Creating generic Value/Transfer-Object

i have written an application which gets a gui created via xml. so it depends on configuration which gui elements appear. the inputted data of the elements (index of selected radiobutton, data of textfield etc) shall now be stored in a database and therfore transfered within a value object. but im seraching for a good clean way to create this VO generically.
e.g. the gui consists of a textfield and a checkbox the valueobject needs the information to carry a String and a Boolean object.
any suggestions are welcome.

very helpful. i hope its clear to see that a collection with mixed classes is not a too good idea, especially if i need to know their type for saving them to a persistance layer ..
my goal is to avoid a "brute force" on their class-types via instanceof or reflection

Similar Messages

Pass Value/Transfer Object to ejbCreate?

I'm currently doing some entity bean programming and I'm thinking if it's possible to pass a Value Object to the ejbCreate method rather than a long list of parameters for all fields in an EJB.
You see most EJB tutorials that I've come across write ejbCreate as a method that takes in parameters for all fields/properties.
So we call it using say:
customerHome.create(customerId, customerName, ...blah, blah, blah,...); Since we have a Value Object, why don't we just have something like this:
CustomerVO c = new CustomerVO(customerId, customerName, ...blah...);
customerHome.create(c);Doesn't this look better and cleaner?
Anyway, how does the EJB methods mapping works? Why do I call the method .create(...) in Home interface and in the Bean implementation I've .ejbCreate(...) method instead?
What about the rest, say ejbLoad(), ejbStore, ejbRemove()? Just strip all the "ejb" infront and call them .store(), .load(), .remove() in Home interface?
Also, why do only .create(..) appear in Home interface itself? Are the rest (.store(), .load(), .remove())inherited and therefore not have to be specified?

Sorry for the formatting mistake above. Below is the corrected version.
I'm currently doing some entity bean programming and I'm thinking if it's possible to pass a Value Object to the ejbCreate method rather than a long list of parameters for all fields in an EJB.
You see most EJB tutorials that I've come across write ejbCreate as a method that takes in parameters for all fields/properties.
So we call it using say:
customerHome.create(customerId, customerName, ...blah, blah, blah,...); Since we have a Value Object, why don't we just have something like this:
CustomerVO c = new CustomerVO(customerId, customerName, ...blah...);
customerHome.create(c);Doesn't this look better and cleaner?
Anyway, how does the EJB methods mapping works? Why do I call the method .create(...) in Home interface and in the Bean implementation I've .ejbCreate(...) method instead?
What about the rest, say ejbLoad(), ejbStore, ejbRemove()? Just strip all the "ejb" infront and call them .store(), .load(), .remove() in Home interface?
Also, why do only .create(..) appear in Home interface itself? Are the rest (.store(), .load(), .remove())inherited and therefore not have to be specified?

Default values of columns not transferred in SSIS Transfer Objects Task

I am working on a project that is creating a new application, my area of the project being the migration of data from the old application database, transforming it, and populating the new database.
The transformations to the old data are done in a staging database.
At the end of the process, the staging database ends up with a lot of new applications tables, populated with the migrated legacy data.
We need to move these tables from the staging database to (initially) our test databases, but ultimately what will be the live database.
We have tried using the "Transfer SQL Server Objects Task" in SSIS, but have ran into a problem that a lot of the database tables have default values for columns.
These default values are not brought over.
Example. Tables contain a "GUID" field, which has a default of value of newid()
Right clicking and the table generating the CREATE script generates
[GUID] [uniqueidentifier] ROWGUIDCOL NOT NULL CONSTRAINT [DF_tbCRM_Client_GUID] DEFAULT (newid()),
However, the Transfer objects task does not create this default of newid()
Examining the SQL generated by the Import / Export Wizard when investigating this shows that the wizard generates this column as
[GUID] uniqueidentifier NOT NULL
and the column default value is lost.
Is there something i should be setting somewhere to force SSIS to bring these column definitions over correctly?

