code

require 'libvirt'

   conn = Libvirt::open("qemu:///system")
   puts conn.capabilities
   
   File::open("domain.xml") do |f| 
     conn.createDomainLinux(f.readlines, nil)
   end

   dom = conn.lookupDomainByName("mydomain")
   dom.suspend
   dom.resume
   puts dom.xmlDesc

domain.xml

<domain type='kvm'>
  <name>CIJoe</name>
  <uuid>36675cb5-0f94-0ff8-7f07-5defb1a4ee3a</uuid>
  <memory>524288</memory>
  <currentMemory>524288</currentMemory>
  <vcpu>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc-0.12'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/var/lib/libvirt/images/CIJoe.img'/>
      <target dev='vda' bus='virtio'/>
    </disk>
    <disk type='block' device='cdrom'>
      <driver name='qemu'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
    </disk>
    <interface type='bridge'>
      <mac address='52:54:00:20:e5:c1'/>
      <source bridge='br0'/>
      <model type='virtio'/>
    </interface>
    <console type='pty'>
      <target port='0'/>
    </console>
    <console type='pty'>
      <target port='0'/>
    </console>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='-1' autoport='yes'/>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
    </video>
  </devices>
</domain>

Error

vhost.rb:7: undefined method `createDomainLinux' for #<Libvirt::Connect:0x7f117529b5e8> (NoMethodError)
	from vhost.rb:6:in `open'
	from vhost.rb:6

output from vhost.rb

<capabilities>

  <host>
    <cpu>
      <arch>x86_64</arch>
      <model>core2duo</model>
      <topology sockets='1' cores='2' threads='1'/>
      <feature name='lahf_lm'/>
      <feature name='xtpr'/>
      <feature name='cx16'/>
      <feature name='tm2'/>
      <feature name='est'/>
      <feature name='vmx'/>
      <feature name='ds_cpl'/>
      <feature name='pbe'/>
      <feature name='tm'/>
      <feature name='ht'/>
      <feature name='ss'/>
      <feature name='acpi'/>
      <feature name='ds'/>
    </cpu>
    <migration_features>
      <live/>
      <uri_transports>
        <uri_transport>tcp</uri_transport>
      </uri_transports>
    </migration_features>
    <secmodel>
      <model>apparmor</model>
      <doi>0</doi>
    </secmodel>
  </host>

  <guest>
    <os_type>hvm</os_type>
    <arch name='i686'>
      <wordsize>32</wordsize>
      <emulator>/usr/bin/qemu</emulator>
      <machine>pc-0.12</machine>
      <machine canonical='pc-0.12'>pc</machine>
      <machine>pc-0.11</machine>
      <machine>pc-0.10</machine>
      <machine>isapc</machine>
      <domain type='qemu'>
      </domain>
      <domain type='kvm'>
        <emulator>/usr/bin/kvm</emulator>
        <machine>pc-0.12</machine>
        <machine canonical='pc-0.12'>pc</machine>
        <machine>pc-0.11</machine>
        <machine>pc-0.10</machine>
        <machine>isapc</machine>
      </domain>
    </arch>
    <features>
      <cpuselection/>
      <pae/>
      <nonpae/>
      <acpi default='on' toggle='yes'/>
      <apic default='on' toggle='no'/>
    </features>
  </guest>

  <guest>
    <os_type>hvm</os_type>
    <arch name='x86_64'>
      <wordsize>64</wordsize>
      <emulator>/usr/bin/qemu-system-x86_64</emulator>
      <machine>pc-0.12</machine>
      <machine canonical='pc-0.12'>pc</machine>
      <machine>pc-0.11</machine>
      <machine>pc-0.10</machine>
      <machine>isapc</machine>
      <domain type='qemu'>
      </domain>
      <domain type='kvm'>
        <emulator>/usr/bin/kvm</emulator>
        <machine>pc-0.12</machine>
        <machine canonical='pc-0.12'>pc</machine>
        <machine>pc-0.11</machine>
        <machine>pc-0.10</machine>
        <machine>isapc</machine>
      </domain>
    </arch>
    <features>
      <cpuselection/>
      <acpi default='on' toggle='yes'/>
      <apic default='on' toggle='no'/>
    </features>
  </guest>

</capabilities>