Project consists of two Android apps. The first app, named FedCash, takes as input a year or a date range from an interactive user. This app uses a second app, named TreasuryServ, to access a database maintained by the US Department of the Treasury. The database is found at URL http://treasury.io/, which supports most networking protocols, such as JSON and HTTP Clients. In order not to block its user interface during network operations, TreasuryServ defines a bound service in order to access the database. The service in TreasuryServ defines a simple API, described below, for use by FedCash and other apps. Upon receiving an API call from FedCash, TreasuryServ appropriately creates and formats a query to be forwarded to the treasury.io site. After it receives the the site’s response to the query, TreasuryServ will return the requested information back to the FedCash app as the value returned from the API call. For obvious reasons, FedCash must use a worker thread when making API calls on TreasuryServ. The API exposed by TreasuryServ consists of the following three remote methods:
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monthlyCash(int) : List(Integer) — This method takes as input an integer denoting a year between 2006 and 2016 inclusive. It returns a list of 12 Integer values denoting the amount of cash the US Government had on hand at the opening of the first working day of each month of the input year.
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dailyCash(int, int, int, int) : List(Integer) — This method takes as input 4 integers: a day, a month, a year, and a number of working days. The first 3 integers denote a date in the years 2006–2016. The last integer denotes a number of working days between 5 and 25. This method returns a list of integers denoting the cash the government had on hand at the opening of the input date and subsequent working days, as specified by the fourth input parameter.
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yearlyAvg(int) : int — This method takes as input an integer. It returns as output the average of the cash on hand at the opening of each working day in the input year.
In addition to the service, TreasuryServ defines an activity whose sole purpose is to display the status of the service. The service could either be (1) not yet bound, (2) bound to one or more clients but idle, (3)bound and running an API method, and (4) destroyed. The destroyed service could be bound again, if a request comes from a client. App FedCash has two activities. The first activity allows the interactive user to specify a request to be forwarded to TreasuryServ. Define appropriate fields (widgets) allowing a user to select one of the three APIs supported by the service in TreasuryServ and the corresponding input parameters. An additional widget forwards a request to the service. If FedCash was not bound to the service, it will bind to the service at this point. Finally, this activity contains a widget that will unbind FedCash from the service. The second activity consists of two fragments to be displayed side-by-side. This activity is opened by selecting an appropriate button in the first activity. The left fragment contains a list of all the calls made on the service. When a user selects one of the calls, the right fragment will display the result returned by the corresponding API call on the service contained in TreasuryServ. An AIDL spec is used to expose the service’s functionality to the clients. The service’s code is thread-safe(safe from deadlocks and data races); multiple clients could be bound to the service at the same time.