Concepts for Web 2.0 Service Integration
Pavel Drášil, Tomáš Pitner
Masaryk University, Faculty of Informatics, Botanická 68a, 602 00 Brno, Czech Republic
Thorsten Hampel, Marc Steinbring
Department of Knowledge and Business Engineering, University of Vienna, Rathausstr. 19/9, A-1010 Vienna, Austria
Keywords: Web 2.0, Service Classification, Mashup, Business Models, License Agreements.
Abstract: Mashups represent – beside the ease-of-use, high interactivity and social networking factors – another
significant phenomenon of Web 2.0. However, this "mashing process" is mostly based upon ad-hoc
approaches and techniques, rather than upon an in-depth analysis of the "mashing potential" of the services.
Therefore, the first goal of this paper is to provide a conceptual foundation for the mashups – to identify
services being typically integrated into mashups, and propose classification criteria forming a "Mash-Tree"
that were subsequently applied to selected services – representatives of each classification category. We
concentrate mainly on mashing of Web 2.0 services; integration in an enterprise environment is behind the
scope of this paper. Secondly, the mashing potential is studied from three perspectives – technical aspects of
mashability, business models for mashups, and potential legal issues concerning services themselves as well
as the data in them. We hope that the proposed mashup conceptualization together with our analysis of
mashability can help to develop future Web 2.0 mashups that not only better meet stakeholders' expectations
but also respect legal terms and are technologically sound.
Although these days the buzzwords “web 2.0” and
“mashup” have become an important topic of
conversation – backed up by many successful
applications, it is hard to find a clear and concise
definition of the latter term. While the term “web
2.0” a.k.a “new net” per se has already been defined
and discussed since the groundbreaking article by
tim o’reilly was published in 2005 (o’reilly, 2005),
the question of what a “mashup” service actually is
remains. What are the underlying services being
“mashed-up”? What are the main factors for a
successful development of mashups? How do they
differ from conventional solutions? And above all,
do they keep their promise to be a flexible service by
communicating via open and usable application
interfaces? Based on a closer research of particular
mashups and services, this article analyses key
elements for a progressive deployment of services in
the new web.
Web services are probably the most widespread
application of the Service Oriented Architectures
(SOA) concept (Alonso et al, 2004). On one hand
they concentrate on building the service-oriented
application architecture using a set of individual
services. At the same time they take advantage of
standardized protocols, formats and interfaces for
communication and information exchange.
There are two substantial new developments
which form an important basis for the idea of service
oriented infrastructures, namely the ability of
services to be self-described using semantic
techniques, and a new culture of offering flexible
service and customized service usage by mashups.
A mashup service or simply mashup can be
defined as a Web Service or application built upon
the integration of other services or data usually
providing a certain added value, contextualization,
or innovation above the integrated services (Merrill,
2006). Due to their variety, we will identify typical
services being mashed-up and provide
a classification of them, creating a “Mash-Tree” (see
Drášil P., Pitner T., Hampel T. and Steinbring M. (2008).
GET READY FOR MASHABILITY! - Concepts for Web 2.0 Service Integration.
In Proceedings of the Tenth International Conference on Enterprise Information Systems - SAIC, pages 160-167
DOI: 10.5220/0001709501600167
Figure 1) – a view of different components for the
successful development of mashups. This
classification is based upon our recent research and
analysis of established mashups. Respecting the
research notes Service Oriented Architectures from
Gartner Group (Gartner, 1996), where SOA was
mentioned first, this article takes both aspects –
business and technology – into consideration to find
concepts for mashups.
Out of the market research we differentiate six major
types of Web 2.0 services which can be divided by
their general interest and focus of the service they
offer. We have selected popular and representative
services from each group and apply the following
classification to them. A distinction is drawn
between creating, sharing, storing and presenting
content as well as between their
coordination/communication and community
Content Creation
Typical services in this area are wikis
, blogs
even online-databases (such as Google Base
) are
enriched with semantic patterns for self-organized
structuring (e.g. tagging) of peer created content.
