How to study design pattern?

I have learn java for nearly a year and want to know more about design pattern.Fundemanetal instances of basic design pattern are appriciated.Thanks for your answer.

The most famous book on patterns is :
Design Patterns: Elements of Reusable Object-Oriented Software. Gamma et. al.
You should start there if you are interested in the subject.
There are tons of books since then on the subject. There is a list at
http://hillside.net/patterns/books/

Similar Messages

Sample Design pattern problems

I am currently studying design patterns from "Head First design patterns".
Does any body know any website that contains sample design related problems so that I can test my designing skills?
Thanks

[Google for 'design patterns' here at sun.com|http://google.com/search?q=design+patterns+site:sun.com].

How can I develop a web application using EJB design pattern?

I have searched over the web and found quite a lot of tutorials on how to use the EJB design pattern.
I know that there will be a home interface, EJB object interface and a SessionBean.
But the tutorials often only cover a single class, this made me unable to get a complete picture of how EJB design pattern can be implemented into a whole system.
I am now required to devleop an online shopping web application using EJB and JSP page.
I think I will need to create a lot of classes: Member, ShoppingCart, Product...etc.
What I want to ask is that, do I need to create a home interface, EJB object interface and a SessionBean for each of these classes?
I really need some ideas on how to develop this system using EJB + JSP pages.
Many thanks to you all.

For every EJB that you want to create, you will need to code a home and remote interface and a bean class.
You could start getting your ideas here
http://www.theserverside.com/books/wiley/masteringEJB/
http://www.coreservlets.com

Which Design Pattern and how to design using OOP this scenario

I am having trouble designing a module, can anybody help me?
Because it will be hard to maintain this kind of module, I also think that this can test my skill of design pattern usage.
Requirement
This is basically an agricultural project (web application). I need to design a module where some calculation takes place.
There are different crops involved like maize, tomato, okra etc. Each of these crops has different traits.
Each trait has a measurement scale which lies in integer like 200-1000. Now let's say I have planted the crop and done measurement noted down the traits. Now I want to do some sort of measurement. Some measurements are simple and some are complex.
Example
Lets take an example of crop maize. I have recorded observations for 15 traits. (We'll use trait1-trait15 as examples, the actual name can be like plt_ht, yld, etc.)
I recorded 5 observations for each trait:
trait1 trait2 trait3 trait5 trait6..... trait15
01,02,03,04 01,02,03,04 01,02,03,04
User logs into system and selects his crops and enters data for these observations. I have to calculate either average or sum of the data entered for each trait.
Complexity / centre of the problem
So far it's simple but complexity comes when I have some different formulas for some of the traits.
Example: trait YLD has a formula based on which I have to calculate its value, which may also depend on some other traits. Each different crop can have different traits.
All this I am able to do - whenever user selects crop I will check for those specific traits and do calculations (if it's not a special trait then I either average or sum it, based on db entry), but there is a lot of hard coding.
I would like to have suggestions on a better way of handling this.
My code needs to handle both simple and complex calculations.
Simple calculations are easy, I have take average of value entered for trait.
The problem comes when I have to do complex calculations, since each crop have different traits with their own formulas, so to calculate I have to check for crop and then for complex trait. So I have to hardcode the trait name of complex traits.
Can any tell me how I can design this using Java oops [?!?] so that I can make it generic?
I have about 10 different crops. Some calculations are specific to crops, so there will be lot of code like the if below:
hasZeroValue = (HashMap<String, ArrayList<String>>) dataValues[1];
} else if(cropId.equalsIgnoreCase("MZ") && traitName.equalsIgnoreCase("Shelling")) {
 avg=HybridTestDataUtility.calculateAvg(traitName, dataPoint, dataTraits, traitValues,dataPvalues, dataPoint, type);
 avg=avg*dataPoint;
 traitAvg=getMaizeYeild(traitName, traitAvg, population, avg, hybrid, area);
} else if(cropId.equalsIgnoreCase("OK") && traitName.equalsIgnoreCase("YLDGM")) {
 avg=HybridTestDataUtility.calculateAvg(traitName, dataPoint, dataTraits, traitValues,dataPvalues, dataPoint, type);
 //avg=avg*dataPoint;
 Object[] dataValues=getOKRAYield(traitName, traitAvg, population, avg, dividend,hasZeroValue,hybrid,repl);
 traitAvg = (HashMap<String, Float>) dataValues[0];
 hasZeroValue = (HashMap<String, ArrayList<String>>) dataValues[1];
} else if(cropId.equalsIgnoreCase("HP") && traitName.equalsIgnoreCase("w1-w10")) {
 avg=HybridTestDataUtility.calculateAvg(traitName, dataPts, dataTraits, traitValues,dataPvalues, dataPoint, type);
 avg=avg*dataPoint;
 Object[] dataValues=getHotPepperYield(traitName, traitAvg, population, avg,dividend,hasZeroValue,hybrid,repl);
 traitAvg = (HashMap<String, Float>) dataValues[0];
 hasZeroValue = (HashMap<String, ArrayList<String>>) dataValues[1];
} else if(cropId.equalsIgnoreCase("TO") && traitName.equalsIgnoreCase("TLSSG_70")) {
 traitAvg=calculateTLCV(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues,50);
} else if(cropId.equalsIgnoreCase("TO") && traitName.equalsIgnoreCase("TLSSG_100")) {
 traitAvg=calculateTLCV(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues,50);
} else if(cropId.equalsIgnoreCase("TO") && traitName.equalsIgnoreCase("YVMV_60")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("TO") && traitName.equalsIgnoreCase("YVMV_90")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("TO") && traitName.equalsIgnoreCase("YVMV_120")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("TO") && traitName.equalsIgnoreCase("ELCV_60")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("TO") && traitName.equalsIgnoreCase("ELCV_90")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("TO") && traitName.equalsIgnoreCase("ELCV_120")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("OK") && traitName.equalsIgnoreCase("YVMV_60")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("OK") && traitName.equalsIgnoreCase("YVMV_90")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg,dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("OK") && traitName.equalsIgnoreCase("YVMV_120")) {
 traitAvg=tomatoYVMVCalculation(traitName, traitAvg, dataPoint, dataTraits, hybrid, repl, traitValues, dataPvalues);
} else if(cropId.equalsIgnoreCase("OK") && traitName.equalsIgnoreCase("ELCV_60")) {Can anybody think of a way to make a generic approach to this?

