update readme

README.md

@@ -17,6 +17,14 @@ Prefer to use Maven:
 ```
 $ # compile the whole project
 $ mvn clean compile package -Dmaven.test.skip=true
+$
+$ # start redis-server, first need to install it
+$ redis-server
+$
+$ # generate protobuf descriptor sets and put to redis
+$ cd karate-grpc-helper && mvn exec:java -Dexec.mainClass=com.github.thinkerou.karate.helper.Main
+$
+$ # test it
 $ cd karate-grpc-demo
 $ # run all tests
 $ mvn test
@@ -243,6 +251,32 @@ Output JSON string also like:
 
 So, use Redis to save descriptor sets which every generate.
 
+Indicates redis address and ask `karate-karate-core` to use redis, for [example](karate-grpc-demo/src/test/java/demo/helloworld/helloworld-new.feature):
+
+```
+Feature: grpc helloworld example by grpc dynamic client
+
+  Background:
+    * def Client = Java.type('com.github.thinkerou.karate.GrpcClient')
+    * def client = Client.create('localhost', 50051)
+    * def client = client.redis('localhost', 6379)
+
+  Scenario: do it
+    * def payload = read('helloworld.json')
+    * def response = client.call('helloworld.Greeter/SayHello', payload)
+    * def response = JSON.parse(response)
+    * print response
+    * match response[0].message == 'Hello thinkerou'
+    * def message = response[0].message
+
+    * def payload = read('again-helloworld.json')
+    * def response = client.call('helloworld.Greeter/AgainSayHello', payload)
+    * def response = JSON.parse(response)
+    * match response[0].details == 'Details Hello thinkerou in BeiJing'
+```
+
+Only use the line `* def client = client.redis('localhost', 6379)` it's OK!
+
 **TODO:**
 
 - Save `ProtoFullName|InputType|InputMessage|OutputType|OutputMessage|ProtoFileName|RPCAddress` not file content.