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Flex
Data Management Services for .NET |
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This article
describes an implementation of Flex Data Management
Services in WebORB for .NET. The article consists of
four parts. Part 1 (this document) introduces an
example demonstrating usage of data management
operations in .NET from a Flex application. Part 1 consists of the
following sections:
Part 2 of the
article reviews the server-side code responsible
for reading and returning data to the client. Parts
3-4 will describe data synchronization code and
review the client-side of the application.
Part 3 of the
article reviews the code handling data updates
in the server-side.
If you have any comments about the article, or
have any questions about the product and the
integration of Flex Data Management Services in WebORB, post
them to the WebORB interest group at:
http://groups.yahoo.com/group/flashorb/ |
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INTRODUCTION |
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WebORB 2.1
introduces support for Flex Data Management Services for .NET.
The product provides a seamless integration with the
Flex
client-side data services component. Using
WebORB Flex applications can retrieve data from .NET
data sources (in bulk or paged), submit updates,
create or delete records and automatically
synchronize changes between a client and the server.
WebORB does not require
Flex Data Services, however it is important to
download FDS, as it provides access to the
client-side component containing the client-side
mx.data API.
The server-side data
management API in WebORB is very similar to the
one provided by FDS. This guide walks through an
example demonstrating all four basic database
operations commonly known as CRUD (Create, Read,
Update, Delete). You can see the finished example
at:
http://www.themidnightcoders.net/ContactSystem/ContactSystem.html
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OVERVIEW |
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In order to create
and run the example shown above you will need to
download and install the following software:
The diagram below provides an overview
of how all the parts of the example work together. The
architecture is demonstrative of most Flex data-driven
application.
A solution consists of the following
modules:
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WebORB - provides an
implementation of Flex Data Services for .NET. It
manages a collection of destinations. WebORB
contains the logic for interpreting client requests,
executing autonomous data management operations and
updating connected clients with the changes occurred
in the data source.
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Data destination - represents
an executable unit targeted by client application to
execute data management operations. Normally a data
destination is represented by a .NET class
implementing Assembler interface or exposing methods
to retrieve, create, update or delete data in a data
source.
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Data adapter - an object
tying together WebORB's FDS logic and a data
destination. An adapter must implement WebORB data
adapter interface. The product provides a default
implementation, but allows registration of custom
data adapters.
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.NET Data Source - can be any
data source reachable by a 'data destination'
implementation.
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Flex client application - the
box represents an application developed with MXML
and compiled with either Flex SDK or Flex Builder.
It uses the mx.data.DataService API to connect to a
destination managed by WebORB to execute data
management operations.
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PREPARING THE CLIENT SIDE |
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The source code for the example is
available at:
client-side: [FDS2
HOME]\jrun4\servers\default\samples\dataservice\contact
server-side:
\Inetpub\wwwroot\weborb\examples\flex\contact\server-side
database:
\Inetpub\wwwroot\weborb\flexdb.mdb
To run the example, make sure Flex Builder, WebORB and
Flex Data Services products are installed. The
instructions below will guide you through creating a
Flex Builder project, pointing it to WebORB, importing
the example code and then running the example:
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Start Flex Builder. From the main
menu select
File -> New -> Flex Project
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In the "New Flex Project" dialog
window select "Flex Data Services" and "Compile
application locally in Flex Builder" as shown in the
image below:
Click "Next >" to
continue.
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Next step is to configure the
project to point to a WebORB installation. Assuming
WebORB is installed in c:\Inetpub\wwwroot\weborb,
the values in the dialog window should look as
below:
Click "Next >" to
continue.
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Type a name for the project and
click "Next >" to continue;
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The next step is to add a
client-side library containing the data services
API. Select the "Library path" tab as shown in the
image below and click "Add SWC...".
Browse to [FDS
HOME]\flex_sdk_2.0\frameworks\libs
If you are using Flex Data Services 2.0 Beta 3,
then elect
enterprise.swc.
If you are using the production release
of Flex Data Services 2.0 (including FDS
Express), then select
fds.swc
Once you add the swc file, the "New Flex
Project" window should look as the image below:
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Click "Finish". Flex Builder creates
default project workspace and opens ContactManager.mxml. By default the application does
not have an implementation. To simplify the process,
import the code of the finished example.
To do that copy the following items:
ContactManager.mxml (this file will overwrite the
default application mxml)
Hourglass.mxml
mini.mxml
wait.png
samples\contact\Contact.as (make sure to preserve
the path)
from \Inetpub\wwwroot\weborb\examples\flex\contact\client-side
into the folder containing your ContactManager
Flex Builder project.
You can find out the location by clicking right
mouse button on the ContactManager project node and
selecting Properties (see the highlighted text in
the image below):
The client side of the project is ready
to run. There is a minor configuration step for the
server-side. See below for details.
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PREPARING THE SERVER SIDE |
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The database file used by the example
resides in the root of the weborb virtual directory. As
a result, in order to make any changes to the database
(INSERT, UPDATE, DELETE queries), the ASP.NET subsystem
must have the Write permission to modify the file. The
instructions below describe how to grant the permission.
Without these changes, the database can be accessed as
read-only, so only SELECT statement will succeed. Follow
the instructions below to modify database file access
permissions:
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Open Windows Explorer and navigate
to the WebORB installation folder (default location
is c:/Inetpub/wwwroot/weborb)
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Select flexdb.mdb, click right mouse
button and select Properties.
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Select the "Security" tab and click
"Add" to add a user account used by the ASP.NET
system
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In the "Select Users or Groups"
window click "Advanced". New window will open up,
click "Find Now". A list of user account will appear
at the bottom of the window.
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If you are using Windows XP, locate
and select the "ASPNET" account. If you are using
Windows 2003 Server, locate and select the "IUSR_WEB-B"
account. Click OK, to accept the selection, click OK
again to close the "Select Users or Groups" window.
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Select the user you just added from
the list and grant the "Write" permission by
selecting the checkbox in the "Allow" column and
"Write" row. When you are done, the Security tab
should look like in the image below:
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Click Apply to apply the settings
and OK to close the window.
The ASP.NET system now has the
permissions to make changes to the database file.
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RUNNING THE EXAMPLE |
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To run the application select
"Run" -> "Run contactmgr"
from the Flex Builder's main menu. Flex Builders open a
web browser with the application loaded from
http://localhost/weborb/ContactManager/contactmgr.html |
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