There are crops and each crop have traits , traits are actually a mesuremet
scale to decide growth of a seed of a particular crop.
This module is to for planters to observe growth of seeds sowed of certain
crops and take down n no of observation for each trait and upload in csv format.Once they enter
data i have to either avg out the values or sum the values or sometimes
there are more complex function that i have to apply it may differe for each
trait .This is the whole module about.Just to give an idea about how they
will enter data
Hyubrid(seed) trait1 trait2 trait3 trait5 trait6..... trait15
Hybrid1 01 02 03 04 01
HYbrid2 04 06 08 04 01
HYbrid2 04 06 08 04 01
HYbrid2 04 06 08 04 01
HYbrid2 04 06 08 04 01
Once they enter data in this format i have to give result something like
this.
Here avg colum does not necessaryly mean avg it can be sum or any formula
based resutl.Hybrid is the seed for which they record the observation.
I have shown avg column only for two tratis it is actually for all the
traits.
Hyubrid(seed) trait1 Avg trait2 avg trait3 trait5 trait6..... trait15
Hybrid1 01 01 02 04 03 04 01
HYbrid2 04 04 06 10 08 04 01
HYbrid2 04 04 06 12 08 04 01
HYbrid2 04 04 06 14 08 04 01
HYbrid2 04 04 06 12 08 04 01
Hope this clarifies atleat a but
The data are not correctly indented but there is no way i can format it.

How to avoid multiple if else using design patterns.

Hi,
Which design patterns is used to avoid lot of if else in our code . Say for example if the user press 1 the out put should be one, if he press 2 it should be two like this upto 10. So we need to include lot of if-else part. How to avoid the multiple if else using design patter for this scenario. I can't find the solution for this problem can you guys help me?.

