Most Helpful Customer Reviews
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6 of 6 people found the following review helpful:
5.0 out of 5 stars
Good design pattern book in data access !!, February 28, 2004
I am in the process of writing a thesis proposal that utilizing JDBC and TableModeler to access various database platforms as a prototype.While prototyping the model, I encountered a lot of consideration of what is the best approach for certain implementation (mainly on JDBC). While looking into a few of designing books, I found this Data Access Patterns book that fits into my research needs. I have read other book such as Designing Flexible Object Oriented System with UML and not able to apply the concept or see solution in it. It is simply a conceptual book. No practical examples at all. Mr. Nock has explained the design patterns very clearly in each chapter by using JDBC as a media. The examples are very easy to understand as compared to Design Patterns Explained. I am not able to understand codes that implementing graphics in that book. Mr. Nock addressed the pros and cons of the patterns. Many techie books do not even bother to talk about pros and cons. The author has chosen the right title for the book, I realized that many times author received a poor rating because reader expect different contents based on the title of the book. The feature I liked the most - the ¡§Applicability¡¨ section on each chapter. Unlike other patterns book, the author explains the concept and gives example of "what" and "when" to use certain design pattern. This section is pretty much the answer for my thesis obstacles. The answer is in this book!! Minor typos do exist such as in page 390 roll back instead of rollback. In concurrency chapter, author may have mis-used the term of updates locking. It should be Lost Updates instead of Missing updates. Concurrency chapter looks like UDB Lock Concurrency architecture. Additional note - would like to see the quality aspect in each of the patterns. Overall, the book is very well structured, explained and thoughtful. Thank you Mr. Nock !! This is a perfect book for my thesis. Looking forward to read your future publish. Regards, EQ
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5 of 5 people found the following review helpful:
4.0 out of 5 stars
Useful patterns and interesting concepts, December 10, 2004
The book presented 25 patterns grouped in 5 areas, decoupling (conceptual and architectural level), resource, input/output, cache and concurrency.
The most interesting patterns are in resource and cache. Decoupling and concurrency patterns (e.g., data accessor, active domain object, layers, transactions, optimistic/pessimistic lock etc.) are well known and the contents are a bit too light to be very useful, yet the concepts are giving readers some directions.
In resource patterns, some interesting patterns are presented, particularly resource timer automatically releases inactive resource, retryer enables fault-tolerance for data access operations.
In cache patterns, cache collector purges entries whose presence in the cache no longer provides any performance benefits; cache replicator replicates operations across multiple caches.
There are some areas to be improved, first, author should consolidate pattern names with other pattern authors, e.g., data accessor is also known as data access object, active domain object is similar to active record, paging iterator is close to value list handler (though value list handler is more decoupled from underlying data store), the point is, one of the important benefits and purposes for documenting patterns is to build common vocabularies among designers, using different names for same or similar patterns is defeating this purpose. The same pattern name should be used and may be presented as a variation of the original pattern.
Secondly, the examples given in the book is a bit too simple, sometimes, the examples might not justify or validate the interface abstraction is generic enough to handle real world problems, so some tweaking and modification to the pattern would be expected.
Overall, the book is well organized, and contents are easy to follow, most patterns come with class diagrams and sequence diagrams. Good for designers who want to decouple data access from rest of the application, utilize cache to minimize data access and thus boost application performance, manage resources in an efficient and leaking-proof way.
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5 of 5 people found the following review helpful:
5.0 out of 5 stars
Great book on persistence theory, May 10, 2004
I'm in the middle of developing yet another persistence framework for a client, having done it a couple of times before. Each time I refine my ideas about how to do it. I must say that this book has a thorough examination of issues and certainly food for thought as well as answers to a couple of questions I've had. However, I wouldn't say it's a complete design (which it doesn't claim to be). I still found myself picking and choosing which patterns to use as is, which to modify to my liking, and which to discard. Also, I was left with the impression that the book didn't give enough coverage to handling collections of objects. The material is mostly geared toward working with a single object, which is understandable. I just think it would have been helpful to have more discussion about handling collections. For example, what should happen when you request to load an object, but the criteria you passed to the loading mechanism results in data for more than one object being retrieved from the database? Hand back the first object? Raise an exception? If it's covered in the book, I missed it. Further, I would like to see more discussion about WHEN to refresh an object from the underlying database and when to save to the database. I always struggle with that timing issue. Having studied EJB, I like how entity beans keep your bean in synch with the underlying database. But the EJB container intercepts calls and makes those things happen. When coding the persistence layer myself, that's not an option. So, again, this is something I'd like to see some light shed on. Overall, though, a great book if you're interested in reading up on persistence layer patterns.
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