Resizing button Decorator design pattern

I am having the problem in doing the resizing of a button using the Decorator Design Pattern. Plz anyone who is having idea about this please send me the source code for me. I am having very less time to submit.plese replay me as early as possible

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Decorator Design Pattern

Hi all,
Have anybody a example of how to utilize the Decorator Design Pattern?
Whats the functionallity of this pattern?
Thanks.

Check this url:
http://www.castle-cadenza.demon.co.uk/decorate.htm
It gives you a pretty good insight on the Decorator pattern.

Design Patterns, The Decorator

When trying to implement the classic decorator design patterns your decorator executable might look like this: 
<pre>
METHOD validate.
 DATA: Validator TYPE REF TO validation_manager.
 CREATE OBJECT:
 Validator TYPE validation_manager.
 ,Validator TYPE validate_format EXPORTING x_validator = Validator
 ,Validator TYPE validate_values EXPORTING x_validator = Validator
 ,Validator TYPE validate_relation_input EXPORTING x_validator = Validator
 ,Validator TYPE validate_relation_database EXPORTING x_validator = Validator.
 me->lst_result = validator->validate( me->lst_data ).
 WRITE: / 'Processing Validate Activity'.
ENDMETHOD. "validate</pre> 
The validate method ends up in endless resurcion in the memory. The reason is that I'm using the same variable as the resulting instanse and as parameter. It seems like the constructor treats both the result and the parameter as the same field/instanse regardless import parameter such as VALUE/REFERENCE. If I change the method to use an extra field in the method validate like:
 <pre>
METHOD validate.
 DATA:
 validator TYPE REF TO validation_manager
 ,recursive TYPE REF TO validation_manager.
 CREATE OBJECT validator TYPE validation_manager.
 recursive ?= validator.
 CREATE OBJECT validator TYPE validate_format
 EXPORTING x_validator = recursive.
 recursive ?= validator.
 CREATE OBJECT validator TYPE validate_values
 EXPORTING x_validator = recursive.
 recursive ?= validator.
 CREATE OBJECT validator TYPE validate_relation_input
 EXPORTING x_validator = recursive.
 recursive ?= validator.
 CREATE OBJECT validator TYPE validate_relation_database
 EXPORTING x_validator = recursive .
 recursive ?= validator.
 me->lst_result = validator->validate( me->lst_data ).
 WRITE: / 'Processing Validate Activity'.
ENDMETHOD. "validate</pre> 
Now the decorator engine works, but why does the first implementation not work when the same one executes fine in php, c++, delphi, java and other languages. 
If you do not know what I'm trying to discuss, look up "Design Patterns - Simply", and jump to the chapter about the decorator design pattern. I'm trying to use this design pattern for a validation manager within my Business Process Engine, which needs to be able to configure what types of validation needed for on specific process (BPMN). 

