enforce role-based access control through ACLs.

What are ACLs and how are they used in Scripted REST APIs?

  • ACLs (Access Control Lists) restrict access to resources based on user roles, ensuring only authorized users can access certain API endpoints.

How do you access query parameters in a Scripted REST API?

  • Query parameters can be accessed using request.queryParams['parameterName'].

How do you process the request body in a Scripted REST API?

  • The request body is accessed through request.body.data for JSON data and can be parsed and processed within the script.

How can you set the HTTP response status in a Scripted REST API?

  • Use response.setStatus(statusCode) to set the desired HTTP status code in the response.

How do you implement error handling in a Scripted REST API?

  • Use try-catch blocks to catch exceptions, log errors using gs.error(), and set appropriate HTTP status codes and error messages in the response.

What is the importance of logging in Scripted REST APIs?

  • Logging helps in troubleshooting, monitoring, and auditing API usage and errors, making it easier to maintain and support the API.

How do you return complex JSON objects in a Scripted REST API response?

  • Create a JavaScript object or array, populate it with data, and use JSON.stringify() to convert it to a JSON string to be sent in the response body.

What is the use of GlideRecord in Scripted REST APIs?

  • GlideRecord is used to interact with the ServiceNow database, allowing CRUD operations on records within the API scripts.

How would you implement pagination in a Scripted REST API?

  • Implement pagination by accepting limit and offset query parameters, and use these values to limit and skip records in a GlideRecord query.

How do you manage versioning for a Scripted REST API?

  • Include the version number in the base path of the API, such as /api/namespace/v1/resource, and create new versions for significant changes.

What are the best practices for naming endpoints in Scripted REST APIs?

  • Use clear, consistent, and descriptive names for endpoints, typically using nouns for resources (e.g., /api/namespace/v1/users).

How can you test Scripted REST APIs in ServiceNow?

  • Use the REST API Explorer, Postman, or any HTTP client to send requests to the API endpoints and validate the responses.

What should be considered when deploying Scripted REST APIs in a production environment?

  • Ensure thorough testing, implement proper error handling and security, and monitor performance and usage.

How can you optimize the performance of a Scripted REST API?

  • Minimize database queries, use caching strategies, and ensure efficient use of GlideRecord operations.

What tools can be used to monitor the performance of Scripted REST APIs?

  • Use ServiceNow’s built-in monitoring tools, external APM tools, and analyze logs and metrics.

Give an example of a use case for a Scripted REST API in ServiceNow.

  • Integrating ServiceNow with an external incident management system to automatically create incidents based on external triggers.

How would you handle authentication for external systems calling your Scripted REST API?

  • Use OAuth 2.0 for secure token-based authentication, or API keys for simpler integrations, ensuring secure transmission over HTTPS.

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