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| | | What is a "Data Object "? | What is a "Data Object "? 2004-01-02 - By ashraf galal
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<html><div style='background-color:'><P><BR><BR></P>
<P><FONT size=2><FONT face=Arial>is the implementation of the business object
pattern.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office
:office" /><o:p></o:p></FONT></FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">Term:<SPAN style="mso-spacerun:
yes"> </SPAN>Business Object: <o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">An object that implements
business logic and/or business data.<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">Business data and business
logic are implemented in coarse-grained objects called business objects.<o:p><
/o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">In J2EE, business objects are
implemented as session or entity beans.<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">In some cases, a business
object could be an arbitrary java object that provides some services.<o:p></o:p
></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><B><I><SPAN style="FONT-SIZE:
10pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt"> <o:p></o:p></SPAN><
/I></B></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">See attached document for class
and sequence diagrams <o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
COLOR: #330000; FONT-FAMILY: Arial; mso-bidi-font-size: 9.0pt"> <o:p></o:p
></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
COLOR: #330000; FONT-FAMILY: Arial; mso-bidi-font-size: 9.0pt"> <o:p></o:p
></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
COLOR: #330000; FONT-FAMILY: Arial; mso-bidi-font-size: 9.0pt">I do think that
these<SPAN style="mso-spacerun: yes"> </SPAN>diagrams must answer most of
your questions.<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
COLOR: #330000; FONT-FAMILY: Arial; mso-bidi-font-size: 9.0pt"> <o:p></o:p
></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
COLOR: #330000; FONT-FAMILY: Arial; mso-bidi-font-size: 9.0pt">We might
implement the business object using the composite entity pattern (you are right
) or DAO or other different implementation.<o:p></o:p></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
COLOR: #330000; FONT-FAMILY: Arial; mso-bidi-font-size: 9.0pt"> <o:p></o:p
></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><SPAN style="FONT-SIZE: 10pt;
COLOR: #330000; FONT-FAMILY: Arial; mso-bidi-font-size: 9.0pt">Regarding your
question ?</SPAN><TT><SPAN style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY:
Arial">Can the Presentation Tier directly </SPAN></TT><SPAN style="FONT-SIZE:
10pt; COLOR: black; FONT-FAMILY: Arial; mso-fareast-font-family: 'Courier New'"
><BR><TT><SPAN style="mso-ascii-font-family: Arial; mso-hansi-font-family: Arial
; mso-bidi-font-family: Arial"><FONT face="Simplified Arabic Fixed">instantiate
and use "Data Objects"? ?<o:p></o:p></FONT></SPAN></TT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><TT><SPAN style="FONT-SIZE: 10pt
; COLOR: black; FONT-FAMILY: Arial"> <o:p></o:p></SPAN></TT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><TT><SPAN style="FONT-SIZE: 10pt
; COLOR: black; FONT-FAMILY: Arial">We always use the business delegate pattern
to decouple the tier and hide the implementation details. It is better not to
use it directly from client tier (my opinion).</SPAN></TT><SPAN style="FONT
-SIZE: 10pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt"><o:p></o:p></SPAN><
/P>
<P><BR><BR><BR><BR></P><BR><BR><BR>
<DIV>Ashraf Galal <BR>(416)804-8359</DIV>>From: Chad Woolley <LISTS
@(protected)>>Reply-To: An interest list for Sun Java Center J2EE
Pattern Catalog <J2EEPATTERNS-INTEREST@(protected)>>To: J2EEPATTERNS
-INTEREST@(protected) >Subject: What is a "Data Object"? >Date: Tue, 30
Dec 2003 21:41:41 -0700 > >On page 387 of the 2nd edition, in Example 7
.21 for the "Business >Object" pattern, there is the following code: > >
;public class CustomerBO { > // CustomerData is a Data Object > private
CustomerData customerData; > . . . > public CustomerBO(CustomerData
customerData) { > . . . > this.customerData = customerData; > } > .
. . >} > > >What is a "Data Object"?? It's not a Transfer Object,
because the >design note at the end of the chapter on page 390 specifically
>states >that a Business Object should NOT wrap a Transfer Object. It's
also >obviously not a Data ACCESS Object. > >It CAN be a comp
osite object (contain other Data Objects), because >that >is how it is
used in the example. > >It looks like it is just a plain Value Object,
except that Value >Objects >no longer exist in the second edition (except
for the typo >references in >the index that weren't changed to Transfer
Object). > >Is this just an object that holds data? If so, where does it
fit >with >the other patterns? Is it encapsulated within the Business
Tier, or >can >it be exposed to the Presentation Tier? If so, is it meant
to be >transferred within a TransferObject? Can the Presentation Tier >
;directly >instantiate and use "Data Objects"? > >Thanks, >Chad >
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