Hi Matt, Thanks for the formatting..:) I will post the complete program as it's only a prototype program. Trying to get the format under control.
</body>
Report ZDP_DECORATOR_XMP01
REPORT zdp_decorator_xmp01.
parameters: bestimpl TYPE boolean_01 default 0.
TYPES:
BEGIN OF processdata
 ,name TYPE char30
 ,street TYPE char30
 ,zip TYPE char5
 ,city TYPE char30
 ,email TYPE char50
 ,phone TYPE char20
,END OF processdata
,BEGIN OF result
 ,msgid TYPE msgid
 ,msgtyp TYPE msgty
 ,msgno TYPE msgno
 ,status TYPE char1
,END OF result.
CONSTANTS:
true TYPE boolean_01 VALUE 1
,false TYPE boolean_01 VALUE 0.
CLASS validationmanager DEFINITION
CLASS validation_manager DEFINITION.
PUBLIC SECTION.
 METHODS:
 validate
 IMPORTING
 x_data TYPE processdata
 RETURNING
 value(y_result) TYPE result.
ENDCLASS.
CLASS validationmanager IMPLEMENTATION
CLASS validation_manager IMPLEMENTATION.
METHOD validate.
 WRITE: / 'Common validation'.
ENDMETHOD. "validate
ENDCLASS.
CLASS Validate_Decorator DEFINITION
CLASS validate_decorator DEFINITION INHERITING FROM validation_manager ABSTRACT .
PUBLIC SECTION.
 DATA: validator TYPE REF TO validation_manager.
ENDCLASS.
CLASS validate_format DEFINITION
CLASS validate_format DEFINITION INHERITING FROM validate_decorator.
PUBLIC SECTION.
 METHODS:
 constructor
 IMPORTING value(x_validator) TYPE REF TO validation_manager
 ,validate REDEFINITION.
ENDCLASS.
CLASS validate_format IMPLEMENTATION
CLASS validate_format IMPLEMENTATION.
METHOD constructor.
 CALL METHOD super->constructor( ).
 me->validator = x_validator.
ENDMETHOD. "constructor
METHOD validate.
 y_result = validator->validate( x_data ).
 IF y_result-status IS INITIAL.
 WRITE: / 'Now doing the format checks'.
 ENDIF.
ENDMETHOD. "validate
ENDCLASS.
CLASS validate_values DEFINITION
CLASS validate_values DEFINITION INHERITING FROM validate_decorator.
PUBLIC SECTION.
 METHODS:
 constructor
 IMPORTING value(x_validator) TYPE REF TO validation_manager
 ,validate REDEFINITION.
ENDCLASS.
CLASS validate_values IMPLEMENTATION
CLASS validate_values IMPLEMENTATION.
METHOD constructor.
 CALL METHOD super->constructor( ).
 me->validator = x_validator.
ENDMETHOD. "constructor
METHOD validate.
 y_result = validator->validate( x_data ).
 IF y_result-status IS INITIAL.
 WRITE: / 'Now doing the values checks'.
 ENDIF.
ENDMETHOD. "validate
ENDCLASS.
CLASS validate_relation_input DEFINITION
CLASS validate_relation_input DEFINITION INHERITING FROM validate_decorator.
PUBLIC SECTION.
 METHODS:
 constructor
 IMPORTING value(x_validator) TYPE REF TO validation_manager
 ,validate REDEFINITION.
ENDCLASS.
CLASS validate_relation_input IMPLEMENTATION
CLASS validate_relation_input IMPLEMENTATION.
METHOD constructor.
 CALL METHOD super->constructor( ).
 me->validator = x_validator.
ENDMETHOD. "constructor
METHOD validate.
 y_result = validator->validate( x_data ).
 IF y_result-status IS INITIAL.
 WRITE: / 'Now doing the relation input checks'.
 ENDIF.
ENDMETHOD. "validate
ENDCLASS.
CLASS validate_relation_database DEFINITION
CLASS validate_relation_database DEFINITION INHERITING FROM validate_decorator.
PUBLIC SECTION.
 METHODS:
 constructor
 IMPORTING value(x_validator) TYPE REF TO validation_manager
 ,validate REDEFINITION.
ENDCLASS.
CLASS validate_relation_database IMPLEMENTATION
CLASS validate_relation_database IMPLEMENTATION.
METHOD constructor.
 CALL METHOD super->constructor( ).
 me->validator = x_validator.
ENDMETHOD. "constructor
METHOD validate.
 y_result = validator->validate( x_data ).
 IF y_result-status IS INITIAL.
 WRITE: / 'Now doing the relation database checks'.
 ENDIF.
ENDMETHOD. "validate
ENDCLASS.
CLASS process_execution DEFINITION
CLASS process_execution DEFINITION.
PUBLIC SECTION.
 METHODS:
 startevent
 ,getdata
 ,validate
 ,process
 ,endevent.
PRIVATE SECTION.
 DATA:
 lst_data TYPE processdata
 ,lst_result TYPE result.
ENDCLASS. "process_execution DEFINITION
CLASS process_execution IMPLEMENTATION
CLASS process_execution IMPLEMENTATION.
METHOD startevent.
 WRITE: / 'Processing startevent'.
ENDMETHOD. "startevent
METHOD getdata.
 me->lst_data-name = 'Hans Andersen'.
 me->lst_data-street = 'H.C Andersens Boulevard 112'.
 me->lst_data-zip = '1557'.
 me->lst_data-city = 'København'.
 me->lst_data-email = 'hcATandersen.dk'.
 me->lst_data-phone = '0045-31162211'.
 WRITE: / 'Processing Get_Data Activity'.
ENDMETHOD. "getdata
METHOD validate.
 DATA:
 validator TYPE REF TO validation_manager
 ,recursive TYPE REF TO validation_manager
 IF bestimpl = true.
 CREATE OBJECT:
 validator TYPE validation_manager
 ,validator TYPE validate_format EXPORTING x_validator = recursive
 ,validator TYPE validate_values EXPORTING x_validator = recursive
 ,validator TYPE validate_relation_input EXPORTING x_validator = recursive
 ,validator TYPE validate_relation_database EXPORTING x_validator = recursive.
 ELSE.
 CREATE OBJECT validator TYPE validation_manager.
 recursive ?= validator.
 CREATE OBJECT validator TYPE validate_format
 EXPORTING x_validator = recursive.
 recursive ?= validator.
 CREATE OBJECT validator TYPE validate_values
 EXPORTING x_validator = recursive.
 recursive ?= validator.
 CREATE OBJECT validator TYPE validate_relation_input
 EXPORTING x_validator = recursive.
 recursive ?= validator.
 CREATE OBJECT validator TYPE validate_relation_database
 EXPORTING x_validator = recursive .
 recursive ?= validator.
 ENDIF.
Recursive call of the validate and it's successors
 me->lst_result = validator->validate( me->lst_data ).
 WRITE: / 'Processing Validate Activity'.
ENDMETHOD. "validate
METHOD process.
 WRITE: / 'Processing Process Activity'.
ENDMETHOD. "process
METHOD endevent.
 WRITE: / 'Processing endevent'.
ENDMETHOD. "endevent
ENDCLASS.
CLASS mainapp DEFINITION *
CLASS mainapp DEFINITION.
PUBLIC SECTION.
 CLASS-METHODS:
 main.
ENDCLASS.
CLASS mainapp IMPLEMENTATION *
CLASS mainapp IMPLEMENTATION.
METHOD main.
 DATA:
 p89 TYPE REF TO process_execution.
 CREATE OBJECT p89.
 p89->startevent( ).
 p89->getdata( ).
 p89->validate( ).
 p89->process( ).
 p89->endevent( ).
ENDMETHOD.
ENDCLASS.
START-OF-SELECTION.
mainapp=>main( ).
Edited by: Matt on Dec 22, 2009 2:03 PM Fixed formatting

