define the specification document for oss (alibaba#190)

* define the specification document for oss

docs/specs/2018-04-03-zh-cn.md

@@ -275,6 +275,7 @@ test-topic:
 - [RDS](#rds)
 - [MNSTopic](#mns_topic)
 - [TableStore](#tablestore)
+- [OSS](#OSS)
 
 #### Timer
 
@@ -423,7 +424,32 @@ tablestore-trigger-test: # trigger name
         InstanceName: test-inst
         TableName: test-tbl
 ```
+#### OSS
 
+描述类型为 [OSS 触发器](https://help.aliyun.com/document_detail/62922.html) 的对象。
+
+##### 属性
+
+属性名称 | 类型 | 描述
+---|:---:|---
+events| `array` | **必填。** 为 OSS 端触发函数执行的事件，比如参数为 ["oss:ObjectCreated:PutObject", "oss:ObjectCreated:PutSymlink"] 等...
+filter   | `object` | **选填。** 为 OSS 对象过滤参数，满足过滤条件的 OSS 对象才可以触发函数，包含一个配置属性 key，表示过滤器支持过滤的对象键 (key)。 
+key | [key 对象](#key-配置对象) | **选填。** 过滤器支持过滤的对象键
+
+##### 示例：OSS 事件源对象
+
+```yaml
+oss-trigger-test: # trigger name
+    Type: OSS # trigger type
+     Properties:
+      events:
+        - oss:ObjectCreated:*
+        - oss:ObjectRemoved:DeleteObject
+      filter: 
+        key:
+          prefix: source/
+          suffix: .png
+```
 
 ### Property 类型
 
@@ -571,4 +597,17 @@ PathConfig 用于设置自定义域名中路径与函数的映射关系。
   '/a': # path
         serviceName: serviceA
         functionName: functionA
+```
+
+#### key-配置对象
+
+key 配置对象包含的属性包括： `prefix` 和 `suffix` 属性。它们所代表的含义分别为：匹配前缀和匹配后缀。
+
+示例：
+
+```
+key:
+  prefix: source/
+  suffix: .png
+
 ```

docs/specs/2018-04-03.md

@@ -247,6 +247,7 @@ test-log-project:
 - [RDS](#rds)
 - [MNSTopic](#mns_topic)
 - [TableStore](#tablestore)
+- [OSS](#OSS)
 
 #### Timer
 
@@ -396,6 +397,33 @@ tablestore-trigger-test: # trigger name
         TableName: test-tbl
 ```
 
+#### OSS
+
+Describe the object of type [OSS Trigger](https://help.aliyun.com/document_detail/62922.html)。
+
+##### Properties
+
+Property Name | Type | Description
+---|:---:|---
+events | `array` | **Required.** Indicates the type of an OSS event.
+filter | `object` | **Optional.** Filters OSS events. Only OSS objects that meet the filtering condition can trigger a function. This parameter has a key attribute:
+key | [`key configuration object`](#key-configuration-object) | **Optional。** Indicates the key supported by the filter.
+
+##### Example: OSS event source object
+
+```yaml
+oss-trigger-test: # trigger name
+    Type: OSS # trigger type
+     Properties:
+      events:
+        - oss:ObjectCreated:*
+        - oss:ObjectRemoved:DeleteObject
+      filter: 
+        key:
+          prefix: source/
+          suffix: .png
+```
+
 ### Property types
 
 - [Event source object](#event-source-object)
@@ -544,3 +572,17 @@ Example：
         serviceName: serviceA
         functionName: functionA
 ```
+
+#### key configuration object
+
+The properties that the key configuration object contains include the `prefix` and `suffix` attributes. 
+They mean the following: matching prefix and matching suffix.
+
+Example: 
+
+```
+key:
+  prefix: source/
+  suffix: .png
+  
+```