=Paper=
{{Paper
|id=None
|storemode=property
|title=Xodx - A node for the Distributed Semantic Social Network
|pdfUrl=https://ceur-ws.org/Vol-1272/paper_154.pdf
|volume=Vol-1272
|dblpUrl=https://dblp.org/rec/conf/semweb/ArndtT14
}}
==Xodx - A node for the Distributed Semantic Social Network==
https://ceur-ws.org/Vol-1272/paper_154.pdf
Xodx
A node for the Distributed Semantic Social Network
Natanael Arndt and Sebastian Tramp
Universität Leipzig, Institut für Informatik, AKSW,
Postfach 100920, D-04009 Leipzig, Germany
{arndt|tramp}@informatik.uni-leipzig.de
1 Introduction
The world wide web (WWW) is not anymore just an information retrieval sys-
tem [1] but rather an interactive communication medium. Within the last decade
online social networks have evolved and constantly increased in popularity. The
currently most used online social network services, according to their estimated
monthly active users1 , are Facebook (1.27 billion, facebook.com), Google Plus
(541 million, plus.google.com) and Twitter (283 million, twitter.com). Com-
pared to the estimated total users of the WWW of 2.93 billion, over 40 % of the
users of the WWW are actively using Facebook. This concentration on some
single services contradicts the actual organisation of the WWW and the whole
Internet as a network of decentrally organised and interconnected computer
nodes. This situation bears risks regarding the privacy, data security, data own-
ership, reliability of the services and freedom of communication. By building up
a distributed online social network with multiple interconnected services this
risks can be minimised and a much more flexibly expendable network is created.
We present Xodx (http://aksw.org/Projects/Xodx, includes a live demo)
an implementation of a node for the Distributed Semantic Social Network
(DSSN). The DSSN is a general architecture for building an online social network
using Semantic Web standards and additional protocols for real-time communi-
cation. Xodx provides functionality for publishing and editing personal profiles,
adding friends to the friend list, sending and receiving friendship requests, pub-
lishing posts and following other users activities across distributed nodes.
2 Node Intercommunication and Integration in the Web
The complete architecture for the DSSN is proposed in „An Architecture of
a Distributed Semantic Social Network“ [2]. It combines established Web 2.0
technologies i.e. (Semantic) Pingback [3] (Ping) and Activity-Streams published
through PubSubHubbub (PuSH)2 with an RDF data model and the Linked Data
protocol [4]. The consequent use of RDF facilitates the integration of heteroge-
neous data in the data model. By using the Linked Data protocol the DSSN is
1
as estimated on Internet Live Stats: internetlivestats.com, July 13th 2014
2
PubSubHubbub: https://code.google.com/p/pubsubhubbub/
easily integrated with any other Semantic Web application and thus facilitates an
extendable infrastructure. This enables us to build up a completely distributed
network of data and services, which is highly integrated and embedded in the
Web of Data and WWW.
announce 3a ping 3b
Ping
6b notify 6a
publish 2c
5c notify subscribe
subscribe 4b 5a & publish
PuSH PuSH
subscribe 4a
Hub
5b update update 5b
Other DSSN nodes
announce 2b
Notification
Application
Component
Activity
Manager
Sharing
Profile
Streams
read (get) 7
Feeds
announce 2a
create & WebIDs
update 1
Data & Media
Artefacts
Resources
Figure 1. Architecture of an Xodx node and intercommunication between nodes on
the DSSN. [5]
The architecture of the Xodx implementation and the intercommunication
with other nodes is depicted in fig. 1. The profile manager is used for editing the
WebID and adding new friendship relations, it creates and updates the according
resources and activity streams (1). Similarly, the sharing application can be used
for sharing media artefacts and web resource. Updates of the WebID or any other
data or media artefact are announced (2a) by updating the activity stream,
which is then announced to the PuSH service (2b), which in turn publishes the
updates to the PuSH hub (2c). In parallel this change is announced to the Ping
component (3a), which sends a ping to each resource which is mentioned in the
update (3b). With the PuSH service a user can be subscribed to any activity
stream on the DSSN (4a, 4b), which implements a follow functionality. If the
PuSH hub receives a new update announcement from any DSSN node (publish,
5a) it will update all nodes, which are subscribed to the according resource
stream (5b). The PuSH service of the Xodx node will then notify the according
components (5c). When the ping service receives a new ping (6a) it will call
the notification component to generate a new user notification (6b). If other
nodes (or any Linked Data application) browses the DSSN the activity streams,
data & media artefacts and any RDF resource can be retrieved via standard
HTTP-GET-requests (7) according to the Linked Data principle.