Kaarthik Sivashanmugam wrote:
This behavior is by design to maintain backward compatibility with the Copy SQL Server Objects task in SQL Server 2000. Only two constraints (Primary key and foreign key constraints) are expected to be copied by Transfer Objects task.
thank you for you response Sivashanmugam.
How can I move these tables (of which there are over a hundred) from my staging database into the application database - and keep the table definitions correct?
I cannot use the transfer objects task, as this will not define the tables correctly.
I cannot use the import and export wizard, as this will also not define the tables correctly.
This means I will manually have to code the drop, create and inserts for over a hundred tables?

Cannot create a Platform Context object. Exception was "Value cannot be null.

Hi there.
Im trying to integrate a desktop application with Project server 2013 online
(SharePoint ) using SOAP requests.
But doesnt matter what I try, i Always get this exception "Cannot create a Platform Context object. Exception was "Value cannot be null."
Anybody has a hint ?
Thanks

Hi Maycon,
In my opinion, this thread is related to SharePoint 2013-Development and Programming forum. So please post thread on that forum for more effective response. Thank you for understanding. Please refer to the following link.
http://social.technet.microsoft.com/Forums/sharepoint/en-US/home?forum=sharepointdevelopment.
Regards,
We are trying to better understand customer views on social support experience, so your participation in this interview project would be greatly appreciated if you have time. Thanks for helping make community forums a great place.
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HERE to participate the survey.

Transfer Object (Value Object)

Hi Friends
I am want to Use TO in Swing. But i do not know how to.
If You have any knowledge about To in Swings please provide me.
Thanks
---SunnyJain

well that is not what i wanted ..
They have some thing link this usage in J2EE.
http://java.sun.com/blueprints/corej2eepatterns/Patterns/TransferObject.html
I want to make swing client Table to use a Transfer Object to send data and receive data.

Cannot create a new StockTransfer object in SDK DI

I'm having a problem using the V6.7 DI SDK with VB 6.
My code loops through a collection, creating stock transfer entries in SAP BO. The User requirement is to add detail lines to the stock transfer until the from warehouse code changes after which a new stock transfer is created for all items originating from this warehouse, etc.
So I have declared a stock transfer object:
Private SAPStockTransfer As SAPbobsCOM.StockTransfer
Set SAPStockTransfer = SAPCompany.GetBusinessObject(oStockTransfer)
After which I set the appropriate properties of the stock transfer object and add the stock transfer lines as appropriate.
When the warehouse changes I firstly call the add() method of the stock transfer object then I reset the stock transfer object as follows:
Set SAPStockTransfer = Nothing
Set SAPStockTransfer = SAPCompany.GetBusinessObject(oStockTransfer)
The problem is at this stage, the SAPStockTransfer is not re-initialized, as I would have expected, but persists the previously held values.
Am I doing something wrong?

Hi Marinos,
Try calling the garbage collector before re-inistialising the Objects.
Try this:
Set SAPStockTransfer = Nothing
GC.Collect
Set SAPStockTransfer = SAPCompany.GetBusinessObject(oStockTransfer)
If this doesn't work try passing the parameters of the stock transfer into a procedure that will create the Stock Obj, instanciate it, do the stock transfer and the kill the stock obj

(Set SAPStockTransfer = Nothing
GC.Collect)
Call this procedure for each transfer. This must work.

How to combine Session Facade and Transfer object?

