技术求助：有人成功为ServiceNow应用创建JMeter脚本吗？求解决关联难题

Absolutely—plenty of us in the testing and automation space have worked through this exact set of headaches with ServiceNow and JMeter. Let’s walk through actionable solutions to clean up your script, trim bloat, and nail those tricky dynamic value correlations.

Cut Down on Unnecessary Recorded Requests #

Recording every single HTTP call ServiceNow makes will flood your script with noise (static assets, analytics beacons, etc.). Here’s how to fix it:

• Skip full recording for core flows: ServiceNow has a built-in API Explorer (accessible at /api/explorer on your instance) with well-documented REST endpoints. Instead of recording every click, manually build requests only for critical actions (e.g., creating an incident, updating a ticket) using endpoints like /api/now/table/incident.
• Filter static resources during recording: When using JMeter’s HTTP(S) Test Script Recorder, head to the Requests Filtering tab and add exclusion patterns to skip irrelevant files:
  • *.css
  • *.js
  • *.png, *.jpg
  • /stats/* (or other analytics-specific paths for your instance)
    This will drastically reduce the number of redundant requests in your script.

Trim Large POST/Response JSON Payloads #

ServiceNow’s JSON responses can be massive, and POST bodies often include auto-generated fields you don’t need. Try these steps:

• Send only required fields in POST requests: Most ServiceNow table APIs only need a handful of fields (e.g., short_description, caller_id for incidents). Omit auto-populated fields like sys_id, sys_created_on, or sys_updated_by—ServiceNow will generate these automatically.
• Filter response fields with the fields parameter: When making GET requests, append ?fields=sys_id,short_description,caller_id to the URL. This tells ServiceNow to return only the fields you need, making responses smaller and easier to parse for dynamic values.
• Externalize static JSON templates: Store reusable JSON structures in a file (e.g., incident_template.json) and load it with JMeter’s ${__FileToString(/path/to/template.json,,)} function. Replace dynamic values with variables to keep your script clean:

  {
    "short_description": "${incident_short_desc}",
    "caller_id": "${caller_sys_id}"
  }
  

Simplify Dynamic Value Correlations #

ServiceNow’s dynamic values (like sys_id, session tokens, or ETags) can feel overwhelming, but there’s a systematic way to handle them:

• Use JSON Extractor for structured data: For most cases, this is your go-to tool. For example, to extract the sys_id of a newly created incident:
  • Set Reference Name to incident_sys_id
  • Use the JSON Path Expression: $.result.sys_id
    This pulls the exact value you need without parsing the entire response.
• Handle session tokens and cookies: JMeter’s HTTP Cookie Manager automatically manages JSESSIONID and most session cookies. For custom tokens (like X-UserToken), use a Response Header Extractor to pull the token from the login response’s headers, then reference it in subsequent requests’ headers.
• Use Groovy for complex JSON parsing: If dealing with nested arrays or deep objects, a JSR223 PostProcessor with Groovy is more flexible than the JSON Extractor. Example:

  import groovy.json.JsonSlurper
  def responseBody = prev.getResponseDataAsString()
  def json = new JsonSlurper().parseText(responseBody)
  // Extract a nested value from the first result in an array
  vars.put("assigned_to_sys_id", json.result[0].assigned_to.value)
  

• Don’t forget ETags: ServiceNow uses ETags for concurrency control on updates. Extract the ETag header from the initial GET request with a Response Header Extractor, then add an If-Match header to your update request using the ${etag_variable} value.

Quick Pro Tips #

• Test one request at a time: Build your script incrementally—get a single request working (with proper correlations) before adding the next.
• Use JMeter’s Debug Sampler: Add this to your script to inspect variables and confirm your extracted values are correct.
• Leverage sysparm_display_value: If you prefer using human-readable values (like a username instead of a sys_id), add sysparm_display_value=true to your request URL. This lets you correlate using values you can easily identify.

内容的提问来源于stack exchange，提问作者Jovica Spasic