Web-hook Example to Invalidate Cache

Introduction

By default, the ResourceResolver component for demo product catalogs data in the demo project caches result data based on resource space name, operation name, relative resource path, path variables, etc. for 1 minutes ("time-to-live"). So, for the same requests, it will return the cached data without having to invoke the backend REST service again as long the the cached data was not expired in 1 minutes ("time-to-live").

Suppose you want to increase the "time-to-live" internal to maximize cacheability, but you also want to invalidate the whole cache or part of the cache if there's any change occurred in the backend by invoking your custom "Web-Hook" URL. "Web-Hook" is very useful in this scenario to maximize efficiency and performance.

Simple Web-Hook Page Example

The example "Web-Hook" in the demo project, invalidate-cache.jsp, was implemented in most simplified way intentionally for demonstration purpose like the following. But you will realize how easy to implement a "Web-Hook" in a page, servlet or whatever.

You can invoke the demo "Web-Hook" page like the following with the two POST parameters (one to specifiy the target resource space name and the other for "secret" for minimal security):

$ curl http://localhost:8080/site/examples/invalidate-cache.jsp \
    -d "resource_space=demoProductCatalogs&secret=some_secret"

The example "Web-Hook" page is very simple like the following. It simply invokes ResourceServiceBroker#getResourceDataCache(resourceSpace).clear() in the end.

<%--
  Simple ResourceDataCache invalidation example for a resource space.
  This simple JSP page reads two post request parameters, "resource_space" and "secret",
  and clears the associated ResourceDataCache specified by the "resource_space" parameter value.
  For simplicity, this page compares the "secret" parameter with a hard-coded secret string for security.
  In practice, you will probably want to keep the secret in a different store for security, maintainability, etc.
--%>
<%@ page language="java" %>
<%@ page import="javax.servlet.http.HttpServletResponse" %>
<%@ page import="org.slf4j.LoggerFactory" %>
<%@ page import="org.slf4j.Logger" %>
<%@ page import="org.onehippo.cms7.crisp.api.broker.ResourceServiceBroker" %>
<%@ page import="org.onehippo.cms7.crisp.api.resource.ResourceDataCache" %>
<%@ page import="org.onehippo.cms7.crisp.hst.module.CrispHstServices" %>
 
<%!
private static final String DEFAULT_SECRET = "some_secret";
 
private static Logger log = LoggerFactory.getLogger("org.onehippo.cms7.crisp.demo.jsp.invalidate-cache");
%>
 
<%
if (!"POST".equals(request.getMethod())) {
    log.error("Must be a POST request.");
    response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
    return;
}
 
String resourceSpace = request.getParameter("resource_space");
String secret = request.getParameter("secret");
 
if (resourceSpace == null || "".equals(resourceSpace.trim())) {
    log.error("Resource space name is missing.");
    response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
    return;
}
 
if (!DEFAULT_SECRET.equals(secret)) {
    log.error("Wrong secret.");
    response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
    return;
}
 
ResourceServiceBroker broker = CrispHstServices.getDefaultResourceServiceBroker();
 
if (broker == null) {
    log.error("CRISP was not initialized.");
    response.setStatus(HttpServletResponse.SC_NOT_FOUND);
    return;
}
 
ResourceDataCache resourceDataCache = broker.getResourceDataCache(resourceSpace);
 
if (resourceDataCache == null) {
    log.error("No resource data cache for the resource space.");
    response.setStatus(HttpServletResponse.SC_NOT_FOUND);
    return;
}
 
log.info("Resource data cache cleared for resource space: '{}'", resourceSpace);
resourceDataCache.clear();
out.println("Resource data cache cleared for resource space: '" + resourceSpace + "'.");
%>