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Dirk Eddelbuettel: RPushbullet 0.1.0 with a lot more awesome

11 October, 2014 - 11:29

A new release 0.1.0 of the RPushbullet package (interfacing the neat Pushbullet service) landed on CRAN today.

It brings a number of goodies relative to the first release 0.0.2 of a few months ago:

  • pushing of files is now supported thanks to a nice pull request bu Mike Birdgeneau
  • a default device can be designated in the ~/.rpushbullet.json file or options
  • initialization has been rewritten to use recpients which can be indices, device names or, if missing entirely, the (new) default device
  • alternatively, email is supported as another recipient option in which case the Pushbullet service will send an email to the give address
  • pbGetDevices() now returns a proper S3 object with corresponding print() and summary() methods
  • the documentation regarding package initialization, and setting of key, devices, etc has been expanded
  • more examples has been added to the documentation
  • various minor cleanups, fixes, corrections throughout

There is a whole boat load of more wickedness in the Pushbullet API so if anybody feels compelled to add it, fire off pull requests at GitHub.

More details about the package are at the RPushbullet webpage and the RPushbullet GitHub repo.

Courtesy of CRANberries, there is also a diffstat report for this release.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Matthias Klumpp: Listaller + Glick: Some new ideas

10 October, 2014 - 20:59

As you might know, due to invasive changes in PackageKit, I am currently rewriting the 3rd-party application installer Listaller. Since I am not the only one looking at the 3rd-party app-installation issue (there is a larger effort going on at GNOME, based on Lennarts ideas), it makes sense to redesign some concepts of Listaller.

Currently, dependencies and applications are installed into directories in /opt, and Listaller contains some logic to make applications find dependencies, and to talk to the package manager to install missing things. This has some drawbacks, like the need to install an application before using it, the need for applications to be relocatable, and application-installations being non-atomic.

Glick2

There is/was another 3rd-party app installer approach on the GNOME side, by Alexander Larsson, called Glick2. Glick uses application bundles (do you remember Klik from back in the days?) mounted via FUSE. This allows some neat features, like atomic installations and software upgrades, no need for relocatable apps and no need to install the application.

However, it also has disadvantages. Quoting the introduction document for Glick2:

“Bundling isn’t perfect, there are some well known disadvantages. Increased disk footprint is one, although current storage space size makes this not such a big issues. Another problem is with security (or bugfix) updates in bundled libraries. With bundled libraries its much harder to upgrade a single library, as you need to find and upgrade each app that uses it. Better tooling and upgrader support can lessen the impact of this, but not completely eliminate it.”

This is what Listaller does better, since it was designed to do a large effort to avoid duplication of code.

Also, currently Glick doesn’t have support for updates and software-repositories, which Listaller had.

Combining Listaller and Glick ideas

So, why not combine the ideas of Listaller and Glick? In order to have Glick share resources, the system needs to know which shared resources are available. This is not possible if there is one huge Glick bundle containing all of the application’s dependencies. So I modularized Glick bundles to contain just one software component, which is e.g. GTK+ or Qt, GStreamer or could even be a larger framework (e.g. “GNOME 3.14 Platform”). These components are identified using AppStream XML metadata, which allows them to be installed from the distributor’s software repositories as well, if that is wanted.

If you now want to deploy your application, you first create a Glick bundle for it. Then, in a second step, you bundle your application bundle with it’s dependencies in one larger tarball, which can also be GPG signed and can contain additional metadata.

The resulting “metabundle” will look like this:

 

 

 

 

 

 

 

 

 

This doesn’t look like we share resources yet, right? The dependencies are still bundled with the application requiring them. The trick lies in the “installation” step: While the application above can be executed right away without installing it, there will also be an option to install it. For the user, this will mean that the application shows up in GNOME-Shell’s overview or KDEs Plasma launcher, gets properly registered with mimetypes and is – if installed for all users – available system-wide.

Technically, this will mean that the application’s main bundle is extracted and moved to a special location on the file system, so are the dependency-bundles. If bundles already exist, they will not be installed again, and the new application will simply use the existing software. Since the bundles contain information about their dependencies, the system is able to determine which software is needed and which can simply be deleted from the installation directories.

If the application is started now, the bundles are combined and mounted, so the application can see the libraries it depends on.

Additionally, this concept allows secure updates of applications and shared resources. The bundle metadata contains an URL which points to a bundle repository. If new versions are released, the system’s auto-updater can automatically pick these up and install them – this means e.g. the Qt bundle will receive security updates, even if the developer who shipped it with his/her app didn’t think of updating it.

Conclusion

So far, no productive code exists for this – I just have a proof-of-concept here. But I pretty much like the idea, and I am thinking about going further in that direction, since it allows deploying applications on the Linux desktop as well as deploying software on servers in a way which plays nice with the native package manager, and which does not duplicate much code (less risk of having not-updated libraries with security flaws around).

However, there might be issues I haven’t thought about yet. Also, it makes sense to look at GNOME to see how the whole “3rd-party app deployment” issue develops. In case I go further with Listaller-NEXT, it is highly likely that it will make use of the ideas sketched above (comments and feedback are more than welcome!).

Mario Lang

10 October, 2014 - 17:00
GStreamer and the command-line?

I was recently looking for a command-line client for SoundCloud. soundCLI on GitHub appeared to be what I want. But wait, there is a problem with its implementation.

soundCLI uses gstreamer's playbin2 to play audio data. But that apparently requires $DISPLAY to be set.

So no, soundCLI is not a command-line client. It is a command-line client for X11 users.

Ahem.

A bit of research on Stackoverflow and related sites did not tell me how to modify playbin2 usage such that it does not require X11, while it is only playing AUDIO data.

What the HECK is going on here. Are the graphical people trying to silently overtake the world? Is Linux becoming the new Windows? The distinction between CLI and GUI has become more and more blurry in the recent years. I fear for my beloved platform.

If you know how to patch soundCLI to not require X11, please let me know. My current work-around is to replace all gstreamer usage with a simple "system" call to vlc. That works, but it does not give me comment display (since soundCLI doesn't know the playback position anymore) and hangs after every track, requiring me to enter "quit" manually on the VLC prompt. I really would have liked to use mplayer2 for this, but alas, mplayer2 does not support https. Oh well, why would it need to, in this day and age where everyone seems to switch to https by default. Oh well.

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