choreography vs orchestration

I see in more and more articles that authors are using both terms interchangeably. As far as I can tell there is no formal definition, just like with terms agile, microservices, SOA, but... in ancient days when I was studding computer science on a university there was a difference:

• choreography: distributed decision making
• orchestration: centralised decision making

TPC-C current benchmarks for stateful and stateless services running Java.

• Immediately consistency: 1 box: 2000 requests/second with 5 second response time
• Eventually consistent: 1 box: 300 requests/second with a 100 millisecond response time.

It is all achivable, if you are not there you need tools to figure out why.
Switch to stateless services whenever possible. A great article about pushing the boundaries and how important it is in HFT is available in barbarians at the gateways.

Latency Numbers Every Programmer Should Know

I am not sure if 1% of programmers know it, but it is a great reference, kudos to Jeff Dean and Peter Norvig: Latency Comparison Numbers

L1 cache reference                            0.5 ns
Branch mispredict                             5   ns
L2 cache reference                            7   ns             14x L1 cache
Mutex lock/unlock                            25   ns
Main memory reference                       100   ns             20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy              3,000   ns
Send 1K bytes over 1 Gbps network        10,000   ns    0.01 ms
Read 4K randomly from SSD*              150,000   ns    0.15 ms
Read 1 MB sequentially from memory      250,000   ns    0.25 ms
Round trip within same datacenter       500,000   ns    0.5  ms
Read 1 MB sequentially from SSD*      1,000,000   ns    1    ms  4X memory
Disk seek                            10,000,000   ns   10    ms  20x datacenter roundtrip
Read 1 MB sequentially from disk     20,000,000   ns   20    ms  80x memory, 20X SSD
Send packet CA->Netherlands->CA     150,000,000   ns  150    ms
 
Notes
-----
1 ns = 10-9 seconds
1 ms = 10-3 seconds
* Assuming ~1GB/sec SSD

Functors, Applicatives, And Monads In Pictures

Just came across a really need article ilustrating 'Functors, Applicatives, And Monads In Pictures'.

Reseting admin password in Sitecore

Sitecore inside Core db stores users information. In order to reset password to 'b' for a user 'admin' one has to run a following script

UPDATE [aspnet_Membership] SET Password='8dC23rEIsvuttG3Np1L4hJmJAOA=', PasswordSalt=' joeLPwcwMq6L7kyuVfVS7g=='   
WHERE UserId IN (SELECT UserId FROM [aspnet_Users] WHERE UserName = 'sitecore\Admin') 

It is important to set both Password and PasswordSalt.

Resharper and the end of the world

21 December 2012, is the last day of the world. That's why for last 3 hours I am trying to upgrade my Resharper from version 6 to version 7, because the price is 75% off. Unfortunately for the last 3 hours the only response that I got was

But I see a progress! Now I am getting:

I don't have much time - it's still 20 more hours to go till the end of the world.

Major unsolved problems in CS

There is a nice discussion going on on a stack exchange about major unsolved cs problems, so if you are a math fun (as me) it is something to solve on your free time.

Blogs that are not updated

Yes, it is a problem. I am a huge fan of Brian Beckman and Bart de Smert. Unfortunately their blogs have not been updated for a long time. I read majority of their articles, and learned a lot, and I literally mean a lot, because each article requires some research to be done by myself in order to understand everything deeper and better. I ask myself a question, why do people like Hanselman or Haack blog a lot, and people that I prefer don't. Anyway, Brian, Bart I would exchange at least three months of blogging of Hanselman or Haack for a one of your posts. Power to visioners.

Types theory

As for me a theoretical part of Information Technology is a crucial part to understand what is going on in a dynamic environment. By a dynamic environment I mean plenty of frameworks that exists on a market, huge amount of different computer languages and different technologies, models that try to expose some ideas of its creators. But idea is a thing that can be described by a language, and probably if there are few ideas some of them share something in common, and some classes of abstraction can be named between them. This is why I was usually even more interested in a theory that stands behind some technology then the technology itself. Type theory is an example. About four years ago I was a hard core dynamic language purists that enjoyed everything that fully enabled me to express my mind - I loved writing Perl one liners, using sophisticated magic standing behind JavaScript prototyping. It was also a time when I first read a book Types and Programming Languages by C. Pierce. And it was a book that opened by mind to problems, benefits, ideas lying underneath typing, and also showed that static typing by sticking to its discipline allowed programmer to express himself by using a different approach (then dynamic language programmer) but it is hard to say that by sticking to static typing you miss something. As every human being I enjoy discussing my thoughts, ideas with other people, it allowed me to understand topics that I study deeper, more, and also allowed to look at it from a different perspective, a perspective of a person that I talk to (I assume that he spokes back:) ). Huge majority of people that I know do not study theory any more, they tend to read books about a specific technology - like MVC, SharePoint, instead of trying to understand a theory, philosophy standing behind a specific implementation. As a reader can imagine it is hard to find a person to talk to about types theory, but there are other methods/techniques that allowed me to rethink things that I now and get motivated to explore and learn more. This is why I am so happy to find a web page by brothers in arms from Oregon UV. A great place to explore and learn.

