Component-based Scalable Logical Architecture
Encyclopedia
Component-based Scalable Logical Architecture (CSLA) is a software framework
created by Rockford Lhotka
that provides a standard way to create robust object oriented programs using business object
s. Business objects are objects that abstract business entities in an object oriented program. Some examples of business entities include sales orders, employees, or invoices.
Although CSLA itself is free to download, the only documentation the creator provides are his books, which are not free.
CSLA was originally targeted toward Visual Basic
6 in the book Visual Basic 6.0 Business Objects by Lhotka ISBN 1-86100-107-X. With the advent of Microsoft .NET
, CSLA was completely rewritten from the ground up, with no code carried forward, and called CSLA.NET. This revision took advantage of Web Services and the object oriented languages that came with Microsoft .NET (in particular, Visual Basic.NET
and C#).
CSLA.NET was expounded in Expert C# Business Objects ISBN 1-59059-344-8 and Expert One-on-One Visual Basic .NET Business Objects ISBN 1-59059-145-3, both written by Lhotka. Although CSLA and CSLA.NET were originally targeted toward Microsoft
programming languages, most of the framework can be applied to most object oriented languages.
's data model
. For example, an Account table could map to an Accounts (observe the pluralization) collection object (in reality the object model will differ from the relational model, it is therefore necessary to employ Object-Relational Mapping
to resolve the differences). In this case each row in the Account table would map to an Account business object which is contained in the Accounts collection object. This makes it possible to define methods for the collection object that will propagate to its constituent objects. For example, to save all the Account objects in an Accounts collection, one would type:
The Save method will call the Save method on each of its constituent Account objects.
// Inside the Accounts class
public void Save{
// _accounts will normally be some type of array variable with class scope
// that holds all of the Account objects represented in this collection.
foreach (Account acct in _accounts){
acct.Save; // The actual Account object does the work of saving itself to the database
}
}
This method of propagating changes to a collection's constituent object can be used for other common methods and property assignments as well(myAccountsCollection.Load; myAccountsCollection.Active = false;).
Business objects can also contain other collection objects, in effect creating a relationship analogous to a parent child relationship between two tables. For example, the Account object mentioned above can contain an Orders collection object which in turn contains Order objects. In this case, the above call to Save on the Accounts collection object could be written to save all of the Account objects as well as all of the orders associated with each of the accounts.
) are performed by clearly defined methods of the business object associated with the data testing.
or Web Forms, data-bound controls like DataGrids and ListBoxes can be bound to business objects instead of more generalized database objects like ADO.NET
DataSets and DataTables.
s or distributed two-phase commit transactions.
.
Software framework
In computer programming, a software framework is an abstraction in which software providing generic functionality can be selectively changed by user code, thus providing application specific software...
created by Rockford Lhotka
Rockford Lhotka
Rockford Lhotka is an author and columnist who writes on topics concerning Microsoft-centric programming with an emphasis on object oriented design strategies. He is a Microsoft Regional Director, a Microsoft MVP, ASPInsider, and an INETA speaker. He also writes for MSDN Online...
that provides a standard way to create robust object oriented programs using business object
Business object (computer science)
A business object is a type of an intelligible entity being an actor inside the business layer in an n-layered architecture of object-oriented computer programs....
s. Business objects are objects that abstract business entities in an object oriented program. Some examples of business entities include sales orders, employees, or invoices.
Although CSLA itself is free to download, the only documentation the creator provides are his books, which are not free.
CSLA was originally targeted toward Visual Basic
Visual Basic
Visual Basic is the third-generation event-driven programming language and integrated development environment from Microsoft for its COM programming model...
6 in the book Visual Basic 6.0 Business Objects by Lhotka ISBN 1-86100-107-X. With the advent of Microsoft .NET
.NET Framework
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
, CSLA was completely rewritten from the ground up, with no code carried forward, and called CSLA.NET. This revision took advantage of Web Services and the object oriented languages that came with Microsoft .NET (in particular, Visual Basic.NET
Visual Basic
Visual Basic is the third-generation event-driven programming language and integrated development environment from Microsoft for its COM programming model...
and C#).
CSLA.NET was expounded in Expert C# Business Objects ISBN 1-59059-344-8 and Expert One-on-One Visual Basic .NET Business Objects ISBN 1-59059-145-3, both written by Lhotka. Although CSLA and CSLA.NET were originally targeted toward Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
programming languages, most of the framework can be applied to most object oriented languages.
