A Publication Aggregation System Using Semantic
Blogging
Aman Shakya1, Hideaki Takeda2, Ikki Ohmukai2, Vilas Wuwongse 1
1

Asian Institute of Technology, Klong Luang, Pathumthani
12120, Thailand{aman.shakya@ait.ac.th, vw@cs.ait.ac.th}2
National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku,
Tokyo, 101-8430, Japan{takeda, i2k}@nii.ac.jp

Abstract. Researchers need to share information about their publications. They
also desire to share opinions and comments about each other’s publications.
The paper describes a system which demonstrates how semantic blogging canbe used for the purpose. The SWRC ontology has been incorporated in the
blogging system for entering the metadata of publications. The semantic
blogging system provides means to annotate publications. The system is adecentralized publication aggregation system. It utilizes the RSS technology toaggregate posts. The publication metadata is embedded in the RSS to produce
BuRST feed. The RSS aggregator has been extended to handle the BuRST
feeds. The system uses the FOAF links of the authors and friends to explore thesocial network of the research community for aggregation of relevant
information.

1 Introduction
In research communities there is always need of posting and sharing information
about publications. The bibliographic information about publications should follow
some standard metadata schema for being machine processable and interoperable.
SWRC (Semantic Web for Research Communities) [1] is an ontology for modelingentities of research communities such as persons, organizations, publications(bibliographic metadata) and their relationships. Besides posting structured data aboutpublications, there is often need of posting comments or annotations about the
publications. Blogging can be a mechanism for such purposes. There is need ofsharing information in the community in a decentralized way. It is not feasible forresearchers worldwide to be bound to a single centralized information system.
Publications from various relevant sources need to be aggregated. The researcher
should be able to search required publication information from the postings of thecommunity. The paper describes a publication aggregation system for researchcommunities using semantic blogging.

2 Semantic Blogging
Blog, a short form for weblog, is a publicly accessible web-based publication of
periodic articles, usually in reverse chronological order that often serves as a personal
journal. Blogging makes publishing information on the web very easy, unlike web
sites which involve much more elaborate plan and technical effort. It can be a
powerful tool for establishing and maintaining an online community [2,3]. Blogs areuser-oriented providing personal spaces for users on the web. It motivates higher rateof timely information publication. However, filtering, organizing and navigating
through the blogosphere are a challenge in traditional blogging [2].
Semantic blogging is a technology that builds upon blogging and adds semantic
structure to the blog items. The blog items are enriched with metadata. Semantic
blogging uses desirable features of both blogging and the Semantic Web to deal withthe challenges of traditional blogging. The semantic web is well suited forincrementally publishing structured and semantically rich information. On the other
hand, the easy publishing nature of blogging can boost the semantic web by
publishing enough data and resources. Semantic blogging can extend blogging from
simple diary browsing to informal knowledge management [2,3].
2.1 Semantic Blogging for Research Communities
Traditionally blog entries are just unstructured passages of text. However, forpublishing information such as about research publications, there is need of somestructure. Semantic blogging provides this. Research publications can be posted
described by standard metadata.
Often blog entries are written about some publication or resource on the web.
Semantic blogging can provide a way to write blog entries as annotations orcomments to other blog entries or publications.
Blogs provide RSS feeds which are understood by RSS readers. The metadata insemantic blogs can be embedded in the RSS feeds. If a standard vocabulary is used
for the metadata, RSS readers can be extended to process the metadata as well.
Ontologies such as SWRC [1] exist for the research community. Semantic blogging
with RSS aggregation forms a powerful web-based decentralized system. Semantic
blogging can offer an easy, lightweight and flexible mechanism for information
publishing, sharing and aggregation for research communities.
Further blogs provide effective mechanisms to foster communities. Blogrolls list
the friends and associates of the blog-owner and connects his/her blog to theirs.
Moreover, hyperlinks, annotations, comments and trackbacks also serve to tightly linkelements in the community.

