Book Recommendations

Knowing that I read a lot, a friend asked for some recommendations.  Looking through my list on Goodreads of all of the books I've read, I found it hard to give specific recommendations.  

I've found that I've enjoyed 99% of the books I've read; it's rare that I finish a book and regret reading it.  Take that as you may - I dont consider myself any sort of literary critic.  Goodreads does have lots of good lists that can get you started.  For me, starting with authors who have won (or been runners-up) for various awards like the Hugos and Nebulas has worked out pretty well.

Here's a list of books and authors that I remember well enough to recommend

Authors (my favorites that I'll read without even looking at reviews)

• Neil Gaiman
• Neal Stephenson
• William Gibson
• Iain M Banks
• Isaac Asimov
• Arthur C Clarke
• Greg Egan
• Alistair Reynolds

Space Opera/Series

• The Expanse series by James S.A. Corey
• Culture series by Ian M Banks
• Imperial Radch series by Anne Leckie
• Vorkosigan Saga by Lois McMaster Bujold
• The Long Earth series by Terry Pratchett
• Zones of Thoughs series by Vernor Vinge
• Silo series by Hugh Howey
• Subjective Cosmology Series by Greg Egan

Science Fiction (I'm bad at distinguishing between Science Fiction and just Fiction, so dont read much into this category)

• Darwin's Radio by Greg Bear
• The Space between Worlds by Micaiah Johnson
• Lock In by John Scalzi
• Barsk: The Elephants' Graveyard by Lawrence M. Schoen

Fiction/Fantasy

• Neverwhere by Neil Gaiman
• The Graveyard Book by Neil Gaiman
• The Night Circus by Erin Morgenstern
• The Starless Sea by Erin Morgenstern
• The City & the City by China Miéville
• The Masquerade series by Seth Dickinson
• Snow Queen Cycle series by Joan D Vinge
• The Time Quintet series by Madeleine L'Engle
• The Missionaries by Owen Stanley
• Otherland series by Tad Williams

Djinn/Genies (not sure why I've set aside this specific category)

• A Master of Djinn by P Djeli Clark
• The Golem and the Jinni by Helene Wecker
• The Hidden Palace by Helene Wecker

Mythology Remakes/Takeoffs/Alternative Tellings

•  Ariadne - Minotar story told from point of view of King Minos' daughter
•  The Just City by Jo Walton - Socrates and Plato and the Greek gods 
•  Odd and the Frost Giants by Neil Gaiman - Norse myth
•  Norse Mythology by Neil Gaiman
•  The Mere Wife by Maria Dahvana Headley - A Beowulf adaptation

Russia

I'm fascinated by Russian stories because Russia is neither Western/European or Asian and I know so little of its history or culture.  I'm not really into reading straight-up history books, but I do like novels set in Russia. The ones with Russian authors are available in multiple translations; I've found translations by Richard Pevear and Larissa Volokhonsky to be well regarded.

• Classics
• Anna Karenina by Leo Tolstoy
• The Master and Margarita by Mikhail Bulgakov
• The Brothers Karamazov by Fyodor Dostoevsky
• Cancer Ward by Aleksandr Solzhenitsyn
• Historical Fiction/Fiction
• Chimes of a Lost Cathedral by Janet Fitch
• The Revolution of Marina M by Janet Fitch
• Russka: The Novel of Russia by Edward Rutherfurd
• Night Watch by Sergei Lukyanenko

As with the Russian novels, I also find reading novels by non-western authors interesting - both in the way they tell stories, but also because it reveals a little bit about their culture (of which I'm mostly ignorant)

African Authors

• Octavia Butler: Xenogenesis series, currently reading PatternMaster series
• Nnedi Okorafor: Binti, Nsibidi Scripts, Who Fears Death (these are all series)

Asian Authors

• Klara and the Sun by Kazuo Ishiguro
• 1Q84 by Haruki Murakami
• Remembrance of Earth's Past - series by Liu Cixin, Three Body problem to be a Netflix series
• The Memory Police by Yoko Ogawa
• The Windup Bird Chronicle by Haruki Murakami

Backing up with rsync to a bitlocker disk mounted under Ubuntu on Raspberry Pi

Needed to set up backup to a bitlocker drive (corp policy - not allowed to put anything on a driver that's not bitlocker'd).  Corp laptops are set up such that they want to inspect all data written to external devices, so backups ended up being painfully slow (especially when jar files were involved since it wanted to unzip them and scan everything in them).  Decided to go with rsync over ssh from cygwin bash shell.

