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Manager Collection Class (MCC) Pattern

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bryan costanich

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All,

=20

I have captured a pattern that many of you have probably come across or
used before. It is similar to the ECC pattern but is simpler to use and
is a little more .NET friendly

=20

=20

Attached is draft .1 of the document and I would appreciate feedback on
it.

=20

Thanks,

bryan costanich

=20

Attachment below since this list does not support attachments (if you
would like the original word doc file, e-mail me (Click here to reveal e-mail address)
and I will send it (12kb).:

=20

=20

Pattern Section

Description

Name

Manager Collection Class (MCC) [Plain English]

Aliases

=20

Abstract

An object design for data specific applications that follows the basic
model of ObjectManager, ObjectCollection, Object.

Problem

Architects and Developers face diverse application needs but need to
build consumable, maintainable code in the shortest amount of time
possible.

Pattern Type

Architecture/DesignPattern

Forces

* Encapsulation on re-use provides a high ROI when developing
applications because it's easier to consume, maintain, and less code
overall often needs to be developed.

* Object designs that are complex or bloated can be difficult
to understand, difficult to consume, and difficult to maintain.

Solution

Overview

Create an object model that follows the basic pattern of ObjectManager,
ObjectCollection, Object. The complete business entity is illustrated
below:

=20

The basic properties and methods are illustrated below and help to
further explain the relationship between the three objects:

=20

ObjectManager

The ObjectManager manages the repository object data and is used to
retrieve, persist, update, and delete an object or a collection of
objects. The ObjectManager represents the data store and includes the
code that access the data to create the business objects, although this
could be further abstracted from the ObjectManager class and put into an
ObjectDataManager class that handled the data acquisition and
persistence.

ObjectCollection

The ObjectCollection object inherits from the ArrayList .NET class
(although in a c++ implementation it could just as easily be a Vector)
which manages a collection of items and also implement IEnumerable which
enables it to be bound to list controls. The ObjectCollection class
adds an additional method to the ArrayList object that allows objects to
be sorted based on a property.

Object

The Object represents only the properties needed to maintain data upon a
particular object such as a User and is disconnected from the data
source completely. When data within the Object is changed, the Boolean
flag IsDirty is set to true. The object class does not know how to
"Save" or "Update" itself, instead it needs to be passed back to the
ObjectManager class for such functionality. Additionally, a collection
of objects, inside the ObjectCollection class could also passed back to
the ObjectManager class to get persisted in the data store.

Resulting Context

* Simple, easy to consume object model.

* Easily bindable to controls in .NET.

* Flexible architecture.

* Maintainability.

Rationale

* By applying the MCC pattern, solving design issues becomes
much simpler and therefore the solution can be reached more quickly
which in turn costs less.

* The MCC pattern provides a simple yet powerful way to model
real world problems in a manner that is easy to understand and use by a
wide array of developers.

* The simplicity of the MCC pattern provides a higher
probability that it will be understood and consumed, therefore a
consistent object model can be designed an adhered to in an application.

* With the MCC pattern, code is well encapsulated and can be
reused throughout the application. Furthermore, the ObjectCollection
class can easily be built to be reused across multiple projects.

Variants

Manager Collection ManagerClass

If the relationships are more complex than a single layer, for instance
if Users have Pets associated with them, then a Manager Collection
ManagerClass approach can be taken so that the User class also includes
the methods to update, retrieve, and delete Pets. Such an example might
go similar to the following:

* UserManager.GetUser()

* User.GetPet()

* User.UpdatePet(Pet)

One caveat however, is that in a web services scenario in order to
implement this pattern, another object on the Server would actually
implement those manager functions, however, that's another pattern and
is not in the scope of this.

Customized ObjectCollection

Although the MCC pattern calls for a generic ObjectCollection class that
can handle any object, the ObjectCollection class could be customized to
perform specific functions on a collection of classes. For example, if
the ObjectCollection class was implemented as UserCollection,
UserCollection.GetAverageAge() might be implemented.