J2EE Decorating Filter Design Pattern

I have been reading a little bit about J2EE patterns on Sun's web site
          (URL at bottom). The design pattern called "Decorating Filter" involves
          creating servlets that are always executed before and/or after all
          servlets.These always-executed servlets do things such as request
          logging and security.
          The idea sounds really nice to me. You can do a lot, without putting
          code for logging or security in the servlet that people actually
          requested. So, you could request a servlet, but these other servlets are
          executed before/after it automatically.
          Is there a way to do this in WebLogic? Is this "servlet chaining"?
          Thanks,
          Mike


Mike,
          Checkout 6.1 it has filters implemented as part of servlet2.3 spec.
          http://e-docs.bea.com/wls/docs61///////webapp/filters.html
          Kumar.
          Michael Olivieri wrote:
          > I have been reading a little bit about J2EE patterns on Sun's web site
          > (URL at bottom). The design pattern called "Decorating Filter" involves
          > creating servlets that are always executed before and/or after all
          > servlets.These always-executed servlets do things such as request
          > logging and security.
          >
          > The idea sounds really nice to me. You can do a lot, without putting
          > code for logging or security in the servlet that people actually
          > requested. So, you could request a servlet, but these other servlets are
          > executed before/after it automatically.
          >
          > Is there a way to do this in WebLogic? Is this "servlet chaining"?
          >
          > Thanks,
          > Mike

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

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

Producer/Consumer Design Pattern + DAQmx + Event Structure

Dear community users,
at the moment I try to implement the Producer/Consumer Design Pattern into my current project. For this purpose I am trying to make a "minimal-example" in which I use the Producer/Consumer Design Pattern for the data acquisition and analysis (display in GraphXY, calculation etc..) process. In the Producer Loop I perform the data readings via DAQmxRead.VI and in the Consumer Loop, in this example only, I display the data in a GraphXY. At the same time I want to control the data acquisition via an Event Structure, for example Start Measurement/Stop Measurement Buttons. To configure the measurement time, for example if the user only wants to measure 150 sec, I use the Time Out Event of the Event Structure. This is a technique which is often used, when data acquisition and Event Structures are used at the same time (Excuse me if this is wrong!). Due to understand the Producer/Consumer Design Pattern I looked up in the Template\Framework of LabVIEW.
In the attachment you will find my "minimal-example", which -sadly-, not working. What should I do ?
Thank you.
Best regards,
tugrul öztürk
Attachments:
daqEngine_PCP.vi ‏35 KB