I'm too lazy to read a whole text book, but the first google link provides a code sample which made me laugh.
http://www.refactoring.com/catalog/replaceConditionalWithPolymorphism.html
double getSpeed() {
 switch (_type) {
 case EUROPEAN:
 return getBaseSpeed();
 case AFRICAN:
 return getBaseSpeed() - getLoadFactor() * _numberOfCoconuts;
 case NORWEGIAN_BLUE:
 return (_isNailed) ? 0 : getBaseSpeed(_voltage);
 throw new RuntimeException ("Should be unreachable");
}My implementation of The Bridge Over The Parrot Shop
package forums;
import java.util.Random;
abstract class Bird {
private static final Random random = new Random();
abstract double getAirSpeed();
public double getBaseSpeed() {
 return randomDouble(18.96);
protected static double randomDouble(double max) {
 return random.nextDouble() * max;
protected static int randomInt(int max) {
 return random.nextInt(max);
class EuropeanSwallow extends Bird {
double getAirSpeed() {
 return getBaseSpeed();
class AfricanSwallow extends Bird {
private int _numberOfCoconuts;
public AfricanSwallow() {
 this(randomInt(4));
public AfricanSwallow(int numberOfCoconuts) {
 _numberOfCoconuts = numberOfCoconuts;
double getAirSpeed() {
 return getBaseSpeed() - getLoadFactor() * _numberOfCoconuts;
public double getLoadFactor() {
 return randomDouble(3.12);
class NorwegianBlue extends Bird {
private boolean _isNailed;
private double _voltage;
public NorwegianBlue() {
 this(randomInt(10)<2, randomDouble(12.0));
public NorwegianBlue(boolean isNailed, double voltage) {
 _isNailed = isNailed;
 _voltage = voltage;
double getAirSpeed() {
 return _isNailed ? 0 : getBaseSpeed(_voltage);
double getBaseSpeed(double voltage) {
 return getBaseSpeed() * (1+(voltage/Math.PI));
public class AirSpeedTest
public static void main(String[] args)
 System.out.println("EUROPEAN: "+new EuropeanSwallow().getAirSpeed());
 System.out.println("AFRICAN: "+new AfricanSwallow().getAirSpeed());
 System.out.println("NORWEGIAN_BLUE: "+new NorwegianBlue().getAirSpeed());
}... and the requisite background for the uninitiated [NORWEGIAN_BLUE|http://www.youtube.com/watch?v=4vuW6tQ0218] and [EUROPEAN v AFRICAN|http://www.youtube.com/watch?v=4b4bGAoVR7g].
You have to know these things when you're a King you know.
Cheers. Keith.

Design patterns,about value object ,how?why?could you give me a soluttion

design patterns,about value object ,how?why?could you give me a soluttion
use value object in ejb,thanks
i want not set/get the value in ejb,find the method to solve it ,use value
object ?
how? thanks.

Hai
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If you are connected to a cabinet and it doesn't say FTTC is available, ask your neighbor to-do the same test (they have 2 be infinity connected). If they are, then proceed to contact the moderators here. Though it could not be showing because all the ports have been used up in the FTTC Cabinet.
If this helped you please click the Star beside my name.
If this answered your question please click "Mark as Accepted Solution" below.

How to create plug and play design pattern on a environment

Hi All,
Help me to get a best design for my problem statement.
Problem Statement: I have to create a platform where I should be able to plug and play different components. explaining better with example
Example:
1. I have to create a platform for school
2. In this school platform we have to plug in multiple components like "Student", "Teacher", "Subjects", "ClassPeriods" etc.,
3. These components should be easily plug/unplug and play
4. Like, the component "ClassPeriods" want to purchase from Vendor 1 and plug it to "School" platform it should work.
5. Incase if we want to unplug the "ClassPeriod" component provided bfy Vendor 1 from "School" platform and want to plug the "ClassPeriod" from Vendor 2. then the Design should support without any extra effort.
Suggest me the best design pattern for the problem
This design pattern is for ASP.Net
Thanks,
S.Kannan

Sounds like you're looking at 'Composition'. As a background, and possible solution, take a look at MEF;
http://mef.codeplex.com/
http://pauliom.wordpress.com

ABAP Object X Design Patterns X Extreme Program

Hi Evebody,
Im postgraduate in Object Oriented Analysis and Programming.
Ive been working with ABAP procedural development for two years and Ive started to work with ABAP Objects has few months.
Id like to get deeply knowledge in my developments skills, could someone tell me if ABAP Object X Designer Patterns X Extreme Program is a good path to follow?
Id like to share material and guides about this topic.
Ive already bought these books to help me.
ABAP Objects - H. Keller; Hardcover (Pre-Order)
Design Patterns Explained - Alan Shalloway
Ill be very grateful with any help.