Example

The classic business problem of users needing to be added, deleted, and
modified in a database is an example of where the MCC pattern can be
used. The basic model might look like the following:

=20

In order to retrieve a User, the static method UserManager.GetUser() is
called and a variety of information could be passed in.
UserManager.GetUser would then return a User object that matched the
information passed to the GetUser method. If the user object IsDirty
and needed to be updated, a call to the UserManager.UpdateUser() method
could be called, passing in the User object of the user to be updated.
If the user needed to be deleted, a call to UserManager.DeleteUser(),
with either the UserID or the User object passed in would do the job.

If a collection of users needed to be retrieved and displayed, then a
call to UserManager.GetUsers() would be called, and an ObjectCollection
of User objects would be returned. This collection could then be easily
bound to a list control and the proerties of each User could be
displayed appropriately. To update or remove the Users, the respective
UpdateUsers() and DeleteUsers() methods could be called on the
UserManager class.

Code Example

Object Code

(to be inserted later)

Databinding

<asp:DataGrid ID=3D"dtgDataGrid1" Runat=3D"server"
AutoGenerateColumns=3D"False">

<Columns>

<asp:BoundColumn DataField=3D"property1"
HeaderText=3D"Property 1"/>

<asp:BoundColumn DataField=3D"property2"
HeaderText=3D"Property 2"/>

</Columns>

</asp:DataGrid>

Related Patterns

Engine Collection Class (ECC)

The ECC pattern is very powerful similar pattern that is slightly more
complex and offloads a lot of responsibility of the manager class into
the collection class.

Known Uses

This pattern finds itself extremely useful in the context of .NET
because of it's ability to return a bindable collection of objects to
web controls.

Version Number

.1 - Draft Version

Revision History

December 5, 2001 - Pattern Captured, Bryan Costanich.

Retirement/Refresh Information

This pattern should be refreshed once the .NET final release is out.
Additionally, when major new technology paradigms are released such as
J2EE or .NET, then this patter should be evaluated for applicability and
retirement or refreshment might be in order.

Keywords

Design Pattern, Architecture Pattern, MCC, .NET, Enterprise, Components,
Object Model

=20

=20

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<div class=3DSection1>

All,

 

I have captured a pattern =
that many
of you have probably come across or used before. It is similar to =
the ECC
pattern but is simpler to use and is a little more .NET =
friendly

 

 

Attached is draft .1 of the =
document
and I would appreciate feedback on it.

 

Thanks,

bryan =
costanich

 

<div style=3D'border:none;border-bottom:solid windowtext =
1.0pt;padding:0in 0in 1.0pt 0in'>

Attachment
below since this list does not support attachments (if you would like =
the
original word doc file, e-mail me (<a =
href=3D"mailto:Click here to reveal e-mail address">Click here to reveal e-mail address</a>)
and I will send it (12kb).:

</div>

 

 