Hello All!
I'm working on an enterprise application. Presentation layer is a stand alone client, business logic is build on the Glassfish v2.1 and MySQL is used as a database. The client is connection to the GlassFishj server remotely using EJBs.
I have problems with business logic architecture.
Here is the brief description of backend application architecture design:
1. Session Facade pattern is used to simplify the client and application server interface and to provide application layers between backend (http://java.sun.com/blueprints/corej2eepatterns/Patterns/SessionFacade.html).
2.Transfer Object pattern to define update transfer objects strategy in order to decrease network overhead during client and application server interactions and to provide version control for objects. Transfer objects are designed as simple java business serializable objects. (http://java.sun.com/blueprints/corej2eepatterns/Patterns/TransferObject.html)
3. Originally the backend application consisted of three modules: users, storage and orders, but at the end I have decided to divide my application into the following parts - assortments, map, menu, orders, transactions, users.
4. All MySQL database transactions are via JDBC using procedures. No use of entity beans.
Questions:
1. I have some doubts about using Session Facade and Transfer object patterns at the same time. At first I'd mike to cite the definitions of the patters from the SUN official web site.
* Use a session bean as a facade to encapsulate the complexity of interactions between the business objects participating in a workflow. The Session Facade manages the business objects, and provides a uniform coarse-grained service access layer to clients.
* Use a Transfer Object to encapsulate the business data. A single method call is used to send and retrieve the Transfer Object. When the client requests the enterprise bean for the business data, the enterprise bean can construct the Transfer Object, populate it with its attribute values, and pass it by value to the client.
* So, if I use Transfer Object along with Session Facade, it makes some difficulties with object version control, because I 2 or
3 transfer objects controls with the 1 bean class. The best option for Transfer object Pattern is that each transfer object should have its own bean class to provide ability of object's version control. In the case it can bring the network overhead because of frequent remote calls caused by the large number of the bean classes.
* So, should I use the both patterns? If yes, how to manage the interaction the patterns. If no, which one to use.
2. E.g. I have a huge list of the Order objects and each Order object consists of other complicated objects. So, would I have trouble to transfer that list over network? If yes, how to manage it.
Thank you!
Astghik

Astghik wrote:
Hello All!
I'm working on an enterprise application. Presentation layer is a stand alone client, business logic is build on the Glassfish v2.1 and MySQL is used as a database. The client is connection to the GlassFishj server remotely using EJBs.
I have problems with business logic architecture.
Here is the brief description of backend application architecture design:
1. Session Facade pattern is used to simplify the client and application server interface and to provide application layers between backend (http://java.sun.com/blueprints/corej2eepatterns/Patterns/SessionFacade.html).
I would simply recommend establishing a service tier. Your services should be stateless. You can go the extra mile and have a session facade, but in the majority of cases, coding to an interface for your service accomplishes the same goals.
2.Transfer Object pattern to define update transfer objects strategy in order to decrease network overhead during client and application server interactions and to provide version control for objects. Transfer objects are designed as simple java business serializable objects. (http://java.sun.com/blueprints/corej2eepatterns/Patterns/TransferObject.html)
