MQTT的学习研究（九）基于HTTP GET MQTT 抓取消息服务端使用

官方参看文档：

HTTP GET 接收主题请求协议和响应协议
http://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/topic/com.ibm.mq.csqzau.doc/ts21230_.htm

HTTP POST 发布主题请求协议和响应协议
http://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/topic/com.ibm.mq.csqzau.doc/ts21220_.htm

HTTP DELETE 订阅主题请求协议和响应协议
http://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/topic/com.ibm.mq.csqzau.doc/ts21240_.htm

请求响应头各个字段的含义的讲解
http://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/topic/com.ibm.mq.csqzau.doc/ts21250_.htm

响应错误处理
http://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/topic/com.ibm.mq.csqzau.doc/ts21340_.htm

HTTP GET: WebSphere MQ bridge for HTTP command

The HTTP GET operation gets a message from a WebSphere® MQ queue. The message is left on the queue. The HTTP GET operation is equivalent to browsing a WebSphere MQ queue.

Syntax

Request

>>-+-DELETE-+-- --| Path |-- --HTTP version--CRLF--------------->
   '-GET----'                                       

   .-CRLF---------------.  .-CRLF---------------.   
   V                    |  V                    |   
>----+----------------+-+----+----------------+-+--------------->
     '-general-header-'      '-request-header-'     

   .-CRLF----------------------------.   
   V                                 |   
>----+-----------------------------+-+-------------------------><
     '-| Entity-header (Request) |-'     

Path

|--/--contextRoot--/-------------------------------------------->

>--msg/--+-queue/--queueName--+-------------+-+--/--------------|
         |                    '-@--qMgrName-' |      
         '-topic/--topicName------------------'      

entity-header (Request)

|--+----------------------------------------------+-------------|
   +-standard entity-header-- --entity-value------+   
   +-x-msg-correlId - --correlation ID------------+   
   +-x-msg-msgId - --message ID-------------------+   
   +-x-msg-range-- --range------------------------+   
   +-x-msg-require-headers-- --entity header name-+   
   '-x-msg-wait - --wait time---------------------'   

Note:

1. If a question mark (?) is used it must be substituted with %3f. For example, orange?topic should be specified as orange%3ftopic.
2. @qMgrName is only valid on an HTTP POST

Response

>>-HTTP version-- --HTTP Status-Code-- --HTTP Reason-Phrase--CRLF-->

   .-CRLF---------------.  .-CRLF----------------.   
   V                    |  V                     |   
>----+----------------+-+----+-----------------+-+-------------->
     '-general-header-'      '-response-header-'     

   .-CRLF-----------------------------.                      
   V                                  |                      
>----+------------------------------+-+--+---------------+-----><
     '-| Entity-header (Response) |-'    '-CRLF--Message-'   

entity-header (Response)

|--+-----------------------------------------+------------------|
   +-standard entity-header-- --entity-value-+   
   +-x-msg-class-- --message type------------+   
   +-x-msg-correlId-- --correlation ID-------+   
   +-x-msg-encoding-- --encoding type--------+   
   +-x-msg-expiry-- --duration---------------+   
   +-x-msg-format-- --message format---------+   
   +-x-msg-msgId-- --message ID--------------+   
   +-x-msg-persistence-- --persistence-------+   
   +-x-msg-priority-- --priority class-------+   
   +-x-msg-replyTo-- --reply-to queue--------+   
   +-x-msg-timestamp-- --HTTP-date-----------+   
   '-x-msg-usr-- --user properties-----------'   

HTTP GET example

HTTP GET gets a message from a queue. The message remains on the queue. In WebSphere MQ terms, HTTP GET is a browse request. You could create an HTTP DELETE request using a Java client, a browser form, or an AJAX toolkit.

Figure 1 is an HTTP request to browse the next message on queue called myQueue.

The request contains the HTTP request header x-msg-wait, which instructs WebSphere MQ bridge for HTTP how long to wait for a message to arrive on the queue. The request also contains the x-msg-require-headersrequest header, which specifies that the client is to receive the message correlation ID in the response.

Figure 1. Example of an HTTP GET request

GET /msg/queue/myQueue/ HTTP/1.1
Host: www.example.org
x-msg-wait: 10
x-msg-require-headers: correlID

Figure 2 is the response returned to the client. The correlation ID is returned to the client, as requested in x-msg-require-headers of the request.

Figure 2. Example of an HTTP GET response

HTTP/1.1 200 OK
Date: Wed, 2 Jan 2007 22:38:34 GMT
Server: Apache-Coyote/1.1 WMQ-HTTP/1.1 JEE-Bridge/1.1
Content-Length: 50
Content-Type: text/plain; charset=utf-8
x-msg-correlId: 1234567890

Here's my message body that will appear on the queue.