
requirement to all COM solutions is that they must 
be based on open-source technologies that open up 
new possibilities. 
The specific requirements necessary to evolve 
the core banking EA towards an EDA approach are: 
the definition of business events; the design of a 
reference architecture, which identifies the 
integration points with the specific EA, and the 
description of the initial governance approach to 
manage the new elements.  
This paper is organized as follows. First, section 
2 covers related work and puts our work in 
perspective. Section 3 gives an overview of the 
background of the project: EDA and BKS main 
concepts. Then, a proposed solution to introduce 
EDA in BKS is presented in section 4. Section 5 
includes an operational validation though a case 
study and a non-functional validation focussing on 
performance. Finally, section 6 concludes the paper 
and introduces areas of future research. 
2 RELATED WORK 
Diverse studies have tackled the introduction of 
business events in existing architectures of different 
domains. Most of them describe general approaches 
for EDA and SOA integration such as (Taylor et al., 
2009) or (Malekzadeh, 2010), while others address 
only specific issues of the EDA integration like 
modelling, simulation, methodologies, performance, 
etc. For example, (Clark and Barn, 2012) proposes 
an EDA modelling notation and its associated 
simulation language; (Weigand, 2011) describes 
unified event ontology and a methodology for event-
driven business processes; and (Vidačković et al., 
2010) explains a business-oriented development 
methodology for event processing.  
The papers reviewed provide the theoretical basis 
to evolve EAs. Most of them include a validation 
exercise through a case study in the application field. 
However, they are usually academic or simplified 
examples, not practical experiences for real-world 
EAs, since most companies, and banks in particular, 
do not usually publish them. Our contributions are 
focused on this last point, a real-world EA evolution 
and its associated solutions, which we think are of 
the utmost interest for engineers and practitioners. 
 
 
 
 
 
3 BACKGROUND 
3.1  Event Driven Architecture 
EDA is a software architecture style based on 
multiple entities communicating asynchronously via 
announcements or notifications, known as events. 
Instead of the traditional synchronous, request-
response interaction model, where a requestor asks 
for services or messages and waits for an answer 
from a replier; in EDA, events are transmitted in a 
fire-and-forget mode. In other words, events are 
communicated without a previous request and 
without being concerned about what happens 
afterwards with them. 
Basically, an event is a change in a state within a 
particular system or domain that merits attention 
from other systems (Taylor et al., 2009). The term 
has been given other meanings, depending on the 
context. It can refer to the actual occurrences (the 
things that have happened), which are also known as 
instances of a particular type of events. On the other 
hand, we can use ‘event’ or ‘notification’ to specify 
the particular communication of an event instance. 
Generally, the word ‘event’ is used in both cases 
without distinction. We will use ‘event instance’ or 
‘event notification’ where its distinction is relevant. 
We can think about different types of event 
taking place in a company, such as events related to 
low-level technical information, software activity, 
user actions or business data. Furthermore, we may 
also consider events happening outside the company 
(e.g. stock exchange markets, social networks or any 
other data sources). By way of example, low-level 
technical events can be information from sensors, 
ATM status, network data or activity in many other 
devices. Software events can indicate calls to 
methods, execution of services or exceptions in the 
execution of a program or a process. We may 
understand user events as actions or information 
generated by both customers and workers of a 
company. Finally, this paper focuses on business 
events. They are those generated by the core 
company activities and represent relevant 
information that has impact on its economic 
development and management. For instance, in a 
financial institution, business events can derive from 
the registration of new customers, canceling of 
services, money withdrawals, or the contracting of 
products such as credits, mortgages, etc. 
A generic EDA is made up of three core layers: 
producers, channel and consumers (Figure 1). The 
process begins at the producer layer, detecting, 
creating and sending events through a channel, and 
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