3 Relevant WorkA semantics based publication management system using RSS and FOAF has been
described in [4]. The application collects information in BibTex format from several
locations and information about people by crawling FOAF files. All the information isstored in RDF format in a central store. The SWRC ontology has been used. The
shortcoming of the system is that it is centralized. We have to access the central
unified store or the web service provided. Besides, the authors still have to write the
BibTex files which is harvested by the system.
Bibster [5] is a peer-to-peer application for sharing bibliographic metadata among
researchers. Bibster also uses SWRC as the application ontology and uses the ACM
topic hierarchy as the domain ontology for classification of metadata entries. Bibsteris decentralized and doesn’t require the authors to produce BibTex files. However, thesystem is limited to a peer-to-peer network. Blogs make a wide community on the
web instead of being restricted to a peer network. Like peer-to-peer systems blogging
can also be decentralized. Moreover, blogging supports commenting.
The Semantic Blogging Demonstrator1 developed by HP labs as a part of the
Semantic Web Advanced Development-Europe (SWAD-E) project also uses thebibliographic domain [2,3]. The blog entries and bibliographic items have beenmodeled as different things. The fact that the blog entry annotates the bibliographic
item has been modeled by a ‘contains’ property. Blog entries contain bibliographic
items [3]. The demonstrator offers semantic navigation, view and query capabilities.
The system also provides a metadata import facility - SemBlogIT! It provides a way
to attach items to blog entries and a category chooser functionality also. The
implementation of the RDF store is a single file containing metadata for all blog
items. The system is centralized and doesn’t offer cross-blog data aggregation.
The semantic blogging system described in [6] is based on egocentric methods.
The closeness between the contents is determined by the distance between authors on
the human network. The project extends the concept of RSS to describe metadata likeinter-site relation. The metadata has been called “RDF Content Summary (RCS)”.
RCS uses additional modules for ordinary hyperlinks and trackbacks. The personal
publishing suite [7] consists of two software – “RNA” and “glucose”. RNA is a web
application which subscribes RSS files and builds a site tree based on RDF. Glucose
is a standalone RSS aggregator.
BuRST. BuRST (Bibliography Management using RSS Technology) [8] is alightweight specification for publishing bibliographic information using RSS 1.0 andbibliography-related metadata standards. The specification defines guidelines about
how to use existing vocabularies instead of defining additional vocabulary. An RSS
module for bibliographic items has been defined using the SWRC and FOAF
ontologies. The SWRC ontology should be used to provide metadata about the
publication. It is recommended to use the FOAF vocabulary to provide detailed
descriptions of persons related to publications.

1 http://www.semanticblogging.org/semblog/blog/default/

4 Requirements and Design
The requirements of the system are based on the needs of research community as
pointed out in the introduction. These can be summarized as below.
• Users should be able to post blog entries and metadata about publications
easily from anywhere on the web.
• It should be possible to post blog entries as comments or annotations to otherpublications or entries.
• The system should be fully decentralized as ordinary blogging systems.
• The system should be able to aggregate relevant information from multiple
blogs in the community
To meet the above requirements we have the following design policies.
Integration of RDF metadata store with blogs. The existing blogging infrastructureneeds to be supplemented by an RDF metadata store following a standard metadata
schema.
Use of trackbacks and annotations. Trackback facility offered by blogs can beutilized for commenting on posts. Standard blogging tools would be able to trace thetrackback to determine the commenting blog entry. Trackbacks provide backward linkto the commented post. Additionally, an annotation mechanism could be developed tocomment in the forward direction.
Extended RSS. RSS mechanism is well established for the decentralized operation ofblogs. RSS can be extended to incorporate the publication related metadata.
Maintaining compatibility with RSS would allow the system to reap the benefits of
RSS and have interoperability with blogging systems.
Powerful aggregation. Aggregation plays an important role for a decentralized
system like this. Existing aggregation tools can be adapted for the purpose.
Aggregation for the research community can be realized using FOAF links as FOAF
is a popular mechanism for forming communities. Further searching the aggregate canbe done by parsing the RDF metadata.