> And do you think these themes are a great combination
> for ABAP development?
Design pattern are very abstract and can be used with any OO programming language. The implementations will differ but the core concepts are always the same.
XP is an agile development process and can also be used with any programming language.
Learning what design pattern are and how to use them is very important in my opinion. Most companies expect that you are familiar and have experience with them.
Extreme Programming (XP) on the other side is different. When I began to explore XP it got me started on how software should be developed in general. Since the concepts behind XP are quite different, it should at least stimulate you to start thinking about how you develop software at the moment and if there might be better ways of doing it.
If you have only time to study one subject go for the design pattern. You might also consider reading the following books if you want to improve your OO coding skills:
<a href="http://www.amazon.com/Refactoring-Improving-Design-Existing-Code/dp/0201485672/ref=pd_bbs_sr_1/102-4989641-7820932?ie=UTF8&s=books&qid=1173448197&sr=8-1">Refactoring: Improving the Design of Existing Code (a true classic)</a>
<a href="http://www.amazon.com/Refactoring-Patterns-Addison-Wesley-Signature-Kerievsky/dp/0321213351/ref=pd_bbs_sr_2/102-4989641-7820932?ie=UTF8&s=books&qid=1173448197&sr=8-2">Refactoring to Patterns (Shows how to improve code by introducing design pattern)</a>
cheers
Thomas

Software design patterns

Dear members,
As part of a research degree, I am conducting an online survey on the use
of software design patterns within software design projects, especially
when used within the scope of integrating applications (e.g. web services,
EAI etc). The aim is to investigate how use of software design patterns can facilitate software reuse and save time and cost with software development
The study doesn�t assume the use / knowledge of software design patterns as
a pre-requisite for filling the online survey as we are collecting views of
software developers with different background and experience.
Your response would be treated as confidential and the online survey and
results are anonymous (no name, address � etc is required).
All those who completed the survey with valid E-mail address will receive
copy of the aggregated results and any related publications, though giving
E-mail is optional.
The survey is expected to take 5 minutes to complete.
The link to the online survey is at
http://integrationsolutions.co.uk/Patterns_may.htm
Many thanks for helping with this study.
Contact details: [email protected]
University of Bolton UK( http://www.bolton.ac.uk)
Project web site (Under construction http://www.integrationsolutions.co.uk
).

the only problems i could find is...
1. sensors and display unit may vary...
2. each measurement should displayn their hi and low values which can b considered as a common function...
3. the display should vary according to user's request
this is the scenario...
could you help me to find the real problems and to apply patterns
Weather Monitoring Station
This system must provide automatic monitoring of various weather conditions. The system will have sensors to measure:
Wind speed
Wind direction
Temperature
Barometric pressure
Humidity
The system must also provide the following derived measurements.
Wind chill(derived from temperature, wind speed and humidity).
Dew point temperature(derived from temperature and humidity)
Temperature trend(derived from recent temperature readings)
Barometric pressure trend(derived from recent pressure readings)
The user can request the system to report the highest and lowest values of any of the four primary measurements during the previous 24 hour period.
The user has a screen display that continuously indicates all nine primary and derived measurements, as well as the current time and date.
The user may direct the system to display the 24 hour maximum or minimum values of one primary measurement, together with the time of that report value.
The user will be able to calibrate the sensors against known values and to set the current time and date.

What is the best design pattern for this problem?

