Databases Reference
In-Depth Information
T
1
T
2
T
4
T
3
Web browser
Middle-tier
object layer
Relational
database
Figure 9.5
The four-translation web-object-RDBMS model. This model
is used when objects are used as a middle layer between a web page
and a relational database. The first translation (T1) is the conversion
from HTML web pages to middle-tier objects. The second translation
(T2) is a conversion from middle tier objects to relational database
statements such as SQL. RDBMSs return only tables so the third
translation (T3) is the transformation of tables back into objects. The
fourth translation (T4) is converting objects into HTML for display in
web pages.
Imagine using this process on a daily basis as you return home from a long day at the
office. You'd take off your clothes and start by removing all of the thread, dismantling
your clothes bit by bit, and then putting them away in uniform bolts of cloth. When
you get up in the morning to go to work, you'd then retrieve your needle and thread
and re-sew all your clothes back together again. If you're thinking, “This seems like a
lot of unnecessary work,” that's the point of the example. Today, NoSQL document
stores allow you to avoid the complexities that were caused by the original require-
ments to store flat tabular data. They really allow development teams to avoid a lot of
unnecessary work.
There have been multiple efforts to mitigate the complexities of four-step transla-
tion. Tools like Apache Hibernate and Ruby on Rails are examples of frameworks of
tools that try to manage the complexity of object-relational mapping. These were the
only options available until developers realized that using a NoSQL solution to store
the document structure directly in the database without converting it to another for-
mat or shredding it into tables and rows is a better solution.
This lack of translation makes NoSQL systems simpler to use and, in turn, allows
subject matter experts (
SME
s) and other nonprogramming staff to participate directly
in the application development process. By encouraging
SME
s to have a direct involve-
ment in building applications, course corrections can be made early in the software
development process, saving time and money associated with rework.
NoSQL technologies show how moving from storing data in tables to storing data
in documents opens up possibilities for new ways of using and presenting data. As you
move your systems out of the back room to the World Wide Web, you'll see how
NoSQL solutions can make implementation less painful.
Next we'll look at combining a no-translation architecture with web standards to
create a development platform that's easy to use and portable across multiple NoSQL
platforms.