Your VI will never stop due to the Ok Button that stops the producer loop is read OUTSIDE of the loop. Add an event case for it.
Move the Start and the Ok Button inside of their respective event cases. This will allow the latch to reset when they are read.
Change the Ok Button to a stop button.
Use a Greater Or Equal instead of Equal for the measurement time comparison. What if somebody randomly changes it to 0 on you? Again, you will never stop.
Is the DAQ only supposed to read for "Measurement Time". Right now, it constantly reads. So if you don't use the DAQmx Read, you will get a buffer overflow error. You need to put the DAQmx Start Task inside of the Start event case and then the Stop DAQmx Task inside of the Timeout event case when the measurement time is exceeded. You should also perform the read regardless inside of the Timeout event case.
I HATE telling the consumer loop to stop by destroying the queue. You can look data that way. Instead, send something an empty array. In the consumer, check for an empty array. If it is empty, stop. Destroy the queue only AFTER BOTH LOOPS HAVE COMPLETED.
You should also report your errors in some way. Simple Error Handler at the minimum.
Since you are using Continous Samples, don't limit the buffer. Leave the Samples per Channel unwired on the DAQmx Timing VI.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Choice of design pattern for data acquisition system

Hello all
I have a trouble about selecting the suitable design pattern / architecture for a data acquisition system.
Here is the details of the desired system:
There is data acquisition hardware and I need to use it by observing parameters on User interface.
the data acquisiton period, channel list to scan should be chosen on User interface. Besides, there are many user interface interactions. e.g. if user selects a channel to add scanlist, then I need to enable and make visible some other parts on user interface.
When user completes the channel selection, then he will press the button to start data acquisition. Then I also need to show the scanned values on a graph in real time and log them in txt file.
I know that I cannot use producer consumer pattern here. because the data acquisition loop should wait for parameters to scan channels. and it works in a given period by user. so the user interface loop performs higher rate then consumer loop (data acquisition loop). it means queue will be bigger bigger. if I use notifier it will loss some data come from user interface.
is there any idea about that ? is there any suitable design pattern for this case ?
Thanks in advance
best regards
Veli BAYAR
Embedded Systems Software and Hardware Engineer
"You live in a graphical world. Why not program in one?"
Solved!
Go to Solution.

johnsold wrote:
Veli,
I recommend the Producer/Consumer model with some modifications.
You might need three loops. I cannot tell for sure from your brief description.
The User Interface loop responds to the user inputs for configuration and start/stop of acquisition. The parameters and commands are passed to the Data Acquisition loop via a queue. In this loop is a state machine which has Idle, Configuration, Acquisition, and Shutdown states (and perhaps others). The data is sent to the Processing loop via a different queue. The Processing loop performs any data processing, displays the data to the user, and saves it to file. A notifier can be used to send the Stop or shutdown command from the User Interface loop to the other loops. If the amount of processing is minimal and the file write times are not too long, the Processing loop functions might be able to occur in the Timeout case of the UI loop Event structure. This simplifies things somewhat but is not as flexible when changes need to be made.
I am not sure that a Design Pattern for this exact setup exists but it is basically a combination of the Producer/Consumer (Events) and Producer/Consumer (Data) Design Patterns.
Lynn
Check out this thread: http://forums.ni.com/t5/LabVIEW/Multiple-poll-case-structures-to-event-help/td-p/2551309
There are discussions there about a 3-loop architecture that may help you.
Jeff
Jeffrey Zola

SAP Fiori - Layout Design patterns

Dear All Gurus,
This may be a layman question but expecting your expert advice and perspective on this.
I am creting a fully customized fiori application -" Purchase Order Creation " and User wants to have the UI design very simillar to SAP screens(ME21n) adding only required fields into that.
I know that fiori has a design pattern(Ex : Main items in left and details in right side , 'back' button etc..) which gives me a good impression. But if I go ahead with user's requirement will there be an impact ? Ex : performance / run on mobile.
Thanking you all in advance..
Tags edited by: Michael Appleby

Hi Masayuki,
Thank you for the reply..
+Target device: windows desktop(mainly) and mobile
+Who will use: Employees (mainly)/MRP specialist
+Number of users: 500
+Is there Purchase Requisition process before Purchase Order : NO . Direct PO creation. But PO Approval is there using srtandard Fiori App.
+PO will be created entering everything manually
+Where is the data source for creating PO? : Original data is on paper

Is this a good design pattern?