The idea of the transfer object is very similar to the Command pattern. I think if you investigate that pattern, it will be more obvious. The transfer object reduces network latency by consolidating all the parameters into an object, ideally, this also consolidates multiple method calls. If you combine a transfer object (or command object) with a service tier, you get the best of both worlds. The service can delegate calls to helper objects (or other services or components) using the data in the transfer / command object.
3. Originally the backend application consisted of three modules: users, storage and orders, but at the end I have decided to divide my application into the following parts - assortments, map, menu, orders, transactions, users.
The is your domain. It will vary from application to application. The principles above are more general (e.g., patterns and architectural tiers) and should apply to most domains. However, your actual use case may require something different.
4. All MySQL database transactions are via JDBC using procedures. No use of entity beans.
Consider using something like iBatis or Spring's JDBC templating to make your life easier with JDBC.
Questions:
1. I have some doubts about using Session Facade and Transfer object patterns at the same time. At first I'd mike to cite the definitions of the patters from the SUN official web site.
* Use a session bean as a facade to encapsulate the complexity of interactions between the business objects participating in a workflow. The Session Facade manages the business objects, and provides a uniform coarse-grained service access layer to clients.
* Use a Transfer Object to encapsulate the business data. A single method call is used to send and retrieve the Transfer Object. When the client requests the enterprise bean for the business data, the enterprise bean can construct the Transfer Object, populate it with its attribute values, and pass it by value to the client.
* So, if I use Transfer Object along with Session Facade, it makes some difficulties with object version control, because I 2 or
3 transfer objects controls with the 1 bean class. The best option for Transfer object Pattern is that each transfer object should have its own bean class to provide ability of object's version control. In the case it can bring the network overhead because of frequent remote calls caused by the large number of the bean classes.
* So, should I use the both patterns? If yes, how to manage the interaction the patterns. If no, which one to use.
Versioning is a separate issue. Generally, the more coarsely grained your transfer / command object is, the more changes are likely to impact dependent objects.
Your command or transfer object does not have to be a vanilla JavaBean, where you are basically creating a bean that has data from other objects. You can simply use your command / transfer object to encapsulate already existing domain objects. I see no need to map to a JavaBean with what you have described.
Generally, a method signature should be understandable. This means that many times it is better to pass the method, say, two coarsely grained objects than a signature with a dozen primitives. There are no hard and fast rules here. If you find a method signature getting large, consider a transfer / command object. If you want one service to delegate calls to a number of other services, you can also create a transfer / command object to furnish the controlling service with the data it needs to invoke the dependent services.
2. E.g. I have a huge list of the Order objects and each Order object consists of other complicated objects. So, would I have trouble to transfer that list over network? If yes, how to manage it.
This is a large, open-ended question. If you are going to display it to a user on a screen, I do not see how you avoid a network transfer with the data. The general answer is to not pass the data itself but rather a token (such as a primary key, or a primary key and a start and stop range such as you see on a Google search result). You do want to limit the data over the network, but this comes at a cost. Usually, the database will receive additional load. Once that becomes unacceptable, you might start putting things into session. Then you worry about memory concerns, etc. There is no silver bullet to the problem. It depends on what issues you are trying to address and what trade-offs are acceptable in your environment.
Thank you!
AstghikBest of luck.
- Saish

