I wish to create a college project on a simple online multiplayer management game which will involve players setting orders for the day/week and then obtaining profits. Being a relative beginner I am unable to figure out the architecture required for this task.
As far as I am concerned I would be needing the following things:
A text interface to display the status of ongoing events and to set orders in a web browser.
A certain application that would calculate the results every minute and update the database.
A database
Sorry for being so newbish, but any advice or links or books on how to proceed will do.
Please comment if any more information is required.
Any programming language would be fine. Pick a lang / arch you or someone in your group are familiar with. I'm mostly a PHP/ZF, Linux, Postgres guy. So I would...
Write a little ZendFramework app to collect your user's data and save to postgres database. I'd host it on a little Linux server. I like slicehost.com $20/mon, but there are cheaper. Or make friends with someone with a server.
Then for the update of the orders, use a cron job to run every minute. If the update process is complex, use another PHP script, else just straight SQL.
Why do you need to run updates every minute? Are people going to be updating it that often, if they are making orders for a day or week?
I would start with deciding on the equations that will be used in your model.
Then, that will help decide what you need in the database, to give the parameters to the model.
Then, once you have the database, you need to get information from the user, so decide what you need from the user.
For example you should have some random event that will make certain items go up or down in demand, or have resources become more common.
So, you may want to have information in the database that lists what each product is composed of.
If the model will have external information, or, if it is based on what others make, so, for example, last week shoes were not produced, so those that made shoes made a profit. This week everyone is making shoes, so there is too many, so the price went down.
This is why I think starting with your model, and testing your assumptions is the first step.
Any language, system, database will work well, just do what you feel comfy with. When you design the UI, do you want it to look fine on iphones and the Blackberry Razor? Then that will have a big impact on how you design the UI.
Related
I am an automated-test engineer and call it occupational hazard, I keep thinking towards making automated testing efficient and easy.
Couple of weeks back, I was thinking, in fact just wondering, if we could introduce a new process where I force designers/developers to provide me a wireframe for every single or unique screen in the web application.
Example: In a hypothetical web application, if home page displays differently for different profiles like associates, approvers, auditors and managers, I want a wireframe for each of those profiles. But if there are 2 managers (data combinations) in the organisation, I don't expect wireframe for these 2 managers as just data is changing and structure would remain same from automated-testing perspective.
This helps in automation in the following manner:
Say a sprint starts and it's decided that 2 new features shall be developed in this sprint.
Wireframes for these 2 new features shall be provided to the whole team at the begining of the sprint say in sprint-planning meeting.
Using these wireframes I would automate my testcases and when the actual screens are deployed, I would just run my automated-testcases. Of course they will fail due to some minor issues but they will be easy fixes. This is way better than not starting automation until the actual screen are deployed.
If this approach is possible, I will later demand for id and name properties of user controls (like links, buttons, edit boxs, check boxes, radio buttons etc) along with wireframes. I am aware that some teams are already sharing id and names properties of user controls with their automated-testing team upfront so that they can automate the testcases even before actual screens are deployed. You could say my idea is little enhanced version of that.
It sounded impractical so I stopped thinking towards it but later felt like I should ask the community if it's possible? if yes, what's the overhead on the overall design/development team.
Some developers reading this might think that pffhhh... we are packed with stuffs already and this would be an overhead. But trust me. Early collaboration with testers and automate-testers would really help the quality of the application. So if the overhead is well within the limit, we could think towards introducing this process.
Please let me know your views.
Okay, first of all I want to tell you that I am new to all this techniques mentioned in the title.
I want to make an new app. Think of it as a real time trading engine (like for stocks for example).
So, there are two things that really matter:
Speed / Performance: Everyone has to see trades in realtime
Security: Same trades can be made simultaneously but only one can be successful
I thought about an approach like this:
If a user wants to buy 10 peaces of stock X for $100 each he places an order which I store with Redis (speed) and push it to all clients with socket.io. Well, as soon as another user wants to sell 15 peaces for $100 the script should check if there is an open buy order. If so, it saves it as a successfull transaction in MongoDB (persistance) and closes the buy order of 10 peaces.
In this example 5 peaces are left. The script would display that with a calculation like this: 15 (sell at $100) minus 10 (buy at $100) equals 5 left. Every time someone want's to trade something this calculation would be made because I don't know how many stocks are left for trading else.
Edit: Or I could subtract 10 peaces of the 15 peaces in Redis so that I don't need to calculate every time. But if something would go wrong, I wouldn't know what the original data was. That's a problem.
