4:32 a.m.
Hi,
I am exploring the possibility of creating ruby bindings for libvirt.
The only attempt I found after some searching is this:
http://www.cs.ucsb.edu/~ckrintz/racelab/jisha/
Following the SWIG method as described in the above URL, I have
gotten to the following point:
[root@dell1 libvirt_ruby]# irb
irb(main):001:0> require 'libvirt_ruby'
=> true
irb(main):002:0> conn = Libvirt_ruby.virConnectOpenReadOnly("")
=> #<SWIG::TYPE_p__virConnect:0x2aaaaabc46c8>
irb(main):003:0> dom = Libvirt_ruby.virDomainLookupByID(conn, 0)
=> #<SWIG::TYPE_p__virDomain:0x2aaaaabb5df8>
irb(main):004:0> ret = Libvirt_ruby.virDomainGetInfo(dom, info)
NameError: undefined local variable or method `info' for main:Object
from (irb):4
irb(main):005:0>
I am not sure how to create and pass in a ptr to a virDomainInfo
struct object into the virDomainGetInfo call within ruby.
Note that I was trying to following the info1.c example on the
libvirt website:
http://libvirt.org/examples/info1.c
As you can tell, this is the first time I am trying to create any
sort of language bindings for a C library.
Some questions:
1. Is there a better way of creating ruby bindings for libvirt
besides SWIG? If so, any pointers on what should be done?
2. Alternatively I can try to make my ruby code use libvirt-python
bindings as a python library. Has anyone done so? Any problems with
this approach?
cheers,
mengkuan
8:01 a.m.
On Thu, Aug 30, 2007 at 05:32:19PM +0800, Meng Kuan wrote:
Hi,
I am exploring the possibility of creating ruby bindings for libvirt.
The only attempt I found after some searching is this:
http://www.cs.ucsb.edu/~ckrintz/racelab/jisha/
Following the SWIG method as described in the above URL, I have
gotten to the following point:
[root@dell1 libvirt_ruby]# irb
irb(main):001:0> require 'libvirt_ruby'
=> true
irb(main):002:0> conn = Libvirt_ruby.virConnectOpenReadOnly("")
=> #<SWIG::TYPE_p__virConnect:0x2aaaaabc46c8>
irb(main):003:0> dom = Libvirt_ruby.virDomainLookupByID(conn, 0)
=> #<SWIG::TYPE_p__virDomain:0x2aaaaabb5df8>
irb(main):004:0> ret = Libvirt_ruby.virDomainGetInfo(dom, info)
NameError: undefined local variable or method `info' for main:Object
from (irb):4
irb(main):005:0>
I am not sure how to create and pass in a ptr to a virDomainInfo
struct object into the virDomainGetInfo call within ruby.
Honnestly, I don't know ruby so no idea.
Note that I was trying to following the info1.c example on the
libvirt website:
http://libvirt.org/examples/info1.c
As you can tell, this is the first time I am trying to create any
sort of language bindings for a C library.
Some questions:
1. Is there a better way of creating ruby bindings for libvirt
besides SWIG? If so, any pointers on what should be done?
There is a formal XML definition of the libvirt API
http://libvirt.org/libvirt-api.xml
The waythe python bindings are built is that a python script parses
this XML and then generate the C and python modules needed for the
bindings. I'm not sure this really helps you but at least this mean
you don't have parse the C header files if you want to automate the
process.
2. Alternatively I can try to make my ruby code use libvirt-python
bindings as a python library. Has anyone done so? Any problems with
this approach?
No idea. But I would be a bit worried about piling up layers like
that, might work for you though..
Daniel
--
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard | virtualization library http://libvirt.org/
veillard(a)redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/
2:18 a.m.
On 30 Aug 2007, at 9:01 PM, Daniel Veillard wrote:
> 2. Alternatively I can try to make my ruby code use
libvirt-python
> bindings as a python library. Has anyone done so? Any problems with
> this approach?
No idea. But I would be a bit worried about piling up layers like
that, might work for you though..
Yes, that was my worry too. Hopefully I don't have to do it this way.
Thanks for your input, Daniel.
cheers,
mengkuan
12:56 p.m.
On Thu, 2007-08-30 at 17:32 +0800, Meng Kuan wrote:
Hi,
I am exploring the possibility of creating ruby bindings for libvirt.