<table class=3DMsoTableGrid border=3D1 cellspacing=3D0 cellpadding=3D0
style=3D'border-collapse:collapse;border:none'>
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<td width=3D127 valign=3Dtop bgcolor=3Dblack =
style=3D'width:95.4pt;border:solid windowtext 1.0pt;
background:black;padding:0in 5.4pt 0in 5.4pt'>
Pattern Section
</td>
<td width=3D463 valign=3Dtop bgcolor=3Dblack =
style=3D'width:347.4pt;border:solid windowtext 1.0pt;
border-left:none;background:black;padding:0in 5.4pt 0in 5.4pt'>
Description
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Name
</td>
<td width=3D463 valign=3Dtop =
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none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
Manager
Collection Class (MCC) [Plain English]
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Aliases
</td>
<td width=3D463 valign=3Dtop =
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none;border-bottom:solid windowtext 1.0pt;border-right:solid =
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</td>
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<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
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Abstract
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
An
object design for data specific applications that follows the basic =
model of ObjectManager,
ObjectCollection, Object.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Problem
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
Architects
and Developers face diverse application needs but need to build =
consumable,
maintainable code in the shortest amount of time =
possible.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Pattern Type
</td>
<td width=3D463 valign=3Dtop =
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none;border-bottom:solid windowtext 1.0pt;border-right:solid =
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Architecture/DesignPattern
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Forces
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
·
Encapsulation on re-use provides a high =
ROI when
developing applications because it’s easier to consume, =
maintain, and
less code overall often needs to be developed.
·
Object designs that are complex or bloated =
can be
difficult to understand, difficult to consume, and difficult to =
maintain.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Solution
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
Overview
Create
an object model that follows the basic pattern of ObjectManager, =
ObjectCollection,
Object. The complete business entity is illustrated =
below:
<img border=3D0 width=3D269 height=3D195
src=3D"cid:image001.gif@01C17D86.05102B80">
The
basic properties and methods are illustrated below and help to further
explain the relationship between the three objects:
<img border=3D0 width=3D413 height=3D109
src=3D"cid:image002.gif@01C17D86.05102B80">
ObjectManager
The
ObjectManager manages the repository object data and is used to =
retrieve,
persist, update, and delete an object or a collection of =
objects. The ObjectManager
represents the data store and includes the code that access the data =
to
create the business objects, although this could be further abstracted =
from
the ObjectManager class and put into an ObjectDataManager class that =
handled
the data acquisition and persistence.
ObjectCollection
The
ObjectCollection object inherits from the ArrayList .NET class =
(although in a
c++ implementation it could just as easily be a Vector) which manages =
a
collection of items and also implement IEnumerable which enables it to =
be
bound to list controls. The ObjectCollection class adds an =
additional method
to the ArrayList object that allows objects to be sorted based on a =
property.
Object
The
Object represents only the properties needed to maintain data upon a
particular object such as a User and is disconnected from the data =
source
completely. When data within the Object is changed, the Boolean =
flag IsDirty
is set to true. The object class does not know how to =
“Save” or
“Update” itself, instead it needs to be passed back to the =
ObjectManager
class for such functionality. Additionally, a collection of =
objects, inside the
ObjectCollection class could also passed back to the ObjectManager =
class to
get persisted in the data store.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Resulting Context
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
·
Simple, easy to consume object model.
·
Easily bindable to controls in .NET.
·
Flexible architecture.
·
Maintainability.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Rationale
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
·
By applying the MCC pattern, solving =
design
issues becomes much simpler and therefore the solution can be reached =
more
quickly which in turn costs less.
·
The MCC pattern provides a simple yet =
powerful
way to model real world problems in a manner that is easy to =
understand and
use by a wide array of developers.
·
The simplicity of the MCC pattern provides =
a