Now the questions are:
Would you make it like this? Better ideas maybe?
What would happen if two users make the exact same order in the same time? Could it happen, that it gets stored two times in MongoDB as different successfull transactions? Of course you could run an audit over Redis and MongoDB and compare it. But that would be a horrible solution.
Hope you understand what I'm trying to ask. Thanks in advance!
First of all if you do not know anything from the stack you are using, it is not a good idea to tell I need high performance (high availability, good security and so on). Being absolutely new to all the tools you are using you should be happy if it will just work.
As for your question: first of all take a look how other people have done similar things. Here is an open source bitcoin trading engine which uses node.js which makes it an excellent example to study (it is complex, so take a deep breath). If you want to use mongo you need to know that it does not support transactions, so you need to take a look how to implement them by yourself there. These two examples are really good in explaining it.
Updating can performance test script e.g. with LoadRunner can take a lot of time and be quite frustrating. If there has been some updates with the applications, you usually have to run the script and then find out what has to be changed, update and run again and so on. Does anyone have some concrete best practices how to ease this updating inferno? One obvious thing is good communication with developers.
It depends on the kind of updates. If the update is dramatic, like adding new fields for user to fill in, then, someone has to manually touch up the test scripts.
If, however, the update is minor, for example, some changes to the hidden fields or changes to the internal names of user-facing fields, then it's possible to write a script that checks the change and automatically updates the test script.
One of the performance test platforms, NetGend, automatically takes care of the hidden fields and the internal names of user-facing fields so it's very easy to create a script to performance-test a HTML form. Tester only needs to fill in the values that he/she would have to enter using a browser, so no correlation is necessary there. Please send me a message if you need to know more about it.
There are many things you can do to insulate your scripts from build to build variability. The higher up the OSI stack you go the lower the maintenance charge, but the higher the resource cost for the virtual user type. Assuming changes are limited to page level resources and a few hidden fields here and there for web sites or applications, then you can record in HTML mode. You blast the EXTRARES sections as the page parser in HTML mode will automatically parse the page and load the page resources even without an explicit reference - It can be a real pain to keep these sections in synch if you have developers who are experimenting quite a bit.
Next up, for forms which have a very high velocity in terms of change consider the use of a web_custom_request() for the one form. You can use correlation statements to pick up all of the name|value pairs as needed and build the form submit dynamically. There will be a little bit more up front work for this but you should have pay offs at around the fourth changed build where you would normally have been rebuilding some scripts.
Take a look at all of the hosts referenced in your code. Parameterize all of these items. I have a template that I use for web virtual users which pairs a default value and the ability to change any of the host names via the control panel extra attributes section. Take a look at the example for lr_get_attrib_string() for how you might implement the pickup and pair that with a check for NULL and a population with a default value in your code
This is going to seem counter intuitive, but comment your script heavily for changes that are occurring often so you know where to take the extra labor change up front to handle a more dynamic data set.
Almost nothing you do with any tool can save you from struuctural changes in the design and flow of the app, such as the insertion of a new page in the workflow, but paying attention to the design on the high change pages, of which there are typically a small number, can result in a test code with a very long life.
Of course if your application is web services based then there is a natual long life to the use of exposed public services. Code may change on the back end of the service, but typically the exposed public interface is very stable.
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This thread is a follow up to my previous one. It's in fact 2 questions, so I hope no one minds, as they are dependent on each other.
We are starting a new project at work and we consider it as a great opportunity to try Agile techniques in action. We had a brainstorming about ideas we read in several books and articles, and came up with concept that would suit us the best: 2 weeks iteration, followed by call with clients who would choose what stuff they want to have in next iteration. I just have few more questions, which we couldn't figure out ourselves.
What to do in the first iteration?
What to, generally, do in the first few iterations if we start from the scratch? Just give it a month of development to code core of the application or start with simple wire-frames with limited pre-coded functionality? What usually clients want to see? Shiny stuff that doesn't work or ugly stuff that does work?
How to communicate with clients?
Our initial thought it to set the process to something like this:
alt text http://img690.imageshack.us/img690/2553/communication.png
Is it a good idea to have a Focal Point on client side or is it better to communicate straight with all the clients to prevent miscommunication?
Any thoughts are welcome! Thanks in advance.
In my opinion, a key success factor for agile development is to focus on delivering value for the customer in each iteration. I would definitely pick "ugly stuff that does work" over "shiny stuff that doesn't work". Doing shiny UIs and trying to get the client to understand hat business logic takes a lot of time to implement is always risky which Joel Spolsky has written a good article about.
