我正在使用Angular 7服务器端渲染（SSR），并在后端使用连续的API调用来面对此问题。通常在访问主页时会进行这些调用，然后继续调用相同的URL。可能是什么原因？ 我已经在使用HttpTransferState和HttpTransferCache来避免请求重复，但这是SSR的正常现象吗？
172.31.20.55 - - [20/Mar/2019:17:12:07 +0000] "GET /api/products/ HTTP/1.1" 200 9222 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:07 +0000] "GET /api/category/ HTTP/1.1" 200 210 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:07 +0000] "GET /api/questions/?paginate=false HTTP/1.1" 200 267281 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:08 +0000] "GET /api/articles/?paginate=false HTTP/1.1" 200 105351 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:08 +0000] "GET /api/category/ HTTP/1.1" 200 210 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:08 +0000] "GET /api/products/ HTTP/1.1" 200 9222 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:08 +0000] "GET /api/questions/?paginate=false HTTP/1.1" 200 267281 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:09 +0000] "GET /api/articles/?paginate=false HTTP/1.1" 200 105351 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:10 +0000] "GET /api/questions/?paginate=false HTTP/1.1" 200 267281 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:10 +0000] "GET /api/articles/?paginate=false HTTP/1.1" 200 105351 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:36 +0000] "GET /api/category/ HTTP/1.1" 200 210 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:36 +0000] "GET /api/products/ HTTP/1.1" 200 9222 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:37 +0000] "GET /api/category/ HTTP/1.1" 200 210 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:37 +0000] "GET /api/products/ HTTP/1.1" 200 9222 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:37 +0000] "GET /api/questions/?paginate=false HTTP/1.1" 200 267281 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:38 +0000] "GET /api/articles/?paginate=false HTTP/1.1" 200 105351 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:38 +0000] "GET /api/category/ HTTP/1.1" 200 210 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:38 +0000] "GET /api/products/ HTTP/1.1" 200 9222 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:39 +0000] "GET /api/questions/?paginate=false HTTP/1.1" 200 267281 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:39 +0000] "GET /api/articles/?paginate=false HTTP/1.1" 200 105351 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:40 +0000] "GET /api/questions/?paginate=false HTTP/1.1" 200 267281 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"
172.31.20.55 - - [20/Mar/2019:17:12:40 +0000] "GET /api/articles/?paginate=false HTTP/1.1" 200 105351 "-" "Mozilla/5.0 (Linux x64) node.js/8.15.1 v8/6.2.414.75"