higher probability that it will be understood and consumed, therefore =
a
consistent object model can be designed an adhered to in an =
application.
·
With the MCC pattern, code is well =
encapsulated
and can be reused throughout the application. Furthermore, the =
ObjectCollection
class can easily be built to be reused across multiple projects.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Variants
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
Manager Collection =
ManagerClass
If
the relationships are more complex than a single layer, for instance =
if Users
have Pets associated with them, then a Manager Collection ManagerClass
approach can be taken so that the User class also includes the methods =
to
update, retrieve, and delete Pets. Such an example might go =
similar to the
following:
·
UserManager.GetUser()
·
User.GetPet()
·
User.UpdatePet(Pet)
One
caveat however, is that in a web services scenario in order to =
implement this
pattern, another object on the Server would actually implement those =
manager
functions, however, that’s another pattern and is not in the =
scope of
this.
Customized ObjectCollection
Although
the MCC pattern calls for a generic ObjectCollection class that can =
handle
any object, the ObjectCollection class could be customized to perform
specific functions on a collection of classes. For example, if =
the ObjectCollection
class was implemented as UserCollection, =
UserCollection.GetAverageAge() might
be implemented.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Example
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
The
classic business problem of users needing to be added, deleted, and =
modified
in a database is an example of where the MCC pattern can be =
used. The basic
model might look like the following:
<img border=3D0 width=3D91 height=3D157
src=3D"cid:image003.gif@01C17D86.05102B80">
In order
to retrieve a User, the static method UserManager.GetUser() is called =
and a
variety of information could be passed in. UserManager.GetUser =
would then
return a User object that matched the information passed to the =
GetUser
method. If the user object IsDirty and needed to be updated, a =
call to the UserManager.UpdateUser()
method could be called, passing in the User object of the user to be
updated. If the user needed to be deleted, a call to =
UserManager.DeleteUser(),
with either the UserID or the User object passed in would do the =
job.
If
a collection of users needed to be retrieved and displayed, then a =
call to UserManager.GetUsers()
would be called, and an ObjectCollection of User objects would be =
returned.
This collection could then be easily bound to a list control and the =
proerties
of each User could be displayed appropriately. To update or =
remove the
Users, the respective UpdateUsers() and DeleteUsers() methods could be =
called
on the UserManager class.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Code Example
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
Object Code
(to
be inserted later)
Databinding
<asp:DataGrid =
ID=3D"dtgDataGrid1" Runat=3D"server"
AutoGenerateColumns=3D"False">
 =
; =
<Columns>
 =
; =
 =
<asp:BoundColumn DataField=3D"property1"
HeaderText=3D"Property 1"/>
 =
; =
 =
<asp:BoundColumn DataField=3D"property2"
HeaderText=3D"Property 2"/>
 =
; =
</Columns>
</asp:DataGrid>
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Related Patterns
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
Engine Collection Class (ECC)
The
ECC pattern is very powerful similar pattern that is slightly more =
complex
and offloads a lot of responsibility of the manager class into the =
collection
class.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Known Uses
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
This
pattern finds itself extremely useful in the context of .NET because =
of it’s
ability to return a bindable collection of objects to web =
controls.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Version Number
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
.1
– Draft Version
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Revision History
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
December
5, 2001 – Pattern Captured, Bryan Costanich.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Retirement/Refresh =
Information
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
This
pattern should be refreshed once the .NET final release is out.
Additionally, when major new technology paradigms are released such as =
J2EE
or .NET, then this patter should be evaluated for applicability and
retirement or refreshment might be in order.
</td>
</tr>
<tr>
<td width=3D127 valign=3Dtop style=3D'width:95.4pt;border:solid =
windowtext 1.0pt;
border-top:none;padding:0in 5.4pt 0in 5.4pt'>
Keywords
</td>
<td width=3D463 valign=3Dtop =
style=3D'width:347.4pt;border-top:none;border-left:
none;border-bottom:solid windowtext 1.0pt;border-right:solid =
windowtext 1.0pt;
padding:0in 5.4pt 0in 5.4pt'>
Design
Pattern, Architecture Pattern, MCC, .NET, Enterprise,
Components, Object Model
</td>
</tr>
</table>

