Ordinary uptime monitoring asks three things: does the URL respond, with what status code, and how fast.<\/p>\n
All three share a blind spot: they look at the response, not the content.<\/strong><\/p>\n The frame of the page is rendered by a template. The content is filled in from a data source. When the data source comes back with nothing, the frame renders anyway.<\/p>\n So you get a page with a 200, a title, a menu, a footer and a complete structure, and a blank space in the middle.<\/p>\n The monitoring is happy. The visitor sees an empty page.<\/p>\n Our probes no longer look at status codes. They look at how much text is in the main content area<\/strong>.<\/p>\n They grab the main content block, strip the tags and count the characters that are left. Below the threshold, it’s red, whatever the status code says.<\/p>\n The threshold has to be set page by page, since a listing page and a contact page differ by an order of magnitude. If you can’t settle on a number for a page, at least set “not zero.”<\/p>\n “It ran successfully” doesn’t mean “it produced something.”<\/strong> A batch job that exits with code 0 might have processed 300 records, or none.<\/p>\n “The file exists” doesn’t mean “the file has something in it.”<\/strong> A failed write can leave a zero-byte file behind, and most downstream steps only check that it exists.<\/p>\n \u2b50 Every green light should answer one question: does it prove “I finished,” or “the thing is there”?<\/strong> The distance between those two is exactly how much room it has to lie.<\/p>\n","protected":false},"excerpt":{"rendered":" Monitoring says the site is up. The header, menu and footer are all there. The main content area in the middle is completely blank.<\/p>\n","protected":false},"author":1,"featured_media":1014,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[29],"tags":[],"class_list":["post-2148","post","type-post","status-publish","format-standard","has-post-thumbnail","category-web-notes-en-us"],"yoast_head":"\nA page can be a 200 and empty at once<\/h2>\n
Judge by content instead<\/h2>\n
The same shape shows up elsewhere<\/h2>\n