milop said:
Thanks for responding, Mr. Arnold.
I oversimplified the example. The web service is just a channel, I
understand this. It has no business rules in it nor does it communicate
with the data layer.
My business layer resides in separate assemblies (projects). My data
access layer also resides in separate assmblies. Please keep in mind I'm
rewriting an ASP.Net web app that has access to the BL. Processing is
performed on the server so object serialization and such (other than
persisting session state to a database) was not an issue. Creating a new
user type and throwing exceptions when the rules were violated is
handled.
Some like to do it that way, but I have never found that to be a best
practice.
So, back to "converting" this app to web services. After a little
brainstorming I figure the web service project should reference those
assemblies and the client app should also reference those assemblies.
Thus, both apps have copies of the same BL. That's appropriate in my
opinion especially if you want to catch errors at the client when user
types are instantiated and properties are set (for example); basic object
integrity stuff. I don't want to go over the wire just to see if a
PhoneNumber object is valid.
No, a DTO (Data Transfer Object) and a Presentation Layer of a MVP should
sit between the UI and the BLL or Web Servcice, with the DTO on an
Interface used between the UI and MVP. The UI should really be unware of
the BLL or Web Service.
Now, some like to have the Presenter layer in contact with the BLL so it
can be sent back to the UI, since most consider the Presentation layer as
part of the UI setting infront of the Web Service.
My concern is when something in the BL changes. All apps that reference
the BL would need, at the very least, a rebuild. To coordinate this in
Visual Studio I figure I could add all projects into one solution and
rebuild the solution. Thus all apps that reference the BL would get the
same copy of the new assemblies,
Does any of this make sense?
Yeah, but is it a best practice.
So, actually, not only did my original post concern architectural design,
but also a coordination issue inside of Visual Studio.
Also, I'm not quite sure by what you meant when you wrote "The UI/client
app should never consume the Web service directly". If I have a Windows
Forms app and need to call one of the webservice's functions, without
adding a Web Reference, how is it done?
See below and consider MVP.
Yes, I have read a bit on SOA, in a cursory manner, but this is the first
"real" app that I'm doing. I've done plenty of smaller ones where it's
just a slam dunk. This project is a big one.
I'm very familiar with Microsoft's Patterns and Practices, I visit the
site often, and even have some books. I will take a in depth review for
sure, but in the mean time can you offer just a little more assistance
regarding my thoughts, above? I'm a fast learner.
I'll give it to you, and when you're done, you'll know what to do and what
it's all about.
You say you're a fast learner, huh? <smile>
What is Object-oriented-programming?
(OOP) is a programming paradigm that uses "objects" and their interactions
to design applications and computer programs.
The key concepts of OOP are the following:
Class
Object
Instance
Method
Message passing
Inheritance
Abstraction
Encapsulation
Polymorphism
Decoupling
http://en.wikipedia.org/wiki/Object-oriented_programming
No matter what development platform Java, .Net or others OOP is OOP.
http://math.hws.edu/eck/cs124/downloads/OOP2_from_Univ_KwaZulu-Natal.pdf
http://www.blackwasp.co.uk/ObjectOrientedConcepts.aspx
What are design patterns?
Design patterns are recurring solutions to software design problems you
find again and again in real-world application development. Patterns are
about design and interaction of objects, as well as providing a
communication platform concerning elegant, reusable solutions to commonly
encountered programming challenges.
http://www.developer.com/design/article.php/1502691
http://www.dofactory.com/Patterns/Patterns.aspx
http://computerprogramming.suite101.com/article.cfm/patterns_and_antipatterns
http://msdn.microsoft.com/en-us/library/ms954638.aspx
http://www.designpatternsfor.net/Presentations.aspx?tid=3&cid=4
Now, milop get the book and get the DOAFactory software and learn.
http://headfirstlabs.com/books/hfdp/
Head First is in the dofactory.
http://www.dofactory.com/Framework/Framework.aspx
What is Domain Driven Design?
(DDD) is an approach to the design of software, based on the two premises
[1] that complex domain designs should be based on a model, and that, for
most software projects, the primary focus should be on the domain and
domain logic (as opposed to being the particular technology used to
implement the system).
http://en.wikipedia.org/wiki/Domain-driven_design
What is Test Driven Design?
(TDD) is a software development technique that uses short development
iterations based on pre-written test cases that define desired
improvements or new functions. Each iteration produces code necessary to
pass that iteration's tests. Finally, the programmer or team refactors the
code to accommodate changes. A key TDD concept is that preparing tests
before coding facilitates rapid feedback changes. Note that test-driven
development is a software design method, not merely a method of testing.
http://en.wikipedia.org/wiki/Test-driven_development
http://weblogs.asp.net/rhurlbut/archive/2007/07/16/another-tdd-and-ddd-success-story.aspx
What is Model -View- Controller?