 

 

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Reply to this message...

Mitch Denny (VIP)

Bryan,

I have this pattern :)

What you have formalised is a variation on the classic ECC
pattern that has come about by necessity more than anything
for .NET programmers.

Personally, I like yours, its clean, simple and straight
forward to implement. The doco looks good, but does need
some work. For example, spell out the parameters for the
Add, Delete, Update and Get methods on the manager.

Also consider dropping the "Object" suffix on them. That
would allow you to build a situation where you can inherit
from a base implementation of the design pattern.

Now ofcourse, how to you make a generic manager when it
should be talking to the data tier? Well, it sounds like
an opporunity to use delgates to me . . .

----------------------------------------
- Mitch Denny
- http://www.warbyte.com
- Click here to reveal e-mail address
- +61 (414) 610-141
-

-----Original Message-----
From: bryan costanich [mailto:Click here to reveal e-mail address]
Sent: Thursday, 6 December 2001 7:12 AM
To: ngfx-patterns
Subject: [ngfx-patterns] Manager Collection Class (MCC) Pattern

All,

I have captured a pattern that many of you have probably come across or
used before. It is similar to the ECC pattern but is simpler to use and
is a little more .NET friendly

Attached is draft .1 of the document and I would appreciate feedback on
it.

Thanks,
bryan costanich

Attachment below since this list does not support attachments (if you
would like the original word doc file, e-mail me (Click here to reveal e-mail address)
and I will send it (12kb).:

Pattern SectionDescription
NameManager Collection Class (MCC) [Plain English]
Aliases
AbstractAn object design for data specific applications that follows the
basic model of ObjectManager, ObjectCollection, Object.
ProblemArchitects and Developers face diverse application needs but need
to build consumable, maintainable code in the shortest amount of time
possible.
Pattern TypeArchitecture/DesignPattern
Forces. Encapsulation on re-use provides a high ROI when
developing applications because it's easier to consume, maintain, and
less code overall often needs to be developed.
. Object designs that are complex or bloated can be difficult
to understand, difficult to consume, and difficult to maintain.
SolutionOverview
Create an object model that follows the basic pattern of ObjectManager,
ObjectCollection, Object. The complete business entity is illustrated
below:

The basic properties and methods are illustrated below and help to
further explain the relationship between the three objects:

ObjectManager
The ObjectManager manages the repository object data and is used to
retrieve, persist, update, and delete an object or a collection of
objects. The ObjectManager represents the data store and includes the
code that access the data to create the business objects, although this
could be further abstracted from the ObjectManager class and put into an
ObjectDataManager class that handled the data acquisition and
persistence.
ObjectCollection
The ObjectCollection object inherits from the ArrayList .NET class
(although in a c++ implementation it could just as easily be a Vector)
which manages a collection of items and also implement IEnumerable which
enables it to be bound to list controls. The ObjectCollection class
adds an additional method to the ArrayList object that allows objects to
be sorted based on a property.
Object
The Object represents only the properties needed to maintain data upon a
particular object such as a User and is disconnected from the data
source completely. When data within the Object is changed, the Boolean
flag IsDirty is set to true. The object class does not know how to
"Save" or "Update" itself, instead it needs to be passed back to the
ObjectManager class for such functionality. Additionally, a collection
of objects, inside the ObjectCollection class could also passed back to
the ObjectManager class to get persisted in the data store.
Resulting Context. Simple, easy to consume object model.
. Easily bindable to controls in .NET.
. Flexible architecture.
. Maintainability.
Rationale. By applying the MCC pattern, solving design issues
becomes much simpler and therefore the solution can be reached more
quickly which in turn costs less.
. The MCC pattern provides a simple yet powerful way to model
real world problems in a manner that is easy to understand and use by a
wide array of developers.
. The simplicity of the MCC pattern provides a higher
probability that it will be understood and consumed, therefore a
consistent object model can be designed an adhered to in an application.
. With the MCC pattern, code is well encapsulated and can be
reused throughout the application. Furthermore, the ObjectCollection
class can easily be built to be reused across multiple projects.
VariantsManager Collection ManagerClass
If the relationships are more complex than a single layer, for instance
if Users have Pets associated with them, then a Manager Collection
ManagerClass approach can be taken so that the User class also includes
the methods to update, retrieve, and delete Pets. Such an example might
go similar to the following:
. UserManager.GetUser()
. User.GetPet()
. User.UpdatePet(Pet)
One caveat however, is that in a web services scenario in order to
implement this pattern, another object on the Server would actually
implement those manager functions, however, that's another pattern and
is not in the scope of this.
Customized ObjectCollection
Although the MCC pattern calls for a generic ObjectCollection class that
can handle any object, the ObjectCollection class could be customized to
perform specific functions on a collection of classes. For example, if
the ObjectCollection class was implemented as UserCollection,
UserCollection.GetAverageAge() might be implemented.
ExampleThe classic business problem of users needing to be added,
deleted, and modified in a database is an example of where the MCC
pattern can be used. The basic model might look like the following:

In order to retrieve a User, the static method UserManager.GetUser() is
called and a variety of information could be passed in.
UserManager.GetUser would then return a User object that matched the
information passed to the GetUser method. If the user object IsDirty
and needed to be updated, a call to the UserManager.UpdateUser() method
could be called, passing in the User object of the user to be updated.
If the user needed to be deleted, a call to UserManager.DeleteUser(),
with either the UserID or the User object passed in would do the job.
If a collection of users needed to be retrieved and displayed, then a
call to UserManager.GetUsers() would be called, and an ObjectCollection
of User objects would be returned. This collection could then be easily
bound to a list control and the proerties of each User could be
displayed appropriately. To update or remove the Users, the respective
UpdateUsers() and DeleteUsers() methods could be called on the
UserManager class.
Code ExampleObject Code
(to be inserted later)
Databinding
<asp:DataGrid ID="dtgDataGrid1" Runat="server"
AutoGenerateColumns="False">
<Columns>
<asp:BoundColumn DataField="property1"
HeaderText="Property 1"/>
<asp:BoundColumn DataField="property2"
HeaderText="Property 2"/>
</Columns>
</asp:DataGrid>
Related PatternsEngine Collection Class (ECC)
The ECC pattern is very powerful similar pattern that is slightly more
complex and offloads a lot of responsibility of the manager class into
the collection class.
Known UsesThis pattern finds itself extremely useful in the context of
.NET because of it's ability to return a bindable collection of objects
to web controls.
Version Number.1 - Draft Version
Revision HistoryDecember 5, 2001 - Pattern Captured, Bryan Costanich.
Retirement/Refresh InformationThis pattern should be refreshed once the
.NET final release is out. Additionally, when major new technology
paradigms are released such as J2EE or .NET, then this patter should be
evaluated for applicability and retirement or refreshment might be in
order.
KeywordsDesign Pattern, Architecture Pattern, MCC, .NET, Enterprise,
Components, Object Model

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Reply to this message...

bryan costanich

Comments inline

-----Original Message-----
From: Mitch Denny [mailto:Click here to reveal e-mail address]=20
Sent: Thursday, December 06, 2001 6:46 AM
To: ngfx-patterns
Subject: [ngfx-patterns] RE: Manager Collection Class (MCC) Pattern

Bryan,

I have this pattern :)
[bryan]
Yeah, I imagine you do, in fact, I imagine that everyone on this list
has at least SEEN this pattern before, I had just never run across it in
any formalized manner, except for the ECC, and I think that's pretty
different.
[/bryan]

What you have formalised is a variation on the classic ECC
pattern that has come about by necessity more than anything
for .NET programmers.
[bryan]
I'm not sure which ones a variation in which actually. I saw this
pattern a long time before I saw the ECC, it's just that I had never
seen this one formalized. I actually think the two patterns are
substantially different enough not use the term 'variation.' Actually,
in the pattern I put some variations on this one.

As far as necessity for .NET programming, yeah, I like this one a lot
because it fits so well with .NET, although I've actually seen this
implemented in WinDNA a lot. In fact, if I remember right, and I may
not be, Commerce Server 2000 implements something VERY similar to it.
[/bryan/

Personally, I like yours, its clean, simple and straight
forward to implement. The doco looks good, but does need
some work. For example, spell out the parameters for the
Add, Delete, Update and Get methods on the manager.
[bryan]
yeah, I like the simplicity of this one, I think that it's easier to use
because of that, and therefore more likely to be used. I work with a
lot of beginning programmers, and simplicity helps out in that arena.

