XMPP query archive by latest messages

6
votes

I'm reading http://xmpp.org/extensions/xep-0313.html to query Ejabberd for messages archived with a certain user.

This is the xml that I'm sending:

<iq type='get' id='get_archive_user1'>
 <query xmlns='urn:xmpp:mam:tmp'>
  <with>user1@localhost</with>
  <set xmlns='http://jabber.org/protocol/rsm'>
   <max>20</max>
  </set>
 </query>
</iq>

I'm receiving the first 20 messages correctly. To request again I'm adding the tag:

<after>(id in element "Last" from last request)</after>

and this also work fine. What I need is to receive the last 20 messages, not the first 20 messages. How can I achieve this?

3
xmppejabberd

3 Answers

12
votes

XEP-0313 Message Archive Management rely on XEP-0059 Result Set Management for pagination.

RSM specification explains how to get the last page in a Result Set:

The requesting entity MAY ask for the last page in a result set by including in its request an empty <before/> element, and the maximum number of items to return.

It means you need to add an empty <before/> element in your result set query.

Here is an example based on XEP-0313 version 0.4 on how to get the last 20 messages in a conversation with a given user. The query limit is defined by the parameter max (it defined the size of the pages). 

<iq type='set' id='q29302'>
  <query xmlns='urn:xmpp:mam:0'>
    <x xmlns='jabber:x:data' type='submit'>
      <field var='FORM_TYPE' type='hidden'>
        <value>urn:xmpp:mam:0</value>
      </field>
      <field var='with'>
        <value>[email protected]</value>
      </field>
    </x>
    <set xmlns='http://jabber.org/protocol/rsm'>
     <max>20</max>
     <before/>
    </set>
  </query>
</iq>
6
votes

You should add an empty <before/> element:

<iq type='get' id='get_archive_user1'>
    <query xmlns='urn:xmpp:mam:tmp'>
        <with>user1@localhost</with>
        <set xmlns='http://jabber.org/protocol/rsm'>
            <max>20</max>
            <before/>
        </set>
    </query>
</iq>

See here.

4
votes

People who would like to use Smack to fetch this can use below code

 public MamManager.MamQueryResult getArchivedMessages(String jid, int maxResults) {

        MamManager mamManager = MamManager.getInstanceFor(connection);
        try {
            DataForm form = new DataForm(DataForm.Type.submit);
            FormField field = new FormField(FormField.FORM_TYPE);
            field.setType(FormField.Type.hidden);
            field.addValue(MamElements.NAMESPACE);
            form.addField(field);

            FormField formField = new FormField("with");
            formField.addValue(jid);
            form.addField(formField);

            // "" empty string for before
            RSMSet rsmSet = new RSMSet(maxResults, "", RSMSet.PageDirection.before);
            MamManager.MamQueryResult mamQueryResult = mamManager.page(form, rsmSet);

            return mamQueryResult;

        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }