From 8c04e06ce03ab467e23c9082d13f66d4775af4ee Mon Sep 17 00:00:00 2001
From: Peter Stadler <stadlerpeter@yahoo.fr>
Date: Wed, 30 Mar 2016 21:48:04 +0200
Subject: [PATCH] adding HTTP headers ETag and Cache-Control

---
 controller.xql         | 28 +++++++--------------
 modules/controller.xqm | 55 +++++++++++++++++++++++++++---------------
 modules/view-html.xql  |  7 +++++-
 3 files changed, 51 insertions(+), 39 deletions(-)

diff --git a/controller.xql b/controller.xql
index 48fac285b..854c9aaef 100644
--- a/controller.xql
+++ b/controller.xql
@@ -33,10 +33,12 @@ return (
 if(contains($exist:path, '/$resources/')) then
     <dispatch xmlns="http://exist.sourceforge.net/NS/exist">
         <forward url="{concat($exist:controller, '/resources/', substring-after($exist:path, '/$resources/'))}">
-            <set-header name="Cache-Control" value="max-age=3600, must-revalidate"/>
+            <set-header name="Cache-Control" value="max-age=3600,public"/>
         </forward>
     </dispatch>
 
+else if(starts-with($exist:path, '/resources/')) then response:set-header('Cache-Control', 'max-age=3600,public') 
+
 else if(starts-with($exist:path, '/digilib/')) then
     <dispatch xmlns="http://exist.sourceforge.net/NS/exist">
         <ignore/>
@@ -86,22 +88,8 @@ else if (matches($exist:resource, 'A\d{2}[0-9A-F]{4}')) then
  : Caching muss unterbunden werden
  :)
 else if ($exist:resource = xmldb:get-child-resources($config:app-root || '/templates/ajax')) then 
-    <dispatch xmlns="http://exist.sourceforge.net/NS/exist">
-        <forward url="{map:get($exist-vars, 'controller') || '/templates/ajax/' || $exist:resource}"/>
-    	<view>
-            <forward url="{map:get($exist-vars, 'controller') || '/modules/view-html.xql'}">
-                <set-attribute name="docID" value="{functx:substring-after-last(functx:substring-before-last($exist:path, '/'), '/')}"/>
-                <set-header name="Cache-Control" value="no-cache"/>
-            </forward>
-            <forward url="{map:get($exist-vars, 'controller') || '/modules/view-tidy.xql'}">
-                <set-attribute name="lang" value="{$exist-vars('lang')}"/>
-            </forward>
-        </view>
-        <error-handler>
-            <forward url="{map:get($exist-vars, 'controller') || '/templates/error-page.html'}" method="get"/>
-            <forward url="{map:get($exist-vars, 'controller') || '/modules/view-html.xql'}"/>
-        </error-handler>
-    </dispatch>
+    controller:forward-html('/templates/ajax/' || $exist:resource, map:new(($exist-vars, map:entry('docID', functx:substring-after-last(functx:substring-before-last($exist:path, '/'), '/')))))
+    
 
 (:~
  : The CMIF Output of the letters (has to go before the generic *.xml rule) 
@@ -463,6 +451,8 @@ else if($config:isDevelopment and starts-with($exist:path, '/logs/')) then
     </dispatch>
 
 (: zum debuggen rausgenommen um Fehler anzuzeigen:)
-else (:controller:error($exist-vars, 404):)
-    ()
+else if($config:isDevelopment) then util:log-system-out('fail for: ' || $exist:path)
+
+else controller:error($exist-vars, 404)
+    
 )
diff --git a/modules/controller.xqm b/modules/controller.xqm
index 389e650f4..2b1213429 100644
--- a/modules/controller.xqm
+++ b/modules/controller.xqm
@@ -20,23 +20,35 @@ import module namespace str="http://xquery.weber-gesamtausgabe.de/modules/str" a
 import module namespace functx="http://www.functx.com";
 