On the doc, yeah I agree, it's a pretty sketchy draft, but I wanted to
get it out there. Also, my intention was to leave it pretty generic so
it could be used how people needed to, but spelling out the parameters
should definitely be there, at least as a guide for what could be
changed.
[/bryan]

Also consider dropping the "Object" suffix on them. That
would allow you to build a situation where you can inherit
from a base implementation of the design pattern.

[bryan]
yeah, that might not be a bad idea. I've also toyed with documenting it
as <ClassName>Manager, Collection, <ClassName> or something similar. I
want people to understand that it's good practice when using this
pattern to name it something like UserManager, ObjectCollection, User,
etc.
[/bryan]

Now ofcourse, how to you make a generic manager when it
should be talking to the data tier? Well, it sounds like
an opporunity to use delgates to me . . .
[bryan]
yeah, there are a lot of data abstraction patterns that deal
specifically with this that would work well in conjunction, so I stayed
away from it in this pattern.

Thanks for the comments!
[/bryan]

----------------------------------------
- Mitch Denny
- http://www.warbyte.com
- Click here to reveal e-mail address
- +61 (414) 610-141
-

-----Original Message-----
From: bryan costanich [mailto:Click here to reveal e-mail address]=20
Sent: Thursday, 6 December 2001 7:12 AM
To: ngfx-patterns
Subject: [ngfx-patterns] Manager Collection Class (MCC) Pattern

All,

I have captured a pattern that many of you have probably come across or
used before. It is similar to the ECC pattern but is simpler to use and
is a little more .NET friendly

Attached is draft .1 of the document and I would appreciate feedback on
it.

Thanks,
bryan costanich

Attachment below since this list does not support attachments (if you
would like the original word doc file, e-mail me (Click here to reveal e-mail address)
and I will send it (12kb).:

Pattern SectionDescription
NameManager Collection Class (MCC) [Plain English]
Aliases
AbstractAn object design for data specific applications that follows the
basic model of ObjectManager, ObjectCollection, Object.
ProblemArchitects and Developers face diverse application needs but need
to build consumable, maintainable code in the shortest amount of time
possible.
Pattern TypeArchitecture/DesignPattern
Forces. Encapsulation on re-use provides a high ROI when
developing applications because it's easier to consume, maintain, and
less code overall often needs to be developed.
. Object designs that are complex or bloated can be difficult
to understand, difficult to consume, and difficult to maintain.
SolutionOverview
Create an object model that follows the basic pattern of ObjectManager,
ObjectCollection, Object. The complete business entity is illustrated
below:

The basic properties and methods are illustrated below and help to
further explain the relationship between the three objects:

ObjectManager
The ObjectManager manages the repository object data and is used to
retrieve, persist, update, and delete an object or a collection of
objects. The ObjectManager represents the data store and includes the
code that access the data to create the business objects, although this
could be further abstracted from the ObjectManager class and put into an
ObjectDataManager class that handled the data acquisition and
persistence.
ObjectCollection
The ObjectCollection object inherits from the ArrayList .NET class
(although in a c++ implementation it could just as easily be a Vector)
which manages a collection of items and also implement IEnumerable which
enables it to be bound to list controls. The ObjectCollection class
adds an additional method to the ArrayList object that allows objects to
be sorted based on a property.
Object
The Object represents only the properties needed to maintain data upon a
particular object such as a User and is disconnected from the data
source completely. When data within the Object is changed, the Boolean
flag IsDirty is set to true. The object class does not know how to
"Save" or "Update" itself, instead it needs to be passed back to the
ObjectManager class for such functionality. Additionally, a collection
of objects, inside the ObjectCollection class could also passed back to
the ObjectManager class to get persisted in the data store.
Resulting Context. Simple, easy to consume object model.
. Easily bindable to controls in .NET.
. Flexible architecture.
. Maintainability.
Rationale. By applying the MCC pattern, solving design issues
becomes much simpler and therefore the solution can be reached more
quickly which in turn costs less.
. The MCC pattern provides a simple yet powerful way to model
real world problems in a manner that is easy to understand and use by a
wide array of developers.
. The simplicity of the MCC pattern provides a higher
probability that it will be understood and consumed, therefore a
consistent object model can be designed an adhered to in an application.
. With the MCC pattern, code is well encapsulated and can be
reused throughout the application. Furthermore, the ObjectCollection
class can easily be built to be reused across multiple projects.
VariantsManager Collection ManagerClass
If the relationships are more complex than a single layer, for instance
if Users have Pets associated with them, then a Manager Collection
ManagerClass approach can be taken so that the User class also includes
the methods to update, retrieve, and delete Pets. Such an example might
go similar to the following:
. UserManager.GetUser()
. User.GetPet()
. User.UpdatePet(Pet)
One caveat however, is that in a web services scenario in order to
implement this pattern, another object on the Server would actually
implement those manager functions, however, that's another pattern and
is not in the scope of this.
Customized ObjectCollection
Although the MCC pattern calls for a generic ObjectCollection class that
can handle any object, the ObjectCollection class could be customized to
perform specific functions on a collection of classes. For example, if
the ObjectCollection class was implemented as UserCollection,
UserCollection.GetAverageAge() might be implemented.
ExampleThe classic business problem of users needing to be added,
deleted, and modified in a database is an example of where the MCC
pattern can be used. The basic model might look like the following:

In order to retrieve a User, the static method UserManager.GetUser() is
called and a variety of information could be passed in.
UserManager.GetUser would then return a User object that matched the
information passed to the GetUser method. If the user object IsDirty
and needed to be updated, a call to the UserManager.UpdateUser() method
could be called, passing in the User object of the user to be updated.
If the user needed to be deleted, a call to UserManager.DeleteUser(),
with either the UserID or the User object passed in would do the job.
If a collection of users needed to be retrieved and displayed, then a
call to UserManager.GetUsers() would be called, and an ObjectCollection
of User objects would be returned. This collection could then be easily
bound to a list control and the proerties of each User could be
displayed appropriately. To update or remove the Users, the respective
UpdateUsers() and DeleteUsers() methods could be called on the
UserManager class.
Code ExampleObject Code
(to be inserted later)
Databinding
<asp:DataGrid ID=3D"dtgDataGrid1" Runat=3D"server"
AutoGenerateColumns=3D"False">
<Columns>
<asp:BoundColumn DataField=3D"property1"
HeaderText=3D"Property 1"/>
<asp:BoundColumn DataField=3D"property2"
HeaderText=3D"Property 2"/>
</Columns>
</asp:DataGrid>
Related PatternsEngine Collection Class (ECC)
The ECC pattern is very powerful similar pattern that is slightly more
complex and offloads a lot of responsibility of the manager class into
the collection class.
Known UsesThis pattern finds itself extremely useful in the context of
.NET because of it's ability to return a bindable collection of objects
to web controls.
Version Number.1 - Draft Version
Revision HistoryDecember 5, 2001 - Pattern Captured, Bryan Costanich.
Retirement/Refresh InformationThis pattern should be refreshed once the
.NET final release is out. Additionally, when major new technology
paradigms are released such as J2EE or .NET, then this patter should be
evaluated for applicability and retirement or refreshment might be in
order.
KeywordsDesign Pattern, Architecture Pattern, MCC, .NET, Enterprise,
Components, Object Model

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	System.Collections.ArrayList
	System.Collections.IEnumerable
	System.Runtime.Serialization.ObjectManager
	System.Web.UI.WebControls.BoundColumn
	System.Web.UI.WebControls.DataGrid
	System.Windows.Forms.DataGrid

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