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I really have fallen in love with the DDD concept. In short this is how we always work out a project.
All you need in the beginning is a whiteboard and a marker.
1. Define the domains within the scope of your project
2. Define the components within each domain.
3. VERY IMPORTANT: Give the domains and components GOOD names.
4. AGREE on the CONTRACTS of each component
5. Document your Diagram and Contracts.
6. Split the teams up each dealing with their component(s) and let them create UML diagrams.
7. Let each ULM diagram be coded out by a team that did not create the diagram.
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I am trying to make distributed application in RMI/CORBA like ebay : allow individuals to submit classified ads to sell items with an auction system. At the closing date of the auction, the buyers who bid the last (if it exists) has the privilege of being able to acquire the object.A user can at any time be buyer or seller. Information of "user" necessary for the rest are mainly: name, password, bank details.
As want to operate::
1: Get a list of items currently for sale (list or search by keyword possibly). Obtained including a description, a current price, a date (or time remaining) closing of the sale.
When an item is worth :
1: get a minimum of information about the seller
2: the bid there must have authenticated.
Can I get help and little explanation about the architecture?
Thanks
modified 19-Mar-13 20:12pm.
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docomo1 wrote: Can I get help with some code and explanation
Sure.... post some code that you are having trouble with and I am sure that someone can explain it.
If you are wanting someone to write this code for you and then explain it to you, I think you have come to the wrong place.
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haahahaa....ofcourse I m not excepting that...!!!
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docomo1 wrote: ofcourse I m not excepting that
And how do we know that? You did not post any code or ask a question so what is left when all you did was ask for someone to write some code for you?
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Well I am editing it....why u misinterpreted that...if u also know that this is not the place to give the code ...n I already admitted ....but u stick on that point rather than the main subject...strange..!!!
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docomo1 wrote: why u misinterpreted that
I did not misinterpret it. You distinctly asked for someone to write the code for you and then explain it to you. Why did you write that if that is not what you meant?
docomo1 wrote: u stick on that point rather than the main subject
No, you asked for someone to write a bunch of code for you and I simply explained to you that that was not going to happen. Why you keep harping on that instead of posting the code you have written and asking an answerable question is beyond me.
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I think u r good enough to understand the english words....I never ask someone to write code for me....even I admitted that in the first reply. n I dont understand why u take this so seriously ...u forcefully put ur assumption ..if u r interested to help me anyway ..do this otherwise leave it n I have changed the post .i think it is fine enough now.
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docomo1 wrote: u r
You might also like to stop using this childish txtspk, and you will find people will take you more seriously.
Use the best guess
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We are offended that you didn't say, "Send codez! Urgentz!".
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Good Day,
Has anyone had experience (positive or negative) with Software Architecture/Design simulation tools?
Rick
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Hi,
I'm working on a new design for our old (25+) application. In this design should be more than one SQL servers (synchronized via replication). Each SQL server wrapped inside a DAL layer, and those DAL's are grouped using load balancing.
I looking to add cache to this design, and at first I thought that the best place to do so is at the individual DAL, however in this case I have to design a synchronization method between separated DALs.
To solve this synchronization problem I thought about a cache service to serve all the DALs (and maybe other parts of the design).
My question is, according to your knowledge and experience, will it be still effective to use a remote service to cache, or better to design cache synchronization that cross DALs?
Regards,
Peter
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That question is hard to understand.
Persumably you have 25 or more applications. And each of those use 1 or more databases.
After that your explanation loses me.
Do you intend, at some future time to consolidate databases? And that is a hard plan driven by business reasons? Because if not then they is absolutely no reason why any of these should be combined into a single cache.
Is there a distributed transaction model in play? If not then there is no need for "synchronization". And if there is then you should look into an actual distributed transaction model.
And why do you think you need to cache everything? Or even anything for that matter?
And I have no idea what you think "load balancing" means in this context. That term means a way of balancing requests across different servers. A DAL (Data Access Layer) exists within the application and unless all of the applications run on one machine load balancing across multiple applications would be difficult.
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First of all thank you for your time...
and now some explanations to make it clear...
There is only one app - a web one. The application is distributed so the DAL is only a part of it (there are many layers between the UI that sits in the web server and the DAL which is combined, if not necessary physically, with the actual DB). The DAL is designed in a stateless way so we can lunch infinite number of DALs. In case of multiple DALs they grouped with load balancing. And when I say load balancing I mean exactly what you mean...
