add logging doc section

guide/src/SUMMARY.md

@@ -6,3 +6,9 @@
 - [Handler](./qs_4.md)
 - [Resources and Routes](./qs_5.md)
 - [Application state](./qs_6.md)
+- [Request](./qs_7.md)
+- [Response](./qs_8.md)
+- [WebSockets](./qs_9.md)
+- [User sessions](./qs_10.md)
+- [Logging](./qs_11.md)
+- [Static file handling](./qs_12.md)

guide/src/qs_10.md

@@ -0,0 +1 @@
+# User sessions

guide/src/qs_11.md

@@ -0,0 +1,59 @@
+# Logging
+
+Logging is implemented as middleware. Middlewares get executed in same order as registraton order.
+It is common to register logging middleware as first middleware for application. 
+Logging middleware has to be registered for each application.
+
+## Usage
+
+Create `Logger` middlewares with the specified `format`.
+Default `Logger` could be created with `default` method, it uses the default format:
+
+```ignore
+  %a %t "%r" %s %b "%{Referrer}i" "%{User-Agent}i" %T
+```
+```rust
+extern crate actix_web;
+use actix_web::Application;
+use actix_web::middlewares::Logger;
+
+fn main() {
+    Application::default("/")
+       .middleware(Logger::default())
+       .middleware(Logger::new("%a %{User-Agent}i"))
+       .finish();
+}
+```
+
+Here is example of default logging format:
+
+```
+INFO:actix_web::middlewares::logger: 127.0.0.1:59934 [02/Dec/2017:00:21:43 -0800] "GET / HTTP/1.1" 302 0 "-" "curl/7.54.0" 0.000397
+INFO:actix_web::middlewares::logger: 127.0.0.1:59947 [02/Dec/2017:00:22:40 -0800] "GET /index.html HTTP/1.1" 200 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:57.0) Gecko/20100101 Firefox/57.0" 0.000646
+```
+
+## Format
+
+ `%%`  The percent sign
+
+ `%a`  Remote IP-address (IP-address of proxy if using reverse proxy)
+
+ `%t`  Time when the request was started to process
+
+ `%P`  The process ID of the child that serviced the request
+
+ `%r`  First line of request
+
+ `%s`  Response status code
+
+ `%b`  Size of response in bytes, including HTTP headers
+
+ `%T` Time taken to serve the request, in seconds with floating fraction in .06f format
+
+ `%D`  Time taken to serve the request, in milliseconds
+
+ `%{FOO}i`  request.headers['FOO']
+
+ `%{FOO}o`  response.headers['FOO']
+
+ `%{FOO}e`  os.environ['FOO']

guide/src/qs_12.md

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+# Static file handling

guide/src/qs_7.md

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+# Request

guide/src/qs_8.md

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+# Response

guide/src/qs_9.md

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+# WebSockets