0045559: AppCacheManifest request should return 304 http code if it did not change

diff --git a/src/org/openbravo/retail/posterminal/ApplicationCacheComponent.java b/src/org/openbravo/retail/posterminal/ApplicationCacheComponent.java
index 9e5463afb..735b816ac 100644
--- a/src/org/openbravo/retail/posterminal/ApplicationCacheComponent.java
+++ b/src/org/openbravo/retail/posterminal/ApplicationCacheComponent.java
@@ -22,11 +22,15 @@ import java.util.ArrayList;
 import java.util.List;
 
 import javax.enterprise.context.RequestScoped;
+import javax.inject.Inject;
 
+import org.apache.commons.codec.digest.DigestUtils;
+import org.openbravo.client.kernel.StaticResourceProvider;
 import org.openbravo.dal.core.OBContext;
 import org.openbravo.dal.service.OBCriteria;
 import org.openbravo.dal.service.OBDal;
 import org.openbravo.mobile.core.MobileCoreApplicationCacheComponent;
+import org.openbravo.mobile.core.MobileCoreConstants;
 import org.openbravo.retail.posterminal.utility.OBPOSPrintTemplateReader;
 
 /**
@@ -37,6 +41,9 @@ import org.openbravo.retail.posterminal.utility.OBPOSPrintTemplateReader;
 @RequestScoped
 public class ApplicationCacheComponent extends MobileCoreApplicationCacheComponent {
 
+  @Inject
+  private StaticResourceProvider resourceProvider;
+
   @Override
   public List<String> getAppList() {
     // TODO: review this list: is it needed to be hardcoded?
@@ -100,6 +107,31 @@ public class ApplicationCacheComponent extends MobileCoreApplicationCacheCompone
     return resources;
   }
 
+  @Override
+  public String getETag() {
+    final String appNameKey = getAppNameKey();
+    if (resourceProvider.getStaticResourceCachedInfo(appNameKey) == null) {
+      // do something unique
+      return String.valueOf(System.currentTimeMillis());
+    } else {
+      // compute the md5 of the cached content
+      return DigestUtils.md5Hex(resourceProvider.getStaticResourceCachedInfo(appNameKey));
+    }
+  }
+
+  private String getAppNameKey() {
+    return getApplicationName() + "_" + MobileCoreConstants.APP_CACHE_COMPONENT;
+  }
+
+  @Override
+  public String generate() {
+    final String content = super.generate();
+    if (!isInDevelopment()) {
+      resourceProvider.putStaticResourceCachedInfo(getAppNameKey(), content);
+    }
+    return content;
+  }
+
   @Override
   public String getAppName() {
     return POSConstants.APP_NAME;