The only attempt I found after some searching is this:
http://www.cs.ucsb.edu/~ckrintz/racelab/jisha/
Following the SWIG method as described in the above URL, I have
gotten to the following point:
[root@dell1 libvirt_ruby]# irb
irb(main):001:0> require 'libvirt_ruby'
=> true
irb(main):002:0> conn = Libvirt_ruby.virConnectOpenReadOnly("")
=> #<SWIG::TYPE_p__virConnect:0x2aaaaabc46c8>
irb(main):003:0> dom = Libvirt_ruby.virDomainLookupByID(conn, 0)
=> #<SWIG::TYPE_p__virDomain:0x2aaaaabb5df8>
irb(main):004:0> ret = Libvirt_ruby.virDomainGetInfo(dom, info)
NameError: undefined local variable or method `info' for main:Object
from (irb):4
irb(main):005:0>
I am not sure how to create and pass in a ptr to a virDomainInfo
struct object into the virDomainGetInfo call within ruby.
virDomainGetInfo uses the info structure to return the info. It's going
to be hard to replicate that 1-1 in Ruby; but you'd get a much better,
more Ruby-ish API if you structure the various libvirt calls into a
number of classes (Libvirt::Connection, Libvirt::Domain,
Libvirt::DomainInfo etc.) so that your above code would look something
like
conn = Libvirt::connectReadOnly("") # Returns a Libvirt::Connection
dom = conn.lookupDomainByID(0) # Returns a Libvirt::Domain
info = dom.getInfo() # Returns a Libvirt::DomainInfo
I doubt that you can do that with Swig, but it's not terribly hard to
write bindings by hand. Have a look at existing bindings, e.g. for
rpm[1] or gamin[2].
David
[1] http://rubyforge.org/projects/ruby-rpm/
[2] http://www.pablotron.org/software/fam-ruby/
2:11 a.m.
On 31 Aug 2007, at 1:56 AM, David Lutterkort wrote:
On Thu, 2007-08-30 at 17:32 +0800, Meng Kuan wrote:
> [root@dell1 libvirt_ruby]# irb
> irb(main):001:0> require 'libvirt_ruby'
> => true
> irb(main):002:0> conn = Libvirt_ruby.virConnectOpenReadOnly("")
> => #<SWIG::TYPE_p__virConnect:0x2aaaaabc46c8>
> irb(main):003:0> dom = Libvirt_ruby.virDomainLookupByID(conn, 0)
> => #<SWIG::TYPE_p__virDomain:0x2aaaaabb5df8>
> irb(main):004:0> ret = Libvirt_ruby.virDomainGetInfo(dom, info)
> NameError: undefined local variable or method `info' for
> main:Object
> from (irb):4
> irb(main):005:0>
>
> I am not sure how to create and pass in a ptr to a virDomainInfo
> struct object into the virDomainGetInfo call within ruby.
virDomainGetInfo uses the info structure to return the info. It's
going
to be hard to replicate that 1-1 in Ruby; but you'd get a much better,
more Ruby-ish API if you structure the various libvirt calls into a
number of classes (Libvirt::Connection, Libvirt::Domain,
Libvirt::DomainInfo etc.) so that your above code would look something
like
conn = Libvirt::connectReadOnly("") # Returns a Libvirt::Connection
dom = conn.lookupDomainByID(0) # Returns a Libvirt::Domain
info = dom.getInfo() # Returns a Libvirt::DomainInfo
What I was missing was the "-autorename" argument when calling swig,
i.e.
swig -ruby -autorename libvirt.i
After compile and install of the resulting libvirt.so, here's what I
can do in ruby:
require 'libvirt'
conn = Libvirt.vir_connect_open_read_only("")
dom = Libvirt.vir_domain_lookup_by_id(conn, 0)
info = Libvirt::VirDomainInfo.new
Libvirt.vir_domain_get_info(dom, info)
puts info.state # => 1
puts info.maxMem # => 1047552
It's far from ruby-ish, but it works.
I doubt that you can do that with Swig, but it's not terribly
hard to
write bindings by hand. Have a look at existing bindings, e.g. for
rpm[1] or gamin[2].
I'll probably look into writing bindings by hand later on, but at
this time due to my inexperience with C programming and lack of time,
I am thinking of writing Ruby classes that wrap these C calls and use
those Ruby classes instead.
Thanks for the pointers, David. Much appreciated.
cheers,
mengkuan
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4 comments
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participants (3)
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Daniel Veillard -
David Lutterkort -
Meng Kuan