I thought about cache to improve performance of the DAL, but after looking into it I saw that I must
or make some synchronization between local caches
or make some cache server.
My question was about the usefulness of such cache server...
Regards
Peter
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Kornfeld Eliyahu Peter wrote: The DAL is designed in a stateless way so we can lunch infinite number of DALs
Then you have a server, not a DAL.
Kornfeld Eliyahu Peter wrote: My question was about the usefulness of such cache server..
Depends on the data and the nature of the business.
If, for example, you have some small set of data that is used a lot and doesn't change often then caching is doable even with the complication of cross server syncing. As long as there is some allowed latency in the timeliness.
Conversely if you are loading billions of customer records by request from a user then there isn't much point because each request by itself likely has a very limited lifespan in the cache. And you would also need to implement sticky sessions for it to be useful.
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We're developing a couple of web applications and want to allow users some advanced options if they've identified themselves.
The goal is that the user should only remember one username/password for all our applications (and services, we provide all kinds of newsletters and alerts as well).
SSO (Single-Sign On) was the first thing that came to mind, so my question is: what kind of recommendations can you give? I read a little about OpenId, but I know Google, Yahoo, windows live, ... also provides this.
Should we choose an existing service, and wich one is the best or should we write something for ourselves for our company only?
In the (near or further) future I would like to add the personnel as well through ldap or something.
This stuff is completely new to me so any advice, tutorials, recommendations would be helpful.
Thanks!
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I have not a huge experience with SSO but just from how I'd feel as a user I'd say using an existing service as only possibility would be not a great idea.
If you us another service then you should add your own possibility too, such as CodeProject does offer a merged sign-on for codeproject.com and rootadmin.com - combined with the chance to use a Google account for signin in/up.
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To the best of my knowledge you wouldn't be wrong to take a look at a form of Federated Identity Management using a Token Service. OpenId, SAML, WIF and OAuth are all token-based and will take you down the road of claims-based authentication and authorization.
http://en.wikipedia.org/wiki/Claims-based_identity[^]
I would have used something like STS as a starting point for a token service, but our management in their infinite wisdom want us to roll our own token service. This despite the fact that our token service will not be interoperable with anything else as it doesn't support any common standards beyond putting a token on the same HTTP header as other token services do. Oh, and there's no integrity check for our claims and everything is passed as clear text. Well, not as clear text actually, we're base64 encoding the token so it would only take a determined person a couple of extra seconds to walk right on in. Then there's the issue of token size, which is limited, so we'll roll our own zip function to cope with that, even though a decent token service will already do this for you, along with everything else we've implemented for no good reason.
But whatever, rant over. Just don't try and reinvent the wheel like our place does. Token authentication is not a walk in the park by any stretch of the imagination so anything you can use off the shelf will save you a ton or arseache.
STS: http://startersts.codeplex.com/[^]
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Hello,
When I ask questions about architecture I often hear back several arguments to explain this or that choice.
arguments are
* For maintenance
* For performance
* for Security
* For data consistency
What, for you, are valid arguments to make a decision?
Personally I place "data consistency" in number one and it is a non negotiable priority but I think I'm alone to think like that because the current pattern, decisions, modern architectures emphasize maintenance, performance and security.
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Hmmm. That's an interesting question. I would agree that consistency is an important consideration, but how do you define consistency? I ask this because you really need to put a qualification on consistency so that you have a measurable baseline. Unfortunately, this isn't a case of black and white - do you mean instantly consistent (which has a huge impact on your database architecture) or do you mean eventually consistent (whereby you could have an update made from one server and know that this would eventually be updated in all the other servers). There is no hard and fast answer to this question.
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By data consistency I suggest using massively normalization, constraints and triggers in SQL database. This may be very hard to maintain and many architects doesn't like that. I also design my database without duplicate any information. For performance issue some architects already ask me to repeat a column to avoid a join.
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That isn't data consistency. That's just fundamental design. Data consistency is a much broader area - it relates more to things such as transactional consistency or point-in-time consistency.
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I agree with you data consistency is not only my example. From Wikipedia "Data consistency summarizes the validity, accuracy, usability and integrity of related data between applications and across an IT enterprise".
In case of a SQL database data consistency may be assured by transaction, constraints and triggers. In fact I don't see other way to assure data consistency in a SQL database. Now adding trigger, constraints and complex transaction impact performance, security and maintainability.
modified 13-Mar-13 6:22am.
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