The verbs are pretty straightforward for CRUD actions.
What would be the right HTTP verb for only performing an action, something
like an upvote?
Maybe this speaks more to data modeling? Is an upvote a resource or just an attribute? I'm unsure about that. Let's say it does modify the resource directly by calling #upvote on the model.
For example, if I upvote a question here on SO, what verb should be ideally used for that action? I am modifying the resource in a partial manner (PATCH?), but at the same time, I don't want to specify the new value as I could encounter concurrency issues, so this would best be managed by the database. In other words, we want to ask the server to perform an incremental action on a resource. Is that covered by PATCH?
I've seen a similar question asked there, but their case pointed to the creation of a new resource by viewing the job request as an object to be created. Are we in the same case here?
If the PATCH method really would be appropriate, what would it contain?
Maybe this speaks more to data modeling? Is an upvote a resource or just an attribute?
Modelling impacts Implementation
We are usually modelling something from the real world and our choice of representation will seriously affect the capabilities of the developed system. We could implement our vote in two ways: as an attribute on the thing being voted on or as an entity in its own right. The choice will affect how easily we can implement desired features.
Two possible implementations ...
1. Votes as entities
I would model this with a resource which modelled the relationship between the voter and the thing being voted on. Why?
The vote has state:
what was being voted on
who voted,
when did they vote.
was it an up vote or a down vote (you mentioned SO as an example so I include that possibility here)
It is a resource in its own right with interesting behaviour around the votes
maintain a correct count of the votes
prevent multiple up votes / down votes
It can be modelled easily with REST.
I can POST/PUT a new vote, DELETE a previous vote, check my votes with a qualified GET.
The system can ensure that I only vote once - something which would not be easy to do if a simple counter was being maintained.
2. Votes as an attribute
In this implementation, we model the vote as a counter. In this case we have to
Get the entire state of the thing being voted on - maximising the interface between client and server
Update the counter
Put back the updated state - oops, someone already updated the
resource in the meantime!
The server now has no easy way to handle multiple votes from the same person without managing some state 'on the side'. We also have that 'lost update' problem.
Things quickly get complicated.
Final advice
The decision on how you model something should be driven by what you need the system to do.
There is often no correct decision, just the best compromise between effort and value.
Choose a design which most easily implements the most common Use Cases. Common things should be quick and simple to do, uncommon things need only be possible.
Chris
My teammates and I have a very challenging new project to do, and we are supposed to submit it next week. We don't have a single clue about how to do it, and really need help. We are undergraduate students, new to Information Retrieval and AI, and really need your ideas.
The project is roughly:
When an expert is cited in a document,
find an expert with an opposing
opinion & find out what he/she says
about that topic.
We are free to use any programming language, but we are not concerned with the programming. We would like help to get us started. Please give us a rough idea on how to design such a system and how to retrieve information on the internet. How should we get his opinion, then find an opposite opinion?
Simple: use Amazon's Mechanical Turk.
Without that (or an equivalent) you're in trouble. If there are no further constraints on the problem then you will need a full-blown AI, the kind that doesn't yet exist. If there are severe restraints then you might have a chance of doing this in a week. If the expert can be in any field (medicine, politics, history, fashion, science, comic books, etc.) then there will be no single, well-organized repository of essays. You'll have to use Google to find Dr. X's opinion. Once you find Dr. X's writing (and let's pray it's text, not audio) you'll have to do some kind of natural language processing to get the thrust of it, even if you're lucky enough to find a descriptive title ("Digital Photography Is Absolutely Great"). Then you have to figure out it's opposite. What's the opposite of "Neil Gaiman draws on folklore for his story ideas"? Figuring out what opinion you're looking for will be a serious problem. After that, things actually get easier: you can google for the subject and use the same magic tools to find the one you're looking for.
So what do have a chance of solving? A search for opinions that someone else has already organised into "pro" and "con". Some online political forums are organised that way. Wikipedia cites opposing views in a special section in some of its articles. Science journals print letters of rebuttal. Look around, you might find a site even more cut-and-dried. Choose a small enough arena and you'll have a tractible problem.
EDIT: Damn, Ben Dunlap beat me to all my major points in a comment. Sigh
Sounds like an NLP problem to me. As for the information about documents and cites, http://citeseerx.ist.psu.edu should be a good starting point.
