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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Information-based Control of Service-enabling Ecosystems</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Robin Fischer</string-name>
          <email>Robin.Fischer@ksri.uni-karlsruhe.de</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Ulrich Scholten</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Simone Scholten</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Stefan Tai</string-name>
          <email>Stefan.Tai@ksri.uni-karlsruhe.de</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>SAP Research</institution>
          ,
          <addr-line>Dietmar-Hopp-Allee 16, 69190 Walldorf</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Universität Karlsruhe (TH), Karlsruhe Services Research Institute (KSRI)</institution>
          ,
          <addr-line>Englerstraße 11, 76131 Karlsruhe</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Continuous optimization of value co-creation in networks of consumers and autonomous service enablers describes a major challenge to mediating platform operators. In analogy to systems theory, we propose to introduce customizable feedback loops from the service-enabling ecosystem to the service enablers via the platform operator. Relevant feedback information can be derived from analysis of network structure, service interactions, and service consumer preferences. In using our method, optimization of individual service offerings and of the network as a whole is facilitated through the platform operator, while retaining the autonomy of each service provider in the network.</p>
      </abstract>
      <kwd-group>
        <kwd>Service-enabling Ecosystem</kwd>
        <kwd>Service Value Net</kwd>
        <kwd>Consumer Preference Cluster</kwd>
        <kwd>Feedback Loop</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1 Introduction</title>
      <p>
        Software platform operators aim at flexibly providing a high variety of product and
service configurations to satisfy individual consumer demand. Within this context, a
platform is conceived as “a building block, which can be a product, a technology, or a
service that acts as a foundation upon which other firms can develop complementary
products, technologies or services” [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. Software platforms build upon modular
software architectures such as service-oriented architecture (SOA), Web application
programming interfaces, and corresponding design rules that allow independent third
parties to autonomously innovate and develop complementary software applications
or electronic services on top of the platform. Examples are Facebook, StrikeIron,
Salesforce or the SAP-Ecohub.
      </p>
      <p>
        In consequence, business ecosystems co-evolve with the core platform offerings.
These ecosystems have become a major source of competitive advantage. Their
market success depends on consumer satisfaction with the “whole product” [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ], delivered
by the platform operator and created conjointly with third party service enablers,
complementing the platform’s offering.
      </p>
      <p>
        As a result, this holds the platform operator responsible for a continuous, efficient
platform evolution and for ensuring that services provided by the ecosystem’s service
enablers, as an essential complement, evolve simultaneously with the platform. This
constellation leads to a problem of information asymmetry between the platform
operator and independent service enablers [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ]: While the platform provider has
access to market information allowing for a market-conform adaptation of the
platform service portfolio, the platform provider does not hold the stakeholding power to
implement change [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. Independent services enablers can implement change, but lack
access to market information. Thus, platform providers are not able to optimize their
service portfolio in function of the actual consumer behavior.
      </p>
      <p>The paper at hand responds to this void by introducing a method that supports the
platform operator to effectively empower service enablers to optimize their services
and the platform’s service portfolio in a self-organized manner. Our approach is based
upon system theory and follows principles as applied in control engineering. In the
next section, we will provide general thoughts on the importance for co-evolution in
business ecosystems. The illustrative example provided in section 3 will thereafter
motivate our further analysis of the relation between business ecosystems,
serviceenabling ecosystems, intermediating platforms, and consumer preference clusters. The
highlighted shortcomings in terms of ecosystem controllability and information
asymmetry will lead to the introduction and description of our feedback-based
approach in section 4. Before we summarize our work and point to future research in
section 6, we will relate our work to state-of-the-art research in section 5.</p>
    </sec>
    <sec id="sec-2">
      <title>2 Co-evolution in Business Ecosystems</title>
      <p>
        Successful platform operators depend on a robust, highly productive business
ecosystem of complementary third party companies to co-create the platform’s overall value
proposition and to support its market adoption [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. Therein, “the performance of a
firm is a function not only of its own capabilities or of its static position with respect
to its competitors, customer, partners, and suppliers, but of its dynamic interactions
with the ecosystem as a whole” [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. Business ecosystems are understood as an
“economic community supported by a foundation of interacting organizations and
individuals [...]. This economic community produces goods and services of value to
customers, who are themselves members of the ecosystem” [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. The participants of the
business ecosystem – embracing service enabler, lead producers, competitors, consumers
and other stakeholders – “work co-operatively and competitively to support new
products, satisfy customer needs, and eventually incorporate the next round of
innovations” [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. They co-evolve their capabilities and roles over time, and tend to align
themselves with the directions set by one or more central companies, the platform
operator. These dependencies, however, evoke particular indirect network effects,
determining the platform’s market success and profitability: The more external
companies join the value net in order to create complementary innovations, the more
valuable the platform becomes. This dynamic causes more users to adopt the platform
and more complementors to enter the ecosystem [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ].