Contemporary Web 2.0 services also enable text
processing (e.g. Google Docs
) or spreadsheet
calculations (e.g. Zoho
As an orthogonal technology, various services
can be combined with syndication feeds like RSS
(Really Simple Syndication) or Atom that bring
hypertext characteristics to effectively any kind of
Content Sharing
Along with the fundamental ideas of Web 2.0
(O’Reilly, 2005), the added value of user-generated
content is further amplified by its distribution and
online availability. Web 2.0 services offer many
opportunities to share a wide range of media and
documents. We will mention the most prominent
categories as represented by Flickr
or Google
1 or
for photo sharing, Adobe Share
documents, MediaMax
and DivShare
multimedia sharing services, while Slideshare
V3 Solution and Resource Center
are suited to
sharing slide presentations and screencasts.
Each service provides a certain kind of access
management. Open and cooperative group policies
may limit access to online information depending on
the level of publicity or confidentiality. OpenID
and Enterprise Sign On Engine
are examples of
Authentication and Authorization Infrastructures
(AAI) enabling service access via a light-weight
identity service.
Content Storage
In addition to this end-user content sharing, we also
come across services providing generic storage and
data management functionality for other services,
thus contributing to the “web as the platform”. One
of the most successful ones is Amazon S3
acting as
the underlying data storage for many famous data-
heavy services. There are also infrastructural
services analyzing web traffic for maintenance and
marketing purposes, see
or Google
Content Contextualization, Presentation and
These services provide content created by
interacting with other web interfaces for a final
enriched presentation to the user. Thus,
communication via APIs (Application Programming
Interfaces) and customization possibilities form the
added value of these services. Services for
presenting web-based desktops
or geo-referenced
map presentations (like Google Maps
) can be
noted. Individual information retrieval and bundling
are gaining more and more importance these days
which technically means interconnecting services
via their application interfaces. Services like Yahoo!
18 or
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or Dapper
fit into this class. In future these
services will consequently also be provided under
different license models. At present, there are
service providers, e.g. Postini, Inc.
, utilizing
Google Apps API directly in their customers’
infrastructure. Contextualizing data services like
verifying postal codes or ordering numbers from
third party services is a promising next step into
flexible web service integration.
Figure 1: The Mash-Tree shows qualities of Web 2.0
Coordination and Communication
Having started with web-based e-mail services at the
beginning of the Internet era, most e-mail providers
now supply complex communication and
collaboration possibilities. As an example, the
Google service suite, i.e. Google Calendar together
with GMail enhanced by Google Talk as well as the
integration of instant messaging features into Yahoo!
Mail provide an open API-based access. Unlike
complex e-mail infrastructures like Microsoft
Exchange, lightweight web-based collaboration
services (like Zimbra
) are approaching flexible
service interoperability. Typically, they utilize tags
for personal e-mail content structuring. Zimbra’s
special features are its encapsulated modules
(Zimlets) for integrating APIs provided by distinct
client applications.
Communities are playing a decisive role in the
success of the development of Web 2.0 services, as
most of them exhibit a strong network effect and
may even depend on reaching a critical mass
(Hendler & Golbeck, 2007). People with similar
interests and/or common activities use social
networking services such as MySpace
, or even more specialized community
Table 1 depicts services selected from each
classification category.
Table 1: Service Classification Overview.
Content Creation Blogger
Google Docs
Zoho Online Office
Sharing Adobe Share
Picasa Web Albums
Storage Amazon S3
Presentation and
Google Maps
Community Communication GMail + GTalk
Coordination Backpack
Google Calendar
Google Groups
Remember The Milk
Community MySpace
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We will now concentrate on technological, business,
and legal aspects of mashing the Web 2.0 services.
We will show which techniques, protocols, and
formats are predominantly used as well as what
quality of support developers can expect from the
service providers. Finally, we will discuss what
business and legal issues are related to the mashing
development and operating.
3.1 Technological Aspects
Mashing Techniques
Nowadays, many web services are loudly supporting
the principles of Web 2.0. Unfortunately, some of
them are using this fashionable label for marketing
purposes only and are somewhat remote from
implementing its ideas. One of the basic principles
of Web 2.0 – “web as a platform” – is hard to
implement without services offering their
functionality for programmatic access. Our analysis
correlates with another result (Novak & Voigt,
2007) and shows an alarming lack of realization of
Web 2.0 principles, since one third of the services
reviewed have been created for direct usage by
humans only.
Services without an application programming
interface can be (from strictly technological point of
view) accessed using web-scraping techniques, i.e.
analyzing the HTML code of their web interface and
then simulating user actions normally performed in a
web browser. This is, however, unreliable, error-
prone and disputable from a legal point of view.
