由dispatcher直接支持FCGI SCGI WCGI访问oracle - noradle/noradle-dispatcher GitHub Wiki

参考

• CGI,FCGI,SCGI,WCGI比较
• http://python.ca/scgi/protocol.txt
• http://www.fastcgi.com/drupal/
• http://nginx.org/en/docs/http/ngx_http_scgi_module.html
• http://nginx.org/en/docs/http/ngx_http_fastcgi_module.html

SCGI 思路

connection graph

                                       (parse scgi protocol stream data)
         (scgi)                           (scgi)      v
nginx  ----------> noradle-dispatcher  -----------> oracle
                           ^
         (just pipe connection to a free oracle connection)

process cycle

• 使用 unix domain socket 连接 nginx 和 noradle-dispatcher
• 使用 nginx scgi_param 配置
  • 指定连接到那个 db,
  • 指定连接到那个 dbu，
  • 指定连接 noradle-dispatcher 的那个监听口 (代表了 oracle 实例和 dbu 的组合)
• noradle-dispatcher
  • 找空闲的oracle连接，找到就绑定该连接，否则就进队列等有空间连接再处理
  • pipe to oracle，不包括 socket end
  • 接受 oracle 回复的 frame，去掉 frame head，直接转发 frame body
  • 接收到 end frame 后，向 SCGI socket 发送 end，并释放该 oracle 连接
• oracle 可以直接读 SCGI 内容
  • noradle-dispatcher 对原始包前增加 noradle 协议内容，主要是 protocol=SCGI，而不是 HTTP/DATA/NDBC
  • 发送给 oracle 的 request header 需要解析，名称从大写改成小写，换行分隔符从“\0”改成“\r\n”
• 实现和 noradle-http 类似的 noradle-scgi 模块
  • 不解析 http 格式 request，解析 scgi 格式的 request，但是同样的对 url,query-string,cookie 进行解析后再发送到oracle
  • 实现 in-process, 直接调用 in-process dispatcher API 接口发送请求，接受响应

goodness

• nginx pipe to noradle-dispatcher then dispatch to oracle, noradle-dispatcher doesn't parse request/response content, just dispatch, lowest overhead, best performance
• only one noradle-dispatcher can hold all oracle reverse connections and dispatch all nginx SCGI request, configuration is minimal, just listen port/path to oracle db/dbu mapping is ok

FCGI

connection graph

              (dispatch on connect and kept mapping)  (parse fcgi protocol stream data) 
         (FastCGI)              v                                v
nginx ===============> noradle-dispatcher <=========== oracle server processes
  (multiple connections kept)   ^
                    (just as a multi-path tunnel)

process cycle

• 启动 noradle-dispatcher for fastGI
• 接受到 web server 管理查询包，回复单连接，多路复用，并发数按照端口映射到的cid从oracle取来填写
• 接受到 FCGI_BEGIN_REQUEST 后，查找是否有free oSlot，有就绑定，没有就 buffer，记录 FCGI[port][request_id] 绑定信息
  • oSlotID bound
  • buffered array
• 如果可以有oSlot发送，先发送一个 noradle input stream 头，其中包含了基本信息，就是协议为fcgi，通道附加信息等等
• 后续还有该 request_id 的数据包，直接转发到绑定的 oSlot 或者继续 buffer
• oracle 侧看到是 fcgi 信息，则按照 raw fcgi 协议来处理

SCGI vs FCGI

Aspect	SCGI	FCGI
request parsing	un-touched	partial parse header(8 bytes)
response	wrap in noradle frame, discard head, pipe body	wrap in FCGI frame, pipe all

advantages of direct dispatch

• node.js do dispatch only, do no parse tunneled data
  • no cluster need: lowest overhead one process is ok, no need for cluster, just simple
  • no version lock: any version of node.js is ok, if only support stream that can pause/resume, do flow control
  • no copyright problem: no 3rd-party node.js module need, just relay protocols data to oracle where data is parsed
• file in db
  • upload file go into database, pl/sql handle them directly, integrate seamlessly
  • cached data(including partial) save in database, cache policy integrate seamlessly
• oracle parse protocol content, leveraging multi-processes and RAC/DG scalibility
  • SCGI: parse header length, body length
  • FCGI: parse record header, got request_id, bind/dispatch to oSlot
• response from oracle
  • is just untouched
  • but how dispatcher determine the end of response?, must wrap in noradle frame
  • SCGI: just discard head and return body, head name-value pairs add extra CRLF
  • FCGI: use its name-value format, wrap in its frame
• a big nginx server and a group of oracle 12c cloud databases
  • all internet request go to nginx server and dispatch to oracle databases
  • one server deploy nginx in DMZ
  • all other servers deploy oracle12c
  • create pluggable databases on these oracle cloud database
  • the architecture is just clear and simple

              (with dispatcher)      (pluggable databases)     
  clients   |   nginx server   |  oracle cloud database servers
------------|------------------|--------------------------------
(internet)  |    (DMZ area)    |          (intranet)
           HTTP             SCGI/FCGI  

接入多样性的意义

接入类型	接入拓扑	意义
noradle-http	通过 dispatcher	和其他 node.js 处理器 meshup 处理，灵活不受限制的策略和定制可能，支持最多的http特性
raw HTTP	dispatcher 直接提供	部署方案最为简单，除了 dispatcher，什么都不需要
raw HTTP	nginx -> dispatcher	通过 nginx 导流，性能更好
raw SCGI	nginx -> dispatcher	基于 CGI 的输入环境，参考用
raw FCGI	nginx -> dispatcher	实现 nginx 到 dispatcher 的多路复用，性能最佳