      </p>
      <p>
        Once having adopted a platform strategy, its long-term success depends on
continuous innovation and renewal [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ], embracing continuous services portfolio
optimization and provision of superior customer value. Therefore, the platform operator is
obliged to control the business ecosystem, characterized as complex self-organizing
web of direct and indirect relationships between independent actors to co-create and
deliver value, whereas the value of the total offering is determined and driven by the
consumer. However, given the non-linear and autonomous behavior of independent
services enablers, the platform operator cannot simply demand innovation or
optimization of services by relying on top-down efforts to implement change. On the
contrary, he has to encourage service enablers to keep on optimizing the complementary
offerings and, therefore, the complete offer. This implies empowering and stimulating
service enablers to invest in optimizing their service offerings by providing them with
key market information. However, the participants still face the problem of
information asymmetry [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]: Neoclassical theory postulates total disposability of market
information to the vendor allowing for market-conform adaptation of his service
portfolio [10; 11]. Being positioned in a dyadic relation with the platform operator (or the
next tier service enabler) constitutes a significant limitation of accessible information
(information asymmetry). The consequence is services out of phase with the actual
market demand.
      </p>
      <p>In summary, the platform operator’s challenge with respect to its ecosystem relates
to its lack of active control mechanisms as the complementary services are in the
service enabler’s ownership. The resulting question is how can they be influenced?
Potential dominator-based control strategies are not subject of this paper and are
hence neglected. Rather, our approach builds on the value creating emergent
characteristics of networks and shared value. Thus, the platform operator’s influence should
leverage the common source of revenue: consumer satisfaction. They therefore need
to enable the ecosystem to better respond on the consumers’ preference patterns. We
suggest influencing the ecosystem by providing key market information to service
enablers. In the following, we will discuss the prominent role of platform operators in
collecting relevant information on service consumption. Based on concepts of control
theory, we will further describe how key market information can be fed back in a
customized way.</p>
    </sec>
    <sec id="sec-3">
      <title>3 Illustrative Example</title>
      <p>
        At the outset, it is useful to shed light on the state-of-the art. In [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] we analyzed a
range of platform operators for Web services based on longitudinal data. As an
illustrative example, in the following we will discuss StrikeIron (www.strikeiron.com),
which showed the best performance in the selection group. The company works with
mechanisms similar to other platforms like Salesforce (www.force.com) in the Web
application segment or the Apple App Store (www.apple.com) for iPhone
applications.
      </p>
      <p>Since 2008, StrikeIron operates a two-sided Web service delivery platform named
IronCloud. IronCloud facilitates data distribution for Web service enablers and Web
service consumption for commercial users. The service-enabling ecosystem is
constituted through companies or independent developers, who provide software or online
services and who look for a platform to broadly market their services. Consumers of
StrikeIron’s Web services are enterprises, who look for cost-effective standardized
solutions for managing data distribution, including metering, monitoring and
authentication.</p>
      <sec id="sec-3-1">
        <title>Influence Area 1</title>
      </sec>
      <sec id="sec-3-2">
        <title>Influence Area 2</title>
        <sec id="sec-3-2-1">
          <title>Client</title>
        </sec>
        <sec id="sec-3-2-2">
          <title>Access</title>
        </sec>
        <sec id="sec-3-2-3">
          <title>Point</title>
        </sec>
        <sec id="sec-3-2-4">
          <title>Web Service</title>
        </sec>
        <sec id="sec-3-2-5">
          <title>Domain of Web Service Provider</title>
          <p>
            In contrast to classical e-Markets that simply syndicate services (influence area 1 of
fig. 1), StrikeIron operates all services on its own domain, having influence on the
transaction flow (influence area 1) as well as on the complete runtime environment
(influence area 2). This allows for a proactive optimization of runtime related quality
factors before initiating feedback-based optimization [
            <xref ref-type="bibr" rid="ref3">3</xref>
            ] of Web services.