 declare function controller:forward-html($html-template as xs:string, $exist-vars as map()*) as element(exist:dispatch) {
-    <dispatch xmlns="http://exist.sourceforge.net/NS/exist">
-    	<forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), $html-template))}"/>
-    	<view>
-            <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), 'modules/view-html.xql'))}">
-                <set-attribute name="docID" value="{$exist-vars('docID')}"/>
-                <!-- Needed for register pages -->
-                <set-attribute name="docType" value="{$exist-vars('docType')}"/>
-            </forward>
-            <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), 'modules/view-tidy.xql'))}">
-                <set-attribute name="lang" value="{$exist-vars('lang')}"/>
-            </forward>
-        </view>
-        <error-handler>
-            <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), '/templates/error-page.html'))}" method="get"/>
-            <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), '/modules/view-html.xql'))}"/>
-        </error-handler>
-    </dispatch>
+    let $etag := controller:etag($exist-vars('path'))
+    let $modified := not(request:get-header('If-None-Match') = $etag)
+    return (
+        <dispatch xmlns="http://exist.sourceforge.net/NS/exist">
+            <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), $html-template))}"/>
+            <view>
+                <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), 'modules/view-html.xql'))}">
+                    <set-attribute name="docID" value="{$exist-vars('docID')}"/>
+                    <!-- Need to provoke 304 error in view-html.xql if unmodified -->
+                    <set-attribute name="modified" value="{$modified cast as xs:string}"/>
+                    <!-- Needed for register pages -->
+                    <set-attribute name="docType" value="{$exist-vars('docType')}"/>
+                </forward>
+                {if($modified) then 
+                <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), 'modules/view-tidy.xql'))}">
+                    <set-attribute name="lang" value="{$exist-vars('lang')}"/>
+                </forward>
+                else ()}
+            </view>
+            {if($modified) then
+            <error-handler>
+                <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), '/templates/error-page.html'))}" method="get"/>
+                <forward url="{str:join-path-elements((map:get($exist-vars, 'controller'), '/modules/view-html.xql'))}"/>
+            </error-handler>
+            else ()}
+        </dispatch>,
+        response:set-header('Cache-Control', 'max-age=120,public'),
+        response:set-header('ETag', $etag)
+    )
 };
 
 
@@ -253,14 +265,19 @@ declare %private function controller:resource-id($exist-vars as map(*)) as xs:st
         else ()
 };
 
-
 declare %private function controller:media-type($exist-vars as map(*)) as xs:string? {
     'html'
 };
 
-
 declare %private function controller:forward-document($exist-vars as map(*)) as element(exist:dispatch) {
     switch($exist-vars('docType'))
     case 'persons' return controller:forward-html('/templates/person.html', $exist-vars)
     default return controller:forward-html('/templates/document.html', $exist-vars)
 };
+
+declare %private function controller:etag($path as xs:string) as xs:string {
+    let $lastChanged := config:getDateTimeOfLastDBUpdate()
+    let $params := string-join(for $i in request:get-parameter-names() order by $i return request:get-parameter($i, ''), '')
+    return
+        util:hash($path || $lastChanged || $params || 'bar', 'md5')
+};
diff --git a/modules/view-html.xql b/modules/view-html.xql
index b28bde0b0..6491e2631 100644
--- a/modules/view-html.xql
+++ b/modules/view-html.xql
@@ -51,5 +51,10 @@ let $lookup := function($functionName as xs:string, $arity as xs:int) {
  : Run it through the templating system and return the result.
  :)
 let $content := request:get-data()
+let $modified := request:get-attribute('modified') = 'true'
 return 
-    wega-util:stopwatch(templates:apply#4, ($content, $lookup, $model, $config), ())
+    if($modified) then wega-util:stopwatch(templates:apply#4, ($content, $lookup, $model, $config), ()) 
+    else ( 
+        (:util:log-system-out('cached ' || $model('docID')),:) 
+        response:set-status-code( 304 )
+    )