Smart data
A business object encapsulates all the data and behavior (including persistence logic) associated with the object it represents. For example, an order object will be the only part of the program to load an order, obtain or assign the order's member data (order numbers, etc...), save the order, and so on.Typed Collections
The framework defines a standard way to create collection objects which represent a collection of objects. This allows an object model to map well to a relational databaseRelational database
A relational database is a database that conforms to relational model theory. The software used in a relational database is called a relational database management system . Colloquial use of the term "relational database" may refer to the RDBMS software, or the relational database itself...
's data model
Data model
A data model in software engineering is an abstract model, that documents and organizes the business data for communication between team members and is used as a plan for developing applications, specifically how data is stored and accessed....
. For example, an Account table could map to an Accounts (observe the pluralization) collection object (in reality the object model will differ from the relational model, it is therefore necessary to employ Object-Relational Mapping
Object-relational mapping
Object-relational mapping in computer software is a programming technique for converting data between incompatible type systems in object-oriented programming languages. This creates, in effect, a "virtual object database" that can be used from within the programming language...
to resolve the differences). In this case each row in the Account table would map to an Account business object which is contained in the Accounts collection object. This makes it possible to define methods for the collection object that will propagate to its constituent objects. For example, to save all the Account objects in an Accounts collection, one would type:
myAccountsCollection.Save;
The Save method will call the Save method on each of its constituent Account objects.
// Inside the Accounts class
public void Save{
// _accounts will normally be some type of array variable with class scope
// that holds all of the Account objects represented in this collection.
foreach (Account acct in _accounts){
acct.Save; // The actual Account object does the work of saving itself to the database
}
}
This method of propagating changes to a collection's constituent object can be used for other common methods and property assignments as well(myAccountsCollection.Load; myAccountsCollection.Active = false;).
Business objects can also contain other collection objects, in effect creating a relationship analogous to a parent child relationship between two tables. For example, the Account object mentioned above can contain an Orders collection object which in turn contains Order objects. In this case, the above call to Save on the Accounts collection object could be written to save all of the Account objects as well as all of the orders associated with each of the accounts.
Object persistence
Data creation, retrieval, updates, and deletes (CRUDCRUD (acronym)
In computer programming, create, read, update and delete are the four basic functions of persistent storage. Sometimes CRUD is expanded with the words retrieve instead of read or destroy instead of delete...
) are performed by clearly defined methods of the business object associated with the data testing.
Persistence state maintenance
CSLA defines a standard way of allowing a business object to maintain information about its "persistence state". In other words, an object knows when it is new (it represents data that hasn't been saved yet) and when it is dirty (it needs to be saved to the database either because it is new or because its member data has been changed since it was last loaded). Business objects can also be marked for deletion so they can later be deleted (for example when a user has pressed a button confirming his or her intention to delete the rows.)n-Level undo
This feature makes it possible for an object or collection of objects to maintain a collection of states. This allows the object to easily revert back to previous states. This can be useful when a user wants to undo previous edits multiple times in an application. The feature can also allow a user to redo multiple edits that were previously undone.Business rule tracking
Allows objects to maintain collections of "broken rule" objects. Broken rules will exist for an object until it is in a valid state, meaning it is ready to be persisted to the database. BrokenRule objects are usually associated with validation logic such as ensuring that no alphabetic characters are entered into a phone number field. For example, if an Account object has a PhoneNumber property, and that property is assigned a phone number with alphabetic characters, the Account object's IsValid property will become false (making it impossible to save to the database) and then a new BrokenRule object will be created and assigned to the Account's Broken Rules collection. The rule will disappear when the invalid phone number is corrected making the Account object capable of saving itself to the database.Simple UI creation
Using Windows FormsWindows Forms
Windows Forms is the name given to the graphical application programming interface included as a part of Microsoft .NET Framework, providing access to native Microsoft Windows interface elements by wrapping the extant Windows API in managed code...
or Web Forms, data-bound controls like DataGrids and ListBoxes can be bound to business objects instead of more generalized database objects like ADO.NET
ADO.NET
ADO.NET is a set of computer software components that programmers can use to access data and data services. It is a part of the base class library that is included with the Microsoft .NET Framework. It is commonly used by programmers to access and modify data stored in relational database systems,...
DataSets and DataTables.
Distributed data access
Using Web Services, an object can perform its data access on the client machine or a server. It can also be configured to use manual database transactionDatabase transaction
A transaction comprises a unit of work performed within a database management system against a database, and treated in a coherent and reliable way independent of other transactions...
s or distributed two-phase commit transactions.
Web Services support
Business logic created with the CSLA.NET framework can easily be exposed as a web services to remote consumers..
External links
CSLA Training- Rockford Lhotka's website
- The CSLA Framework; what is in it for me? Articles illustrating CSLA deliverables (version 1.n and version 2)