Regroup packages related to logging into a separate module and polish document (#1355)

pom.xml

@@ -76,6 +76,7 @@
         <module>sentinel-demo</module>
         <module>sentinel-benchmark</module>
         <module>sentinel-cluster</module>
+        <module>sentinel-logging</module>
     </modules>
 
     <dependencyManagement>

sentinel-extension/pom.xml

@@ -22,7 +22,6 @@
         <module>sentinel-datasource-spring-cloud-config</module>
         <module>sentinel-datasource-consul</module>
         <module>sentinel-datasource-etcd</module>
-        <module>sentinel-logging-extension-slf4j</module>
     </modules>
 
 </project>

sentinel-logging/pom.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>com.alibaba.csp</groupId>
+        <artifactId>sentinel-parent</artifactId>
+        <version>1.7.2-SNAPSHOT</version>
+    </parent>
+    <artifactId>sentinel-logging</artifactId>
+    <packaging>pom</packaging>
+
+    <modules>
+        <module>sentinel-logging-slf4j</module>
+    </modules>
+
+</project>

sentinel-extension/sentinel-logging-extension-slf4j/README.md → sentinel-logging/sentinel-logging-slf4j/README.md

@@ -1,22 +1,19 @@
 # Sentinel Logging Extension SLF4J
 
-To use Sentinel Logging Extension SLF4J with Log4j2, you should add the following dependency firstly:
+To integrate logs of sentinel into your project which uses slf4j for bridge of logging you can
+simply introduce following dependency to your project:
 
 ```xml
 <dependency>
     <groupId>com.alibaba.csp</groupId>
-    <artifactId>sentinel-logging-extension-slf4j</artifactId>
-    <version>x.y.z</version>
-</dependency>
-<dependency>
-    <groupId>org.slf4j</groupId>
-    <artifactId>slf4j-api</artifactId>
-    <version>${slf4j.version}</version>
+    <artifactId>sentinel-logging-slf4j</artifactId>
+    <version>${sentinel.version}</version>
 </dependency>
 ```
-If you want to use Slf4j with Log4j2, you can add dependencies of Log4j2 and the binding about Log4j2 and SLF4J.
-Then you should provide logging configuration as specification of the logging framework. 
-And you can add Sentinel's Loggers that it name is `sentinelRecordLogger` or `sentinelCommandCenterLogger` for your needs. For example: 
+
+And if you want to control level of logging special for sentinel the loggers that sentinel uses
+are called `sentinelRecordLogger` and `sentinelCommandCenterLogger`. For example in XML configration
+coming with log4j2 implementation:
 
 ```xml
 <?xml version="1.0" encoding="UTF-8" ?>
@@ -45,5 +42,3 @@ And you can add Sentinel's Loggers that it name is `sentinelRecordLogger` or `se
     </Loggers>
 </Configuration>
 ```
-
-

sentinel-extension/sentinel-logging-extension-slf4j/pom.xml → sentinel-logging/sentinel-logging-slf4j/pom.xml

@@ -3,13 +3,13 @@
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <parent>
-        <artifactId>sentinel-parent</artifactId>
+        <artifactId>sentinel-logging</artifactId>
         <groupId>com.alibaba.csp</groupId>
         <version>1.7.2-SNAPSHOT</version>
     </parent>
     <modelVersion>4.0.0</modelVersion>
 
-    <artifactId>sentinel-logging-extension-slf4j</artifactId>
+    <artifactId>sentinel-logging-slf4j</artifactId>
     <packaging>jar</packaging>
 
     <properties>
@@ -57,4 +57,4 @@
         </dependency>
 
     </dependencies>
-</project>
+</project>