- Taschenbuch: 334 Seiten
- Verlag: Packt Publishing (26. Oktober 2012)
- Sprache: Englisch
- ISBN-10: 1849518289
- ISBN-13: 978-1849518284
- Größe und/oder Gewicht: 19 x 1,9 x 23,5 cm
- Durchschnittliche Kundenbewertung: 2 Kundenrezensionen
- Amazon Bestseller-Rang: Nr. 497.404 in Fremdsprachige Bücher (Siehe Top 100 in Fremdsprachige Bücher)
Akka Essentials (Englisch) Taschenbuch – 26. Oktober 2012
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Über den Autor und weitere Mitwirkende
Munish K. Gupta
Munish K. Gupta is a Senior Architect working for Wipro Technologies. Based in Bangalore, India, his day-to-day work involves solution architecture for applications with stringent non-functional requirements (NFRs), Application Performance Engineering, and exploring the readiness of cutting-edge, open source technologies for enterprise adoption.
He advises enterprise customers to help them solve performance and scalability issues, and implement innovative differentiating solutions to achieve business and technology goals. He believes that technology is meant to enable the business, and technology by itself is not a means to an end.
He is very passionate about software programming and craftsmanship. He is always looking for patterns in solving problems, writing code, and making optimum use of tools and frameworks. He blogs about technology trends and Application Performance Engineering at http://www.techspot.co.in and about Akka at http://www.akkaessentials.in
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Unfortunately, the author chose to write the book in a way that simply repeats this documentation. Most of the book follows this simple recipe: Akka provides feature X, this is how it looks like in Java, this is how it looks like in Scala. And that's it.
For this reason, I have to advice others to read the original (and obviously much more up-to-date) documentation on akka.io instead of wasting money on this book. I was expecting the book to give me actual insights beyond the mere documentation. Instead of telling me how to do this or that with akka, I expected to learn why one should do it this or that way. What are the pros and cons of various approaches, what are best practices, etc. etc.? Rarely did I even find a single sentence that goes beyond simply explaining what a feature does.
While it's nice that the book covers both Java and Scala, it is extremely annoying to find that the author repeats each and every code listing in both languages. Instead of explaining how to get from one to the other in general, and then sticking to one in the examples it's all redundantly copied. Sometimes even the explanation paragraphs are repeated for the listings in both languages. In essence, you can easily subtract one third from the number of pages due to that redundancy. Do I even need to mention that you can find code samples for all these features on akka.io in both languages anyways?
I was also sceptical at first about the language quality of the book after reading a few articles on the author's blog.Lesen Sie weiter... ›
Die Freude an dem Buch wird nur dadurch etwas getruebt, dass es zu viele kleine Fehler enthaelt. Die haette ein guter Lektor (oder der Autor selber) bemerken muessen.
Die hilfreichsten Kundenrezensionen auf Amazon.com (beta) (Kann Kundenrezensionen aus dem "Early Reviewer Rewards"-Programm beinhalten)
- Author describes a small piece of code or class and defines it (errors exist here, incorrect names, etc)
- seems correct in the final listing of all code
Minus a star for this reason, but workable just skip ahead to the master code pages and you'll be fine. I also wish they'd just split this into 2 books (java & scala) but it works.
Also a word of warning, if you're unfamiliar with the actor model you may need even smaller "baby steps" before reading this book. You might understand the concept of hardline multithreading but this is really different, you have to abandon many of those practices. I recommend reading the chapters on Actors from "Scala for the Impatient" or "Programming in Scala: A Comprehensive Step-by-Step Guide, 2nd Edition" as a companion. I've read both of these books and they are worth buying outright, ("Scala for the Impatient" appears to be listed at a good price for the Kindle lately)
Keep in mind, Akka is now set to replace the Scala's version of Actors in 2.11 (they are not exactly the same) - however, it helped me to learn Scala's simple approach first.
It is a useful addition to the excellent Akka documentation.
The coverage of STM is a great deal more detailed and is perhaps the most useful chapter.
However there is an unfortunate error.
The BurstyMessageRouter example is not thread safe.
The text implies a router is a form of actor and hence is intrinsically thread safe.
The Akka documentation indicates that is not true:"..the code which decides which route to take is invoked concurrently from all possible senders and hence must be thread-safe,.."
For example the paragraph:
"We have Thread.sleep() because there is no guarantee in which order the messages are processed. The first Thread.sleep() method ensures that all the string sentence messages are processed completely before we send the Result message."
Complete rubbish! using Thread.sleep() as means to synchronize concurrent threads. The list goes on and on.
I approached the book because I was interested in a MapReduce solution with Akka. Indeed this book covers MapReduce but it is completely flawed and the result is non-deterministic from run to run! I have discussed the two main concurrency hazards in stackoverflow (http://stackoverflow.com/questions/17291851/mapreduce-implementation-with-akka).
All in all I really do NOT recommend this book. I have no idea where the reputation of this publisher is going to by publishing this rubbish.