5 System Architecture

Publishing System

Aggregation System

SWRC
ontology

Aggregate
Search
BuRST
feed

Blogs

RSS
Aggregator

Store

FOAF
Crawler

Publication
metadata
FOAF+
profilesBlogentriesRDF Metadata

OutputFig. 1. System architecture of Semantic Blogging Publication Aggregation System

Fig. 1 shows the architecture of the developed system. The architecture consists of
two sub-systems – Publication system and Aggregation system.
The publication system facilitates the user to publish blog entries and metadata
about publications. The blogs are enriched semantically by using the SWRC ontology
for metadata about publications. The metadata is stored in an RDF metadata store
connected to the semantic blog. BuRST feeds publish the blog contents ininteroperable and machine processable form. The publication system also helps topublish FOAF profiles of the blog-owners.
The decentralized aggregation system uses RSS technology to aggregate
publication data from multiple blogs. FOAF profiles and crawled FOAF links areused to determine appropriate feeds to be aggregated. The aggregated output is shownon the blog interface itself. The aggregate search allows the user to search for
publications and posts by various criteria.
5.1 Publication Metadata and Blog Entry
The publication Metadata follows the SWRC ontology. The semantic blog developed
provides the entry forms for the metadata of different SWRC publications. Fig. 2
shows an example of the metadata entry interface for SWRC article publication type.
The metadata schema has been taken from SWRC expressed in OWL. Additionally,few elements have been added to the schema file to control the GUI of the forms. For
instance, input control for the abstract should be a text area of enough size. The
system provides a lightweight metadata interface to the users, unlike sophisticatedinterfaces of ontology editors.
Blogging has been made convenient by employing javascript bookmarklets. The
bookmarklet has to be saved in the bookmarks list of the browser. If the user wants toblog a web page or a blog entry, he simply clicks the bookmarklet link from thebrowser. The bookmarklet captures the title, URL, and trackback ping URL of thecurrent blog entry which is being annotated. The form for the new blog entry is thenautomatically populated with these items as shown in fig. 3. The trackback ping URL
is discovered if the blog embeds the information about the trackback ping URL in an
RDF snippet as specified in the trackback technical specification by Six Apart [9].
Though some blogging systems provide similar mechanism of easy data import, they
don’t extract the trackback ping URL from the page.

Fig. 2. Metadata entry interface for SWRC article

Blog entries as annotations. The bookmarklet also captures the URL of the current
page so that the user can annotate the URL. The blog entry would be about the URL,
possibly a publication. A trackback ping is also sent to the annotated blog entry if
desired. Traditionally, blogs support trackbacks only and they just act as one way
links. If user A writes a blog entry about a post by B, B receives a trackback from A.
B and the readers of B’s blog know that A has written something related. However,readers of A’s blog do not know that it is related to B’s blog. An annotates element
has been introduced in the RDF metadata to model this action of annotation. Fig. 3
shows the normal blog entry interface where the annotates field can be seen. The
trackback URL is also seen populated in the figure. The annotation is manifested as alink in the blog page as shown in fig. 4. Clicking on the link navigates the user to theannotated blog entry or resource. Fig. 4 shows both a normal blog entry and apublication.

Fig. 3. Normal blog entry interface

5.2 Blogs
Blojsom2 has been used as the blogging platform. It is a Java based open source
software which can host multiple blogs for different users. However, the blogs in thecommunity may be based on any system provided that they produce BuRST feeds [8].
But BuRST feeds are needed only for publication metadata. In fact, the system canaggregate information from any RSS feed.

Fig. 4. The blog interface

5.3 RDF Metadata Store
The metadata about the publications are stored in RDF format in a MySQL databasewith the help of Jena3. Jena is a semantic web framework which can be used tomanipulate RDF and OWL. The use of database for RDF storage can address the
problem of scalability which may occur in systems using a single text file to store all
RDF metadata as in [2,3].The data is stored in the form of RDF triplets. The RDF
metadata points to the concerned blog entry using the permalink of the entry. The

