使用libvirt技术监控虚拟机（二）
关于XML：
在libvirt中，虚拟机的信息是以XML的形式存储的，我们可以用方法来获取一个虚拟机（也就是一个Domain）的XML文件
char *caps; caps = malloc(sizeof(char)*1024);caps = virDomainGetXMLDesc(allDomains[numOfDom],4);free(caps);
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使用
fprintf(stdout, "Capabilities:\n%s\n",caps);
把caps输出如下：
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<domain type='xen' id='1'>??????????????????????????????????? //虚拟机类型于虚拟机id
? <name>test1</name>
? <uuid>3eae3e71-a7c2-2bb0-035b-a6e1011ddc24</uuid>
? <memory>556032</memory>
? <currentMemory>524288</currentMemory>
? <vcpu>1</vcpu>
? <os>
??? <type>hvm</type>
??? <loader>/usr/lib/xen/boot/hvmloader</loader>
??? <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/lib/xen/bin/qemu-dm</emulator>
??? <disk type='file' device='disk'>
????? <driver name='file'/>
????? <source file='/var/lib/xen/images/test1.img'/>
????? <target dev='hda' bus='ide'/>
??? </disk>
??? <interface type='bridge'>????????????????????????
????? <mac address='00:16:3e:74:03:53'/>
????? <source bridge='xenbr0'/>
????? <script path='vif-bridge'/>
????? <target dev='vif1.0'/>
??? </interface>
??? <serial type='pty'>
????? <source path='/dev/pts/2'/>
????? <target port='0'/>
??? </serial>
??? <console type='pty' tty='/dev/pts/2'>
????? <source path='/dev/pts/2'/>
????? <target port='0'/>
??? </console>
??? <input type='mouse' bus='ps2'/>
??? <graphics type='vnc' port='5901' autoport='yes' keymap='en-us'/>
? </devices>
</domain>
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device件值对里装的是I／O信息，Interface里装的是网络信息
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