1,virConnectGetLibVersion

API call obtain the version of libvirt software in use on the host

it takes a connection pointer and unsigned long pointer as input,

2,virConnectGetVersion

API call obtain version of the host virtualization software in use

3,virConnectGetURI

API call obtain URI current connection

4,virConnectIsEncrypted

API call 判断以建立的virtualizationHypervisors 是否是加密的

5,virConnectIsSecure

API call 同上判断virtual conn 是否加密

if succesful returns 1 for a secure connection and 0 for an insecure connection

if an error occurred -1 will be returned;

6,libvirt Enevt loop integration;

libvirt APIs use a basic request/response architecture that is generally synchronous

libvirt application calls a libvirt API (the request) which doesn‘t return until the action is complete (the response)

a libvirtd server can also generate asynchronous messages and send them to
the libvirt application