For each paper, there are several citations which refer to the paper. At the very minimum, you have to scan the abstract of the paper and that of the citations and run your own algorithm to figure if any citation is of the opposing opinion. Maybe your professor can give you hints on some approximate heuristic, but as far as I know it is a really hard problem.
I would be watching this thread for more interesting approaches.
Automatically submit a Google search request similar to "expert_name sucks", "expert_name wrong", or something like that. Find the first result that has "PhD" with a document link in the same sentence and return the link.
I think you might be blowing this up a little too big... as an undergraduate project, I would approach it a little more small scale.
Unless your specification says you must use actual internet resources, you would be better off creating your own database of custom short documents. Add metadata to each document stating the points they make about certain topics.
Next, I would create a list of citations which link to each document and add some metadata representing that experts stance on the topic. When someone reads a document, I would augment the list of citations with lists of links to documents which have alternative views on that topic.
Basically it would consist of these tables:
Document (id, data)
DocumentPoints (documentId, topic, stance)
Citation (documentId, topic, stance)
And when someone loads up a document, the citations are pulled up as well. For each citation, you search DocumentPoints for the same topics with different stances. The most difficult part of this project would be creating the 5 or 6 documents you need to have data in your database. After that the solution is trivial.
On a side note, most of these other answers are telling you to use some existing solution... don't do that unless the assignment tells you to. You'll be much better off understanding the problem and various ways to solve it (this is definitely not the only/best one) if you work through the entire problem yourself. When the teacher asks you to do something not supported by whatever product you chose to implement your solution on, you wouldn't be able to fix it. If you had just written it yourself, you could just as easily implement to the new spec as well.
I'm writing some children's Math Education software for a class.
I'm going to try and present problems to students of varying skill level with randomly generated math problems of different types in fun ways.
One of the frustrations of using computer based math software is its rigidity. If anyone has taken an online Math class, you'll know all about the frustration of taking an online quiz and having your correct answer thrown out because your problem isn't exactly formatted in their form or some weird spacing issue.
So, originally I thought, "I know! I'll use an expression parser on the answer box so I'll be able to evaluate anything they enter and even if it isn't in the same form I'll be able to check if it is the same answer." So I fire up my IDE and start implementing the Shunting Yard Algorithm.
This would solve the problem of it not taking fractions in the smallest form and other issues.
However, It then hit me that a tricky student would simply be able to enter most of the problems into the answer box and my expression parser would dutifully parse and evaluate it to the correct answer!
So, should I not be using an expression parser in this instance? Do I really have to generate a single form of the answer and do a string comparison?
One possible solution is to note how many steps your expression evaluator takes to evaluate the problem's original expression, and to compare this to the optimal answer. If there's too much difference, then the problem hasn't been reduced enough and you can suggest that the student keep going.
Don't be surprised if students come up with better answers than your own definition of "optimal", though! I was a TA/grader for several classes, and the brightest students routinely had answers on their problem sets that were superior to the ones provided by the professor.
For simple problems where you're looking for an exact answer, then removing whitespace and doing a string compare is reasonable.
For more advanced problems, you might do the Shunting Yard Algorithm (or similar) but perhaps parametrize it so you could turn on/off reductions to guard against the tricky student. You'll notice that "simple" answers can still use the parser, but you would disable all reductions.
For example, on a division question, you'd disable the "/" reduction.
This is a great question.
If you are writing an expression system and an evaluation/transformation/equivalence engine (isn't there one available somewhere? I am almost 100% sure that there is an open source one somewhere), then it's more of an education/algebra problem: is the student's answer algebraically closer to the original expression or to the expected expression.
I'm not sure how to answer that, but just an idea (not necessarily practical): perhaps your evaluation engine can count transformation steps to equivalence. If the answer takes less steps to the expected than it did to the original, it might be ok. If it's too close to the original, it's not.
You could use an expression parser, but apply restrictions on the complexity of the expressions permitted in the answer.
For example, if the goal is to reduce (4/5)*(1/2) and you want to allow either (2/5) or (4/10), then you could restrict the set of allowable answers to expressions whose trees take the form (x/y) and which also evaluate to the correct number. Perhaps you would also allow "0.4", i.e. expressions of the form (x) which evaluate to the correct number.
This is exactly what you would (implicitly) be doing if you graded the problem manually -- you would be looking for an answer that is correct but which also falls into an acceptable class.
The usual way of doing this in mathematics assessment software is to allow the question setter to specify expressions/strings that are not allowed in a correct answer.
