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I have been doing a coding in for last 7 months. Most part of it has been the updations to the very poorly coded software in asp. Now I am going to redevelop entire software in asp.net. I want it to be very efficient. I need some tips and guidance about how to plan project and design a good database. Thanks in advance for help.
As far as planning for the project is concerned you first need to create your application's pages on paper. Write all your ideas on the paper.
Draw each and every page on paper and complete it with your new ideas.
Then taking every page's feature into consideration draw the database tables. This is a very careful phase. So include every aspect of your application's functionality.
For designing the database follow these steps :
List all entities
Find Relationships [E-R matrix]
Draw Cardinality
Define Primary keys
Draw ERD
Eliminate many-to-many relationships
Identify attributes [attribute entity matrix]
Map attributes - only 1:1 with each entity
Draw final ERD
More help here
Structured process you must know to develop a web application
Here's my super-quick spiel about database design.
A database is two things. It is a 'logical engine', and it is a 'physical engine'. It is a logical engine in that it allows you to create meaningful models of entities. It is a physical engine in that it processes bits of data to update or return results.
I suggest paying about equal attention to each of these aspects when designing a new system. To adress the first, work out the relational model and normalize as far as possible. To address the second, think about where you might want to denormalize for speed, what indexes you'll need to speed the processing, etc.
It's good that you ask, this is one of the most anti intuitive things in software development. My approach would be: pick one feature, implement it in ASP.NET, and convince your users to move over. You'll be surprised how many things you missed, or how actual performance compares to developer testing.
The quicker you iterate, the better your replacement project will be, and the less time you spend on things that don't really matter. There's a excellent blog post at Coding Horror about this; it's called Boyd's Law of Iteration.
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I know this question has been asked in various forms over and over again but I cannot find a single complete answer and I believe it is a general problem in the RDBMS/data area and industry. To explain the problem I will tell you a short (and maybe boring) story!
The Story
"I have a friend" who works in A company that uses 100+ systems. The scale and size of these systems vary from full-blown ITIL to custom/in-house, single purpose, LAMP/SQLite/CSV-based solutions. The vast majority of these systems, at one point or another use a database/data-store... Big-data has now become a trend, and A company though it is a very good idea to keep (or log) historical data from all systems forever! For that reason they have built a "warehouse". My friend is responsible for writing software that will do the analysis on some of this data ... however, he is kinda confused. There are thousands of tables in that warehouse containing data from the beginning of time (1970s I think :)).
The Problem
[Since I started telling you about this guy, I should probably continue]
My friend is very upset because of the lack of documentation in that warehouse. It seems that no-one knows what is what?! Few of the problems he faces (and I quote):
Man, some fields are constants... they have a special meaning to the application but I have no way of knowing? But that is OK... cause some other fields are bit-masks! Different bit values in the field have different meaning!
and he continues...
That's not all... these are the easy cases you know... Since we have data from multiple systems, we end up with a situation where different systems refer to the same thing in a different way... how can I explain it to you... for example, a network device has an FQDN, however some systems treat it as the primary key, some others don't and instead they allocate an auto-increment integer value, which in turn they use for foreign keys (you know... referencing this device).
and he can go on forever!
The Question
[Yes, it is one question]
He says:
We have come a long way regarding documentation in the software world... we have started with documents, moved to wikis and concluded to inline docblocks serving both as parameter/signature documentation and as wiki! We can auto-generate documentation, clear enough that a person in the other hemisphere and side of this world can easily follow!
and he continues:
... in the data side of things, we also had major achievements! Storage methods, serialization, transmission and data analysis techniques have evolved tremendously... We have also managed to map database tables into objects and in some cases we can even represent relationships!
So why the frell don't we have a standard method/technique of documenting our data structures in an RDBMS?
... he concluded :)
Enough with my friend, so my comments:
I know about comments on fields in various systems, but that is usually enough for a "deprecated" and not for an explanation
Updating a wiki or even worse a document, every time you release a database patch is not a solution... that patch should contain the relevant documentation!
ER diagrams can be easily generated based on the schema information, however this is not the easiest form of documentation to read... for anything more than 10 tables!
There is the saying (please comment if you know who said this! - respect)
Documentation is like sex: when it is good, it is very, very good; and when it is bad, it is better than nothing
Why SQL doesn't provide the means to any?
Any kind of documentation would get stalled if not maintained.
Also, the SQL world provides all kind possibilities to document things:
comments in SQL files
comments in columns/tables metadata
as you said - E/R diagrams
the classic way of documenting stuff - docs and wikis
good discipline in adhering to an intuitive naming scheme for the things in DB - I think this should be the standard
We have all the tools we need, we just have to convince our managers to let us write the docs (lol)
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I've just finished two days of agile/scrum coaching at work which was great. I'm a a novice to professional programming so I needed it. However, I'm struggling very much with the notion of vertical slicing. In particular I cannot see how a database schema can emerge from several developers working separately across all development tiers (front middle and back)? Designing the database schema all in one go is called horizontal slicing and it's considered a no-no. I'm familiar with object relational mapping - slightly - from having worked with frameworks like Grails. But again, I still designed the schema first and worked from there.
To be clear, I am not arguing against the case for agile/scrum/vertical slicing, rather I am asking how it is possible? - in particular when it comes the mapping of objects the the database schema, how can this be done by several developers in tandem and not from the beginning?
This article which i really like seems to - if i've read it correctly - suggest that the database schema should be designed in the spring planning stage before any user stories are implemented.http://www.vertabelo.com/blog/notes-from-the-lab/data-modeling-in-agile-development-one-data-modelers-experience
The idea of a vertical slice is that you do the minimum amount needed to deliver some functionality.
Now it could be that the minimum amount of database design you need to do for the first story is the complete schema. But I think that is unlikely.
For example, to get the first bit of functionality working, do you need the tables related to authentication? What about the tables that do auditing? Maybe some parts of the schema are not related to certain functionality. Say you have a shopping basket application and one aspect of the schema relates to customer's saving their favourite look-and-feel. Could that part of the schema be left until the corresponding story is started?
If you have several developers following this approach then it is going to require a lot of conversation and coordination. Continuous integration of the database schema can really help. So as a developer makes changes to the schema regression tests are run to ensure it hasn't interfered with the other developers work.
This post explains it pretty well: http://blogs.adobe.com/agile/2013/09/27/splitting-stories-into-small-vertical-slices/
You do not necessarily have to have different people working on each piece of the vertical slice. It is more about breaking each part into smaller pieces to achieve incremental results.
From the above article:
Each slice is comprised of any work needed to be done in an architectural layer as well as any testing and integration that may need to be done to make it ready to release.
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Currently I am working on porting a benchmark application to another system. I am working alone, so I am frustrated about which software methodology I really have to use. Please give me some ideas.
I am going to assume you're wondering which Agile approach to use on your project as you tagged your question accordingly.
Agile is mainly about:
Delivering working software continuously and regularly
Aiming at technical excellence and avoiding technical debt
Improving the way we work and retrospecting regularly
I'd say whatever you use, even your very own approach to software development, if you can check those three items from the list, then you're pretty much Agile to me. Some people need strict guidelines and artifacts and that's fine, they help people become Agile but are far from being mandatory despite the dogmas out there.
Here's how I would approach your situation.
Take a step back and try to identify the most important features or abilities of this benchmarking application. By most important, I mean those features that the people using it in the end cannot live without. Once you have a list of those, put them on post-it notes, index cards, trello, jira or whatever tool you want to use.
Split each of those features into full-stack chunks of functionality that are business driven. I'm not talking about technical tasks here, but smaller features usable by actual people. I usually opt for the "Grandma Driven" approach here, asking myself "would grandma be able to understand what I'm trying to do?". It's just to make sure I'm focusing on a full stack feature and not a technical task like "populate database". One way to see this is also by applying dimensional planning to each of the features you identified (http://www.xpday.net/Xpday2007/session/DimensionalPlanning.html).
Set yourself an iteration length (I usually go for 1 or max 2 weeks when I'm working alone) and get to work one small item at a time. Don't write code for later, only what you need to solve the problem at hand. Quality is not an option. Focus on good coding and testing practices.
At the end of your iteration, check how many features you implemented and put that number somewhere on a chart, in a google spreadsheet or whatever. This will help you see if you're on track. Get feedback from colleagues or any potential users of the system and reflect on that feedback. It's not because you're porting to another platform that you can't make it better.
If you end up not having small enough granularity with what's left or not enough stuff in your list of things to do, spend some time repeating steps 1 to 3.
At the end of each iteration, keep tracking how many items you did just to see if you still have a good enough pace. If not, ask yourself why and change something in the way you work or get help. Again, your main focus is to make progress and deliver software that works at the end of each iteration.
It might not answer your question and I know I didn't give you an answer of the type, use kanban, scrum or whatever but I truly believe it's not appropriate in your specific case and would only generate overhead and boredom for you.
