XEP-0329: File Information Sharing

4.1 Traversing Files¶

If a requesting entity wishes to know what files are being shared by an offering entity, it can do so by sending the following query:

<iq type='get'
    from='juliet@capulet.com/chamber'
    to='romeo@montague.net/home'
    id='1234'>
  <query xmlns="urn:xmpp:fis:0" />
</iq>

If the offering entity wishes to share files with the requesting entity, it may respond with a list of shared folders. It MUST not include any files in this response.

<iq type='result'
    from='romeo@montague.net/home'
    to='juliet@capulet.com/chamber'
    id='1234'>
  <query xmlns="urn:xmpp:fis:0">
    <directory name='documents'/>
    <directory name='pics'/>
    <directory name='audio'/>
  </query>
</iq>

if the offering entity has no files to offer

<iq type='result'
    from='romeo@montague.net/home'
    to='juliet@capulet.com/chamber'
    id='1234'>
  <query xmlns="urn:xmpp:fis:0" />
</iq>

Requesting the list of files and directories within a directory.

<iq type='get'
    from='juliet@capulet.com/chamber'
    to='romeo@montague.net/home'
    id='1235'>
  <query xmlns="urn:xmpp:fis:0" node="documents" />
</iq>

When replying with a list of files, the offering entity can choose to either reply with verbose information on the file using the file attributes defined by Jingle File Transfer (XEP-0234) [1] or it may reply only with the 'name' attribute, which is required and MUST be included in every response.

It is RECOMENDED, when the list files to be sent is small, that a verbose response be made (in order to avoid going back and forth requesting information), and that a non-verbose reponse be made otherwise. This recomendation is made to save bandwidth.

<iq type='result'
    from='romeo@montague.net/home'
    to='juliet@capulet.com/chamber'
    id='1235'>
  <query xmlns="urn:xmpp:fis:0" node="documents">
    <file xmlns='urn:xmpp:jingle:apps:file-transfer:4'>
      <name>test.txt</name>
      <date>1969-07-21T02:56:15Z</date>
      <desc>This is a test. If this were a real file...</desc>
      <range/>
      <size>1022</size>
      <hash xmlns='urn:xmpp:hashes:1' algo='sha-1'>552da749930852c69ae5d2141d3766b1</hash>
    </file>
    <file xmlns='urn:xmpp:jingle:apps:file-transfer:4'>
      <name>test2.txt</name>
    </file>
    <directory name="secret docs" />
  </query>
</iq>

If the requesting entity wants to get detailed information about a file. It can do so by providing its full path.

<iq type='get'
    from='juliet@capulet.com/chamber'
    to='romeo@montague.net/home'
    id='1236'>
  <query xmlns="urn:xmpp:fis:0" node="documents/test2.txt" />
</iq>

<iq type='result'
    from='romeo@montague.net/home'
    to='juliet@capulet.com/chamber'
    id='1236'>
  <query xmlns="urn:xmpp:fis:0">
    <file xmlns='urn:xmpp:jingle:apps:file-transfer:4'>
      <name>test2.txt</name>
      <size>1000</size>
    </file>
  </query>
</iq>

5.1 Using Result Set Management¶

Result Set Management (XEP-0059) [4] defines a way of limiting the results of a request. There are some considerations to use result sets along with this extension.

First, it is defined that the requesting entity is the one that sets the limit of the number of items that can be replied. So it is up to the requesting entity to choose a sensible number.

Second, since this protocol defines a way of handling the directory tree structure by allowing file tags to be children of a directory tags, it becomes difficult to define items for Result Set Management. Therefore, when responding to a request, the offering entity MUST NOT send directory tags with files as their children.

5.2 Out of Band Transfer¶

One obvious way to overcome the limitations of sending large stanzas in-band, is to transfer that information out of band. Out-of-Band Stream Data (XEP-0265) [5] could be used for that purpose. It is hereby RECOMMENDED its implementation when the offering entity has a massive amount of files that would not be practical to advertise in-band.

It is further recommended that when using XEP-0265, the entire directory structure, along with all the files in the shared folder and subfolders, be exchanged in one single reply. Also, all the files attributes should be included. This is to avoid wasting bandwidth initiating out of band streams going back and forth.

6.1 File identification¶

As it was previously discussed, when requesting detailed information about a file, only the "name" attribute is required, but it is strongly RECOMMENDED that the hash attribute be included, in order to reduce the chances of sending the wrong file. When requesting the file to be transferred using Jingle File Transfer (XEP-0234) [1], the information that must be provided has to identify the file uniquely. It is then RECOMMENDED that when requesting a file, the full path of the file in the shared folder be included in the "name" attribute.

<iq type='get'
    from='juliet@capulet.com/chamber'
    to='romeo@montague.net/home'
    id='1237'>
  <jingle xmlns='urn:xmpp:jingle:1'
          action='session-initiate'
          initiator='juliet@capulet.com/chamber'
          sid='uj3b2'>
    <content creator='initiator' name='a-file-request' senders='responder'>
      <description xmlns='urn:xmpp:jingle:apps:file-transfer:4'>
        <file>
          <name>pics/test4.png</name>
          <size>10740</size>
        </file>
      </description>
    </content>
  </jingle>
</iq>

6.2 File Sharing in MUCs¶

For the most part, discovering files in a MUC is exactly the same as what has been described in this document. However, it is RECOMMENDED that a participant in a MUC should have a single shared folder associated with the entire room, as opposed to advertise different files to different participants of the room. This is to reduce the complexity of the client software. Also, due to volatile nature of the participants in a room, keeping track of permissions is more trouble than what it is worth.

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1. XEP-0234: Jingle File Transfer <https://xmpp.org/extensions/xep-0234.html>.

2. XEP-0096: SI File Transfer <https://xmpp.org/extensions/xep-0096.html>.

3. XEP-0135: File Sharing <https://xmpp.org/extensions/xep-0135.html>.

4. XEP-0059: Result Set Management <https://xmpp.org/extensions/xep-0059.html>.

5. XEP-0265: Out-of-Band Stream Data <https://xmpp.org/extensions/xep-0265.html>.