Hi,
I am working with a team to create an application that can acquire data from up to 24 thermcouple channels. We plan to create a wizard to assist the user in setting up the test (specifiying stop conditions, sample rate, channels to sample, output file, and email/text notifications). After the setup, if the user does not cancel out, then the program continues. We have defined parallel loops and their roles, trying to fit into a producer/consumer design pattern. I have attached the main file which shows the structure of the program. We are trying to keep it clean and modular. Before diving into development, we are finalizing a detailed design specification so that different people can work on each of the loops' subvis. I was hoping that people could review the block diagram and offer suggestions for improvement or validate that we have chosen a good method of implementation.
Notes about the block diagram
The plan is for data driven stop conditions to be detected by Event Notifier, handled by the Main UI event, and then the Data Collector is instructed to stop (as well as the Main UI loop). When Data Collector stops, it releases queues, the queue reference becomes invalid, and then the loops with the Dequeue will be stopped.
I am not sure if an additonal event structure should be in the DataCollector to specifically handle the Stop button on the UI because if it is in the Main UI event structure, the DataCollector would not be stopped immediately. This is important to stop quickly because the sample rate could be VERY long. I understand about using an event structure instead of WAIT, but didn't know if there is an efficient way leaving it down in the Main UI event structure....????
Data Collector is the producer, it currently only collects data and passes it on. If the program is going to contain a start collection button, or pause/resume, I need to figure out how to handle this with the Main UI event structure.
Event Notifier consumes data from the Data Collector. It looks at all data and should set a flag if a stop condition is met. The flag will be handled by the Main UI event structure to tell Data Collector to stop. The event notifier also sends a notification to the Email/Text Caller when thresholds have been exceeded warranting a reason for the user to be notified via text or email.
Email/Text Caller waits for notification and then calls a subVI to send an email or text with certain data and channel information. The subVI call is lengthy, so we decided to put this in its own loop instead of a case structure inside the Event Notifier.
Report Generator logs all collected data to a file. A second queue was used, but uses the same data as the first. Is this the correct implementation since two consumers need the same data?
Main UI - handles changing of sample rate, possibly the stop button, possibly start/pause/resume of data collection. Also handles when Event Notifier sets flag for a data driven stop condition, which then should provide a mechanism to stop the Data Collector.
A big question that i have is.... Should the Main UI event structure just be in the Data Collector so that the loop can be stopped immediately? All of the UI events (stop button, start/pause/resume data collection) directly effect the Data Collector. Should the data Collector have a state machine instead?
I feel that the 3 consumer loops (Event notifier, Email/Text Caller, and Report Generator) seem like a good implementation, but i am not confident about the Data Collector and Main UI loops. Should they be combined?
Solved!
Go to Solution.
Attachments:
updatedMain.vi ‏13 KB

A couple of thoughts:
Overall it looks workable- remember to name your queus and notifiers- then you can depop the BD and launch each loop in its own sub-vi without wiring all those queues between loops- Just obtain ref to named queue.
"Data collector" needs a supervisor to control how often the data is collected- I'm thinking a QSM with "init- collect- stop" states. A simple timed loop could produce the "time to acq ticks" under control of the sample rate control. This puts both the DAQ init and cleanup functions within the Data Collector's perview so it aids coehesion and solves the exit without waiting for the loop to iterate.
I'm not a fan of duplicating data- I assume analisys is pretty much just some comparisons- so it is pretty quick- Why not append summary data to the same queue? And make it a single element queue- the report loop can then inspect the queue and look for a summary data "index" - if its greater than the last index written append the darn data to the report? Preview queue works great for these situations.
Do not combine the UI handeler with anything else! Do you see the snag?- hint: here thar be spaghetti. keep the functions seperated for solid scalable and maintainable code.
One last thought: Its getting less popular to stop loops on the error out of a dequeue. First it returns a default element that can cause your listeners some headaches. Second it doesn't let you run cleanup code. Use a stop command <enum> built into the element data as an executive to determine when to stop. We'll try to get the examples updated to show current best practices.
Jeff

