Making a Choice in Java

Encoding QR Code JIS X 0510 in Java Making a Choice
Making a Choice
QR Code Generator In Java
Using Barcode creator for Java Control to generate, create QR Code ISO/IEC18004 image in Java applications.
So, how do you choose between the three patterns It's not an easy choice, and it very much depends on how complex your domain logic is Figure 24 is one of those nonscientific graphs that really irritate me in PowerPoint presentations because they have utterly unquantified axes However, it helps to visualize my sense of how the three compare With simple domain logic the Domain Model (116) is less attractive because the cost of understanding it and the complexity of the data source add a lot of effort to developing it that won't be paid back Nevertheless, as the complexity of the domain logic increases, the other approaches tend to hit a wall where adding more features becomes exponentially more difficult
Encode Barcode In Java
Using Barcode encoder for Java Control to generate, create bar code image in Java applications.
Figure 24 A sense of the relationships between complexity and effort for different domain logic styles
Scanning Bar Code In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
Your problem, of course, is to figure out where on that x axis your application lies The good news is that I can say that you should use a Domain Model (116) whenever the complexity of your domain logic is greater than 742 The bad news is that nobody knows how to measure the complexity of domain logic In practice, then, all you can do is find some experienced people who can do an initial analysis of the requirements and make a judgment call
Generate QR-Code In Visual C#.NET
Using Barcode encoder for .NET Control to generate, create QR Code image in VS .NET applications.
There are some factors that alter the curves a bit A team that's familiar with Domain Model (116) will lower the initial cost of using this pattern It won't lower it to same starting point as the others because of the data source complexity Still, the better the team is, the more I'm inclined to use a Domain Model (116)
Print QR Code In .NET
Using Barcode maker for ASP.NET Control to generate, create QR Code image in ASP.NET applications.
The attractiveness of a Table Module (125) depends very much on the support for a common Record Set (508) structure in your environment If you have an environment like NET or Visual Studio, where lots of tools work around a Record Set (508), then that makes a Table Module (125) much more attractive Indeed, I don't see a reason to use Transaction Scripts (110) in a NET environment However, if there's no special tooling for Record Sets (508), I wouldn't bother with Table Module (125)
Drawing QR Code In .NET
Using Barcode encoder for .NET Control to generate, create QR-Code image in Visual Studio .NET applications.
Once you've made it, your decision isn't completely cast in stone, but it is more tricky to change So it's worth some upfront thought to decide which way to go If you find you went the wrong way, then, if you started with Transaction Script (110), don't hesitate to refactor toward Domain Model (116) If you started with Domain Model (116), however, going to Transaction Script (110) is usually less worthwhile unless you can simplify your data source layer
Denso QR Bar Code Printer In VB.NET
Using Barcode creator for Visual Studio .NET Control to generate, create QR Code 2d barcode image in .NET framework applications.
These three patterns are not mutually exclusive choices Indeed, it's quite common to use Transaction Script (110) for some of the domain logic and Table Module (125) or Domain Model (116) for the rest
Printing Code 39 Extended In Java
Using Barcode maker for Java Control to generate, create ANSI/AIM Code 39 image in Java applications.
Service Layer
EAN-13 Supplement 5 Encoder In Java
Using Barcode drawer for Java Control to generate, create EAN13 image in Java applications.
A common approach in handling domain logic is to split the domain layer in two A Service Layer (133) is placed over an underlying Domain Model (116) or Table Module (125) Usually you only get this with a Domain Model (116) or Table Module (125) since a domain layer that uses only Transaction Script (110) isn't complex enough to warrant a separate layer The presentation logic interacts with the domain purely through the Service Layer (133), which acts as an API for the application
Data Matrix Drawer In Java
Using Barcode encoder for Java Control to generate, create Data Matrix 2d barcode image in Java applications.
As well as providing a clear API, the Service Layer (133) is also a good spot to place such things as transaction control and security This gives you a simple model of taking each method in the Service Layer (133) and describing its transactional and security characteristics A separate properties file is a common choice for this, but NET's attributes provide a nice way of doing it directly in the code
Bar Code Maker In Java
Using Barcode creation for Java Control to generate, create bar code image in Java applications.
When you see a Service Layer (133), a key decision is how much behavior to put in it The minimal case is to make the Service Layer (133) a facade so that all of the real behavior is in underlying objects and all the Service Layer (133) does is forward calls on the facade to lower-level objects In that case the Service Layer (133) provides an API that's easier to use because it's typically oriented around use cases It also makes a convenient point for adding transactional wrappers and security checks
EAN128 Creator In Java
Using Barcode generator for Java Control to generate, create EAN128 image in Java applications.
At the other extreme, most business logic is placed in Transaction Scripts (110) inside the Service Layer (133) The underlying domain objects are very simple; if it's a Domain Model (116) it will be one-to-one with the database and you can thus use a simpler data source layer such as Active Record (160)
USS Codabar Creator In Java
Using Barcode generator for Java Control to generate, create ABC Codabar image in Java applications.
Midway between these alternatives is a more even mix of behavior: the controller-entity style This name comes from a common practice influenced heavily by [Jacobson et al] The point here is to have logic that's particular to a single transaction or use case placed in Transaction Scripts (110), which are commonly referred to as controllers or services These are different controllers to the input controller in Model View Controller (330) or Application Controller (379) that we'll meet later, so I use the term use-case controller Behavior that's used in more than one use case goes on the domain objects, which are called entities
Barcode Printer In .NET Framework
Using Barcode printer for ASP.NET Control to generate, create bar code image in ASP.NET applications.
Although the controller-entity approach is a common one, it's not one that I've ever liked much The use case controllers, like any Transaction Script (110), tend to encourage duplicate code My view is that, if you decide to use a Domain Model (116) at all, you really should go whole hog and make it dominant The one exception to this is if you've started with a design that uses Transaction Script (110) with Row Data Gateway (152) Then it makes sense to move duplicated behavior to the Row Data Gateways (152), which will turn them into a simple Domain Model (116) using Active Record (160) However, I wouldn't start that way I would only do that to improve a design that's showing cracks
Bar Code Generation In VB.NET
Using Barcode encoder for Visual Studio .NET Control to generate, create bar code image in Visual Studio .NET applications.
I'm saying not that you should never have service objects that contain business logic, but that you shouldn't necessarily make a fixed layer of them Procedural service objects can sometimes be a very useful way to factor logic, but I tend to use them as needed rather than as an architectural layer
ECC200 Drawer In C#.NET
Using Barcode generation for .NET Control to generate, create Data Matrix image in VS .NET applications.
My preference is thus to have the thinnest Service Layer (133) you can, if you even need one My usual approach is to assume that I don't need one and only add it if it seems that the application needs it However, I know many good designers who always use a Service Layer (133) with a fair bit of logic, so feel free to ignore me on this one Randy Stafford has had a lot of success with a rich Service Layer (133), which is why I asked him to write the Service Layer (133) pattern for this book
Barcode Maker In .NET
Using Barcode generation for VS .NET Control to generate, create barcode image in .NET framework applications.
Decoding UPC - 13 In Visual Studio .NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET applications.
Bar Code Scanner In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.