Listen for Document And Media view/download events - audit

Question

I want my code to be called everytime someone views or downloads anything in Document And Media:
View:
Download:
The content URLs of the view and download (to which the HTTP response is an actual preview image or PDF itself being transfered) are respectively:
http://localhost:8080/documents/20143/0/invoice_ABC_2017.10.27.pdf/c44fd479-331b-f393-7879-973c5cecf086?version=1.0&previewFileIndex=1
http://localhost:8080/documents/20143/0/invoice_ABC_2017.10.27.pdf/c44fd479-331b-f393-7879-973c5cecf086?download=true
The responses to both requests seems to be built by WebServerServlet.sendFile, a part of Liferay which is unfortunately not an OSGi module.
My first instinct would have been to implement ModelListener, but it only has methods for creation/update/deletion events, nothing for read events.
How to intercept these events in Liferay? (7 EE DXP)

Answer 1

Model listeners are connected to the CRUD operation that can happen on an entity.
You could attach your self to the download action. Have a look here https://dev.liferay.com/develop/tutorials/-/knowledge_base/7-0/converting-strutsactionwrappers-to-mvccommands

Answer 2

Preview
Preview (in the sense of the preview page being displayed by any user) can be intercepted by deploying a component that takes the place of the MVCRenderCommand.class service. To do that, copy Liferay's ViewFileEntryMVCRenderCommand.java and add your code in the render method:
#Component(
property = {
"service.ranking:Integer=100",
"javax.portlet.name=" + DLPortletKeys.DOCUMENT_LIBRARY,
"javax.portlet.name=" + DLPortletKeys.DOCUMENT_LIBRARY_ADMIN,
"javax.portlet.name=" + DLPortletKeys.MEDIA_GALLERY_DISPLAY,
"mvc.command.name=/document_library/view_file_entry"
},
service = MVCRenderCommand.class
)
public class MyViewFileEntryMVCRenderCommand implements MVCRenderCommand {
#Override
public String render(
RenderRequest renderRequest, RenderResponse renderResponse)
throws PortletException {
DoMyAuditThing();
[...]
}
[...]
}
Download
Download (in the sense of a Document and Media being actually downloaded) can be intercepted by creating a Servlet Filter (copied from the Liferay plugin samples) with this liferay-hook.xml configuration:
(UPDATE: Just after writing this code I realized that there is now a better way to write Servlet Filters)
<hook>
<servlet-filter>
<servlet-filter-name>Sample Filter</servlet-filter-name>
<servlet-filter-impl>com.liferay.sampleservletfilter.hook.filter.SampleFilter</servlet-filter-impl>
<init-param>
<param-name>hello</param-name>
<param-value>world</param-value>
</init-param>
</servlet-filter>
<servlet-filter-mapping>
<servlet-filter-name>Sample Filter</servlet-filter-name>
<before-filter>SSO Open SSO Filter</before-filter>
<url-pattern>/documents/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
</servlet-filter-mapping>
</hook>
Note the <url-pattern>/documents/*</url-pattern> part.
The Filter class:
public class SampleFilter implements Filter {
#Override
public void doFilter(
ServletRequest servletRequest, ServletResponse servletResponse,
FilterChain filterChain)
throws IOException, ServletException {
String uri = (String)servletRequest.getAttribute(
WebKeys.INVOKER_FILTER_URI);
// Extract information
String[] tokens = uri.split("/");
if(tokens.length < 6) {
System.out.println("Failed to parse download URI (Too few slashes): " + uri);
filterChain.doFilter(servletRequest, servletResponse);
return;
}
long groupId;
try {
groupId = Long.parseLong(tokens[2]);
}
catch(NumberFormatException e) {
System.out.println("Failed to parse download URI (Group not a number): " + uri);
filterChain.doFilter(servletRequest, servletResponse);
return;
}
String uuid = tokens[5];
System.out.println("group:" + groupId + " uuid:" + uuid);
DLFileEntry fileEntry = DLFileEntryLocalServiceUtil.fetchDLFileEntryByUuidAndGroupId(uuid, groupId);
// Send it to your audit
[...]
filterChain.doFilter(servletRequest, servletResponse);
}
}
A problem is that it seems to also catch unnecessary events when showing the Document and Media page... I investigate.

Answer 3

You could implement the Service Wrapper and in particular the getFile method. This method it’s called when the user request the download of the file.