Wednesday, February 8, 2012

Book review: Working with NHibernate 3.0

It's been a while since I wrote my last book review, mostly because I'm still trying to figure out when it adds value to write one. For this one it was pretty obvious, there are far too little reviews out there.

Being new to NHibernate, and NHibernate being known as having a steep learning curve, I thought it would be a good idea to do some reading. Searching for books on NHibernate 3.0 on Amazon only yielded three results: NHibernate 3 beginner's guide, NHibernate 3.0 cookbook and working with NHibernate 3.0. None of these books have a decent amount of reviews, so I had to pick judging by the cover and summary. I chose the last one.

The book Working with NHibernate 3.0 by Benjamin Delcamp Perkins contains six chapters, covered over 213 pages.

The first chapter very briefly explains what an ORM is, and then starts looking at configuring NHibernate. This means setting up the session factory and its configuration, creating entities and mapping them to the database (using XML and code), but also configuring log4net (NHibernate's logging framework), serializing startup and interceptors and events. These last two subjects felt a little misplaced in this chapter though.

In the first chapter the foundation for the Guitar store example application is laid. This example application is written in WPF, which bothered me a bit. Not because I dislike WPF, but because when I'm reading a book on a data access technology I really don't want it to be littered with fragments of XAML and code-behind. To make matters worse, the author suggests using a console application to test your queries. I think it would have been far more valuable to use real unit tests to prove the queries are correct, more like this. Another complaint about the example application that I read in another review is that there are no scripts available to set up the database, which might be discouraging if you want to follow along.

Chapter two, three and four cover the various NHibernate query API's: HQL (Hibernate Query Language), ICriteria and LINQ. Every chapter implements the same or at least similar queries. Concepts covered in these chapters are simple queries, complex queries, detached queries, futures and aggregates. I think these chapters succeed in giving a good overview of the ways you can use NHibernate to query data. Also the tips on how to use futures, various fetch modes, the stateless session and aggregates to improve performance will prove useful in the future.

The fifth chapter covers managing state and saving data. In this chapter, the author explains the various ways you can handle database concurrency, listing the advantages and disadvantages of each option. NHibernate caching is also explained, looking at first and second-level caching. Further in this chapter, you can find an example of a custom data type implementation. Finally we arrive at saving data with NHibernate. Next to the standard way of saving data, the author explains the use of Evict, Merge and Persist.

The last chapter, covering only 9 pages, shows how you should set up NHibernate in an MVC3 application.

Conclusion

Although this book doesn't do a great job showing you how to use NHibernate in the real world, it does do a decent job giving you a basic overview of NHibernate's capabilities. Reading this book when you're new to NHibernate will save you from a few costly common NHibernate pitfalls. I don't think I will be able to use this book for reference, but it should be easier now - knowing the correct terminology - to search in the NHibernate documentation online.

My rating: 3/5. Do you advise other books on NHibernate?

2 comments:

  1. Nh 3.0 cook book is good but I still feel there's a space for a better intro book.

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  2. Agreed. Thanks for the heads up also on this book, every little helps :)

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