If the client wants enhancements to the UI, they can always put that as a requirement for the next iteration.
Regarding communication with clients I think that your scetch should be slightly adjusted. Talking in scrum terms your "focal point" is called "product owner". Having one person coordinating with the clients is good, as it can take quite a lot of time to get the different stakeholders agree on the needs. However the product owner (or focal point) should be in direct contact with the developer, without going through the project manager. In fact, the product owner and the project manager has quite distinct roles that gain a lot by being split on two people.
The product owner is the stakeholders' voice to the development team. The project manager on the other hand is responsible for the wellbeing of the project team and often keeps track of budget etc. These roles sometimes has opposing agendas, and having them split on two people gives a healthy opportunity for negotiation between conflicting interests. If one person has both roles, that person often tend to favour one of them, automatically reducing the other one. You don't want to work on a team where the project manager always puts the client before the team's needs. On the other hand no customer wants a product owner that always puts the team's needs first, neglegting the customer. Splitting the responsibilities on two people helps to remedy that situation.
I'd agree with Anders answer. My one extra observation is that many clients find it impossible to ignoire the Ugly. They get concerned about presentation rather than function. Hence you may need to bite the bullet and do at least one "Nice" screen to show that you will pay attention to presentation details.
What to, generally, do in the first few iterations if we start from the scratch?
Many teams use an Iteration Zero to:
setup the development infrastructure (source control, development machines, the automated build, a continuous integration process, a testing environment, etc),
educated the customer and agree with him on the methodology,
create an initial list of features, identify the most important and do an initial estimation,
define time of meetings (planning meeting, demo, retrospective), choose the the iteration length.
Iteration Zero is very special because it doesn't deliver any functionality to the customer but focus on what is necessary to run the next iterations in an agile way. But subsequent iterations should start to deliver value to the customer.
Just give it a month of development to code core of the application or start with simple wire-frames with limited pre-coded functionality?
No, don't develop the core of your application during one month. Instead, start delivering vertical slice of the application (from the UI to the database) immediately, not horizontal slices. This doesn't mean that a screen has to be complete (e.g. implement only one search field in a search screen) but it should ideally be representative of the final look & feel (unless you agreed with the customer on an intermediate step). The important part is to build things that provide immediate value to the customer incrementally.
What usually clients want to see? Shiny stuff that doesn't work or ugly stuff that does work?
To my experience, they want to see demonstrable progresses and you want to get feedback as soon as possible.
Is it a good idea to have a Focal Point on client side or is it better to communicate straight with all the clients to prevent miscommunication?
You need one person to represent the clients (who is called the Product Owner in Scrum):
he provides a single authoritative voice
he has a perfect knowledge of the business (i.e. he can answer questions)
he knows how to maximize the ROI (i.e. how to prioritize functionalities)
Agile generally wants to provide the client something valuable, quickly.
So I certainly would not spend "month of development to code core of the application". To me, that smells of the "big up front design" anti-pattern. Also, see YAGNI.
Get as much information from the clients about what they need soonest, and implement that in your first iteration. "Valuable" is in the eye of the client. Thet will know if they want to see slick UI (maybe they want to give a slide show about the product at a trade show, so functionality can be fake) or simple working features (maybe you're developing something that they need to start using ASAP). Business Value is what they say will help them do their job.
I'd make my iterations as short as I can (your 2 weeks could work, I suggest considering 1 week) If you absolutely can't have your dev team and your clients co-located, instead of having a call with the clients, I suggest a meeting. Demo what you've done over the previous iteration and solicit feedback about what should stay, what should change, and what should be added.
As others have said, your "Focal point" sounds like a Product Owner. What worries me about your drawing is if it is meant to imply that devs don't interact with the PO or the clients. One thing that makes Agile work is when there is lots of communication. Having communication to/from the dev team always filtered through the Project Manager is almost certainly bound to result in miscommunication, unnecessary work, and missed details.
I agree with the two answers given but I would just add one thing from personal experience. Are your customers bought in to the change towards quick iterations? As well as providing feedback after each iteration which is going to require the customer performing usability tests on each feature.
Now I don't know what your groups relationship is with your customer but its not unusual for customers to take a "Put request in - get working system out" attitude in that they are enthusiastic when giving requirements but not so forthoming with time when it comes to testing the feature.
Now this may be totally inappropriate to your situation but its always worth considering how your customer workflow will have to change as well as your groups.