Mashing on Server or Client
The basic decision developers have to make when
designing a mashup service is whether the code
accessing particular services and combining their
functionality will be run on a server or on client.
Both variants have their advantages and
disadvantages and further elaboration of this
problem is beyond the scope of this article (see
however Ort et al., 2007). What is important here is
that apart from the traditional server-side model,
there are also client-side models in which developers
have very limited possibilities in terms of operations
allowed and available technologies.
Protocols and Formats
The technical realizations of APIs in services that
offer such a possibility differ a lot (cf. Table 2).
However, all APIs except those of instant messaging
and emailing services use HTTP as a communication
protocol. The reasons for this are clear – its
simplicity and the fact that it can easily pass through
firewalls in the Internet.
Table 2: Services, API, and Protocols.
Service Official API
Adobe Share REST
Amazon S3 REST, SOAP
Backpack XML over HTTP
Blogger GData no
Calendarhub no
Clipmarks no
Diigo no
DivShare REST
Google Base GData
Google Calendar GData
Google Docs GData
Google Groups no
MediaMax REST
MySpace no
Picasa Web Albums GData
Remember The Milk REST
SlideShare REST no
Zoho Online Office REST, XML-RPC
Although some services utilize the traditional RPC
(Remote Procedure Call) messaging model in the
form of either SOAP (Simple Object Access
Protocol) or XML-RPC (eXtensible Markup
Language with Remote Procedure Call), the most
popular messaging model today is REST
(Representational State Transfer). The term is,
however, often used in a much looser sense than it
was defined in Fielding (2000), meaning that the
service offers a simple interface transmitting
domainspecific data over HTTP without an
additional messaging layer. The data is transferred in
HTTP responses in various formats including
service-specific XML, JSON (JavaScript Object
Notation), binary data and plain text. For data
retrieval, RSS and ATOM formats are very popular.
In addition to pre-defined RSS/ATOM channels,
services usually provide their users with the
possibility of defining their own channels with data
selected by user-specified criteria.
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Google, one of the major Web 2.0 companies,
developed its own generic protocol for reading and
writing data on the Internet, called GData. It is based
on RSS and ATOM, and allows data updates, too.
Google uses this home-made protocol in all its APIs.
It is not an exception when a service offers more
API variants or even more semantically equivalent
APIs. Service client developers can choose not only
which format they want to receive data in (XML,
JSON etc.), but sometimes also which messaging
model and protocol they want to use (REST, SOAP
or XML-RPC). The two main reasons for this are the
freedom of choice for developers and – especially in
newly established services which are trying to attract
users away from competitive services – copying the
API of some rival service in order to make the
transition between services easier
(e.g. offers API).
The relationship between technology
standardization and service „mashability“ is depicted
in Figure 2.
Developer Support
The basic support for service client developers is
API documentation. This can be found in a variety
of forms and extents with every service offering a
public API. Some services go even further and
provide libraries, which facilitate the use of their
API in specific programming environments (Java,
JavaScript, PHP, Ruby, or .NET). Where no library
is officially provided, there are third-party libraries
which can do the job. “Third party” usually
represents some enthusiastic service user(s).
Figure 2: Technological Standards and Integration.
Authentication and Authorization
Services often require client applications developers
to request an “API key” that uniquely identifies
every client application when accessing the service
through its API. This allows services to set limits to
the usage of their API (e.g. to one query per second
or 1,000 queries per day for a registered application,
as SlideShare does). Such limits are not an issue for
single-user applications but this is quite a rare case
in the “web as a platform” environment. For multi-
user applications such limitations can be a serious
3.2 Business Aspects
When the understanding of the “Web Service“
concept in general is only of a technical nature (as
described in the last section), the counterpart in an
economic sense is service supply and demand.
Mashups can be seen as a specific combination of
existing services that bring a particular added value.
This combination is more than just technical services
and their interaction with each other. Repercussions
also occur for the non-technical service in general.
For instance, the popular service “Google Maps” can
be found in other solutions integrating (geo)spatial
information such as Trulia
. It presents information
which is enriched with governmental and private
data collections. But what are the essential elements
of successful acceptance?
Out of our survey on well-established mashups,
their success can be seen in their implementing of
the following basic conditions. It is a combination of
access to information, semantic enrichment and
individuality of the service (see Figure 3).
