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Browser Synthetic Monitoring uses geographically distributed agents to generate snapshots and aggregate metrics of web page download performance on a continuing basis. This allows you to monitor the performance of critical pages independently of user generated load. You can compare synthetic and real user load by page and region to get a deeper understanding of what is impacting any, particularly outlier, performance issues. You can also use synthetic data to test for SLA compliance.
There are two ways of using Synthetic:
- Scheduled jobs: Use this to create a performance baseline for your pages, and to make sure they continue to perform well. Using this feature requires a Synthetic Pro license. See here for more information.
- On-demand snapshots: Use this to check out an immediate issue. This feature is available with both Synthetic Lite and Pro licenses.
For 4.2, Browser Synthetic Monitoring is only supported in accounts that use the SaaS-based EUM Cloud for EUM processing. Accounts that use an on-premise EUM Server do not support Synthetic.
- Open the application in which you are interested.
- Select the appropriate option in the left navigation bar.
The Jobs, Sessions, and Pages options are only displayed if you have a Browser Synthetic Pro license.
- Create and manage scheduled jobs using Jobs.
- Analyze the stages of individual job instances, including script-based multi-page runs, using Sessions. This feature is backed by the Event Store.
- See detailed aggregate metric breakdowns using Pages.
Create and view on-demand snapshots using On-Demand.
Browser Synthetic produces many of the same metrics as Browser RUM with the addition of some Synthetic only metrics.
Performance metrics derived from synthetic jobs can also be seen in the Metric Browser, just like RUM metrics.
There are metrics for specific tests and, under the Synthetic Jobs heading, for Synthetic job health overall.
Alerting and Synthetic
There are two types of events generated by Synthetic that can be used to trigger Policies and Actions:
Availability is based on the status of the request
- Single URL jobs
- Warning = 4xx response (BROKEN)
- Critical = 5xx response, time out, cannot contact application (FAILED)
- Scripted jobs
- Warning = your script threw an uncaught exception (BROKEN)
- Critical = your script had an assertion failure or timed out (FAILED)
Warning or Error events trigger automatic retries. To avoid initiating an alert based on a single, possibly anomalous, run of the job, select Warning/Error confirmed after retest.
Performance events are based on criteria you set up when you set up scheduled jobs.
- Click + Add to add a new job.
- In the New Job popup, scroll down to Configure Performance Thresholds:
- Click + to add a performance threshold for triggering a warning event.
- Select a performance threshold, enter a value that will trigger a warning event, and then select when the event should fire—immediately or after 2, 3, 5, or 10 consecutive failures.
- You can select multiple performance thresholds by clicking the + multiple times.
The table below gives descriptions for the supported performance thresholds.
|End User Response Time||When the |
|Time Until Page Is Fully Loaded||When the page will be fully loaded|
|Visually Complete Time||When the viewport has been rendered|
|First Byte Time||When the first byte is received|
|Start Render Time||When the page starts to render|
|Bytes per Pageview||The number of bytes per page view|
You can use Synthetic Availability and Performance events to trigger policies, which can, for example, send an alerting email.
- In the left navigation bar, click Alert & Respond -> Policies
- Click +Create Policy
- Look in Other Events
For more information on using Policies, see Configure Policies.
In general, Browser Synthetic Monitoring is most useful for HTML end points. But it is possible to use Synthetic to test JSON end points, for example, a REST API. However be aware that IE does not fully support JSON response contents, so you should select Chrome or Firefox if you chose to use Synthetic in this way. For version 4.2.3 and later, IE does support JSON response contents.