By Floyd Marinescu
In truth, the booklet isn't a foul ebook, it provides an engaging but difficult subject, tips to layout EJB (or in a broader experience, J2EE program) utilizing layout styles. notwithstanding, this ebook has a wide intersection with middle J2EE styles, which not just contains extra styles (on all layers), but additionally is written in a extra transparent and finished way.
Except the styles awarded in either books, (Session Facade, info move Object(DTO), DTO Factory(Assembler), EJBHomeFactory(Service Locator), enterprise Delegate...) the writer brought, "EJB Command" trend, which in practice(IMO), has constrained utilization in server part firm software, because it distributes the enterprise common sense to command items (usually the buyer) and therefore will reason company ideas duplication and extra importantly, more durable to alter the foundations later on account that its distribution;
"Generic characteristic entry and knowledge move Hashmap" development, that's not anything yet utilizing map to move facts. This back will undergo in disbursed functions, for the reason that either consumers and server need to agree on map key protocol and it's tougher to add/change the keys later;
"Data entry Command" trend, which derives from either command and knowledge entry object(DAO, provided in Core), not just will this trend undergo the cons of command development utilization in company dispensed software, but in addition capability complexity in command processing to ensure dead-lock occasions, facts integrity, and should turn out with loads of small personalized command classes.
Even although the writer pointed out the cons of those styles sincerely, i believe the danger outweighs the ease in an entry-mid point firm program layout publication which attempts to educate designers how make an outstanding design.
A few good stuff that have been ignored out by way of center J2EE styles are "Business Interface", "Version Number", "Dual continual Entity Bean", "Primary Key Generation". yet those should be locate in different places, fairly, "Version quantity" and "Primary Key iteration" are extra within the database/tranaction area than EJB domain.
Chapter6 "From necessities to Pattern-Driven layout" is meant to be a case examine, yet is gifted in a imprecise and never derived technique to step via, it additionally lacks the traditional iterative/refactoring layout kind, if every little thing is easy and in position to make an ideal layout selection, then i'd imagine the instance wouldn't be actual. even though, I do just like the author's layering variety definition from Presentation, software, companies, area, to Persistence.
Chaper7 is set improvement, development, checking out, deployment strategy, it truly is absolutely inappropriate to the layout development subject, and too brief to be precious, and there are numerous solid books (instead of just one bankruptcy) within the e-book store.
Chapter8 is ready JDO, back, a unmarried bankruptcy wouldn't make readers' day.
Chapter9 is sweet, it really is approximately idioms, solid practices vs. pitfalls in J2EE software layout. even though, the checklist is just too brief and doesn't offer find out how to refactor the undesirable layout to stable one in comparison with center J2EE Patterns.
Overall, there are constrained beneficial contents provided during this booklet, and that i had feeling lot of stuff (unrelated) have been crammed in exactly to refill the gap to make it a decent-sized e-book. i'd suggest middle J2EE styles over this one while you're attracted to J2EE program utilizing layout styles. just one of those books will stand last...
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Additional resources for EJB Design Patterns: Advanced Patterns, Processes, and Idioms
This mixing of presentation logic with business logic is a poor application design for any serious deployment. ■■ Poor maintainability. Usage of the Java Transaction API causes middleware logic for performing transactions to be interlaced with application logic. It is much cleaner to separate the two via declarative transactions, so that we can tweak and tune our middleware without affecting our business rules. ■■ Poor separation of development roles. A common practice on largescale projects is to separate the development tasks of presentation logic programmers (such as servlet/jsp developers) from the business logic/middleware programmers (EJB developers).
If the use case succeeds/fails then the system will notify the user by email. Some companies might implement a system in such a way that a human being would make a phone call, and so on. If the application requirements allow it, some applications could use a polling model. That is, an end user will be assigned a particular place they can go to check the status of their request, similar to a tracking number used by modern courier services. The takeaway point here is that when using the Message Façade pattern, developers must devise novel ways to communicate the results of a use case to the client.
EJB Layer Architectural Patterns ■■ Allow for creating complex graphs of DTOs. By writing DTO creation logic up front, developers can create complex graphs/hierarchies of DTOs that can be used to transfer the data from complex entity bean hierarchies containing one-to-one, one-to-many, many-to-many, and cyclic relationships, and combinations of such relationships. This provides clients with fine-grained control over what parts of entity bean data they need to display. For non-Web clients such as Java applications and applets, the ability to get non-tabular data is particularly important.