Hope that helps anyway, good luck with your project.
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Hi guys let's say I have a new project an inventory system. I will be using Java. I go to my client gather some requirements and after I gather them I will model those requirements. Which should I do first? my class diagrams/domain models? or data model? and why? i would really like you opinion on this. what do you do in the real world in software development?
im using these techs: Java, Hibernate(ORM), Scrum(methodology), postgresql(database)
Don't do either one first. Create a domain (object) model and an ER model in parallel. They should be very similar except that the domain model is concerned with data and behavior while the ER model is concerned only with data.
However you need to be very careful to avoid a pitfall that many practitioners, even experts ones, fall into. That is the confusion between analysis and design. Both your domain model and your ER model should be analysis models and not design models. That means that they describe the problem and the requirements, and not the features you are going to add when you design the solution.
In particular, many of the ER diagrams you see in this forum are really relational data models, even though they use ER notation. And they incorporate design features like foreign keys and don't limit themselves to features that are inherent in the information requirements.
Failure to pin down the requirements fairly precisely before design begins is a major source of failure in large scale projects. In small scale projects, not so much.
My 2 cents...
Data tends to be longer-lived, more stable and ultimately more important than code. So your approach should be data-centric. If you structure and normalize your data properly (and ER diagram is important tool for doing that), the rest will naturally follow.
IMO you should definitely not start thinking about your Data Model first.
The reason is that it's up to your Domain Layer to address all business needs.
Your Domain Layer must be agnostic. It should not be tied to any specific technical implementation nor reference any kind of framework. It should be self contained and work alone. When designing your Domain Layer, do not think about persistence or even the way your data will be displayed. If you need methods to store your data, or methods to gather information from specific UI container like Session, just use Interfaces.
When designing a Data Model, you're tied to the RDBMS you're going to use to store your data. You will think about the way your schema will be structured to store and access data efficiently. But the thing is that the Business doesn't care about how good your queries will perform.
It's always a good thing to defer critical decisions like the UI, frameworks, database and so on, when you can. That way you focus only on business needs.
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What would you suggest for the following scenario:
A dozen of developers need to build and design a complex system. This design needs to be documented for future developers and the design decisions must be noted. These reports need to be made about every two months. My question is how this project should be documented.
I see two possibilities. Each developer writes about the things they helped design and integrate and then one person combines each of these documents together. The final document will probably be incoherent or redundant at times since the person tasked of assembling everything won't have much time to adjust every part.
Assume that the documentation parts from each developer arrive just a few days before deadline. A collaborative system (i.e. wiki) wouldn’t work properly since there wouldn’t be anything to read until a few days before deadline.
Or should a few people (2-3) be tasked with writing the documentation while the rest of the team works on actually developing the system? The developers would need a way to transfer their design choices and conclusions to the technical writers. How could this be done efficiently?
We approach this from 2 sides, using a RUP style approach. In the first case, you'll have a domain expert who is responsible for roughing out the design of what you're going to deliver - with developers chipping in as necessary. In the second case, we use a technical author - they document the application, so they should have a good idea of how it hangs together, and you involve them right through the design and development process. In this case, they can help to polish the design, and to make sure that it matches what they thought was being developed.
We use confluence (atlassian's wiki-like-thing) and document all kinds of different "things". The developers do it continiously, and we push each other for docs - we let peer pressure decide what is necessary. Whenever someone new comes along he/she is tasked with reading through everything and to find out what still is correct. The incorrect stuff is either deleted or updated as a consequence of this. We're happy when we can delete stuff ;)
The nice thing about this process is that the relevant stuff stays and the irrelevant stuff is deleted. We always "got away" from the more formalized demands by claiming that we could always construct the word documents they wanted if "they" needed them. "They" never needed them.
I think alternative 2 is the less agile, because it means a new stage to the project (although it may be in parallel with tests).
If you are in an agile model, then just add documentation (following a guideline) as a story.
If you are in a staged approach, then I would nevertheless ask developers to work on documentation, following some guidelines, and review that documentation along the design and the code. Eventually, you may have a technical writer reviewing everything for proper English, but that would be a kind of "release" activity.
I think you can use Sand Castle to document your project.
Check it out
Sand Castle from Microsoft
It's not a complete documentation, but making sure that interfaces etc. are commented using Doxygen-style comments means writing code and documenting it are closer together.
That way, developers should document what they do. I still think a review by the architect(s) is needed to ensure consistent quality, but ensuring people document what they do is the best way to ensure they follow the architecture.