Doc: move donwload from CODING to PROTOCOL

doc/CODING.md

@@ -194,42 +194,7 @@ Form save
 Download
 --------
 
-A download might be:
-  * a single file (any type, will be detected on the fly), 
-  * an export of several files as a ZIP archive,
-  * an export of a T3-'XML'-Page converted to Excel,
-  * a converted HTML page to PDF,
-  * a PDF file, concatenated on single PDF files and/or converted HTML page to PDF.
-    
-'api/download.php' will be called with a SIP (no other vars used). The SIP contains:
-  * DOWNLOAD_EXPORT_FILENAME - any target filename, if none given take DOWNLOAD_OUTPUT_PDF ('output.pdf'). 
-  * DONWLOAD_MODE - file / pdf / excel / zip. If not specified:
-      a) 'file' is the default if only one is given and if this is a file.
-      b) 'pdf' is the default if there are multiple TOKEN_URL, TOKEN_URL_PARAM, TOKEN_FILE in SIP_DOWNLOAD_PARAMETER found.
-  * SIP_DOWNLOAD_PARAMETER (base64 encoded) - contains all parameter to source elements. 
-    Format: <format 1>:<element 1>|<format 2>:<element 2>|...|<format n>:<element n>|
-    
-    <format>: TOKEN_URL, TOKEN_URL_PARAM, TOKEN_FILE
-    <element>: depending on the token - see below
-    
-    URL:  a) 'u:http://w3c.org', b) 'u:w3c.org/', c) 'u:w3c.org/2017/index.php?issue=23'
-    URL_PARAM:  a) 'U:id=export&r=123', b) 'U:id=export&r=123&_orientation=landscape&_page-size=a3'
-    FILE: a) 'f:fileadmin/example.png'
-      
-    * In URL_PARAM extra parameter used by `wkhtmltopdf` can be specified. All Parameter, starting with '-'
-      will be extracted from the regular URL_PARAM and instead forwarded as options to `wkhtmlpdf`
-    
-  * The base64 encoding is necessary:
-    * to deliver multiple elements with the same token (e.g. multiple PDF files to concatenate).
-    * special parameter names, like 'id', should not force the regular interpretation of 'id' during conversion to a SIP. 
-      
-During preparing and delivering the download, a popup shows a spinning gear by default. The popup itself will display an
-individual message. The popup needs some HTML code (only once per T3 page). 
-Download links might be generated in `report` as well as in `subrecords of forms`. To trigger the generation of the HTML 
-popup code, a variable DOWNLOAD_POPUP_REQUEST in STORE_SYSTEM will be set to 'true' (string) in class Link(), as soon as 
-the first download link is rendered. During internal rendering of the download link, the const text token 
-DOWNLOAD_POPUP_REPLACE_TEXT and DOWNLOAD_POPUP_REPLACE_TITLE will be replaced with individual texts, defined per download link.
-
+See PROTOCOL.md > Download
 
 Print
 -----

doc/PROTOCOL.md

@@ -21,7 +21,7 @@ JSON Response from the server containing at least:
 	{
 		"status": "success"|"error",
 		"message": "<message>"
-    }
+	}
    
 `status` indicates whether or not the request has been fullfiled by
 the server (`"success"`) or encountered an error (`"error"`). On
@@ -336,6 +336,62 @@ Server Response
 :	The response contains a [Minimal Response].
 	[Redirection Response] may be included.
 
+### Download
+
+Request
+:  api/download.php
+ 
+Request Method
+:	GET
+
+URL Parameters
+:	`s=<SIP>`
+
+Server Response
+:	header("Content-type: $mimetype");
+	header("Content-Length: $length");
+	header("Content-Disposition: inline; filename=\"$outputFilename\"");
+	header("Pragma: no-cache");
+	header("Expires: 0");
+	file_get_contents($file);
+ 
+A download might be:
+  * a single file (any type, will be detected on the fly), 
+  * an export of several files as a ZIP archive,
+  * an export of a T3-'XML'-Page converted to Excel,
+  * a converted HTML page to PDF,
+  * a PDF file, concatenated on single PDF files and/or converted HTML page to PDF.
+
+'api/download.php' will be called with a SIP (no other vars used). The SIP contains:
+  * DOWNLOAD_EXPORT_FILENAME - any target filename, if none given take DOWNLOAD_OUTPUT_PDF ('output.pdf'). 
+  * DONWLOAD_MODE - file / pdf / excel / zip. If not specified:
+      a) 'file' is the default if only one is given and if this is a file.
+      b) 'pdf' is the default if there are multiple TOKEN_URL, TOKEN_URL_PARAM, TOKEN_FILE in SIP_DOWNLOAD_PARAMETER found.
+  * SIP_DOWNLOAD_PARAMETER (base64 encoded) - contains all parameter to source elements. 
+    Format: <format 1>:<element 1>|<format 2>:<element 2>|...|<format n>:<element n>|
+    
+    <format>: TOKEN_URL, TOKEN_URL_PARAM, TOKEN_FILE
+    <element>: depending on the token - see below
+    
+    URL:  a) 'u:http://w3c.org', b) 'u:w3c.org/', c) 'u:w3c.org/2017/index.php?issue=23'
+    URL_PARAM:  a) 'U:id=export&r=123', b) 'U:id=export&r=123&_orientation=landscape&_page-size=a3'
+    FILE: a) 'f:fileadmin/example.png'
+      
+    * In URL_PARAM extra parameter used by `wkhtmltopdf` can be specified. All Parameter, starting with '-'
+      will be extracted from the regular URL_PARAM and instead forwarded as options to `wkhtmlpdf`
+    
+  * The base64 encoding is necessary:
+    * to deliver multiple elements with the same token (e.g. multiple PDF files to concatenate).
+    * special parameter names, like 'id', should not force the regular interpretation of 'id' during conversion to a SIP. 
+      
+During preparing and delivering the download, a popup shows a spinning gear by default. The popup itself will display an
+individual message. The popup needs some HTML code (only once per T3 page). 
+Download links might be generated in `report` as well as in `subrecords of forms`. To trigger the generation of the HTML 
+popup code, a variable DOWNLOAD_POPUP_REQUEST in STORE_SYSTEM will be set to 'true' (string) in class Link(), as soon as 
+the first download link is rendered. During internal rendering of the download link, the const text token 
+DOWNLOAD_POPUP_REPLACE_TEXT and DOWNLOAD_POPUP_REPLACE_TITLE will be replaced with individual texts, defined per download link.
+
+
 ### Typeahead
 
 The Client initiates Typeahead actions via a GET request. A JSON key/value dict will we be send back as response.