--- sourceDocument: Brazil API Reference sourceDocumentLink: https://www.servicenow.com/docs/r/api-reference Release : - brazil ft:locale : - en-US ft:publication_title : - Brazil API Reference ft:clusterId : - crapiref bundleId : - crapiref workflow : - Creator --- # Scripted REST API example - streaming vs object serialization # Scripted REST API example - streaming vs object serialization {#ariaid-title1} Release version: Brazil Updated September 10, 2026 ![](https://www.servicenow.com/docs/portal-asset/ico-clock) 4 minutes to read Summarize ![AI sparkle icon](https://servicenow.com/docs/portal-asset/ai-sparkle-icon) Summarized using AI This content was generated using new OpenAI-powered functionality. Results are provided on an as is basis and are not guaranteed to be accurate or complete. ## Summary of Scripted REST API example - streaming vs object serialization This guide explains two approaches to sending JSON responses in ServiceNow Scripted REST APIs: streaming responses and object serialization. It helps you choose the right method based on response size, format, and performance requirements, providing sample code for each approach to return incident records. Show full answer Show less ## Streaming Responses Streaming allows you to send response data progressively, improving response time and instance performance, especially for large or variable-sized payloads or non-JSON/XML formats. However, it requires manual formatting of the response, setting HTTP status, and headers. The provided streaming example uses `response.getStreamWriter()` to write JSON data for up to 100 incident records directly to the output stream, enabling faster delivery as data is generated. Additionally, streaming supports pagination of large datasets using the `chooseWindow()` method on scoped GlideRecord objects, allowing you to limit records per response efficiently. ## Object Serialization Object serialization leverages ServiceNow's built-in serialization and content negotiation for JSON or XML responses. It requires building the entire response object before sending, which may delay responses and consume more system resources for large datasets. The example shows collecting incident records into an array and returning the complete array, letting ServiceNow handle JSON serialization and HTTP headers automatically. ## Choosing Between Streaming and Object Serialization * **Use object serialization** when your response is simple, consistently sized, and in JSON or XML format, benefiting from ease of implementation and automatic handling by ServiceNow. * **Use streaming** when dealing with large, variable-sized responses, non-JSON/XML formats, or when you need faster response times and better instance resource management at the cost of increased scripting complexity. ## Practical Benefits for ServiceNow Customers * Improved API performance and scalability by choosing streaming for large or complex responses. * Simplified API development for straightforward responses using object serialization. * Flexibility to implement pagination in streaming APIs to manage large datasets efficiently. * Control over response content formatting and HTTP headers when streaming. These examples demonstrate how to send a JSON response using streaming and using default object serialization. ## Streaming vs object serialization When sending a response, you can send a response as a stream or serialize an object. There are advantages and disadvantages to either approach. Pick a technique based on the needs of your integration. Generally, if the response object is simple, can be represented as XML or JSON, and is a consistent size, use object serialization. If using a format other than XML or JSON or if the size of the response varies, use streaming. ## Streaming the response Using a streaming responses provides advantages in response time, instance performance, and content flexibility, but adds additional complexity to the script. When using streaming, you are responsible for formatting the response, setting the response status, and setting the Content-Type header. When streaming a response, the requesting user receives a response quickly because the entire response does not need to be created before starting streaming. This example demonstrates a Scripted REST Resource script that returns an array of incident records using streaming. /** * Sample Scripted REST Resource that returns custom JSON objects with properties from Incident GlideRecords * This sample uses ServiceNow JavaScript API to query incident records * and then iterates over those records to build and stream a custom JSON object that * includes some values from the incidents */ (function runOperation(/*RESTServiceRequest*/ request, /*RESTServiceResult*/ response) { var writer = response.getStreamWriter(), hdrs = {}, table = 'incident', record_limit = 100, gr = new GlideRecord(table); hdrs['Content-Type'] = 'application/json'; response.setStatus(200); response.setHeaders(hdrs); gr.setLimit(record_limit); gr.query(); // start building response object writer.writeString("{\"results\":["); // iterate over incident records and build JSON representations to be streamed out. while (gr.next()) { var incidentObj = {}; incidentObj.number = gr.number + ''; incidentObj.short_description = gr.short_description + ''; writer.writeString(global.JSON.stringify(incidentObj)); if (gr.hasNext()) { writer.writeString(","); } } // close the response object writer.writeString("]}"); })(request, response); A request to this resource returns the following response. // sample response /* HTTP/1.1 200 OK Content-Type: application/json Server: ServiceNow // sample response number of records returned has been truncated for this example { "results": [ { "number": "INC0011301", "short_description": "lorem ipsum short description 0 my new incident" }, { "number": "INC0011302", "short_description": "lorem ipsum short description 1 my new incident" }, { "number": "INC0011303", "short_description": "lorem ipsum short description 2 my new incident" }, { "number": "INC0011304", "short_description": "lorem ipsum short description 3 my new incident" }, { "number": "INC0011309", "short_description": "lorem ipsum short description 8 my new incident" }, { "number": "INC0011310", "short_description": "lorem ipsum short description 9 my new incident" }, { "number": "INC0011311", "short_description": "lorem ipsum short description 0 my new incident" }, { "number": "INC0011312", "short_description": "lorem ipsum short description 1 my new incident" }, { "number": "INC0011313", "short_description": "lorem ipsum short description 2 my new incident" }, { "number": "INC0011314", "short_description": "lorem ipsum short description 3 my new incident" }, { "number": "INC0011315", "short_description": "lorem ipsum short description 4 my new incident" }, { "number": "INC0011326", "short_description": "lorem ipsum short description 15 my new incident" } ] } */ ## Streaming pagination {#r_ScriptedRESTExampleStreamVsLO__section_xxx_3jp_myb} To paginate large tables so that you only send a limited number of records per query, use the [Scoped GlideRecord - chooseWindow(Number firstRow, Number lastRow, Boolean forceCount)](https://www.servicenow.com/docs/FgjTlm40d6FI5VbkwXi4qQ#r_ScopedGlideRecordChooseWindow_Number_Number_Boolean "Sets a range of rows to be returned by subsequent queries.") method. The Community article [Paginated Glide Record + Expanded GR Method Support](https://www.servicenow.com/community/developer-articles/paginated-glide-record-expanded-gr-method-support/ta-p/2300446) exemplifies how to use chooseWindow() to achieve pagination, which you can adapt to your own particular use case. ## Building an object Using object serialization allows you to take advantage of ServiceNow provided serialization and content negotiation. When serializing an object instead of streaming, the entire object must be created and serialized before the client receives a response. This may delay the response, or require a large amount of system resources if the response object is very large. Object serialization is available only for XML or JSON responses. Responses using a different format must use streaming. This example returns the same Incident data as the streaming example, but collects all of the response data in an array before sending the response. /** * Sample Scripted REST Resource returns an array of custom JSON objects that include 2 incident properties. * This sample uses ServiceNow JavaScript API to query incident records and then iterates * over those records building a custom JSON object that includes 2 values from the incident records. * note that because we are returning a simple JSON object we can rely on built in serialization * to set the content-type header as well as response status. The 'result_arr' object will not be returned * until it has been completely built and stored */ (function runOperation(/*RESTServiceRequest*/ request, /*RESTServiceResult*/ response) { var table = 'incident', record_limit = 100, result_arr = [], gr = new GlideRecord(table); gr.setLimit(record_limit); gr.query(); // iterate over incident records and build JSON representations to be streamed out. while (gr.next()) { var incidentObj = {}; incidentObj.number = gr.number + ''; incidentObj.short_description = gr.short_description + ''; result_arr.push(incidentObj); } return result_arr; })(request, response); A request to this resource returns the following response. /* HTTP/1.1 200 OK Content-Type: application/json;charset=UTF-8 Server: ServiceNow // sample response number of records returned has been truncated for this example { "result": [{ "short_description": "lorem ipsum short description 0 my new incident", "number": "INC0011301" }, { "short_description": "lorem ipsum short description 1 my new incident", "number": "INC0011302" }, { "short_description": "lorem ipsum short description 2 my new incident", "number": "INC0011303" }, { "short_description": "lorem ipsum short description 3 my new incident", "number": "INC0011304" }, { "short_description": "lorem ipsum short description 4 my new incident", "number": "INC0011305" }, { "short_description": "lorem ipsum short description 5 my new incident", "number": "INC0011306" }, { "short_description": "lorem ipsum short description 6 my new incident", "number": "INC0011307" }, { "short_description": "lorem ipsum short description 7 my new incident", "number": "INC0011308" }, { "short_description": "lorem ipsum short description 8 my new incident", "number": "INC0011309" }, { "short_description": "lorem ipsum short description 9 my new incident", "number": "INC0011310" }] } */