ErlangExercises

Erlang applications for academic purposes

math_server

Server evaluates arithmetic expressions: addition, subtraction, multiplication, division. Input data sent as parameters in the URL query. The first parameter specifies the arithmetic operation, the next - the next action arguments. The input language of HTTP requests in EBNF notation:

URL                   = IP addr. & port No ,  request ;
IP addr. & port No    = “127.0.0.1:8080?” ;
request               = calculation , “&” , integer , { “&” , integer } ;
calculation           = “plus” , “minus”, “mult”, “div” ;
integer               = “0” | [ "-" ] , digit ;
digit                 = “0” | digit without 0 ;
digit without 0       = “1” |  “2” |  “3” |  “4” |  “5” |  “6” |  “7” |  “8” |  “9” ;

dict_rest

REST application for creating and managing a Polish-English dictionary. The available API includes methods (word ": word" is a variable meaning a word in Polish language which is the password in the dictionary):

Request	Request Method	Additional argument	Meaning
/list	GET	NO	Display with meanings saved words
/get/:word	GET	NO	Display word: word with meaning
/create/:word	POST	YES header: Content-Type - application/x-www-form-urlencoded body: content - word_meaning_:word	Add word:word
/update/:word	POST	YES header: Content-Type - application/x-www-form-urlencoded body: content - word_meaning_:word	Update the meaning of the word: word
/delete/:word	DELETE	NO	Delete the word: word
/help	GET	NO	Display help (all available API commands)
/

Server methods:

Method	Meaning
allowed_methods/2	Listing of supported HTTP requests
content_types_provided/2	Redirecting GET requests to the appropriate methods due to the format of the returned response
content_types_accepted/2	Redirecting POST requests to the appropriate methods due to the format of the query received
db_to_json/2	Redirecting GET queries with returned JSON response to the appropriate methods due to the type of API query
db_to_text/2	Redirecting GET queries with the returned response in text format to the appropriate methods due to the type of API query
text_to_db/2	Redirecting POST requests to the appropriate methods due to the type of API query
delete_resource/2	The method called when using the / delete method
resource_exists/2	A method that verifies word existing in the dictionary
get_record_list/2	A method that returns all saved words with meanings in JSON format
get_record_list_text/2	A method that returns all saved words with the meanings in a text format
get_one_record/2	The method returns a single word with the meaning in JSON format
get_one_record_text/2	The method that returns the word with the meaning in text format
create_record_to_json/2	The method that saves the new word with the meaning to the dictionary
update_record_to_json/2	The method updating the dictionary by updating existing word meaning
get_help/2	A method that returns all available API commands in JSON format
get_help_text/2	A method that returns all available API commands in text format

Adding the word "mirror" with the meaning to the dictionary:

ws_calc

Client-server appliacation using WebSocket protocol that reconstructs th operation of a simple calculator operating on a set of real numbers. The server provides mathematical operations:

• binary operations:
  • adding,
  • subtraction,
  • multiplication,
  • division,
• unary operations:
  • square root,
  • reverse.

An equality operator completes calculations and displays the final result or reset calculations (AC). The client is an HTTP site with JavaScript scripts used to communicate with the server.

Attributions

• http://davekuhlman.org/cowboy-rest-add-get-update-list.html
• https://freshman.tech/calculator/

Credits

• Monika Grądzka
• Robert Kazimierczak