          </p>
          <p>To allow and to ensure interoperability, StrikeIron provides predefined Web
application programming interfaces. Also, several directives for purposes such as
authentification are imposed on the service-enabling ecosystem to achieve a basic level of
manageability and security. In a verification routine before Web service publishing,
StrikeIron automatically verifies whether the basic directives are followed. If not,
feedback is given to the respective service enabler, who has to mend and to rerun the
routine.</p>
          <p>StrikeIron’s consumption-based feedback is mainly focused on service level
management quality (availability, accessability, successability, response time). According
to the company’s own information (www.strikeiron.com), multiple consumption
agents from remote geographic locations constantly ping, invoke and inspect the Web
services and their responses on a minute-by-minute-basis and thus create a real-time
picture of the respective quality parameters of their Web services. This information is
compiled and reported to the service enablers in real-time to motivate performance
optimization. Furthermore, an escalation routine is in place to alarm service engineers
at StrikeIron or the respective service enablers to rapidly resolve problems at an early
stage. If necessary, StrikeIron excludes underperforming services from its platform.</p>
          <p>Feedback like publicly displayed usage information is missing. Also, StrikeIron
does not provide consumer-based mechanisms for reputation measurement or a
disclosure of a service’s relevance. This complementary feedback information is applied
e.g. by Salesforce to provide orientation to the consumers and to motivate its service
enablers to retouch a specific service in case of consumer-perceived
underperformance.</p>
          <p>With the focus on service level management quality, StrikeIron limits itself to the
optimization of purely transactional parameters. Feedback-based methods to measure
the services’ business value or extra-functional qualities related to security (e.g. trace
management) and business process management are missing. Also, no analysis of
consumption behavior is provided.</p>
          <p>In conclusion, we believe that an enhancement of StrikeIron’s existing feedback
mechanisms would allow its service-enabling ecosystem to not only improve basic
Web service quality, but to also lead to a better alignment of the overall product-mix
in function of the consumer requirements. Lacking more enhanced feedback methods,
the StrikeIron platform currently shows a bias towards elementary services like
address verification or currency conversion, which are of limited value.</p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4 Closing the Loop</title>
      <p>In the following, we introduce a method to develop more sophisticated feedback for
advanced guidance of service enablers. We will also outline steps for its technical
realization.</p>
      <p>As depicted in fig. 2, business ecosystems embrace the economic community
including service enablers, the platform and the consumers, while service-enabling
ecosystems take account of the service enablers only. Service Value Nets (SVN), in
turn, are instances of business ecosystems, consisting of service enablers, the
intermediary, the consumers as well as their respective relations within one period of
composite service generation and consumption. The intermediary of the SVNs in our
case is a software platform that mediates between service consumers and service
enablers.</p>
      <p>Consider a setting that consists of a software platform, which mediates between a
first tier of services and a set of service consumers: A first tier service (S1.1, S2.1,
S3.1) may be a basic service (S2.1), or a complex service (S1.1, S3.1) that aggregates
other services (e.g., S1.2). We consider service-enabling ecosystems to be open pools
of services. Thus, service-enabling ecosystems comprise both services that are
frequently consumed in various types of SVNs (e.g., S2.3) and services that actually
never participate in any type of business transaction (e.g., S2.2). We furthermore
distinguish different types of SVNs by means of classifying mediated service
consumers into consumer preference clusters (CPCs) that subsume service consumers
according to their preference patterns (see section 4.2) and structural network
information (see section 4.3). CPCs allow us to locate service subsets of the ecosystem that
