Introduction

This page describes the notation that is used for all string based data structures using in the NavWin MVP system. The notation and characters have been carefully selected to allow data to be compactly stored, sent and parsed by JavaScript.

Notation Elements

The following syntax is used:

<x> means x is some item in the system

{<x>} means zero or more item x in the system

[<x>] means the element is optional. It is a single occurrence

<x>| <y> means either <x> or <y> but not both

@ is the literal character ‘@’ a field separator

+ is the literal character ‘+’ and it is an object separator

Special Character Replacements

If the element <x> has any of the following embedded characters ‘\’, ‘@’ or ‘+’ then when they are stored, in general, they are directly replaced as follows:

‘\’ becomes ‘\1’

‘@’ becomes ‘\2’

‘+’ becomes ‘\3’

When they are read, the reverse transformation is done.

Currently there are no other special characters.

Usage of @ and + separators

The special characters ‘@’ and ‘+’ are used to split the message up quickly using String.Split(‘@’) and String.Split(‘+’) notation to convert the string into an array of strings. This works in both C# and JavaScript.

We use ‘@’ as an inner separator  and ‘+’ as an outer separator and this can be loosely interpreted as @ is a field separator and + is an object separator. For example:

Message = “ABD+123@456+MNO@PQR@STU“

On the outer level we can say

OuterMessages = Message.Split(“+”)

To give@

OuterMessages[0] = “ABC”

OuterMessages[1]= “123@456”

OuterMessages[2]= “MNO@PQR@STU”

Now, when we want to process the outer message[2] we can do this

InnerMessage = OuterMessage[2].Split(“@”)

To give

OuterMessages[0] = “MNO”

OuterMessages[1]= “PQR”

OuterMessages[2]= “STU”

Data Types

Although all data is just strings, we assume the following formats for certain types of data as follows.

·         It the data is numeric, then we only use the decimal point notation and no commas e.g. 123456.12 is ok. 123456,12 (European notation) is invalid. 123,456.12 (grouping) is invalid

·         If the data is a date or time we use yyyymmdd, or  hhmiss, or yyyymmddhhmiss where yyyy is the year, mm is the month, dd is the day, hh is 24 hour format hours, mi is minutes, ss is seconds.

·         Booleans are encodes as 0 for false and 1 for true.

·         Strings should not be enclosed in quotes.