Figure 2. Screenshot and feature demonstration of Xodx
Figure 2 shows the home-screen of a logged-in user, it is organised in three
main parts, the top navigation bar, the button and friend-list bar to the right
and the main part with activity stream in the middle. All other resource-views
are organised very similar to the user’s home-screen. The top navigation bar
from left to right has a home button for the user, which also indicates if new
notifications are available. A button to navigate to the list of profiles, available
at the current node. The profile editor enables the user to edit any triple of her
WebID. The right most button is for log-out.
On the right hand side one can view the Activity Feed of the current displayed
resource by clicking on “Show Activity Feed”. If the profile of a person different
from the current user is displayed, an additional button “Add {name} as Friend”
is displayed, to add a friendship relation to the own profile, send a ping to the
respective person for notification and subscribe to his activity stream for updates.
Below the buttons one can find the friend list. It contains a field for adding a
new friend using its WebID-URI and a list of existing friendship relations. By
clicking on the individual entries the user can browse the profiles and further
navigate to the friends of their friends. If the browser reaches a resource, which
is not yet available in the local triple store, it is retrieved according to the Liked
Data principles.
The central part shows the picture and the name of the current user, current
notifications and the sharing application with activity stream. If a new friend
request is send to the node or if the user was mentioned in a post, a new notifi-
cation is generated and displayed in the notification section to inform the user.
Using the sharing application a user can create and share new posts, web re-
sources or photos with his subscribers via PuSH. The activity stream displayed
at the very bottom is a combined stream of the personal stream of the user and
all activity streams she is subscribed to. With the two buttons to the right of
the activity entry a user can generate a reply resource answering to this activity
resource and view the activity feed of this resource, which includes all its replies.
3 Prospect and Future Work
The Xodx implementation demonstrates the feasibility of a semantic social net-
work build by distributed nodes. It already supports the main features of building
friendship relations and sharing resources across the network. Currently some
further features for supporting the work in groups are planed. The practical tests
with multiple nodes already pointed out the usage of the PubSubHubbub proto-
col as a limiting factor. Currently only a few hub implementations are available
and effectively the google reference implementation and instance is the only us-
able hub. So we are trying to substitute the federation protocol with a Linked
Data and Semantic Pingback protocol. But due to the Linked Data nature of
the DSSN we have seen, that it is easy to integrate this social network architec-
ture with any application or data-set on the Web of Data. Possible applications,
which can benefit from the semantic integration with the social network are e.g.
collaborative-wikis, web-logs or personal information management systems. This
concept will give us new opportunities for integrating social functionality in any
web application and thus extend the social web to the whole Internet rather
than some big closed nodes.
References
1. Berners-Lee, T., Cailliau, R., Groff, J.F., Pollermann, B.: World-Wide Web: The
Information Universe. Electronic Networking: Research, Applications and Policy
2(1) (1992) 52–58
2. Tramp, S., Frischmuth, P., Ermilov, T., Shekarpour, S., Auer, S.: An Architecture
of a Distributed Semantic Social Network. Semantic Web Journal Special Issue
on The Personal and Social Semantic Web (2012)
3. Tramp, S., Frischmuth, P., Ermilov, T., Auer, S.: Weaving a Social Data Web with
Semantic Pingback. In Cimiano, P., Pinto, H., eds.: Proceedings of the EKAW 2010
- Knowledge Engineering and Knowledge Management by the Masses; 11th October-
15th October 2010 - Lisbon, Portugal. Volume 6317 of Lecture Notes in Artificial
Intelligence (LNAI)., Berlin / Heidelberg, Springer (October 2010) 135–149
4. Berners-Lee, T.: Linked Data. Design issues, W3C (June 2009) http://www.w3.org
/DesignIssues/LinkedData.html.
5. Arndt, N.: Xodx – Konzeption und Implementierung eines Distributed Semantic
Social Network Knotens. Master’s thesis, Universität Leipzig, Fakultät für Mathe-
matik und Informatik, Institut für Informatik (June 2013)