##Framework

  +-------------------------------+
  |           Horizon             |
  +-------------------------------+
                 |
                 V
  +-------------------------------+
  |  cloudGate RESTFUL handlers   |
  +-------------------------------+
  |        origin APIs            |
  +-------------------------------+
      |            |
      V            V
  +--------+   +------+
  | aliyun |   |amazon|  ...             //processors
  +--------+   +------+

###Request Procedure： Horizon send HTTP request to cloudGate, cloudGate handler process the request, handler call origin APIs only，handler don't know the real processing is, origin APIs is abstract of bottom processing。 The advantage of this is: when expend to other platform, origin APIs and handlers needn't modify， just add processors. On the other hand, if user use amozon image and aliyun oss, we just edit some configure then can realize unify management.

##Modules

▾ modules
  ▾ block_storage
    ▾ aliyun
        __init__.py
        processor.py                   //real processors
    ▸ amazon
      __init__.py
      api_factory.py                   //produce real processor
      handlers.py                      //handle Horizon request
      process_base.py                  //define interface of processor
      url.py                           //define REST urls
  ▸ clustering
  ▸ compute
  ▸ data_processing
  ▸ database_service
  ▸ identity
  ▸ image_service
  ▸ mould
  ▸ networking
  ▸ object_storage
  ▸ orchestration
  ▸ shared_file_systems
  ▸ telemetry

###Module switch

MODULES_SWITCH = {
    "identity": 1,
    "mould": 0,
    "block_storage":1,
    "clustering":1,
    "compute":0,
    "data_processing":1,
    "database_service":1,
    "image_service":1,
    "networking":1,
    "object_storage":1,
    "orchestration":1,
    "shared_file_systems":1,
    "telemetry":1,
}

cloudGate define a switch for all modules, if value is 0 cloudGate will not init that module.

##API version surpport we can define different version handler in url.py, and config witch version is current. and support lower version api.

##UML

    +--------------+        +-------------------+        +-----------------+
    | http handler |<>----->| Processor Factory |------->| Processor Base  |
    +--------------+        +-------------------+        +-----------------+
    | +get()       |                                              ^ 
    | +post()      |                                  ____________|___________  
    | ...          |                             +---|----+   +---|----+      |
    +--------------+                             | aliyun |   | Amazon |     ...
                                                 +--------+   +--------+

##A simple develop example ###Control aliyun ECS reboot ####Horzion request API the reboot api As we can see, the request url is:/v2.1/{tenant_id}/servers/{server_id}/action method is POST. ####Add url in compute/url.py

urls_v2_1 = [
    (r"/v2.1/(.*)/servers/(.*)/action", ServerActionHandler),
]

#if we support other version api, use urls = urls_v2_1 + urls_other_version
urls = urls_v2_1

####Add handler in compute/handlers.py

class ComputeBaseHandler(HttpBaseHandler):
    p = ComputeProcessorFac()

class ServerActionHandler(ComputeBaseHandler):
    def post(self, tenant_id, server_id):
        #call process_base functions
        action = "reboot"
        p.ServerAction(tenant_id, server_id, action)

####Add base processor in compute/process_base.py

class ComputeProcessorBase():
    #define interface of server action
    def ServerAction(self, tenant_id, server_id, action):
        #do nothing juest define interface
        pass

####Add processor in compute/aliyun/processor.py

class AliyunComputeProcessor(ComputeProcessorBase):
    def ServerAction(self, tenant_id, server_id, action):
        #TODO a real action to aliyun server
        pass

####Edit factory in compute/api_factory.py

class ComputeProcessorFac():
    processor = "aliyun"

    def __init__(self):
        if processor == "aliyun":
            return AliyunComputeProcessor()

##deploy cloudGate

1. deploy horizon http://docs.openstack.org/mitaka/install-guide-ubuntu/horizon-install.html
2. deploy cloudGate using command line config ali accesskey access secret, port etc,.
3. config horizon /etc/openstack-dashboard/local/local_settings.py edit AVAILABLE_REGIONS

AVAILABLE_REGIONS = [
    ('http://cloudGateIp:cloudGatePort/v2.0', 'cluster1'),
]