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Image Serving HTTP protocol basic syntax

The HTTP protocol basic syntax is as follows.
request
http:// server /is/image[/ object ][? modifiers ]
server
server_address [: port ]
object
Source object specifier (image path or image catalog entry).
modifiers
modifier *[& modifier ]
modifier
command|{$ macro $}|{. comment }
command
{ cmdName |{$ var }}[= value ]
macro
Name of a command macro.
comment
Comment string (ignored by server).
cmdName
One of the supported command or attribute names.
var
Name of a custom variable.
value
Command or variable value.
server_address , cmdName , macro , and var are case-insensitive. The server preserves the case of all other string values.
value is command-specific and may consist of one or more values separated by commas. Refer to the description of the individual commands for details.

Server identifier

The /is/image root context is required for all HTTP requests to Image Serving.

HTTP decoding

Image Serving first extracts object and modifiers from the incoming request. object is then separated into path elements which are individually HTTP-decoded. The modifiers string is separated into command = value pairs, and value is then HTTP-decoded before command-specific processing.
Unless otherwise noted in the documentation, all unsafe characters must be encoded per the HTTP standard. Refer to the HTTP specification for details.

Comments

Comments may be embedded into request strings anywhere and are identified by a period(.) immediately following the command separator(&). The comment is terminated by the next occurrence of an (unencoded) command separator. This feature may be used to add information to the request which is not for Image Serving use, such as time stamps, database ids, etc.