No code to go with the question. I am trying to settle on the best design pattern for the problem before I code. I want to use an Object Oriented approach.
I have included a basic UML diagram of what I was thinking so far.
Stated simply, I have three devices; Module, Wired Modem, and Wireless Modem.
In the Device Under Test parent class, I have put the attributes that are variable from device to device, but common to all of them.
In the child classes, I have put the attributes that are not variable to each copy of that device. The attributes are common across device types. I was planning to use controls in the class definition that have the data set to a default value, since it doesn't change for each serial number of that device. For example, a Module will always have a Device Type ID of 1. These values are used to query the database.
An example query would be [DHR].[GetDeviceActiveVersions] '39288', 1, '4/26/2012 12:18:52 PM'
The '1' is the device type ID, the 39288 is the serial number, and the return would be "A000" or "S002", for example.
So, I would be pulling the Serial Number and Device Type ID from the Device Under Test parent and child, and passing them to the Database using a SQL string stored in the control of the Active Versions child class of Database.
The overall idea is that the same data is used to send multiple queries to the database and receiving back various data that I then evaluate for pass of fail, and for date order.
What I can't settle on is the approach. Should it be a Strategy pattern, A Chain of Command pattern, a Decorator pattern or something else.
Ideas?

elrathia wrote:
Hi Ben,
I haven't much idea of how override works and when you would use it and why. I'm the newest of the new here.
Good. At least you will not be smaking with a OPPer dOOPer hammer if I make some gramatical mistake.
You may want to look at this thread in the BreakPoint where i trie to help Cory get a handle on Dynamic Dispatching with an example of two classes that inherit from a common parent and invoke Over-ride VIs to do the same thing but with wildly varying results.
The example uses a Class of "Numeric" and a sibling class "Text" and the both implement an Add method.
It is dirt simple and Cory did a decent job of explaining it.
It just be the motivation you are looking for.
have fun!
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

How do you Design and Develop?

How do you Design and Develop?
I know this varies based on alot of things such as knowledge, preference, purpose, resources, etc..but I am curious how different (level of expertise) designers actually prefer or implement their websites. I decided to do this post after two different forums discussions regarding 1.Templates and PHP and 2. Backend Development.
1. How do you generally approach a project?--Wireframe, Freehand (as it comes), PSD template, etc.--Do you have a specific 'methodology' or procedure?
2. What are 2-3 of your main resources / sites / applications etc that you use (and for what?)
Specifically: What do you use (and how) to get up a website? (I know again this depends on a variety of things, but in general..) *also if you would like to comment on your expertise or level maybe helpful.
Do you prefer (Pros/ Cons of:) What advice would you give regarding below?
Your own HTML/CSS/Script based site that you mostly (if not completley) built. (More control and original, but harder / tedious for beginner)
HTML Temlplate (tweak the HTML and CSS)--non framework type (Quick and easy, but usually poor quality, outdated?)--but some can servde as good starting point.
Wordpress (And others like Drupal, Joomla) (Somewhat quick and easy access to tweak a quality WP Theme with ability for alot of features--forms, search, databases, etc (otherwise might have trouble with advanced features w/o good working knowledge og PHP and MYSQL, maybe others?)--but kind of a 'workaround' for real HTML design?
Frameworks types like Foundation, Bootstrap, Skeleton
A combination or hybrid of methods? -- or another method I have overlooked?
Thanks very much for any insight you can offer, hopeully this will lead to a vibrant discussion.-

The websites I build are 95% PHP/MySQL. They are heavy on business logic. I sometimes work with designers, SEO "experts" and (rarely) other coders. I almost never work on the content of websites. The clients do that themselves through the CMS I build for them.
I write every line of code myself except for the use of jQuery and a few PHP code classes adapted from others. I can build a complex website in a matter of minutes by reusing the code libraries and patterns I have developed from previous projects.
I don't use a PHP framework because I have developed my own "pseudo-framework" for the particular kinds of sites I build, but I respect the frameworks that are out there. They can teach you excellent coding habits.
In starting the design and logic of a site, the most essential question is: What is the website (or website project) supposed to accomplish? My clients tell me what they want to accomplish, but I usually decide how to get there. This holds for both business logic and design, because design also must serve the business objectives.
My website projects generally take four months to two years to complete. The client usually dedicates one employee to work as a liaison between me and the rest of the company. Because the sites I build are heavy on the business logic, a great deal of time is spent on testing and debugging. I make testing the responsibility of the client so I can't be held liable if, for instance, a terrible accounting mistake is discovered in the code logic.
I like to use Adobe Illustrator for design development because I became an Adobe Illustrator ACE in 2000; however, I can see that Fireworks is probably the better tool. Photoshop is an important secondary tool.
For general site management and code writing I use both Dreamweaver and ZEND Studio; however, I use Dreamweaver less and less.
I now require all my clients to have their websites (and also domain name registrations, since my company is a domain name reseller) hosted on my VPS server. This prevents anyone from stealing code I have worked for years to develop and also establishes a commitment between myself and the client. When you are starting a web development business, you can't demand this kind of commitment from the client. Even a lot of great seasoned developers can't. It depends on your reputation within the specific industry(ies) you service.

