Extreme Networks EPICenter 4.1, Software Installation Manual

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494 EPICenter Software Installation and User Guide
EPICenter External Access Protocol
Encoding Layer
The encoding of all data transmitted through the transport layer uses a set of HTML/XML-like
encoding rules. All data are transmitted as values enclosed in tags. For example:
<TAG1>value1</TAG1>
The first tag is the begin tag. Following the begin tag, a value is supplied, which can be empty. It is
followed by the end tag. The rules for the tags are:
• A tag is enclosed in < and >.
• Tag content is case insensitive.
• A tag is a begin tag if its first word does not start with /.
•
A tag is an end tag if the first word starts with /.
• A begin tag must be matched with an end tag.
• A begin tag end tag pair can be enclosed within another pair of begin and end tags.
The tags recognized by the EPICenter server are the following:
• <
COMMAND
><
/COMMAND
> encloses an EPICenter server command.
•
<
PARAM
><
/PARAM
> encloses an EPICenter server command parameter.
• <
H2
><
/H2
> encloses a message returned by the EPICenter server.
• <
TABLE
><
/TABLE
> encloses a table returned by the EPICenter server.
• <
TR
><
/TR
> are used in a table response from the EPICenter server.
• <
TD
><
/TD
> are used in a table response from the EPICenter server.
Data values appear between a begin tag and an end tag. Data values are encoded using the following
rules:
• Only HTML-compatible 7-bit ASCII characters are used to represent application data values. All data
values are represented using 7-bit ASCII characters. There is no binary data representation.
• Characters with ASCII value 9, 10, 13, 33, 35–37, 39–59, 61, 63–126 are sent using their original ASCII
values. For example 'a' is sent as 'a', '\n' is represented as '\n'.
• All other ASCII characters and any two byte Unicode characters are sent using “&#vwxyz;”, where
vwxyz is the decimal value of the character. For example, '<' is sent using “&#60;” where 60 is the
decimal value of the ‘<’ character.
• All numeric values of integer, short, long, float, and double format are sent using their textual
decimal representation. For example, 123, 139.32, 23.3e-12.
• A byte is sent using its two digit hex representation in textual form. For example, the byte value
“210” is sent as “D2”.
•
A character array or string is sent as a sequence of characters, each using the encoding rule outlined
in 2 and 3.
• A byte array is sent using a sequence of bytes. Each byte is sent using the encoding rule outlined in
5.
• There is no method for representing a null value.
• All characters are significant if appearing in the data value, including all newlines, carriage returns
and tabs.