Authors: Vera Altamore
Date: 27/03/2020
Version: 1
Change history
| Version | Changes |
|---|---|
The car drivers need to refuel. The entire territory is divided in areas where there are different gas stations at which drivers can refuel. The price of fuel is different at each gas station and the car drivers want to find the gas station in the own area with the lowest price. To solve this problem is implemented EZGas, a crowdsourcing service that allows users to:
-
collect prices of fuels in different gas stations
-
locate gas stations in an area, along with the prices they practice. EZGas is supported by a web application (accessible both via smartphone or PC). The collection of prices in different gas station is at the beginning initializated with data found on the Internet mixed with data sent by the gas station owners and it is updated by the users in runtime. The localization of the gas station and other addictional funtionalities are supported by other service like Google maps.
| Stakeholder name | Description |
|---|---|
| Users | Use the application directly. They are interested in updating the prices of fuel and to find the lowest price in the area. Users can be car drivers or gas station owners. |
| Maps service | Provides the maps to locate the gas stations. A map service can be Google maps. |
left to right direction
actor User as u
actor MapService as ms
a --> (EzGas)
(EzGas) --> ms| Actor | Logical Interface | Physical Interface |
|---|---|---|
| User | GUI | Screen, keyboard, smartphone, Internet connection |
John is a car driver and every morning, before going to work, he always checks the fuel level in his car. When it's necessary a refuel, he wants to do quickly because he can't arrive late at work but he wants also to save money. So when he get in the car he opens the EZgas application on his smartphone to find the gas stations on the way for work with the lowest price. He would like to know not only the gas station with the lowest price but also the distance from it in order to know if he can arrive to that gas station with the remaining fuel.
Bob is the owner of a gas station and every morning if there is a difference in the price of fuel he update the sign in the station with the new price, then he update the price in the EZgas service from the PC in his office.
Alice is a truck driver and during her long trip she stop sometimes in gas stations for a short break. During these stops she can read the actual price of the fuel in that gas station and update it on the web service through her smartphone.
To verify the correctness of the updated price, because there is no way to verify the declatation of the user, an update is done only if at least 3 people agree about the the same price.
| ID | Description |
|---|---|
| FR1 | Management of price |
| FR1.1 | Record the price of fuel at each gas station |
| FR1.2 | Record the reportings of users about the modification of price |
| FR1.3 | Record the number of reportings about a specific gas station to validate the update of price |
| FR1.4 | Validate the update of price |
| FR2 | Management of position |
| FR2.1 | Take the position of a user and show all the gas stations around him. |
| FR2.2 | Calculate the distance between the user and each gas station in his area |
| FR3 | Management of types of users |
| FR3 | Filter the gas station based on the characteristics chosen by the user: type of fuel, type of assistance, type of payment. |
| ID | Type (efficiency, reliability, .. see iso 9126) | Description | Refers to |
|---|---|---|---|
| NFR1 | Usability | Application should be used with no training | All FR |
| NFR2 | Performance | All functions should complete in < 0.5 sec | All FR except FR1.4 |
| NFR3 | Portability | The application is based on web so it is device independent. It is accessible both via smartphone or PC with the only condiction of a stable Internet connection. | All FR |
| NFR5 | Reliability | The reliability of the service is based on the activity and declarations of the users. | Only for FR1 |
| NFR6 | Maintainability | Once the service is launched, the users themselves maintain it functional updating the prices. |
left to right direction
actor User as u
(FR1 Management of price) <|-- (FR1.1 Record the price of fuel at each gas station)
(FR1 Management of price)<|-- (FR1.2 Report change in price)
(FR2 Management of position) <|-- (FR2.1 Check the gas station in the area)
(FR2 Management of position) <|--(FR2.2 Calculate the distance)
(FR2.1 Check the gas station in the area)--|> (Check the gas station with the lowest price in the area) :include
actor MapService as ms
(FR2.1 Check the gas station in the area)--|> (Check the nearest gas station) :include
actor MapService as ms
(FR1.2 Report change in price) -- (FR1.3 | Check the number of reportings )
(FR1.3 | Check the number of reportings ) -- ( FR1.4 | Validate the update of price)
u -->(FR1.2 Report change in price)
u --> (FR2.1 Check the gas station in the area)
u --> (FR3.1 Filter the gas station)
(FR2 Management of position) --> ms
| Actors Involved | User |
|---|---|
| Precondition | The gas station GS exists and works, User u can know the price of the fuel, the GS sells the fuel F, the fuel F has no price yet |
| Post condition | F.price = price |
| F.pricepre == 0, F.pricepost != 0 | |
| Nominal Scenario | The first user arrives in a gas station GS, see the price of a fuel F and set the price of that fuel |
| Variants |
| Actors Involved | User |
|---|---|
| Precondition | The gas station GS exists and works, User u can know the price of the fuel, the GS sells the fuel F, the fuel F has an incorrect prive |
| Post condition | F.price < price |
| F.pricepre != F.pricepost | |
| Nominal Scenario | The user arrives in a gas station GS, see the price of a fuel F and if it different from the actual one sends the new price to the service. After a threashold of notification the price is updated |
| Variants | The notification does not pass the threshold. |
| Actors Involved | Map Service |
|---|---|
| Precondition | The Gas GS station exists, the Map service works |
| Post condition | GS.position = coordinates |
| GS.positionpre = NULL, GS.positionpost = coordinates | |
| Nominal Scenario | A query is sent to the external Map service and the positions of the gas stations are returned |
| Variants |
| Actors Involved | User |
|---|---|
| Precondition | The gas GS station exists, there are no filters on the type of gas station |
| Post condition | GS.Fuel.type = typeFuel && GS.type_of_payment = payment && GS.type_of_assistance = assistance |
| GS.Fuel.type = all && GS.type_of_payment = all && GS.type_of_assistance = all | |
| Nominal Scenario | The user wants to find only the gas stations with specific characteristics |
| Variants |
| Scenario ID: SC1 | Corresponds to UC2 |
|---|---|
| Description | Someone change the price of the fuel at the gas station GS |
| Precondition | The user goes to the gas station and the price on the web service does not correspond to the real one |
| Postcondition | The price of the fuel is updated |
| Step# | Step description |
| 1 | User goes to the gas station |
| 2 | User selects a type of fuel F |
| 3 | User see that the price of the fuel F is incorrect |
| 4 | User notificates the new price of the fuel F at the gas station GS |
| 5 | If the system receives a number of notification larger than the threshold the price is updated |
| Scenario ID: SC2 | Corresponds to UC2 |
|---|---|
| Description | The number of notificaiton is smaller than the threshold |
| Precondition | The user goes to the gas station and the price on the web service does not correspond to the real one |
| Postcondition | The price of the fuel is not updated |
| Step# | Step description |
| 1 | User goes to the gas station |
| 2 | User selects a type of fuel F |
| 3 | User see that the price of the fuel F is incorrect |
| 4 | User notificates the new price of the fuel F at the gas station GS |
| 5 | If the number of notification is smaller than the threshold the price is not updated and will remain like that until new notification will arrive. |
class EzGas
class Driver {
+ name
+ surname
}
class GasStation {
+ name
+ Position
+ Fuel
+ type_of_payment
+ type_of_assistance
}
class Fuel {
+ type
+ price
}
class Position {
+ coordinates
+ actual_distance
}
class Update {
+ N_update
+ GasStation
+Fuel
}
EzGas -- "*" Driver
EzGas -- "*" GasStation
EzGas -- "*" Update
GasStation -- "*" Fuel
GasStation -- "1"Position