E-Health Telecommunication Systems and Networks, 2013, 2, 72-80
Published Online December 2013 (http://www.scirp.org/journal/etsn)
Open Access ETSN
Using a Health Level 7 Interoperability Bus to Support
Legacy Systems in the Health Domain
Rafael Andrade1,2, Aldo von Wangenheim1, Alexandre Savaris1, Karine Petry1
1INCoD, Brazilian Digital Convergence Institute, Federal University of Santa Catarina—UFSC, Florianopolis, Brazil
2Federal Institute of Santa Catarina—IFSC, Florianopolis, Brazil
Email: andrade@telemedicina.ufsc.br, awangenh@inf.ufsc.br, savaris@telemedicina.ufsc.br, karine@telemedicina.ufsc.br
Received December 3, 2013; revised December 20, 2013; accepted December 30, 2013
Copyright © 2013 Rafael Andrade et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
In order to reduce the effort in the integration and actualization of heterogeneous healthcare legacy systems that should
share a common database, we propose the creation of an interoperability bus using the HL7 standard—the HL7Mid-
dleware. This interoperability bus is an intermediate layer responsible for the communication between a database, health
information systems and medical equipment, called HL7Server. Connected systems use the HL7 messaging semantics
to store and retrieve data from the database. We validate our approach with respect to two different criteria: perform-
ance and integration costs. Benchmark tests were executed with and without the use of HL7Middleware and with dif-
ferent network bandwidths. These results demonstrated that the performance of the interoperability bus is higher when
compared to traditional database access for larger volumes of data and when the bandwidth of the user is considerably
lower than the bandwidth of the connection between HL7Server and database. The overall development and deploy-
ment cost was considered low and the reusability degree of wrapper code was considered high, thus suggesting a pro-
gressive reduction of the integration costs of additional services and subsystems of an organization.
Keywords: Middleware; Healthcare; Interoperability Bus; Legacy System; HL7; Telemedicine
1. Introduction
Nowadays, in a scenario of large hospitals or healthcare
organizations, it is still common to find independent het-
erogeneous information systems and usually isolated
from each other. These systems can be associated with
medical devices, such as PACS (Picture Archiving and
Communication System), RIS (Radiology Information
System), or special purpose systems that were developed
originally in a gradual and uncoordinated informatization
process, performed without concern with the integration
between all these information systems. This heterogene-
ity is composed of isolated legacy systems operating in
parallel. Typically, this model disables the sharing and
integration of healthcare information and, consequently,
imposes the duplication of information, like the identifi-
cation of a particular patient, resulting in redundant data
and rework.
An example of an institution with such an informatiza-
tion profile is the Prof. Polydoro Ernani de São Thiago
University Hospital of the Federal University of Santa
Catarina (HU/UFSC), in Florianópolis, Santa Catarina
Brazil. The HU/UFSC (http://www.hu.ufsc.br) is a large
public hospital founded in 1980 with 1600 professional
staffs that receive over 11,000 patients per month and
serve as the school-hospital attached to UFSC. The in-
formatization process was started in 1984 when the hos-
pital received a system composed of a super minicom-
puter model COBRA 480 and a set of terminals. This
system was based upon a proprietary platform produced
by ComputadoresBrasileiros, a military-owned Brazilian
hardware producer [1]. The terminals were installed in
the hospital, and quickly, several information systems
were developed in a proprietary database management
system (DBMS) solution for the COBRA SOD-operating
system. This platform was enhanced and later replaced
by various initiatives in several areas and administrative
sectors from the hospital. With each of these solutions
evolved, today the HU/UFSC has:
A legacy hospital management system (HMS) that
offers also patient admittance and electronic health
record (EHR) services for about 55% of the hospital.
This system was developed as a client/server solution
on the Gupta/Centura [2] platform;
A web-based EHR system that interacts with different
examination acquisition client tools and supports the
hospital image services, covering obstetrics, radiol-
ogy, colonoscopy, cardiology and others. This data-
base is integrated into the EHR of other 401 health
institutions distributed among 291 municipalities of
the Santa Catarina State Public Telemedicine Net-
work (RCTM) [3];
A large set of isolated solutions, such as a Toxicology
Emergency System, a Pharmacy Management System,
and many others. All information systems operate in
an isolated manner with data redundancy.
Our experience is that such a situation is much more
common than one would expect, mainly in large health
institutions with a long history of isolated informatization
initiatives. It represents a major hindrance to an inte-
grated informatization of the health institution as a whole.
This occurs also because the substitution of legacy sys-
tems implies in deep changes in the operational culture
and personnel retraining, besides errors and possible data
loss during the data transfer.
The use of an interoperability standard allows any
system to interpret its local data using universal concepts
and terminologies [4]. This definition motivates the idea
of using a healthcare interoperability standard to inte-
grate different systems and, at the same time, to use these
concepts and terminologies to access data internally, op-
erating on the own database. In order to represent re-
quests and queries through message passing, a standard,
such as HL7, maintaining the compatibility and consis-
tency across systems and database, is employed.
Previous work has been done in the field of the use of
an intermediate layer to allow communication with a
database through specific XML queries [5-7]. More spe-
cifically, some authors employed UN/EDIFACT and
HL7 v. 2.5 in order to allow the integration of healthcare
systems [8,9].
