The Open Protocol Notation Programming Guide 1 Document Version 1 (4/23/2018)
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Application LayerNext a simple application layer protocol is described that travels on top of MiniTCP. The protocol, called Echo, simply echoes data it receives in arbitrary order, but without any lost. Incoming messages carry the string that contains the message to be echoed, plus the user name that initiated the message. protocol Echo; using MiniTcp; // The MiniTCP port is used by the Echo protocol. const Port EchoPort = 99; // Post received by the server with the message to be echoed and the user // that generated the message. message Post { string Content; string UserName; } // The echoed message. message Echo { string Content; } The EchoServer accepts Post messages (sent by the clients) and issues Echo messages, representing the echoed data. The endpoint also keeps a list of users that are allowed to send Post messages. If a message from a user that is not in the list is received, the message is ignored. // The EchoServer is stacked on top of a Socket with the proper ports. endpoint EchoServer over Socket where value.SourcePort == EchoPort && value.DestinPort in EphemeralPorts; accepts Post issues Echo { // Messages that arrived and were not echoed yet. array // List of users that are allowed to request an echo. How this list // is retrieved is abstracted, and can be thought of as being a static // list.
array // The message is accepted only if the user is allowed. In case it is // not, the message will not match the rule and will be just ignored. observe this accepts m:Post{UserName in allowedUsers} { unechoed += [m.Content]; } // When an Echo is issued, to be sure its content is unechoed // add an assertion to validate this logic. observe this issues m:Echo{} { assert m.Content in unechoed; unechoed = unechoed.Remove(m.Content); } } The contract on the endpoint assures that only data that has been posted can be echoed. Observe that since this is our top-level protocol, we do not need process rules to consume messages and dispatch them up the stack. Next, the parsing actor is defined that maps from a TCP socket to the echo endpoint. This parser will be automatically started on a socket that uses the port for the Echo protocol. // This is the actor that listens on the server socket indexed by // the EchoPort. actor autostart EchoServerParser( Socket serverSocket where value.SourcePort == EchoPort) { // A MiniTCP Segment is matched, the Payload is decoded to a Post // message and dispatched to EchoServer. process serverSocket accepts Segment{Payload is m:Post from BinaryDecoder} { dispatch (endpoint EchoServer over socket) accepts m; } // A similar rule for the other direction. //... }
Language ReferenceLexisLexical UnitLexicalUnit ::= LexicalElement* LexicalElement ::= Whitespace | Comment | Token Token ::= Identifier | Keyword | Literal | OperatorOrPunctuator WhitespaceWhitespace ::= any charater with Unicode class Zs | tab characters (U+0009, U+000B) | formfeed character (U+000C) | Newline NewLine ::= carriage return (U+000D) | line feed (U+000A), | next line (U+0085) Comment ::= SingleLineComment | MultiLineComment SingleLineComment ::= // (! NewLine)* MultiLineComment ::= /* ( ! */ )* */ LiteralsLiteral ::= BooleanLiteral | IntegerLiteral | FractionalLiteral | CharacterLiteral | StringLiteral | NullLiteral | NothingLiteral | BinaryLiteral | GuidLiteral | DecimalLiteral BooleanLiteral ::= true | false IntegerLiteral ::= Sign? DecimalDigit+ | ( 0x | 0X ) HexDigit+ | ( 0b | 0B ) BinaryDigit+ | (0o | 0O) OctetDigit+ FractionalLiteral ::= Sign? DecimalDigit* . DecimalDigit+ Exponent? DecimalLiteral ::= FractionalLiteral (m | M) | Sign? DecimalDigit+ (m | M) Exponent ::= ( e | E ) Sign? DecimalDigit+ Sign ::= + | - BinaryDigit ::= 0 | 1 OctetDigit ::= BinaryDigit | 2 |3 |4 |5 |6 |7 DecimalDigit ::= OctetDigit |8 |9 HexDigit ::= DecimalDigit | a | A |b | B |c | C |d |D |e |E|f |F CharacterLiteral ::= ' ( ! ' & VisibleCharacter | \' | CharacterEscape ) ' CharacterEscape ::= \xHexDigit#4 | \xHexDigit#8 | \CharacterEscapeControl CharacterEscapeControl ::= 0 | a |b | f | n | r |t |v StringLiteral ::= SingleLineStringLiteral | MultilineStringLiteral SingleLineStringLiteral ::= " ( ! " & VisibleCharacter | \" | CharacterEscape )* " MultiLineStringLiteral ::= @ " ( ! " & VisibleCharacter | \" | Newline | CharacterEscape )* " BlockLiteral ::= { ( \} | \{ | \\ | VisibleCharater | NewLine | BlockLiteral )* } NullLiteral ::= null NothingLiteral ::= nothing BinaryLiteral ::= $[ ( HexDigit HexDigit )* ] | Base64Literal Base64Literal ::= TO BE DONE GuidLiteral ::= { HexDigit#8 - HexDigit#4 - HexDigit#4 - HexDigit#4 - HexDigit#12 } VisibleCharacter ::= TO BE DONE (specify unicodes) Newline ::= TO BE DONE (specify unicodes for CR or CR LF) The intention of the BlockLiteral is to allow embedding of an alien grammar within OPN. It allows nesting braces without escaping as long as the braces are balanced. If this is not the case, writers have to escape unbalanced braces. The same rule holds for the backslash ( \ ), and can be escaped, that is (\\), if needed. Identifiers and KeywordsQualifiedIdentifier ::= Identifier ( . Identifier )* Identifier ::= KeywordOrIdentifier without Keyword | @ KeywordOrIdentifier | $ StringLiteral KeywordOrIdentifier ::= IdentifierBegin IdentifierContinue* IdentifierEnd | IdentifierSingle IdentifierBegin ::= one of _ Letter IdentifierContinue ::= one of Letter DecimalDigit IdentifierEnd = one of _ Letter DecimalDigit IdentifierSingle = Letter Letter ::= unicode character of class Lu, Ll, Lt, Lm, Lo, Nl, Mn, Mc, Pc, Cf Keyword ::= any of: abstract accepts actor annotation any array as aspect assert autostart binary binding bool break byte case catch change char connection const consumes continue contract decimal default delete dispatch do double enum else endpoint error exception extends extern false finally flags float from for foreach follows get guid if in int interface internal invariant is issues json long map metadata message module new nothing null observe operation operator over override pattern precedes process protocol provides public regex ref return role rule sbyte select set short static string success switch syntax throw treedata true try type typedef uint ulong using ushort value var virtual void where while with xml xpath WeakKeyword::= any of: all bind create exists freeze optional out result some start stop this ignore separator Operators and PunctuatorsNote that multi-character operators (for example &&, >=, #.., and so on) should be considered as single tokens, and therefore they do not allow spaces or tabs interleaved. OperatorOrPunctuator ::= any of: { } [ ] ( ) . , + - * / % ! = < > & ^ ; # ` ? && || == != <= >= => | & ^ ==> <=> ~ .. ... << >> += -= ++ -- ?? #? #.. Directory: download download -> Performance Tuning Guidelines for Windows Server 2008 May 20, 2009 Abstract download -> Northern England’s set-jetting locations download -> Bbc archives: Beyond the programme download download -> Occupational health and safety download -> Dynatest 3031 lwd light Weight Deflectometer download -> Forth coming competitive exams download -> English Olympiad Tasks: 10 th form Аудіювання, 10 клас. Текст download -> Brush High School Morning Announcements Friday, September 05, 2014 all school download -> Year 9 The Arts — Music download -> Years 7 and 8 standard elaborations — Australian Curriculum: Music draft Download 1.37 Mb. Share with your friends:
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