Can anybody explain me creating Generic Datasource using Function module?

Hi,
can anybody explain me creating Generic Datasource using Function module?
Thax in advance,
Ravi.

Generic Extraction via Function Module
/people/siegfried.szameitat/blog/2005/09/29/generic-extraction-via-function-module
1. Create s structure with the fields that you need from the 4 tables . Activate.
2. Goto SE 80 Select The Function Group , Copy , Select the Function module
" RSAX_BIW_GET_DATA_SIMPLE " and Give a New name starting With
Y or Z .
3. SE37 ->Your Function module name -> Change , In table tab give your structure
name by deleting the associated type given in " E_T_DATA " .
4. Now select source code and Do the coding . Give Data source name in Coding .
In your case you have to take data from more that 1 table .
5. Activate the Function Group .
6. In RSO2 Create the Data source , Give the Function Module Name , And Save.
7. RSA3 -> Give data source name and Check for the Records .
Creation of custom datasource. (Using function module)
is an example
1.Create a function group .
2. Structure ZTEST123
ZMATNR MATNR CHAR 18 0 Material Number
ZMTART MTART CHAR 4 0 Material type
ZMBRSH MBRSH CHAR 1 0 Industry sector
ZMATKL MATKL CHAR 9 0 Material group
ZBISMT BISMT CHAR 18 0 Old material number
ZMAKTX MAKTX CHAR 40 0 Material description
3. Create function module (i.e. ZTEST.) .
FM - YMARA_DATA_TRNS
FUNCTION YMARA_DATA_TRNS.
""Local Interface:
*" IMPORTING
*" VALUE(I_REQUNR) TYPE SRSC_S_IF_SIMPLE-REQUNR
*" VALUE(I_DSOURCE) TYPE SRSC_S_IF_SIMPLE-DSOURCE OPTIONAL
*" VALUE(I_MAXSIZE) TYPE SRSC_S_IF_SIMPLE-MAXSIZE OPTIONAL
*" VALUE(I_INITFLAG) TYPE SRSC_S_IF_SIMPLE-INITFLAG OPTIONAL
*" VALUE(I_READ_ONLY) TYPE SRSC_S_IF_SIMPLE-READONLY OPTIONAL
*" TABLES
*" I_T_SELECT TYPE SRSC_S_IF_SIMPLE-T_SELECT OPTIONAL
*" I_T_FIELDS TYPE SRSC_S_IF_SIMPLE-T_FIELDS OPTIONAL
*" E_T_DATA STRUCTURE ZTEST123 OPTIONAL
*" EXCEPTIONS
*" NO_MORE_DATA
*" ERROR_PASSED_TO_MESS_HANDLER
data : ZTEST123 type ZTEST123 occurs 0 with header line.
Maximum number of lines for DB table
STATICS: S_S_IF TYPE SRSC_S_IF_SIMPLE,
S_COUNTER_DATAPAKID LIKE SY-TABIX.
DATA: begin of t_mara occurs 0,
ZMATNR type MATNR,
ZMTART type MTART,
ZMBRSH type MBRSH,
ZMATKL type MATKL,
ZBISMT type BISMT,
end of t_mara.
DATA: begin of t_makt occurs 0,
ZMATNR type MATNR,
ZMAKTX type MAKTX,
end of t_makt.
Initialization mode (first call by SAPI) or data transfer mode
(following calls) ?
IF I_INITFLAG = SBIWA_C_FLAG_ON.
Check DataSource validity
CASE I_DSOURCE.
WHEN 'ZZMARA_DATA'.
WHEN OTHERS.
IF 1 = 2. MESSAGE E009(R3). ENDIF.
this is a typical log call. Please write every error message like this
LOG_WRITE 'E' "message type
'R3' "message class
'009' "message number
I_DSOURCE "message variable 1
' '. "message variable 2
RAISE ERROR_PASSED_TO_MESS_HANDLER.
ENDCASE.
Fill parameter buffer for data extraction calls
S_S_IF-REQUNR = I_REQUNR.
S_S_IF-DSOURCE = I_DSOURCE.
S_S_IF-MAXSIZE = I_MAXSIZE.
ELSE. "Initialization mode or data extraction ?
Data transfer: First Call OPEN CURSOR + FETCH
Following Calls FETCH only
First data package -> OPEN CURSOR
IF S_COUNTER_DATAPAKID = 0.
Determine number of database records to be read per FETCH statement
from input parameter I_MAXSIZE. If there is a one to one relation
between DataSource table lines and database entries, this is trivial.
In other cases, it may be impossible and some estimated value has to
be determined.
select MATNR
MTART
MBRSH
MATKL
BISMT
from mara up to 10 rows
into table t_mara.
if not t_mara[] is initial.
select MATNR
maktx
from makt
into table t_makt
for all entries in t_mara
where matnr = t_mara-zmatnr.
endif.
loop at t_mara.
read table t_makt with key zmatnr = t_mara-zmatnr.
ZTEST123-zmatnr = t_mara-zmatnr.
ZTEST123-ZMTART = t_mara-ZMTART.
ZTEST123-ZBISMT = t_mara-ZBISMT.
ZTEST123-ZMBRSH = t_mara-ZMBRSH.
ZTEST123-ZMATKL = t_mara-ZMATKL.
ZTEST123-zmaktx = t_makt-zmaktx.
append ZTEST123.
clear ZTEST123.
endloop.
clear E_T_DATA.
refresh E_T_DATA.
E_T_DATA[] = ZTEST123[].
ENDIF.
S_COUNTER_DATAPAKID = S_COUNTER_DATAPAKID + 1.
ENDIF. "Initialization mode or data extractio
ENDFUNCTION.
3. Create the data source using transaction (RSO2).
4. If structure exists for the table parameter of your function module then ok else create a structure for the table parameter E_T_DATA.
5. Test the datasource in R/3 using transaction RSA3.
6. Transfer the data source to BW System and replicate it in the BW-System.