Access to Available Information
A necessary precondition for flexibly usable services
is the access to primary sources of information. The
newly created service has access to the primary
source’s data, e.g. purchasing power in relation to
the geographical area based on public surveys.
Besides free access to data, which is in most cases
owned by the government, some service providers
have become specialists in private information
collections, like Navteq
or Claritus
, where access
costs money in the majority of cases.
Value-added Semantic Combination
The success of mashed-up services is based on an
easy way of combining and consolidating existing
information in order to create a new value. The
popularity of services like Yahoo Pipes (addressing
different APIs for a customized search) or Microsoft
Popfly (customizing an API-controlled Web
Desktop), or even a general-purpose IBM Mashup
ICEIS 2008 - International Conference on Enterprise Information Systems
Starter Kit
is based on that advantage. A good
example showing the power of new forms of
mashed-up services is given by Placebase, Inc.,
a company presenting detailed information based on
geo-referenced statistical combination, like a census
or neighbourhood data.
Generating an Individualized Service
Mashing data or information into a meaningful
service requires a focus on customers. Firstly, the
presentation of emerging information out of the
user’s demand is a necessary condition for success.
Mashups must aim at an individual composition of
services to present this information. Secondly,
influenced by a specific “culture” of both, offering
and using services, the attitude of a long-term
balance between taken and given is reached by
allocating web access to the public. In fact, the
success of Google Maps is a result of this attitude.
This diversity of so-called “open web services” will
lead to a customized use of services and a more
accurate settlement of demand again. Deriving from
this fact, a third step can be seen in the flexibility of
the underlying business model. It contains adaptable
license agreements and legal terms of use depending
on the contextualized usage.
Figure 3: Success Factors for a Mashup Service.
In combination with innovative techniques these
business-related principles of the new web are
promising advantages for a Web 2.0 era, see
Figure 3.
3.3 Legal Issues
Each of the services reviewed here, except one
(, provides its users with a document
named “terms of use” or “terms of service” (ToS),
even if it is not obviously visible for the user in
every case. The style of licensing documents ranges
from a list of clear and simple explanations to
complex documents spanning 10 or more printed
pages. The latter is typical especially for services
provided by larger companies (Google, Yahoo etc.).
Some services are aware of this difficulty and
provide users with a simplified version of their ToS,
explaining selected aspects in a more
comprehensible way. Google is the only service
provider offering some ToSs (namely for Blogger
and Google Groups) in Czech.
User-supplied Data Licensing
Many Web 2.0 services are data-centred. The data
can be provided by the service itself or, much more
frequently, by its users. Many services just manage
data provided or created by their users. Therefore the
rules for handling this data are very important.
As a general rule, services do not claim
ownership of data provided by users. On the
contrary, they disavow the data in order to prevent
themselves from accusations of publishing law
infringing data. On the other hand services need to
have special rights to the content due to their
functionality – e.g. image sharing services would not
be able to create thumbnails without the right to
modify supplied pictures. At this point, services’
conditions differ significantly – some services claim
solely the rights necessary for providing their
functionality, while others claim much wider rights,
e.g. using supplied non-private data for advertising
or promotion.
Data privacy is another important criterion. All
services are treating personal data and the data
labelled as “private” as confidential and reveal them
without the submitter’s approval only under very
serious conditions, explicitly named in their ToS.
Almost all services allow their users to restrict
access of other users to supplied data using
sophisticated AAI implementation, but a cross-
service infrastructure is rarely adopted. It usually
includes private access (only owners can access the
data), public access (everybody on the Internet can
see or even modify the data) and also some
specification in between. Approaches to data sharing
vary a lot.
Licensing user-supplied published data for other
service users is not considered by many services and
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is rather left up to users, see Table 3. Only a few
services deal with this type of licensing,
systematically allowing users to assign one of the
pre-defined licenses based on Creative Commons
to every piece of data. Flexible determined license
structures are representing an effective approach to
multidimensional agile usage.
Table 3: Licensing User-generated Content.
Service Licensing for
service provider
Licensing for other
Ad. Share Necessary only
All rights reserved
Backpack Service promotion
Blogger Service promotion?