Does any body have any design patterns of JSF Web Application Developping?

Can any one answer me some questions?
#1.I am an amatuar of people who develop Web Application.For some reason,We choose the JSF to develop our item.through some introduction,I know the UI component of JSF is resided in Server side,is it right?but I am a little confused that:if there are many users who are exploring our jsf website.(to simplify my question,image I had just one web page and just one button)How many UI components(buttons) will be there?How it(they?) works?
#2.Does any body have the success experience (for example design pattern)to develop web applications?if We just concern about the Add,Delete,Modify,Query operations of some data.
I just do my job according to my feeling.
I will give every page a pagebean(backing bean),and I am not sure how to combine the business data with the pagebean.some one suggested that I should use delegate pattern to separate my business log and page logic.But I am still confused by following things:
#2.1 does JSF have the same ability to help us construct the model dialog just like swing to
help us control the operation flow?
#2.2 If there is not,Does the following way work?I put every tabledata's property as corresponed component.if user choosed the row in the table,My Listener will syncronize the row data to the components.But
#2.2.1 if JSF has the components according to the web users' number,how can My Listener tell which component should be update?Should I maintain the map?
#2.2.2 If the problem I imaged above is false,Does any body can tell me how to custom the ListDataModel,so I can use it like Swing?because now I can just use some view data to insert into ListDataModel,but after some selection operation,my business object must be find according to the selected data,it is not an interesting job!
I am waiting for your advice!

Ok I'll try to explain Step by step please correct me if I make any mistake because I have not played much with shared variables.
To create a shared variable to an RT target go to the target if tou have already otherwise add an RT target by right clicking the Project>>Add targets and Devices
Then in the target Right clikc and select the variable as shown below.
Then once the Shared variable settings window opens Enter a variable name and then Select the type "Network Published"
In the right side you can select the data type for the shared variable and even you can choose your custome controls.
After selecting the data type go for the Network and select buffering if required else leave it if you are planning to use the variable just for display purpose.
Then you can enable the RT FIFO if required (Not able to explain how it works and why it is used).
Then after completing the Shared variable setup you can access the variable in the VI in both the Host and the RT.
You can bind the variable to a control so that if any data from the RT is coming you can read the data from that control.
Once you have placed your shared variable in the BD you can change the access typr to read or write depending on your need.
This might not explain the complete shared variable concept but I believe that this would defenelty give you a kick off to start using the shared variable. Please correct or add more comments if anybody know better.
Good luck.
The best solution is the one you find it by yourself

Design Patterns/Best Practices etc...

fellow WLI gurus,
I am looking for design patterns/best practices especially in EAI / WLI.
Books ? Links ?
With patterns/best practices I mean f.i.
* When to use asynchronous/synchronous application view calls
* where to do validation (if your connecting 2 EIS, both EIS, only in WLI,
* what if an EIS is unavailable? How to handle this in your workflow?
* performance issues
Anyone want to share his/her thoughts on this ?
Kris

          Hi.
          I recently bought WROX Press book Professional J2EE EAI, which discusses Enterprise
          Integration. Maybe not on a Design Pattern-level (if there is one), but it gave
          me a good overview and helped me make some desig decisions. I´m not sure if its
          technical enough for those used to such decisions, but it proved useful to me.
          http://www.wrox.com/ACON11.asp?WROXEMPTOKEN=87620ZUwNF3Eaw3YLdhXRpuVzK&ISBN=186100544X
          HTH
          Oskar

Design Patterns Support in Jdev 10.1.3?

Is Design Patterns Support included as part of JDev 10.1.3. I have seen this support in SAP NetWeaver Developer Studio where you have the option of converting existing classes to implement a certain J2EE/J2SE Design Pattern or create a new class(es) to implement a Design Pattern. I believe TogetherSoft has this support.
Any chances this request is consider in the next major release of JDev 10.1.3?