2 http://blojsom.sourceforge.net
3 http://www.hpl.hp.com/semweb/jena.htm

RDF metadata is modeled as description about the permalink. The RDF snippet
shown below is an example metadata for the blog entry at
http://localhost:8080/biblog/blog/default/?permalink=Semantic-Blogging.html
An RDF snippet showing the metadata storage<rdf:Description
rdf:about="http://localhost:8080/biblog/blog/default/?permalink=
Semantic-Blogging.html"><swrc:volume>12</swrc:volume><swrc:keywords>blog, semantic</swrc:keywords><swrc:journal>Journal of Web Semantics</swrc:journal><swrc:author>Eric Miller </swrc:author><swrc:pages>50</swrc:pages><swrc:number>1</swrc:number><swrc:abstract>
This article describes about Semantic Blogging</swrc:abstract><semblog:FOAF_link_of_author>
http://purl.org/net/eric/webwho.xrdf(mailto:em@w3.org)</semblog:FOAF_link_of_author><swrc:type>html</swrc:type><swrc:year>2006</swrc:year><swrc:month>March</swrc:month></rdf:Description>

The blog text is handled by the blogging infrastructure. Blojsom saves the blog text intext files and assigns a permalink to the blog entry which uniquely identifies the blog
entry.
5.4 FOAF Profiles
A web-based interface to maintain the FOAF profile of the blog-owner has been
provided in the blog itself. The information about the blog-owner and his friends ismaintained in a simple readable text file which can be easily understood and updated
by the user. Values from the XFN4 profile are used to define the relation of the blogowner with the persons listed. These relations are mapped into FOAF vocabulary oneto-one. The profile includes the FOAF links of the friends of the blog owner andoptionally their RSS feed URLs. The system publishes the profile on the web in
FOAF syntax. The entries in the FOAF profile are utilized to aggregate RSS feeds as
described later in section 5.6. On the other hand, the list of friends maintained in the
profile also serves as a blogroll for the blog.
5.5 FOAF Crawler
The Elmo scutter5 has been used as a FOAF crawler to find out the FOAF link ofauthors of publications in the research community. The Elmo scutter is a generic RDF
4 http://gmpg.org/xfn/
5 http://www.openrdf.org/doc/elmo/users/index.html

crawler that follows rdfs:seeAlso links in RDF documents. RDF(S) seeAlso is also themechanism used to connect FOAF profiles and thus the scutter allows to collect
FOAF profiles from the Web. The crawler starts crawling from the FOAF profile ofthe blog owner and traces the rdfs:seeAlso links for FOAF links. The rdfs:seeAlso
link is assumed to be a FOAF link if it is an immediate child to a foaf:Person element.
The scutter creates a database of FOAF links of the interlinked community.
While uploading information about publications, the user enters the FOAF links of
the authors also. This can be seen in the input form of fig. 2. To support the user fordata entry, the crawled FOAF database may be searched to find out FOAF links ofauthors in the community. A person is identified by his email address or the
mboxsha1sum (hash of the email address) along with the FOAF link. Elmo also
provides a smusher that merges multiple FOAF profiles of the same person.
5.6 RSS Aggregator
The blogs generate RSS feeds according to the BuRST specification [8]. Fig. 5 showsa part of the BuRST feed generated. Metadata about publications are expressed as
SWRC publication elements in the feed. The authors are embedded as FOAF
elements. These feeds are aggregated by other users on their blogs.
The latest publications and posts by friends of the blog-owner are downloaded
through the feeds and displayed alongside in the blog as shown in fig. 4. Generally,
RSS aggregators are separate standalone applications. However, the system integrates
the RSS aggregator in the blog interface itself. The blog readers have the advantage ofknowing about latest publications of other authors also, relevant to the blog entries.
Further, when a blog entry for a publication is opened, the RSS feeds of the authors of
the publication are downloaded and shown alongside. Thus, relevant posts by theauthors are shown alongside each publication entry. For each aggregated entry, thetitle followed by a collapsible view of the description is shown. For publications, thedescription is generally the abstract. The title has a hyperlink to the concerned blog
entry.
The RSS aggregator makes subscriptions for RSS feeds from the friends’ list of theblog. The FOAF profile, as mentioned in section 5.4, includes FOAF links and RSS
feed URLs of the friends. The RSS feed URL is included in the rss:channel element in
the weblog description as shown in the FOAF snippet below. The rdf:seeAlso elementshows the FOAF link of the person.