(MVC) is an architectural pattern used in software engineering. Successful
use of the pattern isolates business logic from user interface
considerations, resulting in an application where it is easier to modify
either the visual appearance of the application or the underlying business
rules without affecting the other. In MVC, the model represents the
information (the data) of the application; the view corresponds to
elements of the user interface such as text, checkbox items, and so forth;
and the controller manages the communication of data and the business
rules used to manipulate the data to and from the model.
http://en.wikipedia.org/wiki/Model-view-controller
http://msdn.microsoft.com/en-us/library/ms978748.aspx
<
http://weblogs.asp.net/scottgu/archive/2007/10/14/asp-net-mvc-framework.aspx>
http://cristobal.baray.com/indiana/projects/mvc.html
http://www.devx.com/dotnet/Article/29992/0/page/1
What is Model -View- Presenter?
MVP is a software pattern considered a derivative of the
Model-view-controller.
http://en.wikipedia.org/wiki/Model_View_Presenter
http://msdn.microsoft.com/en-us/magazine/cc188690.aspx
http://mrrask.files.wordpress.com/2008/01/model-view-presenter.pdf
http://www.mvcsharp.org/Reworking_ASPNET_MVC_Store/Default.aspx
<
http://www.codeproject.com/KB/aspne...lect=2822806#Reusing the presenter in windows>
<
http://codebetter.com/blogs/jeremy....net-and-the-model-view-presenter-pattern.aspx>
MODEL-VIEW-PRESENTER
http://www.polymorphicpodcast.com/
click 'Shows'
click 'Design Patterns Bootcamp: Model View * Patterns*
view parts 1-5
What is Object Relational Mapping?
(ORM) is a programming technique for converting data between incompatible
type systems in relational databases and object-oriented programming
languages. This creates, in effect, a "virtual object database," which can
be used from within the programming language. There are both free and
commercial packages available that perform object-relational mapping,
although some programmers opt to create their own ORM tools.
http://en.wikipedia.org/wiki/O-RM
http://www.objectmatter.com/vbsf/docs/maptool/ormapping.html
What is Language Integrated Query?
LINQ is a Microsoft .NET Framework component that adds native data
querying capabilities to .NET languages.
Microsoft LINQ defines a set of query operators that can be used to query,
project and filter data in arrays, enumerable classes, XML, relational
database, and third party data sources. While it allows any data source to
be queried, it requires that the data be encapsulated as objects. So, if
the data source does not natively store data as objects, the data must be
mapped to the object domain. Queries written using the query operators are
executed either by the LINQ query processing engine or, via an extension
mechanism, handed over to LINQ providers which either implement a separate
query processing engine or translate to a different format to be executed
on a separate data store (such as on a database server as SQL queries).
The results of a query are returned as a collection of in-memory objects
that can be enumerated using a standard iterator function such as C#'s
foreach.
Many of the concepts that LINQ has introduced were originally tested in
Microsoft's C? research project. LINQ was released as a part of .NET
Framework 3.5 on November 19, 2007.
http://en.wikipedia.org/wiki/Language_Integrated_Query
What is Linq-to-SQL?
LINQ to SQL, a component of Visual Studio Code Name "Orcas", provides a
run-time infrastructure for managing relational data as objects without
losing the ability to query. It does this by translating
language-integrated queries into SQL for execution by the database, and
then translating the tabular results back into objects you define. Your
application is then free to manipulate the objects while LINQ to SQL stays
in the background tracking your changes automatically.
http://msdn.microsoft.com/en-us/library/bb425822.aspx
What is ADO.NET Entities framework?
ADO.NET Entity Framework is an object-relational mapping (ORM) framework
for the .NET Framework. This framework is Microsoft's first ORM offering
for the .NET Framework. While Microsoft provided objects to manage the
Object-relational impedance mismatch (such as a DataSet).
ADO.NET Entity Framework is included with .NET Framework 3.5 Service Pack
1 and Visual Studio 2008 Service Pack 1, released on 11 Aug 2008. It also
includes the capability of executing LINQ against ADO.NET Entity Framework
entities
http://en.wikipedia.org/wiki/ADO.NET_Entity_Framework
http://msdn.microsoft.com/en-us/library/aa697427(VS.80).aspx
http://www.springerlink.com/content/kg3216v2014r00u0/
http://blogs.msdn.com/adonet/archive/2008/03/27/ado-net-entity-framework-performance-comparison.aspx
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