Design and Architecture

copec12-Jul-09 7:08

12-Jul-09 7:08

Thanks so much for this info. A lot of it is new but some of it fits in and clarifies other things that were foggy.

It may show that I don't really understand what I'm talking about, but, in no particular order:

--I used to support some Access apps that ran on MDAC and Access on various clients and there were always problems coming up. That's why I'm drawn to developing a truly independent program.

--I'm definitely leaning toward an RDB data store instead of an OODB, or the other choices, because I already have a working -though improvable- model of the data in RDB (my existing mdb) and it seems like the "best" way to store number data.

--From this and other info I've read I guess it's a two way tie between C++ (I had the Intro to C++ class) and Python (seems to be widely liked) for the front-end (is this right terminology?) with Java still kind of in the running (don't love that it is dependent on JVM).

--Should I not be concerned about stability or security of using something built on a platform, like JVM or .net?

--Could you talk more about this?: "You would need to be able to package and distribute the db with your GUI app, and that might bring problems similar to the MDAC ones with Access."

--I understand what the language and libraries are, but could you explain why I need toolboxes, wrappers (like wxpython)?

--Regarding IDEs, I found these at http://wiki.python.org/moin/IntegratedDevelopmentEnvironments[^]. How do I choose between "IDEs with introspection-based code completion and integrated debugger" and "IDEs with integrated gui builder"?

And thank you again. I really appreciate your help.

riced12-Jul-09 21:07

12-Jul-09 21:07

copec wrote:
developing a truly independent program

Not sure you can develop a completely independent program. If you create an executable (i.e. .exe) it will almost certainly depend on some system .dlls - pretty much unavoidable. It will also depend on having an RDBMS (e.g. SQL Server) if you use a relational db.

copec wrote:
don't love that it is dependent on JVM

You don't need the JVM on user's machines, just the JRE - at least that's my understanding. If you use C++ to create a .Net app, user's would need the .Net framework installed. I don't know Python so don't know its dependencies.

copec wrote:
Should I not be concerned about stability or security of using something built on a platform, like JVM or .net?

These are probably concerns irrespective of platform. How critical they are depends on the nature of the app.

copec wrote:
Could you talk more about this?: "You would need to be able to package and distribute the db with your GUI app, and that might bring problems similar to the MDAC ones with Access."

Once the app is created you have to have some means of distributing it. If it comprises a .exe plus supporting .dlls and a rdb back end you have to get them onto the user's machine. With 'traditional' .exes there are issues with differing versions of .dlls (commonly referred to as dlHell, similar to MDAC issues. These have pretty much gone away in .Net - there's no problems with having multiple versions of the same .dll.)

copec wrote:
explain why I need toolboxes, wrappers (like wxpython)?

Strictly you don't, if you are prepared to create your own widgets such as buttons, textboxes and comboboxes to populate forms (you would have to create a widget for the form as well). If you take C++ as an example, the language itself does not provide any GUI widgets at all. So to create a GUI you need a toolbox of widgets that you can hook up to. MS Visual Studio provides such a toolbox that's available to any of the languages it supports (true even before .Net e.g. VB6 and VC++). I don't know what the wxpython wrapper does (quick Google says it's a wrapper around a widget toolkit).
So it looks like if you use Python you have to make sure the wxpython wrapper plus the toolkit plus Python runtime (I think it uses a VM like Java since it compiles source to bytecode) is installed on user machine.

copec wrote:
How do I choose between "IDEs with introspection-based code completion and integrated debugger" and "IDEs with integrated gui builder"?

Ideally you want an IDE that has auto completion (Intellisense in MS speak), an integrated debugger and a gui builder. This is what VS provides. Which you choose depends on how confident you are with the language. Auto completion is useful (reduces silly typos). An integrated debugger will allow you to step through code line by line to find errors. A GUI builder is almost essential but you could write all the code you need in Notepad - I've done this for simple C# apps but it's a pain. It's just so much easier to drag and drop controls onto a form in the designer than to craft code to place them exactly where you want them to be.

Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis

copec14-Jul-09 11:15

14-Jul-09 11:15

Thanks again, David.