An example FOAF snippet<Person rdf:nodeID="n5"><name>Morten Frederiksen</name><weblog><Document rdf:about="http://wasab.dk/morten/blog/"><dc:title>Binary Relations</dc:title><rdfs:seeAlso><rss:channel
rdf:about="http://www.wasab.dk/morten/blog/feed/rdf"/></rdfs:seeAlso></Document></weblog><rdfs:seeAlso
rdf:resource="http://www.wasab.dk/morten/blog/archives/au
thor/mortenf/foaf.rdf"/></Person>
When a single publication entry is opened, the RSS feeds of the authors are only
aggregated. The RSS feed of the author is determined through the FOAF link of theauthor. The FOAF links of authors are entered while posting the publication on theblog as described in section 5.5.
Flock6 RSS aggregator, a java based open source, has been used as the RSS
aggregator. Flock uses subscriptions represented in OPML7 syntax. The appropriate
OPML is produced as the subscription list by our system. Flock uses this to aggregate
feeds and displays the result in the blog. The aggregator downloads the feeds atregular intervals to keep contents up-to-date. The refresh interval can be configured asa setting. Hence, the latest posts are shown in the aggregated list. The Flockaggregator has been extended to handle BuRST feeds. If the RSS feeds are in BuRST
format, publications can be distinguished from other posts and SWRC metadata canbe extracted. The system separates the list of publications and non-publications.
Besides BuRST, the system also supports RSS 1.0, RSS 0.91 and RSS 2.0.

6 http://flock.sourceforge.net
7 http://www.opml.org/

Fig. 5. BuRST feed

5.7 Aggregate Search
The aggregated BuRST feeds can be searched and sorted by SWRC fields like title,
author, type, etc as shown in fig. 6. A web based interface has been provided for the
search. The user can specify the search criteria by entering values in different
metadata fields. If values for multiple fields are specified, logical And operation isdone on the conditions. Only a limited number of attributes have been implemented
for demonstration purpose. However, it would be quite straightforward to extend thesearch interface into a more complete one. The search results can be sorted inascending or descending order by clicking on the headers of different fields. Search isdone by filtering the aggregated RSS feeds according to the search criteria provided
through the web-based form.
The aggregate search is different from the search provided by the blogging system.
The normal search provided by the blogging system does a text search over the entriesof the particular blog. The aggregate search does a metadata based search overmultiple blogs. The feature would be useful to search out desired publications from alarge aggregated collection of RSS feeds.

Fig. 6. Aggregate search of publications

6 Discussion
The work serves the need of research communities to share information aboutpublications and comment on these. Current systems like the publication management
system [4] and the semantic blogging demonstrator [2,3] are centralized. Peer-to-peer
systems like Bibster [5] are limited to a peer network and moreover don’t provide thefacility of commenting. The presented work tries to combine the functionalities ofpublication management systems and semantic blogging systems. Semantic blogging
is suitable for the need of posting both structured bibliographic metadata andunstructured comments or annotations. Further, RSS aggregation mechanism helps topool information from relevant sources and present them on the blog. The presented
work is an attempt to develop a decentralized aggregation system based on semantic
blogging. The system tries to aggregate relevant posts and publications from thesocial network by tracing the FOAF links of co-authors and friends of researchers.
Thus, the system also strengthens the sense of community.

7 Future work
The domain ontology, such as a topic hierarchy, could be incorporated in the blogging
system as a future work. The ontology would help to categorize the blog entries andpublications. Basically, only the publication class has been used from the SWRC. The
full features of the ontology could be utilized in the future. Further, inference could be
employed based on the ontology to deduce useful semantic relations. Another future
work could be collecting information by harvesting of widely existing BibTex files.

Acknowledgement
The authors would like to thank the Asian Institute of Technology, Thailand and the
National Institute of Informatics, Japan to arrange the opportunity for the research.
The support and guidance from professors and colleagues in both the institutes werehighly valuable for conducting the research.

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