[vbox-dev] Help with sessions
Lucas Charles
lucas.charles at unine.ch
Thu Nov 4 09:46:38 GMT 2010
Ok, thank you very much for taking the time to answer !
Lucas
On Tue, Nov 2, 2010 at 11:35 AM, Klaus Espenlaub <klaus.espenlaub at oracle.com
> wrote:
> On 26.10.2010 00:44, Lucas Charles wrote:
>
>> Hi Nikolay,
>>
>>
>> Thank you very much for sorting this out, now it's solved.
>> What I actually didn't get was that I had to close the session after
>> openRemoteSession. (My bad)
>>
>> I just had one question, it seems to me that using snapshot (Either
>> restore the snapshot or start from a saved one) can be really expensive
>> if I have modifications on the harddrive.. It takes something like 5-10
>> seconds to recover form a snapshot that has been done after an install
>> of a few package in an Ubuntu guest.
>>
>
> That sounds quite plausible... loading a saved state alone isn't for free
> if your VM has lots of RAM configured. You could have a peek at VBox.log if
> you wonder where the time is spent. If it's in the management of diff images
> it doesn't show up there though, since it's done before the VM is started.
>
> All snapshot management operations are complex file operations, especially
> if you delete non-"leaf" snapshots. Restoring some snapshot is comparably
> simple, it "only" means creating a new diff image (and potentially deleting
> the previous one), which doesn't need much file I/O. It still depends
> heavily on the disk speed and load.
>
> Klaus
>
>
>> - Does it make any sense ?
>>
>> Lucas
>>
>> On Mon, Oct 25, 2010 at 4:46 PM, Nikolay Igotti
>> <nikolay.igotti at oracle.com <mailto:nikolay.igotti at oracle.com>> wrote:
>>
>> Hi Lucas,
>>
>>
>>
>> Lucas Charles wrote:
>>
>> Thanks also for reminding me the change of the API, I also
>> remember that there should be an xpcom-like API for java in the
>> next version.
>>
>> Yes, but look and feel of both WS and XPCOM API shall be the same,
>> and you can use pretty much the same Java code for both.
>>
>> I understood that openRemoteSession is used to start a vm and I
>> used this call to open several vms.
>> The problem is how to access this session once it has been opened.
>>
>> To create a session object you may want to use getSessionObject().
>> Complete example can be found in
>> src/VBox/Main/webservice/samples/java/jax-ws/clienttest.java which
>> is also shipped with SDK.
>>
>>
>>
>> Up to know I passed the same session object to every open remote
>> session call, which is apparently wrong.
>> I tried to reused this session object to command the snapshots,
>> and it apparently failed. I understood that a session is
>> linked to one machine, so it makes sense that I cannot reuse
>> them everywhere.
>>
>> Yes, you need one session per machine. See my getSessionObject()
>> remark above.
>>
>>
>>
>> I saw in some threads in the mailing list that I could create
>> one IWebsessionManager to start all the vms and then
>> create one IWesessionManager per machine started to create new
>> session objects. Is it really the right thing to do, since the
>> IVirtualbox is a singleton.
>>
>> You need different managers if you maintain connection to multiple
>> VirtualBox hosts, if you all your VMs run on the same host/port
>> there is no need for multiple managers.
>>
>> Nikolay
>>
>>
>>
>> On Mon, Oct 25, 2010 at 11:14 AM, Nikolay Igotti
>> <nikolay.igotti at oracle.com <mailto:nikolay.igotti at oracle.com>
>> <mailto:nikolay.igotti at oracle.com
>> <mailto:nikolay.igotti at oracle.com>>> wrote:
>>
>> Hi Lucas,
>>
>>
>> First of all, please keep in mind that for next major release
>> there will be significant rework of both session API and
>> the way it's accessed from Java. Having said that, with 3.x
>> approach, which is, indeed not very straightforward,
>> openRemoteSession() API is just a way start a new VM, so
>> it's not
>> possible to use one remote session to start several VMs -
>> you have to openRemoteSession() for every VM you want to start.
>> Please refer to SDK documentation, and vboxshell.py TUI example
>> (while in Python, patterns of API usage is the same).
>>
>>
>> Hope that will help,
>> Nikolay
>>
>>
>> Lucas Charles wrote:
>>
>> Hello everyone,
>>
>> I'm stuck with a problem related to the sdk for java-ws.
>> I want to manage several machines on a given host from
>> my java
>> client.
>>
>> I need to start vms Take snapshots of the one I started at
>> given intervals.
>> After a new boot I need to restore the machines to their
>> latest snapshot.
>> Start them and redo snapshots.
>>
>> The problem I'm facing is how to open sessions.
>>
>> Yet I'm starting the vms by calling
>> ------
>>
>> IWebsessionManager mgr;
>>
>> IVirtualBox vbox
>>
>> mgr = new IWebsessionManager("http://localhost:18083");
>>
>> vbox = mgr.logon("", "");
>>
>> ISession session = mgr.getSessionObject(vbox);
>>
>> IProgress prog = vbox.openRemoteSession(session,
>> machineToStart.getId(), "gui", "");
>>
>> prog.waitForCompletion(-1);
>>
>> -----
>>
>> Isn't it a problem to call openRemoteSession with the
>> session
>> I got from IWebSessionManager::getSessiontObject() ?
>> Because I then use only one session to start several vms.
>>
>> My next question is when I want to take snapshots of every
>> machines I have in charge.
>>
>> Which session object should I use to get the IConsole ?
>> Can/Must I reuse the one I used upon calling
>> openRemoteSession() ? Reusing seems to work, if I
>> control only
>> one machine but fails with more than one.
>>
>> Best Regard,
>> Lucas Charles
>>
>>
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