If you happen to be interested in existing software, there's the open-source Stack http://www.stack.bham.ac.uk/ (or various commercial options such as MapleTA). I suspect most of the problems that you'll come across have also been encountered by Stack so even if you don't want to use it, it might be educational to look at how it approaches things.
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How do you go about the requirements gathering phase? Does anyone have a good set of guidelines or tips to follow? What are some good questions to ask the stakeholders?
I am currently working on a new project and there are a lot of unknowns. I am in the process of coming up with a list of questions to ask the stakeholders. However I cant help but to feel that I am missing something or forgetting to ask a critical question.
You're almost certainly missing something. A lot of things, probably. Don't worry, it's ok. Even if you remembered everything and covered all the bases stakeholders aren't going to be able to give you very good, clear requirements without any point of reference. The best way to do this sort of thing is to get what you can from them now, then take that and give them something to react to. It can be a paper prototype, a mockup, version 0.1 of the software, whatever. Then they can start telling you what they really want.
See obligatory comic below...
In general, I try and get a feel for the business model my customer/client is trying to emulate with the application they want built. Are we building a glorified forms processor? Are we retrieving data from multiple sources in a single application to save time? Are we performing some kind of integration?
Once the general businesss model is established, I then move to the "must" and "must nots" for the application to dictate what data I can retrieve, who can perform what functions, etc.
Usually if you can get the customer to explain their model or workflow, you can move from there and find additional key questions.
The one question I always make sure to ask in some form or another is "What is the trickiest/most annoying thing you have to do when doing X. Typically the answer to that reveals the craziest business/data rule you'll have to implement.
Hope this helps!
Steve Yegge talks fun but there is money to be made in working out what other people's requirements are so i'd take his article with a pinch of salt.
Requirements gathering is incredibly tough because of the manner in which communication works. Its a four step process that is lossy in each step.
I have an idea in my head
I transform this into words and pictures
You interpret the pictures and words
You paint an image in your own mind of what my original idea was like
And humans fail miserably at this with worrying frequency through their adorable imperfections.
Agile does right in promoting iterative development. Getting early versions out to the client is important in identifying what features are most important (what ships in 0.1 - 0.5 ish), helps to keep you both on the right track in terms of how the application will work and quickly identifies the hidden features that you will miss.
The two main problem scenarios are the two ends of the scales:
Not having a freaking clue about what you are doing - get some domain experts
Having too many requirements - feature pit. - Question, cull (prioritise ;) ) features and use iterative development
Yegge does well in pointing out that domain experts are essential to produce good requirements because they know the business and have worked in it. They can help identify the core desire of the client and will help explain how their staff will use the system and what is important to the staff.
Alternatives and additions include trying to do the job yourself to get into the mindset or having a client staff member occasionally on-site, although the latter is unlikely to happen.
The feature pit is the other side, mostly full of failed government IT projects. Too much, too soon, not enough thought or application of realism (but what do you expect they have only about four years to make themselves feel important?). The aim here is to work out what the customer really wants.
As long as you work on getting the core components correct, efficient and bug-free clients usually remain tolerant of missing features that arrive in later shipments, as long as they eventually arrive. This is where iterative development really helps.
Remember to separate the client's ideas of what the program will be like and what they want the program to achieve.
Some clients can create confusion by communicating their requirements in the form of application features which may be poorly thought out or made redundant by much simpler functionality then they think they require. While I'm not advocating calling the client an idiot or not listening to them I feel that it is worth forever asking why they want a particular feature to get to its underlying purpose.
Remember that in either scenario it is of imperative importantance to root out the quickest path to fulfilling the customers core need and put you in a scenario where you are both profiting from the relationship.
Wow, where to start?
First, there is a set of knowledge someone should have to do analysis on some projects, but it really depends on what you are building for who. In other words, it makes a big difference if you are modifying an enterprise application for a Fortune 100 corporation, building an iPhone app, or adding functionality to a personal webpage.
Second, there are different kinds of requirements.
Objectives: What does the user want to accomplish?
Functional: What does the user need to do in order to reach their objective? (think steps to reach the objective/s)
Non-functional: What are the constraints your program needs to perform within? (think 10 vs 10k simultaneous users, growth, back-up, etc.)
Business rules: What dynamic constraints do you have to meet? (think calculations, definitions, legal concerns, etc.)