are involved in the value generation for distinct groups of similar consumption – in
other words, services that target the same CPC. For the scenario shown in fig. 2, we
identify three types of SVNs: SVN1 provides value for CPC1, which is created by
S1.1, S1.2, S1.3, and S2.3 and mediated through the platform. Similarly, SVN2
provides value for CPC3 by use of S3.1, S3.2, S3.3, S2.3 and the platform. S2.1 is
directly mediated over the platform and consumed by customers of CPC2, which makes up
SVN3.</p>
      <p>m S1.3
e
t
s
y
s
o
c
E
lign S2.3
b
a
n
e
e
c
i
rve S3.3
S
S2.2
S3.2
S2.1
S3.1
m
r
o
f
t
a
l
P</p>
      <p>CPC 1
CPC 2
CPC 3</p>
      <p>
        Fig. 2: Business Ecosystem
4.1 Feedback in Business Ecosystems
Our feedback mechanism follows ideas as applied in control engineering [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. These
kinds of feedback control systems aim at leveling the control path by monitoring the
actual value tapped at the end of the control path (see fig. 3). An active regulator
compares the actual value to a given set value (in fact, negated actual value and set
value are summarized) resulting in a modified control value. Based on the newly
adjusted control value the new actual value is tapped again, which is where the
feedback loop is closed. Since disturbances may influence the control path by random
noise or a steady change in the external environment, the actual value may be
disturbed. In these cases, the feedback to the regulator allows for re-leveling actual and
set value.
      </p>
      <p>Set
Value</p>
      <p>Regulator</p>
      <p>Control
Value</p>
      <p>Disturbances
Control Path</p>
      <p>Actual
Value
Given these introductory considerations on feedback control systems, we are now
able to formulate a feedback control system for business ecosystems that is likewise
made up of the interconnected entities of a control path and a regulator (see fig. 4).
SVNs represent the control path of the feedback control system. Similar to control
engineering, we monitor the output (actual value) of individual SVNs (e.g., value,
performance, dynamic consumer behavior) as raw data to generate feedback for each
service enabler.</p>
      <p>
        Based on the received feedback on actual performance and in alignment with
commercial goals (set value), each service enabler now may readjust his service
proposition. Concordant with control engineering, the set screw for service parameter
modification is depicted in a detached imaginary component, called regulator. Hence,
the network self-organizes. Service enablers may modify their value proposition by
internal “process transformation” [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ] or through a selective replacement of their
respective service enablers. This then causes a “system transformation” [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
      <p>Service Enablers</p>
      <p>SSeSetett
VVVaalaululueee</p>
      <p>Reguulalattoorr
RReeggulator</p>
      <p>Control</p>
      <p>Value
Feedback</p>
      <p>Control Path
S1.3
S2.3
S3.3</p>
      <p>S1.2
S2.2
S3.2</p>
      <p>S1.1
S2.1
S3.1
m
lftraPo</p>
      <p>CPC1
CPC2</p>
      <p>
        CPC3
Extended Analysis
The system is characterized by a small cause, large effect principle through non-linear
interactivity: The interaction of the service enablers, platform operator and consumers
causes a so-called macroscopic effect – meaning a coherent behavior of the SVN.
Feedback incites enforced reverse adaptation on the micro-level (the service enablers’
offerings). The results of a first optimization (e.g., reaction on shifting consumer
preferences) again will trigger feedback. Over time, the service-enabling ecosystem
will line up to a temporary equilibrium: Once there is no deviation anymore between
the service enabler’s commercial goals (set value) and the actual value, the
configuration stops growing until the next adaptation is initiated [
        <xref ref-type="bibr" rid="ref15 ref16">15, 16</xref>
        ].
      </p>
      <p>
        In general, we consider two types of aggregated feedback: preference feedback and
structural feedback. In our approach to provide business level feedback we
furthermore propose interpreted feedback, which combines information of both types of
aggregated feedback. In the following, we will outline our understanding of feedback
information to illustrate the concept of feedback systems for service-enabling
ecosystems.