Transfer Object pattern question

Hi, developers!
I created a Transfer Object pattern class, that has an array field. See below:
class TOClass {
private int[] values;
//notice that I am using clone() method
public int[] getValues() {
return (int[])values.clone();
public void setValues(int[] values) {
this.values = (int[])values.clone();
}Would you do like I did?
Thanks in advance!

Thank you, you all!
I am testing the solution you presented, Saish, and I am verifying yet. But I see that the problem of manipulation of data continues, like dubway said. But, this discussion gave me a lot of ideas! (I didn�t know Collections.unmodifiableList() method yet, very interesting method). I will continue my researchs for the best solution.
But I have to worry only when the getter method is used, because I don�t know what other developers will do with the value returned. I don�t need to worry about setter, because the only person that sets is me, and nobody else.
And one more thing. My TO class does not contain only one field. There are other fields: Strings, BigDecimals, etc, but these other fields are easy, I just have to create getters and setters for them. There is only one field that has the "behaviour of an array". But because of the fact that there are other fields, to not make this class complicated and "dirty" visually, I really want to use simple getters and setters methods, only. Your solution is not providing getters and setters exactly, Saish. I want to follow the Transfer Object pattern, whose feature is the existence of getters and setters, only.

Copying value of objects, not reference?

This has been bothering me for a while. I learned that when you set one object equal to another you are really just assigning the same reference to both, so that if one is altered they are both altered. Well, how can you set one object equal to the value of another but not the same reference so that altering one will not alter the other. My concern stems from returning arrays in methods. Since the reference itself is passed, any changes I make to the array are permanent, correct, and not just existing inside the method? So I was thinking maybe the best solution would be to use a tmp{] variable that is equal to the VALUE of the array I pass in, and then return that, so the original array is not altered in any way. Is this the customary practice for dealing with such situations? If not, what is typically done? Oh and just for future reference, because it might be of value to know, how DO I copy a value and not a reference? (and yes, that WAS on purpose ;) )

violagirl23 wrote:
My concern stems from passing arrays to [KRC] methods. Since the reference itself is passed, any changes I make to the array are permanent, correct, and not just existing inside the method? So I was thinking maybe the best solution would be to use a tmp{] variable that is equal to the VALUE of the array.Both georgemc and tschodt have already given you some good pointers, I'll try not to reiterate the same advise.
This is an old "problem", discussed at length by folks much smarter than myself, and (IMHO) there still is no definitive question, let alone universal answer. What I mean is that sometimes this ability to modify the contents of a collection or array within a method is highly desirable; and sometimes of course it's just a source of bugs, when a noob calls your method not realising that it modifies the contents of the passed array (which shouldn't make it past unit testing anyway)... So, I think probably the best thing I can do for you is to give you the terms to google.
What you're talking about is called a defensive copy... which, especially with arrays and collections, typically involves a deep copy (make a copy of every attribute of every object, all the way down the reference tree)... as apposed to Arrays.copyOf, which is a shallow copy, i.e. it just copies the references to the "top" objects.
If you're writing a system from scratch you could decide to implement clone methods for everything you ever need to defensive copy. Cloning is ugly, no matter how you cook it. It requires every part of the class heirarchy being cloned to support the clone method (properly).
In the past, I've tried to write a "generic" copy method, in the abstract-base-type of a class heirarchy using reflections. Everything I've tried has "pretty fatal" flaws. The only "proper" solution (AFAIK) is to just implement clone in every single frickin class... and that's a lot more "boiler plate" code than I personally think should be required to implement such a common, mundane task.
Alternately, you could make all your data transfer objects immutable, so a shallow copy (Arrays.copyOf) of the array is enough to protect the calling code from unexpected changes to the array contents because you are passing "a copy" of the references to things-that-cannot-change... So the callee cannot mutate a pointed-to object, and if the callee changes which object an array element points-to, you won't "see" the change... and of course the callee cannot change which array your reference points to, because Java passes references by value.
Google all the italic stuff... Sun's stuff is the best, then lookout for IBM's stuff, and most Wikipedia articles are really good (a few not so good).
HTH. Cheers. Keith.