Curry’s anticipation of the types used in programming languages

I found a really interesting paper about types. Well written, easy read. It gave me a great background of history of combinatory logic, how it evolved and fought for it's place in a current math world. Enjoy the reading.

Functional Programming with Bananas, Lenses, Envelopes, and Barbed Wire

Today I finally found time (and will) to read a this classy paper. My first impression, well written, it is not boring, or too technical/mathematical. If a term might be unclear or unfamiliar to the read, then there is a reference to it, and there are plenty of resources on the web to get you going. Personally, it challenges me to start a small research on some subject while reading a paper, and it only makes a main paper more interesting. I hate when I need to read a paper that deals with a subject that I am familiar with, and when I have to go through all the basics and easy stuff (stuff that I already know) just to find an answer to the question that I am looking for.

Ghostscript for GSView under windows 64 bit arch

I was trying to find forgotten by me information about type reduction for lambda calculus. I went to get Barendregt Lambda Calculi with Types, to find out that it's Postscript version. Because on my fresh box I didn't have GSView I had to download it from a web. By default it tries to find gsdll64.dll in it's path, but a compiled version of a new release of Ghostscript (9.0) is delivered in a plain file form - it does not install anywhere and does not register itself in any path. In order to make it available for GSView one needs to fire up GSView and select Options->Advanced Configure-> in 'Ghostscript DLL' insert a path to the library.

Biosimilarity

We did it! Lucius Gregory Meredith was resin money for his book - Monadic Design Patterns. Greg is a full time (hard) worker and was having trouble to find time to finish writing his book. He wanted to make it good and helpful to other people, and making something good or even better requires time. I also find myself doing much better job when I do not have some other tasks on my mind, so truly understand his position. Greg was able to gather enough money by Kickstart web page to take a career break (or at least few days break) and spend his time on writing his book. Greg good luck, and hope to receive my copy as soon as it is going to be ready. Just want to add that Greg is one of the best Computer Scientists/Mathematicians that I met in my life, he is somehow my mentor and guru. Cheers.

Particle Video

I really enjoy, some projects that people have. By just looking at it I can see that the person who did it, spent plenty of time making it good, and he had a great time doing it. That's why I enjoy the final (or at least current) version so much.

ycombinator and things I read

Recently a friend of mine send me a link to ycombinator - great resource for someone like me. So, if you like to read things that are more pragmatic then going deep but stay focused on one technology, methodology or technic, then this is something like /. but more techie. Simply I love it, usually, really short articles behind, on various subjects. Some time ago I spend tremendous amount of time looking for some good resources of techie knowledge, and so far /. is the only thing I am using on daily basis, but ycombinator seems to be great as well.

In terms of books, recently I read:
Knuth's The Art Of Programming (first 3 tomes)
Avodey's Category Theory (Oxford Logic Guides)

I enjoy reading few books at this same time (well, almost this same). When a part of book, or some topic is not really interesting, I switch to second book, and give my brain a fresh topic.

In terms of Knuth's books, I enjoy the way how they are written, easy to read, with sense of humor. Excellent exercises at the end of each topic. I don't like the MIX language. It is too old fashion to me. Sometimes, dealing with the language is harder then the algorithm itself, and a problem is more about how to write the code well (or even, how to write it), and not how to deeply understand, why some operations take place, and why they are done now, and that way. But still I recommend this book.

I spend some time deciding between Category Theory (Oxford) and Basic Category Theory for Computer Scientists (MIT). The O book is newer and bigger than M book, but also more expensive. I made a decision, base on fact that I am more Oxford then MIT boy (sorry chaps:)). So far I love it, easy to understand, lot's of new stuff to learn. I don't see to many exercises that are good for me, and It makes it hard to test new knowledge.

Slashdot audio reader sucks

It is a good idea, but the voice is terrible, it is so much beter to read it on your own:

slashodt audio

And it also reminds me about Apple/Amazon ebook problem. Why is that Apple does not have any technical book (to read, or listen, on iPhone/iPad). And there are many that are avaiable on Amazon, but 'only' for kindle, and kindle is in my opinion not as good as iPad.

Amazon book price

How come kindle books are more expensive then a hardcover? This is so weird. There was a time when I loved to buy a pdf books, because the shipment prize was killing me. Now days you can't even buy a pdf book, and a version for kindle is more expensive then the hardcover book, have a look here:

Refactoring book at Amazon

Hardcover: $52.96
Kindle edition: $57.11

Why is that?

Like a month ago I bought an eBook from ebooks.com. I decided to buy an eBook because the shipment price was a joke. They allowed me to download it or to view it online. But I couldn't download it because it requires Adobe Reader with some kind of anti piracy protection (DRM support perhaps). Unfortunately Adobe Reader didn't want to register on my machine, because Ebooks.com Adobe Reader license key was not valid. I spend 3 hours talking back and forward with Ebooks.com people and Adobe people and no one could help me. And they didn't even allow me to download it in a different format or in a different way. I was so pissed off! I sticked with a ‘view online’ option, which really sucks. And you can't even print a book.

What is going on with an eBook word?