4.2 Requirements for Preference Feedback
In order to analyze the consumers’ service preferences based on their actual
consumption (consumption feedback), we propose to identify typical consumption patterns
within the extended analysis component. Such a component could make use of the
OASIS quality model WSQM (see fig. 5) to asses and aggregate individual consumer
preferences. On the topmost level, the WSQM is grouped into Business Value
Quality, Service Level Measurement Quality, Business Process Quality, Suitability for
Standards, Security Quality, and Manageability Quality. Based on [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ], we further
divide those categories into 21 subgroups, leading to a service’s specific quality
bundle Q = {q1, …, q21} on the provider side and to weighted preference bundles P =
{ω1q1, …, ω21q21} on the consumers’ side. Thereby, the weighting factor ωi describes
the relative importance given to each quality parameter of a specific service by a
particular group of service consumers.
      </p>
      <p>Aggregated feedback on service quality and respective consumption preferences
(preference feedback) can be read directly or indirectly derived from observable data.
In the following, we provide requirements on the abilities to observe respective
quality parameters.
4.2.1 Directly Observable Quality Parameters
Out of all quality parameters, Service Level Management Quality related parameters
are potentially the easiest to observe. Availability, for instance, could be tracked by
pinging mechanisms as performed in the example of StrikeIron. Due to this
simplicity, it is the most frequently applied feedback approach and can be found in most of
the service intermediaries and platform operators today. Response Time, Maximum
Throughput, Accessibility and Successability on the other hand require observing
service interactions. Solutions ranging from network-level monitoring to automated
agents exist and may be applied here. Functionalities to observe, log and analyze
basic service interactions are fundamental to an extended analysis.</p>
      <p>Among the directly observable Business Value Quality parameters, we consider
Service Cost to be critical. We thus require functionality to identify cost information,
for instance from SLAs or service descriptions. Service Recognition can either be
received from external sources like the Google Relevance or similar indicators.
Service Reputation may also be surveyed through consumer-based ratings, as
implemented by platform operators like Ebay or Amazon. Service Reputation can be either
score-based (quantitative) or descriptive (qualitative). Thus, features such as tracking,
inspecting and external sourcing are also required in the extended analysis.</p>
      <p>
        The parameters of Business Process Quality, Suitability for Standards, Security
Quality and Manageability Quality can only be monitored if the services are of native
structure, that is, services are programmed and designed to conform to the platform
operator’s specifications [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. If so, the services can be inspected through automated
scanning routines. Figure 6 summarizes and correlates directly observable parameters
with functionalities for their respective observation.
      </p>
      <p>Quality</p>
      <p>Quality Parameter</p>
      <p>Monitoring methods
ping invoke inspect track ext.</p>
      <p>source
native
only
Business Value
Quality
Service Level
Management
Quality
Business Process
Quality
Suitability for
Standards
Security Quality
Manageability
Quality</p>
      <p>Service Cost
Service Recognition
Service Reputation
Response Time
Maximum
Throughput
Availability
Accessibility
Sucessability
Reliable Messaging
Transaction
Processing
Collaborability
Conformability
Interoperability
Authorization
Management
Trace Management
Distributed
Authorization
Manag. Information
Offerability
Observability
Controllability
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
v
(v)
v
v
v
v
v
v
v
v
v
v
v
v
4.2.2 Indirectly Observable Quality Parameters
According to our study, two parameters cannot be observed directly (see fig. 7).
However, as these parameters are of high importance, an indirect approach needs to
be derived. In the following, we identify the steps allowing for their observation.</p>
      <p>
        The Service Aftereffect describes the direct impact of a service on the consumer’s
system. The term “system” here stands for the service’s application context (e.g., the
targeted software system or organizational unit). However, we do not know the
consumer’s system nor do we know the individual return-on-investment (ROI) of a
particular service. But we can measure a service’s magnitude to create aftereffect
indirectly by analyzing whether a particular consumer sources his demanded service from
the service enablers. If yes, we can assume that he was satisfied. If he sources a
service of similar functionality in later purchases from a new supplier, we can suppose
that those new supplier provides higher utility. According to sampling theory, similar
tendencies created from a statistically relevant amount of homogeneous users will
indicate that the decision is not an arbitrary individual case, but satisfies the
requirement of representativity [
        <xref ref-type="bibr" rid="ref22 ref23">22, 23</xref>
        ].