For fun (and since I didnt want this stuff on my personal machines), I decided to buy a Raspberry Pi and use that as my rsync target with the bitlocker disk mounted using dislocker.

I think I start out trying to install a packaged version with apt-get, but had dependency problems (might have had something to do with trying to run under Ubuntu on Raspberry Pi) , so reverted to these instructions: http://blog.airbuscybersecurity.com/post/2016/01/Mounting-Bitlocker-Volumes-Under-Linux

On the server side, I ended up with two scripts:

vmdiskmount:

dislocker-fuse -V /dev/sda1 -u -- /mnt/dislocker
mount -t ntfs-3g -o loop /mnt/dislocker/dislocker-file /mnt/vmdisk
mount | grep vmdisk

vmdiskumount:

umount /mnt/vmdisk && umount /mnt/dislocker
mount | grep dislocker

The mount script will prompt you for your bitlocker passphrase.  Note that shutting down the server without unmounting dislocker first can supposedly cause scary things to happen with the bitlocker encryption.

I also setup usermapping to map between windows SIDs and my linux user/group.  This goes in /mnt/vmdisk/.NTFS-3G/UserMapping:

# User mapping proposal :# -------------------- cut here -------------------1001::S-1-5-21-4271255075-229453548-3213529333-6405:1001:S-1-5-21-4271255075-229453548-3213529333-513::S-1-5-21-4271255075-229453548-3213529333-10000# -------------------- cut here -------------------

On the client side, its just standard rsync commands to send the data. Again, corp security required more dancing - cygwin needed to run as admin, but you cant do that directly anymore, so you have to run a DOS window as admin and launch cygwin from there. Also, trying to rsync the c drive doesnt work well because only the trusted installer user has write privs, so rysnc gets locked out as soon as it syncs the root directory on c: (which is the first thing it does).  Trick is to specify directories under c: as the rsync sources rather than the c drive itself.

Recursive queries from a custom validator

Just spent the morning tracking down a stack overflow while trying to implement a grails custom validator.

I have a domain class that has a parent/child relationship with itself (instance form a tree). When I update instances, I need to make sure that I haven't created a cycle (the instance has itself as its own parent/ancestor)

To do this, I created a custom validator to check that the object doesnt have itself as its own parent and that its parent is not also a child/descendent

class Afsc 
{
  String id 
  String code 
  Afsc parent  

  def afscService 
  def sessionFactory
  ...
  static constraints = {
    ...
    parent (nullable: true, validator: { val, obj ->
      if (obj.id && (val?.id == obj.id)
          || obj.afscService.getChild(obj, val.code)) {
        return 'AFSC.cannot.be.cyclic'
      }
    })
  }
...
}

The fun part is that getChild() does a recursive search checking to see that the instance doesnt have its parent as a child:

  def getChild(parent, targetCode) {
    def children = Afsc.findAllByParent(parent)
    def child = children.find {
      it.code == targetCode
    }
    if (!child) {
      children.each {
        child = child ?: getChild(it,targetCode)
      }
    }
    return child
  }

When I tried this, I started getting stack overflow exceptions.  Long story short, it turns out that using  findAllByParent() causes hibernate to flush changes before executing the query.  Well, guess what happens when changes are flushed?  That's right - the validator gets called.  Which calls getChild().  Which calls findAllByParent().  Which causes a flush.  Which gives us infinite recursion and a stack overflow.

Once I figured out what was going on, it wasnt too hard to find the solution - tell grails/hibernate not to automatically flush changes:

    parent (nullable: true, validator: { val, obj ->
      if (obj.id && val) {
        if (val.id == obj.id) {
          return 'AFSC.cannot.be.cyclic'
        }
        def originalFlushMode = obj.sessionFactory.currentSession.flushMode
        obj.sessionFactory.currentSession.flushMode = org.hibernate.FlushMode.MANUAL
        try {
          if (obj.afscService.getChild(obj, val.code)) {
            return 'AFSC.cannot.be.cyclic'
          }
        }
        catch(Exception e) {
          return e.getMessage()
        }
        finally {
          obj.sessionFactory.currentSession.flushMode = originalFlushMode
        }
       
      }
    })

Update 04-Apr-2014:

Today I was writing a custom validator and something was telling me that querying the database from a validator might cause problems, so I decided to google a bit to see if I was right.  I guess it was my subconscious reminding me that I'd already solved this problem once before.

Having seen a couple of other solutions for this problem, it seems like a better solution might be
to use the withNewSession() domain class dynamic function so that the query can be performed in a new session.  See http://adhockery.blogspot.com/2010/01/upgrading-grails-11-12.html for an example.

