BadBank simulates the internal settlement system of a (bad) bank. The system periodically processes input files and generates reports.

Syntax:

$ dotnet run --project BadBank.Demo INPUT OUTPUT FREQUENCY

Example (Bash):

$ mkdir -p BadBank/{input,output}
$ dotnet run --project BadBank.Demo BadBank/input BadBank/output 30

Arguments:

• INPUT is a folder path that will be watched for new files
• OUTPUT is a folder path to which reports will be written
• FREQUENCY is the processing frequency in seconds (integer)

The input files are written in the BadBank Transaction Language (see below).

Example file (input.bbtl):

open Alice
deposit Alice 100
open Bob
send 25 from Alice to Bob
withdraw 15 from Bob
withdraw 20 from Alice

If the file alice-bob.bbtl is put into the INPUT folder, its processing will start after FREQUENCY seconds the latest. If multiple files are put into the INPUT folder, they will be processed in alphabetical order (case-sensitive).

Input files will be deleted after processing! So better create a backup for them while testing.

The result will be published as alice-bob.bbrf (BadBank Reporting Format) in the OUTPUT folder:

Alice 55.00
Bob 10.00

The following commands are supported:

• open ACCOUNT
  • semantics: open the account with name ACCOUNT
  • pre-condition: no account of name ACCOUNT exists yet
  • post-condition: an account of name ACCOUNT with balance 0.0 exists
• close ACCOUNT
  • semantics: close the account with the name ACCOUNT
  • pre-condition: an account of name ACCOUNT exists
  • post-condition: the account of name ACCOUNT no longer exists
• send AMOUNT from ACCOUNT_A to ACCOUNT_B
  • semantics: send the amount AMOUNT from ACCOUNT_A to ACCOUNT_B
  • pre-condition: both ACCOUNT_A and ACCOUNT_B exist; AMOUNT must be positive (> 0.0)
  • post-condition: balance of ACCOUNT_A decreased, balance of ACCOUNT_B increased by AMOUNT
  • Note: no balance check is performed (balance can become negative)
• deposit AMOUNT to ACCOUNT
  • semantics: deposit the amount AMOUNT for ACCOUNT
  • pre-condition: an account of name ACCOUNT exists
  • post-condition: balance of ACCOUNT increased by AMOUNT
• withdraw AMOUNT from ACCOUNT
  • semantics: withdraw the amount AMOUNT from ACCOUNT
  • pre-condition: an account of name ACCOUNT exists
  • post-condition: balance of ACCOUNT decreased by AMOUNT; balance of ACCOUNT must be >= AMOUNT

See examples in data/input-examples.

• ACCOUNT AMOUNT
  • the account ACCOUNT has the given AMOUNT (formatted as a floating-point number with two fraction digits, e.g. 165.29)

See examples in data/output-examples: