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Re: Many questions about translators
From: |
Carl Fredrik Hammar |
Subject: |
Re: Many questions about translators |
Date: |
Mon, 19 Apr 2010 15:16:48 +0200 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
Hi,
On Sat, Apr 17, 2010 at 10:54:37AM +0200, Patrik Olsson wrote:
> On Fri, 2010-04-16 at 11:52 +0200, Carl Fredrik Hammar wrote:
> > On Thu, Apr 15, 2010 at 10:47:49PM +0200, Patrik Olsson wrote:
> > > 3. Is it possible to have one translator working on two nodes at
> > > the same time (where the nodes have different meaning)? HPM
> > > needs to build one target directory (node one), and then have
> > > the interface directory where the user can control the manager
> > > (node two).
> >
> > Yes, a translator can attach itself to multiple nodes, but if a translator
> > takes an active role in attaching itself it cannot be set as a passive
> > (start on demand) translator.
> >
> > Instead, you probably want some inferior translator that contacts a
> > master translator. For instance, the interface directory could be a
> > separate translator that sends commands to the target directory translator
> > via some specialized interface. This could also allow the user to have
> > several interface directories.
> >
>
> I also had another alternative in mind. That the interface directory is
> derived from the target directory. So if the target is / then the
> interface could be part of that node as /hpm.
Yes, this would be a simple yet effective approach.
> I really don't see the point of several interface directories as they
> would be identical, and it would only complicate handling concurrent
> editing. Besides, if users really want many interface directories, there
> are symlinks.
It mostly shows that this approach is naturally flexible.
Indeed, there is no point if they are identical,
but you bring up a use-case yourself further down.
> > > 4. Is it possible for a translator to provide different views of
> > > the node for different users? For example, could each user have
> > > their own list of packages they want installed and the HPM
> > > translator would use ref-counting to install packages with
> > > ref-count > 0, and/or perhaps even make different packages
> > > appear installed for different users?
> >
> > This is actually possible, as the translator knows the user of the
> > client so it can grant or withhold access. But I suspect that using
> > it to provide different services to different users would violate many
> > assumptions made by clients.
>
> What are "clients" in this context?
The processes using the translator. Though I guess also end-users could
make such assumtions.
> > I wouldn't object using this to provide something like `/dev/whoami'
> > which would contain the UID of the reading process, but I don't think
> > you should consider this possibility for HPM any further. Just go with
> > different translators or nodes for different users.
>
> I think I'll do a mix. Only the interface directory would be different
> for each user. This is also necessary so that users don't overwrite each
> others changes if they are editing the installation list at around the
> same time. If the user cannot install a package with the system HPM
> (e.g. the package is experimental), they would use a private HPM
> instance instead. But they should prefer the system HPM since it won't
> use up their disk quota (and it will save disk space on the system as a
> whole). But perhaps there is another way, so I'll think about it some
> more.
This problem would go away if you allow several interface directories,
one per user. I do think that is the cleanest way to handle this:
different nodes for different directories means there can be no confusion.
However, I think it is best to post-pone discussing how several users
would interact with HPM, and first implement system-wide only, then
private HPMs that overshadows the system one, and then we can discuss
some ability for regular users to make direct use of the system one.
> Thanks for your help.
No problem, glad I could help.
Regards,
Fredrik
- Re: Many questions about translators, (continued)
- Re: Many questions about translators, Carl Fredrik Hammar, 2010/04/16
- Re: Many questions about translators, Samuel Thibault, 2010/04/16
- Re: Many questions about translators, Carl Fredrik Hammar, 2010/04/16
- Re: Many questions about translators, Samuel Thibault, 2010/04/16
- Re: Many questions about translators, olafBuddenhagen, 2010/04/18
- Re: Many questions about translators, Carl Fredrik Hammar, 2010/04/19
- Re: Many questions about translators, olafBuddenhagen, 2010/04/20
- Re: Many questions about translators, Carl Fredrik Hammar, 2010/04/21
- Re: Many questions about translators, olafBuddenhagen, 2010/04/25
Re: Many questions about translators, Patrik Olsson, 2010/04/17
- Re: Many questions about translators,
Carl Fredrik Hammar <=
Re: Many questions about translators, olafBuddenhagen, 2010/04/18