Implementing Pagination in ServiceNow Data Source

Introduction

Handling vast datasets from APIs often presents challenges due to the sheer volume of information returned. Pagination is a critical technique in managing and retrieving data efficiently in such scenarios. This article delves into the significance of pagination within ServiceNow when dealing with extensive data from REST APIs.

Understanding Pagination

Pagination involves dividing large datasets into smaller, manageable parts or pages. Within REST APIs, this technique restricts the data returned per request by specifying a page size and offset. This method significantly eases data retrieval, enhances performance, and reduces the burden on both the API server and the client application.

Setting Up the Data Source

As an illustrative example, this article uses the PokeAPI, a well-known source for Pokémon-related data. To initiate the data source setup in ServiceNow, a few prerequisites are necessary:

1. Accessing the ServiceNow Instance: Logging into the ServiceNow instance.
2. Navigating to Data Sources: Locating and accessing the ‘Data Sources’ section within ServiceNow.
3. Adding a New Data Source: Creating a dedicated data source tailored for the PokeAPI using the Data Stream (IntegrationHub) type. This setup includes assigning a source table and connection alias. The subsequent section details the process of creating a Data Stream.

Implementing Pagination

Managing pagination within the PokeAPI involves regulating the page size and offset values during API requests:

• Defining Page Size and Offset: Determining the ideal page size for efficient data retrieval and managing subsequent pages through offset adjustments.
• Constructing the REST API Call: Creating the necessary REST API call within ServiceNow, configuring parameters such as limit and offset for effective pagination.
• Handling Multi-page Responses: Implementing logic to retrieve subsequent pages of data and merging or processing them as required.

Demonstration with ServiceNow

The article proceeds to outline the practical steps of implementing pagination using the PokeAPI within the ServiceNow platform:

Preparation: Setting up the Data Source requires the existence of an Import Set table and Connection Alias, as well as the creation of a Data Stream in the Flow Designer or directly within the Data Source (to be published for selection). Inputs for the Data Stream, like limit, size, URL, and query, can be specified within the Data Source.
Data Stream Configuration: Within the Data Stream setup, inputs like ‘Limit’ are defined for pagination purposes. Multiple inputs, such as limit, size, URL, and query, can be configured to streamline the pagination process.
Request Configuration: This step involves specifying the method to be used (REST/SOAP/JDBC) and enabling Pagination and Script steps to manage additional logic efficiently.
Pagination Logic: Configuring the logic to determine if a next page exists. In this case, the ‘next’ object may contain the URL for the subsequent page, guiding the pagination process.
Scripted Pagination: Creating the URL with pagination parameters, ensuring precise data retrieval in subsequent requests.
REST Configuration: Specifying the Connection Alias and the link established in the previous step, ensuring seamless communication with the API.
Response Parsing: Configuring the type of response data expected and defining the path to the array containing the items of interest within the response.
Data Splitting: Managing entries to format and organize the output items appropriately. In our case the path to the array with items is: /results.
Script Parser Configuration: Setting up the response object with the required keys to align with the previous steps, ensuring data consistency.
Output Configuration: Defining the output structure, aligning it with the keys utilized in the preceding steps.
Testing: Validating the solution to ensure functionality, displaying a limited output (in this case, 20 records) as a demonstration.
Result: Displaying the final outcome, where 1302 Pokémon entries are added to the User’s table from this Data Source.

Conclusion

Pagination techniques, as exemplified using the PokeAPI within ServiceNow, are indispensable for efficiently managing extensive datasets. Embracing pagination methodologies empowers developers to optimize data retrieval, bolster application performance, and adeptly handle voluminous datasets within ServiceNow applications. Readers are encouraged to explore and implement these techniques independently.