Further Reading in Java

Making QR Code ISO/IEC18004 in Java Further Reading
Further Reading
Making Denso QR Bar Code In Java
Using Barcode generation for Java Control to generate, create QR Code image in Java applications.
Embedded Value has been called a couple of different names in its history TOPLink refers to tit as aggregate mapping Visual Age refers to it as composer
Generate Barcode In Java
Using Barcode drawer for Java Control to generate, create bar code image in Java applications.
Example: Simple Value Object (Java)
Bar Code Scanner In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
This is the classic example of a value object mapped with Embedded Value We'll begin with a simple product offering class with the following fields
QR Code Maker In Visual C#.NET
Using Barcode printer for VS .NET Control to generate, create QR image in Visual Studio .NET applications.
class ProductOffering private Product product; private Money baseCost; private Integer ID;
Generate QR Code ISO/IEC18004 In .NET
Using Barcode maker for ASP.NET Control to generate, create Denso QR Bar Code image in ASP.NET applications.
In these fields the ID is an Identity Field (216) and the product is a regular record mapping We'll map the base cost using Embedded Value We'll do the overall mapping with Active Record (160) to keep things simple
Quick Response Code Maker In Visual Studio .NET
Using Barcode generator for .NET framework Control to generate, create QR Code image in .NET applications.
Since we're using Active Record (160) we need save and load routines These simple routines are in the
QR-Code Maker In VB.NET
Using Barcode printer for .NET Control to generate, create QR image in .NET framework applications.
product offering class because it's the owner The money class has no persistence behavior at all Here's the load method
Draw Bar Code In Java
Using Barcode creation for Java Control to generate, create bar code image in Java applications.
class ProductOffering public static ProductOffering load(ResultSet rs) { try { Integer id = (Integer) rsgetObject("ID"); BigDecimal baseCostAmount = rsgetBigDecimal("base_cost_amount"); Currency baseCostCurrency = RegistrygetCurrency(rsgetString( "base_cost_currency")); Money baseCost = new Money(baseCostAmount, baseCostCurrency); Integer productID = (Integer) rsgetObject("product"); Product product = Productfind((Integer) rsgetObject("product")); return new ProductOffering(id, product, baseCost); } catch (SQLException e) { throw new ApplicationException(e); } }
Code 3/9 Printer In Java
Using Barcode encoder for Java Control to generate, create Code39 image in Java applications.
Here's the update behavior Again it's a simple variation on the updates
GTIN - 12 Encoder In Java
Using Barcode encoder for Java Control to generate, create UPC Symbol image in Java applications.
class ProductOffering public void update() { PreparedStatement stmt = null; try { stmt = DBprepare(updateStatementString); stmtsetBigDecimal(1, baseCostamount()); stmtsetString(2, baseCostcurrency()code()); stmtsetInt(3, IDintValue()); stmtexecute(); } catch (Exception e) { throw new ApplicationException(e); } finally {DBcleanUp(stmt);} } private String updateStatementString = "UPDATE product_offerings" + " SET base_cost_amount = , base_cost_currency = " + " WHERE id = ";
Printing EAN 13 In Java
Using Barcode generator for Java Control to generate, create EAN13 image in Java applications.
Serialized LOB
Bar Code Drawer In Java
Using Barcode creation for Java Control to generate, create barcode image in Java applications.
Saves a graph of objects by serializing them into a single large object (LOB), which it stores in a database field
Encoding USPS Confirm Service Barcode In Java
Using Barcode generator for Java Control to generate, create USPS Confirm Service Barcode image in Java applications.
Object models often contain complicated graphs of small objects Much of the information in these structures isn't in the objects but in the links between them Consider storing the organization hierarchy for all your customers An object model quite naturally shows the composition pattern to represent organizational hierarchies, and you can easily add methods that allow you to get ancestors, siblings, descendents, and other common relationships
Code 39 Full ASCII Creation In VS .NET
Using Barcode maker for VS .NET Control to generate, create Code-39 image in .NET framework applications.
Not so easy is putting all this into a relational schema The basic schema is simple an organization table with a parent foreign key, however, its manipulation of the schema requires many joins, which are both slow and awkward
Encoding Bar Code In Visual Studio .NET
Using Barcode drawer for Visual Studio .NET Control to generate, create bar code image in .NET applications.
Objects don't have to be persisted as table rows related to each other Another form of persistence is serialization, where a whole graph of objects is written out as a single large object (LOB) in a table this Serialized LOB then becomes a form of memento [Gang of Four]
Paint Data Matrix 2d Barcode In Visual Studio .NET
Using Barcode printer for .NET framework Control to generate, create Data Matrix 2d barcode image in .NET framework applications.
How It Works
Barcode Creation In Visual C#.NET
Using Barcode generator for .NET Control to generate, create bar code image in .NET framework applications.
There are two ways you can do the serialization: as a binary (BLOB) or as textual characters (CLOB) The BLOB is often the simplest to create since many platforms include the ability to automatically serialize an object graph Saving the graph is a simple matter of applying the serialization in a buffer and saving that buffer in the relevant field
Make UPC-A Supplement 2 In .NET Framework
Using Barcode creation for VS .NET Control to generate, create GTIN - 12 image in VS .NET applications.
The advantages of the BLOB are that it's simple to program (if your platform supports it) and that it uses the minimum of space The disadvantages are that your database must support a binary data type for it and that you can't reconstruct the graph without the object, so the field is utterly impenetrable to casual viewing The most serious problem, however, is versioning If you change the department class, you may not be able to read all its previous serializations; since data can live in the database for a long time, this is no small thing
Barcode Drawer In VS .NET
Using Barcode encoder for ASP.NET Control to generate, create barcode image in ASP.NET applications.
The alternative is a CLOB In this case you serialize the department graph into a text string that carries all the information you need The text string can be read easily by a human viewing the row, which helps in casual browsing of the database However the text approach will usually need more space, and you may need to create your own parser for the textual format you use It's also likely to be slower than a binary serialization
Make Code 128 Code Set B In .NET Framework
Using Barcode creation for ASP.NET Control to generate, create ANSI/AIM Code 128 image in ASP.NET applications.
Many of the disadvantages of CLOBs can be overcome with XML XML parsers are commonly available, so you don't have to write your own Furthermore, XML is a widely supported standard so you can take advantage of tools as they become available to do further manipulations The disadvantage that XML doesn't help with is the matter of space Indeed, it makes the space issue much worse because its a very verbose format One way to deal with that is to use a zipped XML format as your BLOB you lose the direct human readability, but it's an option if space is a real issue
When you use Serialized LOB beware of identity problems Say you want to use Serialized LOB for the customer details on an order For this don't put the customer LOB in the order table; otherwise, the customer data will be copied on every order, which makes updates a problem (This is actually a good thing, however, if you want to store a snapshot of the customer data as it was at the placing of the order it avoids temporal relationships) If you want your customer data to be updated for each order in the classical relational sense, you need to put the LOB in a customer table so many orders can link to it There's nothing wrong with a table that just has an ID and a single LOB field for its data
In general, be careful of duplicating data when using this pattern Often it's not a whole Serialized LOB that gets duplicated but part of one that overlaps with another one The thing to do is to pay careful attention to the data that's stored in the Serialized LOB and be sure that it can't be reached from anywhere but a single object that acts as the owner of the Serialized LOB