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ServiceNow GraphQL Interview Questions 2024

Sure, here are 30 top-notch interview questions and answers about the ServiceNow GraphQL API based on the documentation:

Question: What is the primary purpose of GraphQL in ServiceNow?
Answer: GraphQL in ServiceNow allows developers to create and expose custom GraphQL APIs to query and manipulate data across the platform. This provides a flexible and efficient way to interact with ServiceNow data and services.

Question: How does GraphQL differ from REST APIs regarding data fetching?
Answer: GraphQL allows clients to specify the exact data they need in a single request, reducing the number of API calls and data over-fetching. REST APIs, on the other hand, may require multiple endpoints and often return fixed data structures, leading to over-fetching or under-fetching of data.

Question: Explain the concept of a ‘Schema’ in GraphQL.
Answer: A GraphQL schema defines the API’s structure, including the types of data available, the relationships between them, and the operations (queries and mutations) that can be performed. It serves as a contract between the client and the server.

Question: What are ‘Resolvers’ in GraphQL, and how are they used in ServiceNow?
Answer: Resolvers are functions that handle the logic for fetching and manipulating data based on the schema definitions. In ServiceNow, resolvers map GraphQL queries and mutations to specific scripts or GlideRecord operations.

Question: Describe the role of ‘Query’ and ‘Mutation’ in a GraphQL schema.
Answer: Queries in GraphQL are used to read or fetch data, while mutations are used to modify data (create, update, delete). Both are defined in the schema and executed by resolvers.

Question: How do you define a custom GraphQL API in ServiceNow?
Answer: In ServiceNow, custom GraphQL APIs are defined using Scripted APIs. Developers create a scripted API, define the schema, and implement resolvers using server-side JavaScript.

Question: What are some advantages of using GraphQL over traditional APIs in ServiceNow?
Answer: Advantages include reduced API calls, precise data fetching, improved performance, strong typing, and more efficient data interaction patterns.

Question: How can you secure a GraphQL API in ServiceNow?
Answer: Security can be enforced using authentication and authorization mechanisms like OAuth, API keys, and ACLs (Access Control Lists). Additionally, input validation and query complexity analysis help prevent abuse.

Question: What are ‘Fragments’ in GraphQL, and how do they improve query efficiency?
Answer: Fragments allow the reuse of common query parts to avoid redundancy. They can be defined once and included in multiple queries, enhancing the code’s readability and maintainability.

Question: Explain how GraphQL handles real-time data updates.
Answer: GraphQL handles real-time data updates through subscriptions, which allow clients to receive updates when data changes. However, in ServiceNow, real-time capabilities might need additional configurations or WebSockets.

Question: What is introspection in GraphQL, and why is it useful?
Answer: Introspection is a feature in GraphQL that allows clients to query the schema for details about the types and operations it supports. It is useful for tools that generate documentation or for clients to understand the API structure dynamically.

Question: How does ServiceNow handle versioning in GraphQL APIs?
Answer: ServiceNow recommends designing GraphQL APIs in a backward-compatible manner, leveraging the flexible schema to add new fields without removing or altering existing ones, thus minimizing the need for versioning.

Question: Describe a typical use case for GraphQL in a ServiceNow application.
Answer: A typical use case might be creating a single endpoint to fetch detailed incident reports, including related records like user information, comments, and attachments, all in one request.

Question: How do you test GraphQL APIs in ServiceNow?
Answer: Testing can be done using GraphiQL or similar tools to construct and execute queries and mutations. ServiceNow also provides API testing capabilities within the platform.

Question: What is the ‘GraphQL Explorer’ role in ServiceNow?
Answer: ServiceNow provides the GraphQL Explorer, a tool for testing and interacting with GraphQL APIs. It allows developers to construct queries and mutations and view the schema.

Question: Can you describe how to paginate results in a GraphQL query?
Answer: Pagination in GraphQL can be implemented using cursors or offset-based pagination. Cursors are recommended for better performance and reliability, using parameters like first, last, before, and after.

Question: What are some common pitfalls when designing GraphQL APIs?
Answer: Common pitfalls include overcomplicating the schema, not properly securing the API, inefficient query designs that can lead to performance issues, and a lack of proper documentation.

Question: How do you handle error management in GraphQL?
Answer: Error management in GraphQL involves returning error objects in the response, which include details about the error. Custom error messages can also be defined in resolvers for more precise feedback.

Question: Explain how batching and caching can improve GraphQL performance.
Answer: Batching groups multiple queries into a single request to reduce the number of round-trips. Caching stores the results of queries to reuse them for subsequent requests, reducing the load on the server.

Question: What is the difference between @include and @skip Directives in GraphQL?
Answer: The @include Directive conditionally includes a field in the query based on a boolean expression, while the @skip Directive excludes a field based on a boolean expression.

Question: How does ServiceNow ensure backward compatibility with GraphQL schemas?
Answer: ServiceNow ensures backward compatibility by following best practices, such as avoiding field removal or renaming and instead opting to deprecate fields and provide alternatives.

Question: What tools or libraries can be used to build and consume GraphQL APIs in ServiceNow?
Answer: Developers can use tools like GraphiQL for testing, Apollo Client for consuming APIs, and various JavaScript libraries for building resolvers and schemas.

Question: How are relationships between data types handled in a GraphQL schema?
Answer: Relationships are handled by defining fields that reference other types. For example, an Incident Type might have a reporter field referencing a User Type, allowing nested queries.

Question: What is the purpose of custom scalar types in GraphQL?
Answer: Custom scalar types define application-specific data types beyond the default ones provided by GraphQL (e.g., Date, URL). They enable precise data validation and formatting.

Question: How do you implement field-level access control in GraphQL?
Answer: Field-level access control can be implemented using resolvers to check user permissions before returning data. ServiceNow’s ACLs can also be leveraged within resolvers for fine-grained control.

Question: Describe the role of GraphQLObjectType In defining a GraphQL schema.
Answer: GraphQLObjectType is used to define the structure of objects in a schema, including their fields and relationships to other types. It forms the building blocks of the schema.

Question: How can you optimize GraphQL queries to prevent performance bottlenecks?
Answer: Optimizing GraphQL queries involves techniques like data loader patterns to batch database requests, query complexity analysis to limit expensive operations, and efficient resolver logic.

Question: Explain the importance of the context Object in GraphQL resolvers.
Answer: The context Object in GraphQL resolvers provides shared data and services (e.g., authentication details, database connections), enabling consistent and secure data access.

Question: How do you handle file uploads in a GraphQL API?
Answer: File uploads in GraphQL can be handled using multipart requests, typically with libraries like graphql-upload Which integrates with existing GraphQL servers to manage file streams.

Question: What are some best practices for designing a GraphQL API in ServiceNow?
Answer: Best practices include defining a clear and concise schema, using descriptive names and documentation, securing the API with proper authentication and authorization, optimizing query performance, and maintaining backward compatibility.

These questions and answers should help you prepare effectively for an interview focused on the ServiceNow GraphQL API.

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