> *Support for the async API in the core* > * > * > Currently we only expose sync / blocking API. This mostly works OK for
FYI, You may be interested to know jclouds had both sync and async APIs and recently dropped support for the async APIs. It was found that they're a big maintenance burden (keeping the sync and sync interfaces in sync), few users actually used them and there were good alternatives offered by third-party utility libraries (google's guava, which is used in jclouds already anyway) that users can use to achieve the same thing. Maybe the maintenance burden is less with python, Java's strict type-checking forced us to have two sets of interfaces, one with actual result values and the other returning 'futures' to retrieve the actual result values from once the operations complete. I wasn't involved in the decision to drop async support, it was part of a number of refactorings to reduce the size of the codebase and thereby its maintenance cost, but if you're interested, you may be able to find out more on the jclouds mailing lists. Regards, Dies Koper > -----Original Message----- > From: Tomaz Muraus [mailto:to...@apache.org] > Sent: Wednesday, 12 June 2013 4:00 PM > To: us...@libcloud.apache.org; dev > Subject: [dev] Libcloud Design Day Recap (improving Libcloud and plans > for the future) > > First of all I want to say thanks to everyone for coming. We had a lot > of > good debates and received some first hand feedback from our users. > Hopefully most of this debates will result into some actual code soon :) > > I've included a short recap and some action items bellow. Each section > first contains a short problem description and a solution we agreed upon > afterwards. > > *Pricing data distribution* > > Currently we bundle JSON file with provider pricing data with every > release. There is no documented and easy way for user to update this file > or for us to ship an updated version without releasing a new version of > Libcloud. > > We should provide easy way to update this file which includes the > following: > > * Command line tool for updating the file - user can specify a custom > URL > to the file. By default it should point to the latest version from the > version control ( > https://svn.apache.org/viewvc/libcloud/trunk/libcloud/data/pricing.j > son?view=co > ) > * Modify the code so it also tries to find the default pricing data file > in > /home/user/.libcloud_data/pricing.json (or whatever) directory > * Document this process and add it to the documentation page > > * Note: Most of code for this functionality already exists ( > https://github.com/apache/libcloud/blob/trunk/libcloud/pricing.py). > We just > need to add a code for downloading a file from a remote server and the > cli > tool. > > *Exception reporting for partial failures in the methods which result > in > multiple API calls / HTTP requests* > * > * > Currently we have no standard interface for exceptions which get raised > during a partial failure in a method which has side affects. Partial > failure means that a function which performs multiple API calls failed > half > way through and this potentially resulted in some (but not all) resources > getting created. > > We should provide a special exception for cases like this. This exception > should contain information about resources which got created. Users can > then use this information to perform "rollback" / cleanup partially > created > resources. > > *Support for the async API in the core* > * > * > Currently we only expose sync / blocking API. This mostly works OK for > simple command line scripts, but it's less than ideal for long running > process or applications which performs a lot of API calls which could > be > made more efficient and faster if we supported an async api. > > As part of this change we would eventually need to refactor every driver > which would also provide other side benefits such as: > > * More maintainable code (smaller functions) > * Easier way to handle partial failures / exceptions > > We didn't come to a consensus on everything, but we agreed on a couple > of > things: > > * Change should be backward compatible, we should default to sync API > and > existing behavior code / shouldn't change > * New async API should be available separately (e.g. under > libcloud.async.* > or whatever it ends up being) > * We should refactor internal code to follow new interfaces defined in > the > PEP 3156 (http://www.python.org/dev/peps/pep-3156/) > * We should start with a small scale experiment and try this in a single > method in a single compute driver > > *Documentation* > > We are weak on the documentation side. > > Going forward we should strictly enforce that every patch which adds new > code / functionality contains documentation and appropriate docstrings. > > *Migrating to git* > > We want to make contributing as easy as possible and SVN doesn't help > with > that and increases barrier to entry. > > Action item here is me opening an Apache Infrastructure ticket for > switching to git. > > *Dropping support for Python 2.5* > > Supporting Python 2.5 adds code complexity which we would like to avoid. > Main problem is that a bunch of CLI tools based on Libcloud usually also > run on older versions of Linux (e.g. RHEL 5) which still ship with Python > 2.5. > > We didn't managed to actually talk about this one, but we should explore > an > option of removing support for Python 2.5 in the future release. > > If you have attended the meetup, feel free to share your notes and or > / > feedback. For other people who didn't attend - you are still more than > welcome and encouraged to share your feedback with us here on the mailing > list. > > - Tomaz
