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## Api docs
### 1. Message
* message = CreateMessage("topicName")
- function description
create a message instance, by setting topic field
- input
topicName: a topic name
- return
a new message instance, after used it, you need call DestroyMessage(message)
* DestroyMessage(message)
- function description
destroy a message instance, delete memmory
- input
message: message instance
* SetMessageTopic(message, topic)
- function description
set topic field value for the message
- input
message: message instance
topic: a topic name
* SetMessageTags(message, tags)
- function description
set tag field value for the message
- input
message: message instance
tags: tag for the topic
* SetMessageKeys(message, keys)
- function description
set key field value for the message
- input
message: message instance
keys: key for the topic
* SetMessageBody(message, stringBody)
- function description
set body for the message
- input
message: message instance
body: message body as string
* SetByteMessageBody(message, byteBody, byteLength)
- function description
set body for the message
- input
message: message instance
byteBody: message body as byte[]
byteLength: byteBody's length
* SetMessageProperty(message, key, value)
- function description
set extend k-v for message
- input
message: message instance
key: string key
value: string value
* SetMessageDelayTimeLevel(message, level)
- function description
set delay level
- input
message: message instance
level: delay level as int
### 2. MessageExt
* topic = GetMessageTopic(msgExt)
- function description
get topic name from a message instance
- input
msgExt: message instance
- return
topic: topic name
* tag = GetMessageTags(msgExt)
- function description
get tag from a message instance
- input
msgExt: message instance
- return
tag: tag
* key = GetMessageKeys(msgExt)
- function description
get message key from a message instance
- input
msgExt: message instance
- return
key: message key
* body = GetMessageBody(msgExt)
- function description
get message body from a message instance
- input
msgExt: message instance
- return
body: message body as string
* value = GetMessageProperty(msgExt, key)
- function description
get a message proprty value from a message instance
- input
msgExt: message instance
key: property key
- return
value: property value as string
* messageId = GetMessageId(msgExt)
- function description
get a message id from a message instance
- input
msgExt: message instance
- return
messageId: message id as string