Third, the way to gather requirements most effectively, and then get feedback on them (which you will do, right?) is to use models. User cases and user stories are a model of what the user needs to do. Process models are another version of what needs to happen. System diagrams are just another model of how different parts of the program(s) interact. Good data modeling will define business concepts and show you the inputs, outputs, and changes that happen within your program. Models (and there are more than I listed) are really the key to the concern you list. A few good models will capture the needs and from models you can determine your requirements.
Fourth, get feedback. I know I mentioned this already, but you will not get everything right the first time, so get responses to what your customer wants.
As much as I appreciate requirements, and the models that drive them, users typically do not understand the ramifications of of all their requests. Constant communication with chances for review and feedback will give users a better understanding of what you are delivering. Further, they will refine their understanding based on what they see. Unless you're working for the government, iterations and / or prototypes are helpful.
First of all gather the requirements before you start coding. You can begin the design while you are gathering them depending on your project life cicle but you shouldn't ever start coding without them.
Requirements are a set of well written documents that protect both the client and yourself. Never forget that. If no requirement is present then it was not paid for (and thus it requires a formal change request), if it's present then it must be implemented and must work correctly.
Requirements must be testable. If a requirement cannot be tested then it isn't a requirement. That means something like, "The system "
Requirements must be concrete. That means stating "The system user interface shall be easy to use" is not a correct requirment.
In order to actually "gather" the requirements you need to first make sure you understand the businness model. The client will tell you what they want with its own words, it is your job to understand it and interpret it in the right context.
Make meetings with the client while you're developing the requirements. Describe them to the client with your own words and make sure you and the client have the same concept in the requirements.
Requirements require concise, testable example, but keep track of every other thing that comes up in the meetings, diagrams, doubts and try to mantain a record of every meeting.
If you can use an incremental life cycle, that will give you the ability to improve some bad gathered requirements.
You can never ask too many or "stupid" questions. The more questions you ask, the more answers you receive.
According to Steve Yegge that's the wrong question to ask. If you're gathering requirement it's already too late, your project is doomed.
High-level discussions about purpose, scope, limitations of operating environment, size, etc
Audition a single paragraph description of the system, hammer it out
Mock up UI
Formalize known requirements
Now iterate between 3 and 4 with more and more functional prototypes and more specs with more details. Write tests as you go. Do this until you have functional software and a complete, objective, testable requirements spec.
That's the dream. The reality is usually after a couple iterations everybody goes head-down and codes until there's a month left to test.
Gathering Business Requirements Are Bullshit - Steve Yegge
read the agile manifesto - working software is the only measurement for the success of a software project
get familiar with agile software practices - study Scrum , lean programming , xp etc - this will save you tremendous amount of time not only for the requirements gathering but also for the entire software development lifecycle
keep regular discussions with Customers and especially the future users and key-users
make sure you talk to the Persons understanding the problem domain - e.g. specialists in the field
Take small notes during the talks
After each CONVERSATION write an official requirement list and present it for approving. Later on it would be difficult to argue against all agreed documentation
make sure your Customers know approximately what are the approximate expenses in time and money for implementing "nice to have" requirements
make sure you label the requirements as "must have" , "should have" and "nice to have" from the very beginning, ensure Customers understand the differences between those types also
integrate all documents into the latest and final requirements analysis (or the current one for the iteration or whatever agile programming cycle you are using ... )
remember that requirements do change over the software life cycle , so gathering is one thing but managing and implementing another
KISS - keep it as simple as possible
study also the environment where the future system will reside - there are more and more technological restraints from legacy or surrounding systems , since the companies do not prefer to throw to the garbage the money they have invested for decades even if in our modern minds 20 years old code is garbage ...
Like most stages of the software development process its iteration works best.
First find out who your users are -- the XYZ dept,
Then find out where they fit into the organisation -- part of Z division,
Then find out what they do in general terms -- manage cash
Then in specific terms -- collect cash from tills, and check for till fraud.
Then you can start talking to them.
Ask what problem they want you want to solve -- you will get an answer like write a bamboozling system using OCR with shark technoligies.
Ignore that answer and ask some more questions to find out what the real problem is -- they cant read the till slips to reconcile the cash.
Agree a real solution with the users -- get a better ink ribbon supplier - or connect the electronic tills to the network and upload the logs to a central server.
Then agree in detail how they will measure the success of the project.
Then and only then propose and agree a detailed set of requirements.
I would suggest you to read Roger-Pressman's Software Engineering: A Practitioner's Approach
Before you go talking to the stakeholders/users/anyone be sure you will be able to put down the gathered information in a usefull and days-lasting way.
