API in Nova

1、nova neutralization api Relevant documents / Directory folder has :
api Catalog
Multiple rpcaip.py
Multiple api.py

2、openstack Several kinds of api

Rest api: The open interface of the project .

Local call api（local api）： In process method calls , And ordinary Python Method call

Rpcapi.py It is the remote call of a function module api

3、Rest API:RestAPI yes openstack Standard external interface , all API Are defined in official documents .

openstack Medium rest api There are two key technologies for implementation ：wsgi and Paste Deployment.

wsgi It's an interface specification . Definition web server and web application Interface between .

Paste Deployment It's a response to wsgi Developed library , Used to configure and load wsgi application and server.openstack All configurations in are made through api-paste.ini Document supply . Through this file, you can directly call Paste Deployment Code to load web server And the above application.

4、openstack service endpoint
Every service (nova,cinder,neutron etc. ) Will be in keystone Register one on service endpoint, This endpoint It's just one. URL. Every rest api Integrity URL It's from this. endpoint+api As defined in the document URI Composed of .

Ps:keystone For each service Definition 3 individual endpoint: One is for the public network (public) The use of ; One is

Intranet oriented (internal) The use of ; Another one is for admi The use of . Usually internal and admin Of endpoint It's the same , It's all used openstack Manage... In the network IP Address .public Need to use the public network IP Address .

5、 Local call api
And remote call api Very similar , Can only be called between processes . There will be one for each service api.py file , This file provides the local call of the service api Interface . Such as compute in api.py. see api.py The file shows , Many of the implementations in this file are actually called by compute Of rpcapi.py

6、 The remote invocation api
Every openstack The project will include multiple functionally independent services (service). Such as nova Will be divided into nova-api,nova-conductor,nova-compute... Besides nova-api Outside , The rest are RPC server.

7、openstack Medium api Usage rule
If it is a cross project call ( Such as nova call keystone,glance etc. ), Use rest api( Through the corresponding python-XXXclient library ). install nova You need to rely on python-cinderclient python-neutronclien python-glanceclient python-keystoneclient, because nova You need to call these rest api. Other projects have similar dependencies .

If it is a cross service call within a project , Then use RPC call , Provided through services rpcapi.py file .