Cheers
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Referring to this buddy question, I want to know how one can manage specs in Scrum process ? I'm facing this problem while assigning tasks to my team for the sprint. Needless to say - I'm new to Agile/Scrum.
Currently, we are using our own specs sheet to map StoryId to SpecId and vice versa. I'm getting the felling that Scrum is more about project management [getting things done on time] and you need a seperate process to manage specs and requirements.
How do we manage specs in a Scrum process ?
The short answer is, you don't.
The important question to ask yourself when writing these specs, is why do we do them? What is the value in the spec?
The value in the spec usually comes in communicating the ideas of the business with the development team. Scrum is designed to bring the business (in the form of the Product Owner) to the development team. By interacting with the team frequently (remember, individuals and interactions over processes and tools), and by seeing working software frequently, the business can work hand in hand with developers to produce software that solves business problems better than by trying to spec out the whole thing before you get to try it out.
This is how Agile projects do a better job of delivering the product the business wants instead of the product they requested.
That said, there are certain base criteria that need to be met. We can test for this, and as with any good tests, we can automate it.
Have a look at BDD and Cucumber. In addition to your User Story, it's good to have a basic set of conditions of satisfaction, preferably in the "Give/When/Then" format. These conditions are the minimum set of criteria for the story to be accepted as complete.
For example, "Given I am logged in, when I log out, then I am taken back to the home page".
If you're going to have acceptance criteria, you're going to want to automate it. The worst part of most specifications is they often end up out of date and collecting dust when the project is complete.
Also, you shouldn't be assigning tasks to the team. Scrum teams are self organizing and anyone should be able to grab any task they feel they can work on while respecting the priority of the stories. Swarming is a big part of the performance benefits of Scrum.
You may want to consider bringing in an outside coach to assist with your transition.
I think that the easiest way is to make the specifications a part of the user stories within the tasks, themselves. Clearly list the acceptance criteria in each one (or if your issue tracking software allows you, create them as first class work item types). Let the issue in whatever you use for work item tracking become the living document.
There are drawbacks, such as finding related issues as specs change over time, but this can usually be managed in the work item tracking tooling, assuming your can relate issues to each other.
The way that we do it is that we (actually a BA, not the developers) creates a sign-off deck for the product owner to review and we collaboratively create tasks off of that. If we cannot create a task, or there are open questions, we will go back to the product owner with those questions and update the deck. All of our decks are organized (in SharePoint) so that we can easily find them in the future.
For me the specs is in the user stories. We define the specs and the tasks duing out initial scrum meeting along with the product owner. The specs and tasks are just for the life time of the scrum iteration as everything might change in the next iteration(in the worst case but there will definitively be changes).
We usually keep track of the specifications and task on a spreadsheet just so that everybody know what they are working on. I have also tried a few software to do this and one of the most interesting ones I have come across is from [VersionOne][1] and also from [Rally][2].
But I still find that using a simple spreadsheet is the fastest and simplest solution.
As I understand SCRUM, it does not take care about specs management. You have to broke/map your specs or specs changes to stories and tasks separately. But you can have a task for this :).
There is a real tension between Scrum and other agile dev methodologies and spec writing. I think there are two big points of tension:
Because agile says everything should
be on an index card, that means you
have to have stuff planned out
enough to fit on an index card.
(E.g. you have to know how it's all
going to work.)
Some things don't make sense in
isolation (what's the use of an
upload file page without a manage
uploaded files page, for instance.)
You don't have to design the whole app all at once, but you have to have a vision of the whole app. Then, especially if you have a separation of designers and programmers, you do functional design for a sprint-sized chunk at a time. Those designs then have to be broken down to story-sized chunks.
This is a lot of up front functional design, and I think that's overlooked in a lot of the talk about agile methodologies. Perhaps some shops have the devs do more of the design. Also, I think it's a lot easier to use scrum/agile for making changes/bug fixes to existing apps rather than building new ones.
The thing I've found most helpful is to fight back on story size. A lot of organizations have gone crazy, saying stories need to be only a few hours. The original scrum book says 16 hours, I think, which is often large enough to fit an entire screen of a web app. So "implement manage my account" could be a story (as opposed to the hundreds-of-tiny-stories approach of "implement username", "implement password" etc.) Then reference your design doc for "Manage My Account" and make sure to have word-perfect screenshots/prototype/mockup so the dev can look at them and copy/paste the text directly into the code they're writing, and they know for sure which fields need to be there (or which links, or which pictures, or whatever).