The Windows Way vs the Unix Way

A colleague comparing VCS systems commented that while TFS includes pretty good bug and issue tracking components, systems like Git and Mercurial have to to be combined with Trac or Bugzilla to get the same set of functionality.   As I was reading his comments, it struck me that this was another great example of the Windows Way vs the Unix Way.

The Unix way is to have lots of small focused tools that do one thing well and that can be plugged together in any combination that meets your particular needs.  Often, there are multiple tools that do approximately the same thing, but in slightly different ways, each convenient to a particular set of needs.  This leads to highly tuned solutions - you can pick exactly the right set of tools that both solve your problem and fit best with your environment.  The down-side to this is that you need to be skilled in knowing how to fit the right pieces together.  Knowing which tools are best suited to your environment takes a good bit of experience - but once you have a solution, it fits like a glove.

The Windows way is pretty much the opposite.  The Windows Way is to construct a single monolithic piece of software that solves a whole general class of problems.  The great thing about this approach is that there's no assembly required.  You dont need to know about lots of different tools and how to make them all work together - you just need to know that one tool.  And because you only need to know one, you can get to be pretty knowledgeable about it.  The downside to this, of course, is that while general solutions can usually do a lot of things, they often do none of them well.  General purpose solutions have to make assumptions about the context is which they will be used, and if you deviate from those assumptions, the solution doesn't operate as efficiently as it could.

So is one better than the other?  Not really.  At least not without having more context.  Sometimes a general purpose solution is sufficient.  Other times, you need the flexibility to be able to create a highly specific solution.  The trick is to know when each is appropriate.

Serendipity

"Engineer for serendipity."

--Roy Fielding

[http://tech.groups.yahoo.com/group/rest-discuss/message/8343]

WSEC

So, earlier I had said that I wasn't really interested in going to the W3C Web of Services Workshop. It ended up that someone else couldn't go, and since I was curious to hear reactions to some of the stuff being presented on day 2, I decided to go ahead and go.

I'm glad I went. There was a lot of good and interesting discussion. I don't think any of the world's problems were solved and I don't think anybody changed their minds about Web Services - although there did seem to be a lot of agreement that REST is good and worth investing time in.

One of the recurring topics was the uniform interface - it seems some people get it and others don't. It always seem to end up in an argument about dispatching - either you do it at the operation level or you do it at the message type level. If I define operations, they're strongly typed and I know exactly what kind of data I'll be getting. If I only have one operation that has to handle different kinds of data, then how do I know what to do with the data - I have to write a big if-statement to figure out how to handle the data. How is that an improvement? Arent you just pushing the dispatching to a different place?

And that's the wrong thing to focus on. I stumbled on this as I was trying to explain to my very dyed-in-the-wool WS-* coworker why the uniform interface is useful. I finally made progress with the following.

Imagine I have a printer with an embedded web server. The printer makes available a web service with associated WSDL that define an operation called getPrinterStatus, and that operation returns an xml document of a type we'll just call DeviceInfo. If I'm writing a client to retrieve the printer's status, I pull in the WSDL generate the stub code and fill in the business logic. Now I can monitor the status of the printer.

Now imagine that some time later, I purchase a copy machine. This copier also has an embedded web server and makes available a web service. The web service has a number of operations, but one of them is getDeviceInfo, and that operation also happens to return an xml document that has the same format as what the printer returns - DeviceInfo.

If I now want my printer monitor client to also be able to monitor my copier, I have to modify the client's code - I have to pull in the copier's WSDL, generate the stubs for its operations and then I can get the DeviceInfo document for the copier.

Now back up and imagine that each of those devices had used HTTP GET in a RESTful way. Because my printer monitor client knows how to handle documents of type DeviceInfo, all I have to do is tell it what the appropriate URI is for each of my devices - I don't have to change any software. Now, instead of only being able to interact with my printer, my client software can interact with any resource that produces DeviceInfo documents in response to a HTTP GET. For free.

I could hear the light bulb click on.

Hot vs Cold

Every winter, there are people who say they'd rather be too hot than too cold. And every summer, there are people who say they'd rather be too cold than too hot. And I'm pretty sure that some of those people say different things depending on the season.

Right now, I know I'd rather be too hot than too cold. Problem is, I'm concerned that I might have a seasonal opinion - but I really can't remember what I thought when it was actually hot out. I'm pretty certain I face this same dilemma every year, and probably twice a year (but I can't remember for sure).

So this year, I'm going to do something about it - I'm writing down my winter-time position on the hot vs cold debate: I prefer heat to cold.

Now, I just have to remember to check back when it's really hot out.