Best architecture and design pattern to use

I am currently designing a moderately sized LabView application and cannot decide on the best architecture/design pattern or combinations thereof to implement.
The program basically polls an instrument connected to a serial port continuously at a 2-10Hz rate. When operator clicks a button to start a run, the polled data is then filtered, has math functions performed on the data, writes collected data to files, and produces reltime graphs and calculates point-by-point statistics. At the completion of a run, some additional data files are written. I pretty much know how to accomplish all these tasks.
What is also required is main-vi front panel interaction by the operator to access a database (via a C# dll with .Net) to query for specifications to apply in order to determine pass/fail status. Setup conditions also need to be changed from time to time by the operator and applied to the data in real time (ie- a measurement offset). I have prototyped the database portion successfully thus far.
For the main vi, I started off using the Top Level Application Using Events design pattern (Event structure within a while loop). Copious use of bundled clusters and shift registers keep the database data updated. I cannot figure out how to have the top level vi concurrently poll the serial device as outlined above. The Event structure is only active when defined control values change, and use of a timeout is no help since it prevent data from being collected while the user is accessing the database. All database and setup parameters must be applied to the data as it comes in from the serial port. Error trapping/recovery is a must.
I believe what I need is two parallel processes running under my main vi (one for database and setup, the other for polling and data processing/display, but what would be the preferred choice here?
Revert back to a polled loop in lieu of Events, use notifiers, occurrences, user-defined events, Producer-consumer loops?
It�s been about 3 years since I have had an application on this level (which used a state machine architecture), and a lot has changed in LabView (using 7.1 Prof Devel). I am currently having a mental block while trying to digest a lot of features I have never used before.
Suggestions Welcome!
Thanks.
~~~~~~~~~~~~~~~~~~~~~~~~~~
"It’s the questions that drive us.”
~~~~~~~~~~~~~~~~~~~~~~~~~~

I suggest a (3) state machine(s) architecture. The first is the user interface. Your main VI is a good start. Another state machine handles the instrument I/O (your serial polling). The third handles all data processing. The three loops run independently. Each has a wait to allow LV's scheduler to share CPU time among the loops. I like queues or functional globals for inter-loop communications.
This allows a lot of flexibility. Each portion can be tested alone. Each can have different timing and priority.
Spend some time thinking about what needs to be done and plan the structure carefully before you do any coding (except for little test programs to try new ideas).
I also like Conway and Watts "A Software Engineering Approach to LabVIEW", published
by Prentice Hall.
Lynn

What is command design pattern? what is the problem that it solves?

Hi i have been reading few articles on command design pattern but was unable to understand what it is and what problem does it solve. As far as my understanding goes if there is a pre specified method in an object that could execute and perform the necessary activities then it is called as command design pattern. Why is it named as command design pattern, it is because in a shell we use commands to retrieve output. For example when we type "dir" in dos command prompt it returns the list of files. so here we have to remember a preexisting exe file named "dir" which does something when used. So here like we call it command because when "dir" is passed to the computers it returns something that is expected. may be the computer obeys the command issued and return something back. So like wise if there is a method that is defined as as the command, for example in struts framework the action class must have a method "execute()" which is called by the framework to execute the necessary action mapped to it. So if there is a predefined method like "execute" in struts then the object is said to be followed command design pattern. So what actually does it solve?
What ever i have written is my understanding from the articles i have read about the design pattern. So kindly correct me if i am wrong. Help me understanding what actual problem does this pattern solves. Thanking you in advance.

This is really off-topic for these forums. You might do better on StackOverflow.com. I'll just say that although the first Design Patterns book came as a revelation to me, it was more for (a) the nomenclature (decorator, factory, facade, etc) which is still with us and (b) about five of the original patterns, which told me things I didn't already know. I've never used any of the others, including Command, and the whole design patterns thing quickly degenerated into farce with what seemed like a sustained attempt to reduce the whole of computer science to design patterns, which really isn't the point. As an example, there is one in another book called Type Object, which is nothing but 3rd normal form, which can be defined roughly in a couple of sentences. This pattern went on for dozens of pages with a very artificial example. I wrote to the mailing list about it: 'Type Object considered hilarious'. I got a rude reply from the original author, which I guess I expected, but also an incredible response from the list owner, saying I should recast my objections in the form of a design pattern. That lost it for me. True story. Moral: don't take this religion, or any IT religion, too seriously. They come around every 18 months or so with the regularity of the next bit of Moore's Law. I've seen dozens of them come and go since 1971, all with something to say, all 90% nonsense.
See here for a longer version of this incident.