Calendhub Data ownership All rights reserved
Clipmarks Complete rights
Diigo Use in their services All rights reserved
DivShare All rights reserved
7 possibilities (CC
Gmail/Talk Necessary only
G. Base Use in their services
Necessary only
G. Docs Necessary only All rights reserved
G. Groups Use in their services,
MySpace Use in their services All rights reserved
Picasa Use in their services,
The Milk
Necessary only
SlideShare Usage for their
7 possibilities (CC
Wikidot Usage in their
14 possibilities (CC
Zoho All rights reserved
Terms of Service
Although each service has its specific ToS, some
aspects are common for all reviewed services.
Firstly, services are, not surprisingly, sensitive about
user accounts – they require accounts not to be
created in any automated way, allowing creating
accounts for humans only, and forbid account
sharing among multiple people. Secondly, services
are anxious about the data and therefore explicitly
prohibit any kind of systematic harvesting or
indexing of its content. The third common point is
software copyright. It is not allowed to copy,
reproduce, alter, modify, reverse engineer or create
derivative works from any of the services.
Table 4: Terms of Service and GUI.
Service Incorporating
Automated access to
Ad. Share forbidden unspecified
Amazon S3 no GUI no GUI
Backpack with permission unspecified
Blogger forbidden unspecified unspecified unspecified
Calendhub forbidden unspecified
Clipmarks forbidden forbidden
Diigo forbidden forbidden
DivShare with permission no robot w/o permission
Flickr with permission via provided intf. only
Gmail/Talk forbidden forbidden
G. Base forbidden via provided intf. only
G. Calendar forbidden forbidden
G. Docs with permission forbidden
G. Groups with permission unspecified
MediaMax unspecified "Reasonable Usage"
MySpace with permission forbidden
Picasa forbidden via provided intf. only
forbidden forbidden
SlideShare forbidden no "burdening" robots
Wikidot limited forbidden
Zoho allowed unspecified
Some services prohibit incorporating their
graphical user interface into other applications or
accessing it via any automated processes (cf.
Table 4). But even in cases where these activities are
not explicitly forbidden, they are probably violations
of the previously mentioned rule. The only service
directly supporting incorporating its GUI into
another application is Zoho, which allows using
Writer, Sheet and Show from its office suite as
editors for appropriate document formats.
All services restrict user supplied content not to
violate copyrights and not to contain vulgarity,
nudity, racism and other improper or illegal
information. For some services, this is the only
limitation. Other services go further and restrict the
data type in accordance with the service’s intention
– to personally taken photos (Flickr), for example.
Another example of content limitation is in Google
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Base which (at the time of writing) allows textual
data to be in English and German only. The
Figure 4. shows a scale of “openess” and
mashability with respect to service and content
Figure 4: Mashability Determined by ToS Factors.
The main goal of this research was to provide a
conceptual, technical, business, and legal foundation
for Web 2.0 mashup development and deployment.
We proposed a basic classification of Web 2.0
services from functional points of view and applied
this classification to a selected set of popular
services. Then, the “Mash-Tree” was proposed.
Further, we have identified “mashing” potential
and issues of the services in three dimensions:
technical, business, and legal. The technical analysis
showed that – despite the overall popularity of
SOAP in enterprise computing – in Web 2.0 the
HTTP and REST are predominantly used.
We have revealed that many often-alluded to
practices like screen scraping can rarely be
implemented legally. Our investigations also
brought interesting results about licensing the user-
generated content stored in the Web 2.0 services.
By highlighting technical success factors as well
as distinguishing different types of business and
legal aspects onto the market, this article contributes
to the improvement of further mashup development.
Our research of well-established Web 2.0
services shows that a full mashing potential has not
yet been achieved in the market. A ubiquitous
practicability and usage is closely linked with self-
description and (machine) readability of a service,
which is not achieved in all cases yet. In a vision of
the New Web, services with different focus can be
flexibly mixed into a new context.
The potential of service mashability for
flexibility of software usage and tailored software
customization is bringing new business models to
bear, replacing previous models produced under
monolithic, fixed infrastructures. Scenario based
licensing as well as cross service charging
(Micropayment 2.0) can be a successful achievement
for users and producers.
We hope that our conceptual framework,
classification and aspect evaluation can serve
mashups developers as well as future research.
The research has been partially supported by the
Czech National Program Information Society,
project 'E-learning in the Semantic Web Context',
No. 1ET208050401.
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