      </p>
      <p>In a similar approach, long-term consumer behavior can be considered: Over what
period of time do consumers invoke specific services? By statistically answering this
question, we can conclude a service’s sustainability. Utilization patterns of bigger
user groups will then allow for generalization.</p>
      <p>We can conclude that for indirectly observing Service Aftereffect and Service
Sustainability, information on individual service interactions is required to be collected
by means of extended analysis. However, the focus is less on timeliness, frequency or
erroneous cases, but on the identification of value co-creating service instances, i.e.
collaborating service enablers.</p>
      <p>Quality
Business Value
Quality</p>
      <p>Quality Parameter
Service Aftereffect</p>
      <p>Service Sustainability
Structural analysis will create the bridge to a more enhanced analysis, which
correlates preference and economic data with the respective SVNs. To do so, we need to
collect information on those. In the following, we outline an approach to observe
structural aspects of SVNs.</p>
      <p>
        As indicated above, the quality parameters Service Aftereffect and Service
Sustainability can be only observed indirectly by correlating recurring SVNs with positive
impact on Service Aftereffect and Service Sustainability. The prerequisite for
indirectly observing these quality factors, though, is the ability to longitudinally observe the
whole structure of SVNs over time. We separate structural changes into process
transitions and system transitions [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
      <p>Monitoring process transitions within an SVN requires tracking and comparison of
service offerings provided by service enablers over time. Extended analysis providing
structural feedback therefore requires the functionality to track versions of service
offerings as well as the capability to identify evolution between two versions.
Identifying system transitions on the other hand requires the tracking of individual service
interactions that are to be performed for value creation within a particular type of an
SVN. Feedback on systems transitions is required to allow for analyzing and defining
SVNs according to particular sets of required service interactions. Required
information includes data on constituting service enablers and their respective interaction
patterns. In order to relate type level information (definition) to instance level data
(execution) both designing and monitoring features are required.</p>
      <p>In the pursuit of our goal to provide vital management information to the service
enablers, we can now correlate preference and structural feedback.
4.4 Interpreted Feedback
The fact that one service consumer sources its desired service from service enabler A
during a particular period of time, but sources from service enabler B afterwards is an
important observation. Potentially, there are plenty of reasons for the change such as a
change in the consumer’s preference pattern, market exit of a service enabler or
optimization of individual service offerings. Identification of these kinds of roots, though,
requires additional information that needs to be interpreted by correlating aggregated
feedback, i.e. correlation of preference feedback and structural feedback.</p>
      <p>As described in section 2, the overall goal of this work is to design feedback loops
that empower the service-enabling ecosystem to better respond to effects like
evolving consumer preference patterns or market changes. The generation of CPCs for
business ecosystems based on structural and preference analysis provides information
on what service is chosen for which preference pattern and which one is omitted.
After correlating preference clusters with their respective financial relevance on the
platform (e.g. cumulated turnover during a specific time period within a particular
preference cluster), the platform operator is in a position to guide each service enabler
towards a specific optimization of quality parameters. The service enablers should be
inclined to heed this advice, if they want to further attain yet unexploited, but
financially interesting consumption clusters. In an example scenario, an enabler of data
storage services may be provided with the information that he could access a
profitable cluster of financial transactions, if only his services had sufficient security quality.</p>
    </sec>
    <sec id="sec-5">
      <title>5 Related Work</title>
      <p>The ideas presented in this paper build upon a variety of existing research. In the
following, we position our approach to related work from system theory and
managing quality of service.</p>
      <p>
        The application of control theory in the field of software systems is not a new
approach. Already 20 years ago, principles of control theory have been applied to the
area of computer networks [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ]. They mainly focus on system identification for
finding optimal convergence and fairness policy for congestion avoidance. Thus, they aim
at deriving a transfer function that allows the modeling of a system’s behavior. Other
applications of systems theory can be found in the area of scheduling in operating
systems [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] or distributed environments such as distributed multimedia systems [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ].
