Customize Link Processing

Introduction

Goal

Customize how internal links are processed in Bloomreach Experience Manager's delivery tier.

Background

Bloomreach Experience Manager is a content-oriented system and therefore its delivery tier must map documents to pages in asitemap.Internal links within a site are created and resolved using this mapping. This process of creating and resolving links provides an extension point through the HstLinkProcessor interface. By implementing this interface developers can pre-process and/or post-process internal links.

HstLinkProcessor

The org.hippoecm.hst.core.linking.HstLinkProcessor interface defines two methods:

• HstLink postProcess(HstLink link)
  Called after the delivery tier creates a link through org.hippoecm.hst.core.linking.HstLinkCreator.

• HstLink preProcess(HstLink link)
  Called before the delivery tier matches a link through org.hippoecm.hst.core.request.HstSiteMapMatcher.

The delivery tier uses a chain of link processors. Any number of custom link processors can be added to the chain through Spring configuration (see example below).

Example

Use Case

Consider a projectcreated from the Bloomreach Experience Manager Maven archetype with the Simple Content featureadded.

Documents of typemyproject:contentdocument are stored in the repository folder/content/documents/myproject/content.

These documents are mapped to a URL and page template through the following sitemap items:

/hst:myproject/hst:configurations/myproject/hst:sitemap:  /content:    jcr:primaryType: hst:sitemapitem    hst:componentconfigurationid: hst:pages/contentlist    hst:relativecontentpath: content    /_any_.html:      jcr:primaryType: hst:sitemapitem      hst:componentconfigurationid: hst:pages/contentpage      hst:relativecontentpath: ${parent}/${1}

As a result, a document /content/documents/myproject/content/sample-document would be available at the URLhttp://localhost:8080/site/content/sample-document.html.

Now suppose you organize your simple content documents using subfolders with names corresponding to the first character of the names of documents inside them. For example:

/content/documents/myproject:  /content:    jcr:primaryType: hippostd:folder    /a:      jcr:primaryType: hippostd:folder      /about-hippo:        jcr:primaryType: hippo:handle      /archetype:        jcr:primaryType: hippo:handle    /b:      jcr:primaryType: hippostd:folder      /best-practices:        jcr:primaryType: hippo:handle      /big-hippo:        jcr:primaryType: hippo:handle    /c:      jcr:primaryType: hippostd:folder      /code-formatting:        jcr:primaryType: hippo:handle      /create-project:        jcr:primaryType: hippo:handle

This means that these documents will be available at URLs like http://localhost:8080/site/content/a/about-bloomreach.html,http://localhost:8080/site/content/b/best-practices.html etc.

However your requirements state that the URLs should not contain the subfolder name and look like http://localhost:8080/site/content/about-bloomreach.html,http://localhost:8080/site/content/best-practices.html etc.

This is a typical use case for a custom link processor.

Solution

The solution is to implementorg.hippoecm.hst.core.linking.HstLinkProcessor as follows:

• For any link created with a relative path starting withcontent/,  e.g.content/a/about-bloomreach, remove the subfolder path element (a/) so it becomes e.g. content/about-bloomreach and meets your URL requirements.
• For any link matched in the sitemap with a relative path starting withcontent/, e.g.content/about-bloomreach, add the subfolder path element based on the first character of the path element followingcontent/, so it becomes e.g.content/a/about-bloomreach and matches the relative content path of the document.

Implementation

HstLinkProcessor Implementation

site/components/src/main/java/org/example/ExampleHstLinkProcessor.java

package org.example;import java.util.regex.Matcher;import java.util.regex.Pattern;import org.hippoecm.hst.core.linking.HstLink;import org.hippoecm.hst.linking.HstLinkProcessorTemplate;public class ExampleHstLinkProcessor extends HstLinkProcessorTemplate {    @Override    protected HstLink doPostProcess(HstLink link) {        String path = link.getPath();        if (path.startsWith("content/")) {            String pattern = "(content/)./(.+)";            Pattern r = Pattern.compile(pattern);            Matcher m = r.matcher(path);            if (m.find()) {                path = m.replaceAll("$1$2");                link.setPath(path);            }        }        return link;    }    @Override    protected HstLink doPreProcess(HstLink link) {        String path = link.getPath();        if (path.startsWith("content/")) {            String pattern = "(content)(/.)(.?)";            Pattern r = Pattern.compile(pattern);            Matcher m = r.matcher(path);            if (m.find()) {                path = m.replaceAll("$1$2$2$3");                link.setPath(path);            }        }        return link;    }}

Spring Configuration

site/components/src/main/resources/META-INF/hst-assembly/overrides/customLinkProcessors.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.1.xsd">  <bean>    <property name="processorsInChain">      <list>        <bean />      </list>    </property>  </bean></beans>