I get your point about dllhell compared with Java or .net, but can't that be avoided also by using unregistered dlls? (I read that somewhere and I don't know the ramifications, I'm just throwing it out there to see what you think).

riced wrote:
So it looks like if you use Python you have to make sure the wxpython wrapper plus the toolkit plus Python runtime is installed on user machine.

Would or could this normally be done during the install of the program itself on the client machine?

If I used an IDE other than VS, like say if I used an IDE for Python, like NetBeans for instance. Would I need to gather my "widget toolkits" and plug them into the IDE somehow, or how do you use them from within the IDE? Or does my question show that I don't quite understand?

Thanks.

riced14-Jul-09 20:55

14-Jul-09 20:55

You can avoid dllHell by using unregistered dlls, my point was that however you create the app there will still be a need to package its components to get them onto user machines. If the app relies on particular system components (e.g. .Net 3.5 framework, JRE or wxPython) you also need to either get them onto to the machines or abort the installation.

As I said I don't know Python so cannot be specific about what is required. However, I understand Python can be used with a wide variety of toolkits and that there's a large number of IDEs that allow you to develop GUI apps.
I would expect that if you download Python it will give the option of installing a toolkit. If it does not, there's likely to be some info on how to install a toolkit. Once that's done I would expect the IDE to either pick up the toolkit or allow you to hook into it.
You might find that the IDE expects to find a particular toolkit installed (a quick google indicates that wxPython is the toolkit most likely to be supported). Sun was doing something to support Python in NetBeans (as of Nov 2008) but I don't know how far it's got.
BTW if you use NetBeans you need to have Java installed - at least you did when I last used it (about 5 years ago). Smile | :)

Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis

copec15-Jul-09 3:49

15-Jul-09 3:49

Thanks for the info, David.

I hadn't considered the issue of installation until now, but I see what you mean about how the user would need all necessary components to be able to run the program. At what point during development would I need to start thinking about, and planning, and taking actions for, the installation process of getting all necessary components onto an end user's machine?

riced15-Jul-09 5:20

Re: OODB or RDB for checkbook/budget program? [modified]

15-Jul-09 5:20

Probably from the start. Smile | :)

If you have a target set of users in mind it is worth finding out what they are likely to have installed. For example if they have .Net 2.0 it would make sense to consider build the app using that framework. There may be good reasons not to do so but then you have to look at having some installation package and the licensing conditions regarding redistribution of the components such as the run time engine (e.g. JRE if you do it in Java).
If you wait until the app is in development you might find that it's difficult or impossible to actually distribute it.

Ideally, you should set up (at least) two machines: one for development and one for production (i.e. to mimic users' machines). You could then install the proposed development platform, build a 'Hello World' app and try to package and install it on the production machine. This would also allow you to test various distribution channels e.g. from CD or via a download from a network.

Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis

copec15-Jul-09 8:11

15-Jul-09 8:11

Maybe some dumb questions here:

1) So there are licensing issues to be dealt with (money?) if I wanted to package the runtime components with the program, all to be installed by the program installer?

2) What about having the installer check for proper runtime software, and if it didn't find it (or a recent enough version), abort the install and tell the user that they need to go download and install the runtime? Maybe even have the installer launch a browser and point it to the install/download page? Is this a viable way of doing it to get around any licensing issues (if I understand what you meant above)?

Thanks again for your help.

modified on Wednesday, July 15, 2009 2:20 PM

riced15-Jul-09 22:28

15-Jul-09 22:28

There are possible issues with licenses. Depends on the particular software and whether you go commercial with the product. Some freely available stuff has restrictions on redistribution in commercial products. Another example, IIRC, MS Office Developer had some elements that could only be used for development.

It would probably be a good idea to check for any existing runtime that the app requires. I think the installer should tell the user if any elements are missing - these should be detailed in documentation as prerequisites.

Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis

copec16-Jul-09 3:51

16-Jul-09 3:51

Thanks for all the help, David.

copec16-Jul-09 15:14

need help in architecting a design for a webapplication

16-Jul-09 15:14

Thanks for all the help David!

shankbond10-Jul-09 3:27

Re: need help in architecting a design for a webapplication

10-Jul-09 3:27

Hi,

I am developing a webapplication(currently), the web application is supposed to simply add data of employees , their will be different types of people(say 10 types of people) modifying the data in the tables of sql server-2005 their will be say around 15-20 different tables with an average of 10 fields per table.

By architecture I mean assistance in designing the application so that the application may support 50 simultaneous users interacting with the web application simultaneously, how should my sql be engineered because in future their will be massive entries getting in the database say 50,000 or so minimum
in two or three tables.

what kind of design should I use to handle such requirements

thank you

Mycroft Holmes11-Jul-09 15:06

Mycroft Holmes

11-Jul-09 15:06

I'm afraid a forum is not where you are going to get a solution to this question. The question is so broad that it is impossible to answer. I can only suggest you hire a consultant to do your design for you or you could employ a senior developer who could do this fairly easily.

Alternative you need to get a book on database design. One rule you can start with, never store data more in more than in place (this does not include foriegn keys of course).

Never underestimate the power of human stupidity
RAH

Re: need help in architecting a design for a webapplication

shankbond12-Jul-09 22:17

Re: need help in architecting a design for a webapplication

12-Jul-09 22:17

HI Mycroft,
Thanks for the suggestion.

Pete O'Hanlon12-Jul-09 22:55

Pete O'Hanlon

12-Jul-09 22:55

Just to add - whatever design you choose, make sure that you include some form of timestamp on your columns so that you can perform concurrency checking when your users update records - that way, you can easily implement a strategy where you choose who manages to update the record, and what messages are displayed if they can't.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

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Re: need help in architecting a design for a webapplication

shankbond13-Jul-09 0:52

Re: need help in architecting a design for a webapplication

13-Jul-09 0:52

thanks Pete for your valuable suggestion

CodingYoshi15-Jul-09 17:15

CodingYoshi

15-Jul-09 17:15

3-Tier architecture can be of great help. If you are developing with .NET then this will become 4-Tire architecture: User Interface, Code Behind, Business Layer, Data Access Layer. Do not make the mistake and design your application architecture exactly the same as database. Remember this, which I read in some text somewhere:

Object oriented programming is not about normalizing data but normalizing behavior.

You know ahead of time you will be interacting with the database so perhaps create utility classes which take a query and execute it, return tables, data readers etc.

Store your connection strings in the .config file.

The only part of your code which should realize this is a web based application is the User Interface and Code Behind files. The rest of your code should be totally ignorant of whether this is a desktop, web or mobile application. This will help in debugging, maintenance etc.

Good Luck!

CodingYoshi

Artificial Intelligence is no match for Human Stupidity.

Re: need help in architecting a design for a webapplication

shankbond15-Jul-09 21:24

Re: need help in architecting a design for a webapplication

15-Jul-09 21:24

CodingYoshi wrote:
Do not make the mistake and design your application architecture exactly the same as database.

Hi Yoshi,
can you please explain what you do you mean here?

Thanks
shank

CodingYoshi16-Jul-09 3:45

CodingYoshi

16-Jul-09 3:45

I have seen people create classes based on database tables but it is not a good practice. For example lets say I have the table s below:

Customers

Orders

Since this is a many to many relationship, to normalize we will create another table called:

CustomersOrders

This is basically the bridging or link table. Now design classes based on these tables and your design is as below:

Customer Class
Orders Class
CutomerOrders Class

You see what I mean. Instead you should have the following classes:

Person
Customer : Person // If later you need employee you can Employee : Person
// Customer should also have an OrderCollection. Remember Aggregation
Address // Both the Customer's shipping and billing address can use this
CustomerCollection
Order
OrderCollection

You will have classes which have methods for performing CRUD operations on these objects and those classes might call other classes for help. You might have many other properties and methods in your Customer class, in addition to the fields in the database, for example, FullName (First Name + ", " + Last Name), GetPendingInvoices() etc.

Do you see now what I mean?
OrdersCollection

CodingYoshi

Artificial Intelligence is no match for Human Stupidity.

Re: need help in architecting a design for a webapplication

shankbond17-Jul-09 22:21