Dear Shmeltzer,
My company just begins the migration from Oracle Form-based application to pure Java EE one. We will be using JDeveloper v10.1.3, persuaded by it fast GUI building, data-binding features. Before that, we have been trying out Eclipse & JBoss.
We are going to use Swing & JSF for client, and JavaEE 5 for midtier. Persistence layer, will be JPA (EJB3 entity bean persistence) and Spring Framework DAO support. Spring DAO is interesting bcos it gives a consistent style of API (we want to support both JDBC & JPA) and consistent Exception hierarchy too. So our midtier will be partitioned (roughly according to Fowler's patterns) into 3 layers: Service, Domain/Biz Object, Data Access. Thus far is pretty standard.
We are still pretty new to this ADF, and are still exploring.
Now, my initial impression with ADF is that it seems to interfere too much with the kind of pattern we had in mind. The fact that ADF hides too much details from us programmers scares me -- it becomes restrictive and we are helpless as to what are going on inside (with those xml, dcx, etc). For e.g. talk about Service Locator pattern, and we cannot seem to figure out how/where it is implemented. Using ADF Data Control and Biz Components will make all the design patterns "disappear" -- we dont see DAO classes anymore bcos it has been automated. It looks more like 2-tier client-server pattern to me. :-)
We are interested to use ADF data-binding features, so
1) Is it still advisable to use Spring DAO layer?
2) Is it possible to just use ADF in the Client / web tier, while the EJB container remains free of ADF technologies?
Regards.

The search for a perfect design pattern

The search for a perfect design pattern
I am searching tip to upgrade a labview program used. I am looking for the best approach to make
my program more robust and scalable.Software and hardware.
Today the system consists of :
GPS, weather station, ultrasound wind sensor, echosounder and a webcamera, all connected to a computer.
The computer OS is XP pro with Labview version 2009 installed. Except for the webcamera all peripherals have serial communication interface.
The webcamera interface is ethernet.
Device                           Data type                 Interval                    Interface
GPS                                NMEA string                1 second                   Serial rs232
Ultrasound wind sensor   NMEA string                1 second                   Serial rs232
Weather, temp,humid     NMEA string               35 seconds                 Serial rs232
Echosounder                  NMEA string               500ms-5 seconds       Serial rs232
                                                                      (depending of depth)
Webcamera                    Jpg                           Snapshot on demand Ethernet
The tasks to be solved
All the data have to be stored.
All the data have to be displayed in real time.
Weather history data must be buffered to be plotted in a graph (pop-up windows).
Absolute wind speed and direction have to be calculated.
Option to send navigation data attached to email at desired time intervals.
Image snapshot at desired time intervals.
The data wich streams into the serial ports are not synchronized and vary in intervals . Would it be a good idea to put all the serial peripherals into a serial device server. Is it possible to let the server place a event in my software, to trigger reading of the data, from the the server. Or how could that be done in other ways?
The perfect design pattern
In version one of the software I use 4 parallel loops to read data at the serial ports, inside these loops the data was separated and outputted to a datasocket server. I used datasocked read in other loops to present and store data. But it did not look good, and yes it was a mess, a really rat nest. I am looking for a better design pattern.
Could some kind of producer/ consumer pattern be the way to go?
Comments and tips are wanted.
TIK

Nice Project! Congratulations ;-)
I am not an expert for large applications. But your project looks nice and manageable. Here my straightforward ideas:
I would build a GUI, with menu bar, pop-up graph display thing.
THen low level tasks with each one handling a RS232 device and feeding queues or fireing notifications.
Maybe handle the snapshots in an event structure on the GUI blockdiagramm.
When GUI and producer tasks are running, close the gap with a middle layer which captures the data and actualizes GUI by reference. For instance the graph-thing-dialogue triggers a "flush queue" and displays the last 200 entries of the array of data.
I often run into issues when having defined too many userevent structures. I guess i am too stupid for that. Thats why i rather use queues (when i dont want to loose data) or notifiers (data is up-to-date). Nevertheless I like a "stop-all-tasks" user event...traditionally.
My team is actually developing a large application. We are using LabVIEW classes and objects.
So have fun!
Yours
RZM

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