Hierarchical data transfer objects confusing Flex compiler...

I just posted this same query on FlexCoders... but then I
thought this might be a better target group to ask, so here goes:
We are working on a set of data transfer objects where we
have matching server-side java classes and client-side AS classes.
Some of these DTO contain lists of other DTOs. As an example:
A.java:
public class A {
List blist
In A.as we have...
class A {
public var blist : ArrayCollection;
And we have B.java and B.as
Then we have a RemoteObject call to pull down a bunch of A
objects....
Here's the problem, Flex does not compile B.as at build-time.
So if B.as has a compiler problem, you never know about it,
except that the 'blist' in A never gets populated. If you break
down the data transfer and debug it. You find that during
RemoteObject call, the blist data comes "down the wire", but as an
ArrayCollection generic Objects, they never get turned into
instances of Bs...
I am guessing that this is happening because at compile time,
there is not direct reference to B in the clientside project. Our
covering .mxml wants one or more A objects, and inside A the blist
is an ArrayCollection. So the compiler doesn't see a reference to
B..
So anyone know how we can fairly seamlessly make sure B.as
gets compiled at build time so we'd know of compiler issues with it
rather than spending lots of time debugging mysterious null values?
(This appears to happen whether the project is set to compile
on the client-side or the server-side. We are using Flex and FDS
2.0.1 and Java 1.5)

up...

Questions on scripts, tables & transfer objects between clients.

1. In script, how to use the same print program for two different layouts? with procedure.!
2. Why cant sapscripts be client independent.?
3. Want to maintain a table in dev server and if i update the data, it should simultanously update in Quality and Production servers. How? please explain in details.
4. How to transfer object between clients.? explain.
Points will be promptly rewarded for HELPFULL answers.!

Hi!
3. With SE01, you can create a transport request for all table entries.
SE01 - Create button - Workbench request - Give description and save
Select the created request and click on Display object list.
Click on Display - Change button
Insert line button
ProgID: R3TR
Object: TABU
Object name: Z_YOUR_TABLE
Double click on the table name
Insert line
Key: *
Save everything
Release the transport in SE10 transaction and transport with STMS transaction.
Regards
Tamá

Transfer Object in JSF, Spring, and Hibernate

The application on which I am working deploys the JavaServer Faces, Spring and Hibernate frameworks.
We are going to use the "transfer object" to move data between J2EE tiers from the front end to the back end and vice versa. In addition, data "types" may need to be converted --
At the front end, the "type" of the data that are entered by users may not match that in the database table. For example, checkboxes may be marked or left blank by users. The "type" of the checkboxes is "boolean" in the JSF backing bean. However, we have either "Y" or "N" for the corresponding field in the database table.
The JSF backing bean holds data as well as controller functionality. Of course, the transfer object holds data only.
With regard to class properties, Is the transfer object an exact copy of the JSF backing bean? And at which tier the data are converted to match their correspoding "types" in the database tables?
We also have the "data objects" which are exact representation of database tables.
Thanks for your advices.

Small example: you can decide in the business layer
whether to convert it to boolean or Boolean (which
has a 3rd state: null).But it all goes back to your data model. If your data model supports null for that property, then of course boolean is a poor choice. If that case one could use Boolean. None of this has anything to do with re-usability, which was your objection.
I think the re-usability question goes back to the data model as well. Suppose your data model says this property is boolean valued. However if your database does not support booleans natively, then you need to map the value for storage in the database. But that is the data persistence layers problem.
OTOH, suppose your data model says that this property may be 'Y' or 'N'. Then the Java class represent the business object should not have a boolean property, we should make it match the data model.
However, I think that most cases where people are storing 'Y' or 'N' in a field in the database fall into the first case, where the data model is a boolean and they are working around limitations in the database. There is no reason in that case to perpetuate the same limitations in the Java code.