      </p>
      <p>
        These approaches, however, rely on very detailed models of linear closed-loop
systems and require time-consuming analyses. They are building upon a set of non-trivial
assumptions that can only be identified through expert knowledge. These assumptions
do not hold for the field of dynamic ecosystems and their respective value nets.
Furthermore, the complexity of SVNs [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] makes a modeling of transfer functions
difficult, if not impossible. As we seek to derive the evolving states of the system from
our feedback information, the availability of ex-ante knowledge on the structure of
SVNs is ruled out. Additionally, as the service enablers and consumers in such a
context are self-organized players in a system of permeable borders, we also need to
consider it as non-linear. Transfer functions of linear nature, as applied [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] are only
valid during periods of temporary equilibrium. However, transitions from one
equilibrium to the subsequent cannot be captured at all. In addition, we aim at monitoring
and influencing business ecosystems in at least near to real-time. To do that, we
cannot rely on expert interviews in order to identify the right set of assumptions.
      </p>
      <p>
        In [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ] an approach is proposed that appears to be more reasonable for our
application domain. The authors identify systems, based on the aggregation of observable
statistical data. In that, they treat the system under control as black boxes to reduce
influences of system complexity and lack of expert knowledge. We go similar ways
by incorporating a regulator into an existing target system (in our case: business
ecosystems). However, their approach on regulator-design is based on the assumption of
system linearity. This is contradicting our perception of dynamically changing SVNs.
Furthermore, our approach differs with respect to providing individual feedback for
each service enabler while in [
        <xref ref-type="bibr" rid="ref20">20</xref>
        ] only a particular software system is considered.
      </p>
      <p>
        In the field of service quality, there exists a variety of work that seeks for providing
a quality definition for software systems and services. However, there is only little
work that focuses on managing the quality of services in business ecosystems or
SVNs. [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ] propose an approach to “increase a software vendor’s flexibility, and
responsiveness to changes in performance and usage of its service-based, online
software, at specific customers and concerning its software in general” [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ]. In their
“Service Knowledge Utilization (SKU)” approach, they propose metrics for both
individual services and service methods. These basic metrics are then aggregated to
indices that provide an overview of a customer’s perceived service performance,
usability and client utilization. The authors furthermore propose and implement a
prototype that provides functionality to track metrics by weaving trace functionality
into existing services. They claim that their systems may be introduced into arbitrary
service environments by following an aspect-oriented approach. Although we share
the same basic idea of using service usage information – or more broadly: feedback –
and providing this information to individual service enablers, we see the following
shortcomings in comparison to our approach. First, SKU is based on the assumption
of a dyadic relationship between service provider and individual customers. Our
concept of business ecosystems, however, comprises platform providers that mediate
between service enablers and consumers. Therefore, generalizing SKU to our domain
of SVNs is constrained. Furthermore, we consider an SVN to be provided through
service-enabling ecosystems, having at least one tier of service enablers. Therefore,
we anticipate further difficulties and open questions by recursively applying SKU for
each transaction that occurs between service enablers of different tiers.
      </p>
    </sec>
    <sec id="sec-6">
      <title>6 Summary and Outlook</title>
      <p>Modern service systems are highly dynamic business ecosystems that typically
comprise multiple consumers, autonomous service enablers, and a mediating platform
operator. The continuous optimization of value co-creation in this setting requires
novel mechanisms for all three roles. To this end, we propose to group consumers into
CPCs, to model the service-enabling ecosystem in terms of the SVNs it supports, and
to introduce customizable feedback loops from the service-enabling ecosystem back
to the service enablers via the platform operator. We distinguish and classify different
kinds of feedback information – preference feedback, structural feedback, and
interpreted feedback – and outline how feedback loops can be implemented by the
platform. Our method capacitates platform operators to share critical market and
consumer information with service enablers, and thus to improve quality and value of both
individual service offerings and the network as a whole.</p>
      <p>This paper describes novel ideas and fundamental concepts in support of a larger
effort to study strategic (service) value networks. In future work, we plan to
exemplify and tailor our method for specific application domains and case studies, to
(continue to) develop and implement platform feedback mechanisms, and to provide
experimental evaluation results.</p>
    </sec>
    <sec id="sec-7">
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