Design patterns implemented in java API

Hi,
I have some questions on design patterns implemented in core java class or in general in java API.
1)Whether
java.util.Collections, the checkedXXX(), synchronizedXXX() and unmodifiableXXX() methods.
can be considered as a decorator pattern?
2) Whether
LinkedHashMap(LinkedHashSet<K>, List<V>) which returns an unmodifiable linked map which doesn't clone the items, but uses them
can be considered as a Bridge pattern?
3) Whether Facade pattern is implemented in java ? If so which API uses it?
4) Whether
• All non-abstract methods of java.io.InputStream, java.io.OutputStream, java.io.Reader and java.io.Writer.
• All non-abstract methods of java.util.AbstractList, java.util.AbstractSet and java.util.AbstractMap
can be considered as a Template method pattern?
5) Whether
• java.util.Comparator#compare(), executed by among others Collections#sort()
can be considered as a Stratergy pattern?
6)
Whether State pattern is implemented in java ? If so which API uses it?
7)
All implementations of java.lang.Runnable are considered as a Command pattern.
8)
Whether
• java.io.InputStreamReader(InputStream) (returns a Reader)
• java.io.OutputStreamWriter(OutputStream) (returns a Writer)
can be considered as an Adapter pattern?
Please clarify.
Thanks.

What do you think, and why?

Can anyone take me in step by step to understand MVC design pattern

Hi Everybody,
I just killed myself trying to understand what is MVC and how to apply it to flash (AS3) the easy way but I could not, there is a lot of information on MVC on google but it is very hard I can not understand it and apply it to anykind of application or game, I had created a lot of games but using flash timeline (puzzle, multipel choice, simple physics interaction) and I understand that we must separte the design interface and the data of the application and the code into diffrent blocks, but what I understand is:
1- making a SWC for the design. (View)
2- use XML or TEXT file for the data.(Model)
3- classes for the code.(Controller)
this is MVC that I understand, but all the tutorials on the net is about creating 3 classes and calling each other in a very diffuclt code to understand, I realy need to work the proffessional way but it is very hard and far away from my understanding.
if any body have a way to let me understand it like making a template for every MVC application or game and explain to me his/her code it will be great, some of my questions are:
1- how we say about a class that it is the view part of the pattern while we have a SWC that hold the intreface graphics?
2- dose making a sepreate class to load and fetch external data sources like xml and text means I had created the model part of the pattern, and why the tutorials on the net do not say that if it is true?
3- making the logic of the application or game sepreated into class for each logic block, makes the controller part of the pattern?
I realy do not know what to ask more because I do not understand the MVC design pattern
Please note: if someone can chat with me on skype it will be great, but if you want to explain here also good but I need to understand it is making me crazy!
thanks in advance

I'm not a pro in this either, but a few things about it make sense to me.
First you don't need to have only three parts, but all the parts you have should be one of the three things (maybe). And they don't need to be a swc, XML/text, or a class.
I recommend the Clock tutorial from Colin Moock's book, Essential Actionscript.And here is someone walking you through it. http://flylib.com/books/en/4.14.1.137/1/
In that example there is a model which keeps track of time like the hours, minutes, seconds, if the clock is running.
There is a controller that lets you set the time, reset the clock, stop the clock, that kind of stuff. This isn't the buttons and stuff that allow you to do that, this is the code that takes the input from the buttons and communicates with the model.
So there would be a view of the buttons that the user would want to push to set the clock or what have you.
And there is a view presenting the time. Now there might be two (or more views). For example you might have an analog clock and a digital clock.
Work through that tutorial. It helped me.

Design Patterns in Dynamic Programming

I mentioned this on a thread some time ago - that many of the GoF patterns disappear in languages such as Lisp, but didn't have the reference handy. Came across it again today so I thought I'd post the link:
http://www.norvig.com/design-patterns/
Pete

hi sourdi
Below are the list of Design pattern in abap .
Singleton: ensuring single class instantiation
Adapter: making class interfaces compatible
Factory: encapsulating object creation
MVC: decoupling business logic from the view
Facade: providing a simplified interface
Composite: treating individual objects and compositions uniformly
Decorator: forming a dynamic chain of components to be used as one by the client
regards
chinnaiya P

Resizing button Decorator design pattern

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