Transfer Objects in EJB 3.0

Hello,
I am building Enterprise application with EJB 3.0 and JSF. In many J2EE books there's that Trasfer Object pattern ( sometimes called Value Object or so), I just wonder what are your experiences in using TO in Java EE ( EJB 3.0).
Because entity beans in EJB 3.0 are POJOs I think that there is no need to
use TO pattern.
Im my app I receive entity from session bean and bind that entity to JSF components. This is the easisest solution for me because I don't build boring
transfer object, and don't have to wory about transformation between TO and Entity beans. Am I doing right or I am maybe missing something??
By reading EJB 3.0 spec. when session bean returns entity it becomes
detached so its just plain java object. ??
I know that using TO you can reduce coupling between client and EJB but
you must implement additional level with TO objects and transformations, so
it looks to me that by using TO you just get more complexity and problems ?
Tell me what are your thoughts and experiences.
Regards,
Niksa Jakovljevic
FOS

Hi Niksa,
Your intuition about EJB 3.0 is correct. One of the advantages of Java Persistence API entities
is that they can be passed directly to clients without having to convert their data to separate transfer
objects. The reason this was a common pattern in EJB 2.x and earlier is that CMP 2.x beans are 1st
class EJB components that are limited in their ability to be used outside of the ejb tier.
--ken

Transfer Object Pattern and Concurrency Transaction Mgmt

I am developing an application that implements a remote rich client. For
performance reasons I have chosen to use the Transfer Object pattern. I
have been very successful with this from a performance standpoint, it
really paid off. I am using it in combination with an assembler pattern
to construct Transfer Objects for the view and to also reassemble domain
objects based on changes made to transfer objects on my client side.
Anyways the only problem I am having with it is I can't seem to figure
out how I should implement optimistic locking with it. Is there a best
practices to handle transaction control here?
I generally try to keep visibility of stale data down, but there are still
situations where concurrent clients could have requested to edit the same
the Transfer Object at the same time. I would ideally like to handle this
using a flavor of optimistic locking. I in fact have implemented
optimistic locking on the domain side, but now I am not sure how or if I
should integrate this into the Transfer Object or View side. The version
field used in optimistic locking is generally a hidden field. The only
way I can see to handle this with the view side is to expose this field on
the Domain Objects and actually store it into assembeled transfer objects.
This seems like it may be a bad idea from a design standpoint.
The problem is the client requests data and it assembled and delivered to the client. Then at some later time the client may send a request to the server to update this data. At this time a new transaction must be started where the server reloads the domain data and copies over the requested changes. Since the domain data was just loaded you wouldn't ever trigger a versioning problem unless the version was maintained on the transfer object and copied over as well. I am developing this project with hibernate on the back end and unfortunately hibernate doesn't acknowledge manual changes to the version field.
I just feel like there must be a better way to do this. I believe that using the Transfer Object or DTO pattern for remote client/server architectures is pretty common. So there must be a best practice to deal with concurrency? Suggestions, insight, lay it on me please.
thx

I personal respect both concepts and am using both in an application I am currently work.
Firstly, I have my Transfer Object which I call xxxData.
Next, the entities are called xxx
I have my DAO classes that handles all CRUD operation. but within the DAO class I have two methods
private <EntityClass> retrieveEntityFromObject(<EntityClassData> data) {}
private <EntityClassData> retrieveEntityFromObject(<EntityClass> entity) {}so with these methods, I separate my business logic from my data layer. My codes will alway use data objects instead of entities. For example, a create method will be
public ProductData createProduct(ProductData data)
entity.persist(retrieveEntityFromObject(data));
}I hope someone understands
Regards

Creating generic Value/Transfer-Object

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