Wiley Professional ADO.NET 2: Programming with SQL Server 2005, Oracle, and MySQL 978-0-7645-8437-4 ユーザーズマニュアル
製品コード
978-0-7645-8437-4
Histor y of Data Access
Over the years, many APIs have been released, all of which work toward the goal of providing
universal data access. Universal data access is the concept of having a single code base for accessing
data from any source, from any language.
universal data access. Universal data access is the concept of having a single code base for accessing
data from any source, from any language.
Having universal data access is important for four reasons: First, developers can easily work on
applications targeting different data stores without needing to become experts on each one. Second,
developers can have a common framework for data access when switching between programming
languages, making the transition to new languages easier. This is especially important in the .NET
Framework, in which developers are expected to be able to easily switch between VB.NET and C#.
Third, it enables developers to more easily write a single application that can be deployed against
multiple data stores. Finally, it provides a level of abstraction between the application and direct
communication to the database to simplify the code the average developer needs to write.
applications targeting different data stores without needing to become experts on each one. Second,
developers can have a common framework for data access when switching between programming
languages, making the transition to new languages easier. This is especially important in the .NET
Framework, in which developers are expected to be able to easily switch between VB.NET and C#.
Third, it enables developers to more easily write a single application that can be deployed against
multiple data stores. Finally, it provides a level of abstraction between the application and direct
communication to the database to simplify the code the average developer needs to write.
Microsoft has conducted surveys to determine which key factors companies are looking for in a
data access layer. They came back with four main points, which they have tried to implement in
their databases and data access components:
data access layer. They came back with four main points, which they have tried to implement in
their databases and data access components:
❑
High performance —
As any developer knows, performance can make or break almost
any application. No matter how much a data access layer may simplify accessing the data,
it absolutely must perform nearly as well or better than the alternatives before it becomes
a viable solution for the majority of applications.
it absolutely must perform nearly as well or better than the alternatives before it becomes
a viable solution for the majority of applications.
❑
High reliability —
If a component consumed by an application is buggy or occasionally
stops working, it is perceived by the users as an error in that application. In addition to
being a liability and annoyance to the company that implemented the application, it also
reflects very poorly on the developer(s) who wrote the application. Any issues, such as
memory leaks, that cause unreliable results are unacceptable to the development community.
It’s also very important to the support personnel that it be fairly maintenance-free. No one
wants to have to reboot a server on a regular basis or constantly apply patches just to keep
an application running.
being a liability and annoyance to the company that implemented the application, it also
reflects very poorly on the developer(s) who wrote the application. Any issues, such as
memory leaks, that cause unreliable results are unacceptable to the development community.
It’s also very important to the support personnel that it be fairly maintenance-free. No one
wants to have to reboot a server on a regular basis or constantly apply patches just to keep
an application running.
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