Use a sound-recorder if it is OK with the other person and the information is bulky.
If you heard something important and you need some reasonable time to write it down, you have two choices: ask the other person to wait a second, or say goodbye to that precious information. You wont remember it right, ask any neuro-scientist.
If you detect that a point need deeper review or that you need some document you just heard of, make sure you make a commitment with the other person to send that document or schedule another meeting with a more specific purpose. Never say "I'll remember to ask for that xls file" because in most cases you wont.
Not to long after the meeting, summarize all your notes, recordings and fresh thoughts. Just summarize it rigth. Create effective reminders for the commitments.
Again, just after the meeting, is the perfect time to understand why the gathering you just did was not as right as you thought at the end of the meeting. That's when you will be able to put down a lot of meaningful questions for another meeting.
I know the question was in the perspective of the pre-meeting, but please be aware that you can work on this matters before the meeting and end up with a much usefull, complete and quality gathering.
I've been using mind mapping (like a work breakdown structure) to help gather requirements and define the unknowns (the #1 project killer). Start at a high level and work your way down. You need to work with the sponsors, users and development team to ensure you get all the angles and don't miss anything. You can't be expected to know the entire scope of what they want without their involvement...you - as a project manager/BA - need to get them involved (most important part of the job).
There are some great ideas here already. Here are some requirements gathering principles that I always like to keep in mind:
Know the difference between the user and the customer.
The business owners that approve the shiny project are usually the customers. However, a devastating mistake is the tendency to confuse them as the user. The customer is usually the person that recognizes the need for your product, but the user is the person that will actually be using the solution (and will most likely complain later about a requirement your product did not meet).
Go to more than one person
Because we’re all human, and we tend to not remember every excruciating detail. You increase your likelihood of finding missed requirements as you talk to more people and cross-check.
Avoid specials
When a user asks for something very specific, be wary. Always question the biases and see if this will really make your product better.
Prototype
Don’t wait till launch to show what you have to the user. Do frequent prototypes (you can even call them beta versions) and get constant feedback throughout the development process. You’ll probably find more requirements as you do this.
I recently started using the concepts, standards and templates defined by the International Institute of Business Analysts organization (IIBA).
They have a pretty good BOK (Book of Knowledge) that can be downloaded from their website. They do also have a certificate.
Requirements Engineering is a bit of an art, there are lots of different ways to go about it, you really have to tailor it to your project and the stakeholders involved. A good place to start is with Requirements Engineering by Karl Wiegers:
http://www.amazon.com/Software-Requirements-Second-Pro-Best-Practices/dp/0735618798/ref=pd_bbs_sr_2?ie=UTF8&s=books&qid=1234910330&sr=8-2
and a requirements engineering process which may consist of a number of steps e.g.:
Elicitation - for the basis for discussion with the business
Analysis and Description - a technical description for the purpose of the developers
Elaboration, Clarification, Verification and Negotiation - further refinement of the requirements
Also, there are a number of ways of documenting the requirements (Use Cases, Prototypes, Specifications, Modelling Languages). Each have their advantages and disadvantages. For example prototypes are very good for elicitation of ideas from the business and discussion of ideas.
I generally find that writing a set of use cases and including wireframe prototypes works well to identify an initial set of requirements. From that point it's a continual process of working with technical people and business people to further clarify and elaborate on the requirements. Keeping track of what was initially agreed and tracking additional requirements are essential to avoid scope creep. Negotiation plays a bit part here also between the various parties as per the Broken Iron Triangle (http://www.ambysoft.com/essays/brokenTriangle.html).
IMO the most important first step is to set up a dictornary of domain-specific words. When your client says "order", what does he mean? Something he receives from his customers or something he sends to his suppliers? Or maybe both?
Find the keywords in the stakeholders' business, and let them explain those words until you comprehend their meaning in the process. Without that, you will have a hard time trying to understand the requirements.
i wrote a blog article about the approach i use:
http://pm4web.blogspot.com/2008/10/needs-analysis-for-business-websites.html
basically: questions to ask your client before building their website.
i should add this questionnaire sheet is only geared towards basic website builds - like a business web presence. totally different story if you are talking about web-based software. although some of it is still relavant (e.g. questions relating to look and feel).
LM
I prefer to keep my requirements gathering process as simple, direct and thorough as possible. You can download a sample document that I use as a template for my projects at this blog posting: http://allthingscs.blogspot.com/2011/03/documenting-software-architectural.html