Differently from previously published work, we pro-
pose a middleware functioning as an independent inter-
operability bus. It is based on the semantics defined by a
standard, as an abstraction layer to represent and manage
all database access. For this purpose, we chose HL7 v.
3.0 [10] for the semantic encoding because it is a stan-
dard used in application software, with a large set of ser-
vices. The HL7 standard also shares data through the
XML syntax for message encoding, thus facilitating the
development of interfaces and wrappers for legacy sys-
The main objective of this work was to develop a
workable solution approach in order to bridge interop-
erability problems through data and services integration
model with low impact. Our approach should support the
progressive integration of legacy applications into a cen-
tral system, acting as a “data hub” to all involved legacy
systems. In order to send and retrieve healthcare infor-
mation from a central database, an HL7Middleware was
projected. This interoperability bus employs the semantic
interoperability provided by the HL7 Standard. HL7 cli-
ents, legacy healthcare systems and medical devices can
send messages based on the HL7 v.3.0 standard to access
the EHR. For this purpose, the system acts as a message
server and communication hub, the HL7Server. It allows
the integration of legacy systems transparently to the
database structure, ensuring a higher level of security and
consistency between systems.
This new database access strategy offers also the ad-
vantage of speeding up the development of ever expand-
ing healthcare information systems. Even if the integra-
tion of legacy systems is not an issue, our approach pro-
vides a database abstraction level, which allows for the
change or addition of requirements without implying in
the addition of database tables or field changes. When
using the HL7Server, it is not necessary to rewrite the
queries performed by new clients at the database level.
Consequently, development risks and time can be re-
duced and the usage of a semantics-based interoperability
philosophy can also render code more readable. Consid-
ering that a healthcare interoperability standard must
provide syntax and semantics to describe the sharing of
health information, we will present a new usage of the
HL7 standard. In order to describe all database access
services, independently if they are originated from legacy
systems, we use HL7 clients to allow heterogeneous
healthcare systems interoperability without the need to
connect directly to a specific database.
2. Objectives
This work was performed with the main objective to de-
velop interoperability architecture to allow the integra-
tion of legacy systems in health institutions in a simple,
efficient manner. We created a security abstraction level
that avoids the legacy systems receive data direct access
from a shared database. The model was developed to
allow the intra- and inter-institutional systems integration,
supporting the integration of services through the Internet.
In our studies we also developed a framework that allows
the easy and fast development of interfacing structures
for legacy systems. We called this architecture HL7Mid-
dleware and it is composed by two components: an
HL7Server, which communicate a central data repository
and different healthcare software and a set of HL7-
Wrappers, which implement the interface to particular
legacy systems. In this paper we discuss the HL7Server
architecture, the HL7Wrapper development philosophy,
costs, performance and the overall communication con-
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Our approach was evaluated under two different view-
3.1. Architecture
1) Performance: in order to measure if the introduc-
tion of an intermediate layer through the HL7Middleware
would represent a bottleneck, we carried out a set of per-
formance tests with and without the HL7Middleware.
We implemented queries with different bandwidth limi-
tations and we measured the response times;
We developed an architecture adherent to the HL7 stan-
dard. HL7 employs a messaging concept to represent
events associated to the healthcare process, such as, e.g.,
patient admission. In HL7 v.3.0 messages are coded as
XML documents. These documents are built accordingly
to a generic information model called the Reference In-
formation Model (RIM) [8].
2) Integration costs: in order to evaluate the integra-
tion costs of legacy systems using this approach, we
monitored and measured the effort for the development,
tests and deployment of HL7Wrappers. For this specific
purpose, we integrated, in a monitored experiment, two
different legacy systems with an inter-institutional cen-
tral data repository.
The main components of our architecture are described
in Figure 1. The semantics defined by the HL7 standard
are maintained in the database access approach of our
HL7Middleware. The HL7Middleware architecture con-
sists of: (a) a server that operates as an HL7 messaging
bus; (b) a set of message templates and stored procedures
representing database access functions associated to each
message category; (c) a mapping of messages, fields and
stored procedures to a database; (d) a database or set of
databases; and (e) client systems of different kinds.
Validation Context
This approach was validated in a web-based EHR con-
text called Integrated Telemedicine and Telehealth Sys-
tem (STT/SC), developed by HU/UFSC and used in
various cities, mainly imaging services and also by the
services from the RCTM. The STT/SC shares a common
database with PACS and desktop systems developed at
UFSC and used at various hospitals in the Santa Catarina
state. As an integration and healthcare information shar-
ing policy, it was defined that the HU/UFSC would pro-
gressively adapt all its services in order to transfer all
healthcare data to the STT/SC.
3.1.1. HL7Serve r
The HL7Server message server operates as an abstraction
layer between a client system and a database. The
HL7Server is responsible for receiving and interpreting
HL7 messages, performing database operations and send-
ing responses to the client system as HL7 messages. This
server is the only instance able to include, alter or retract
data from the database.
3. Material and Methods The HL7Server implements a queue for incoming
messages and communicates through sockets. Each time
a new message arrives at the queue, a parsing process is
In this session we present the HL7Middleware architec-
ture, the main features and the methods employed on our
Figure 1. Schematic vision of the HL7Middleware concept.
started which verifies the syntactic consistency. The type
of all incoming well-formed messages is then identified
and the kind and structure of information to be retrieved
or stored are identified in a mapping table. Parameters
are generated for the associated stored procedure and the
server opens a connection to the database. The procedure
is executed and the connection is immediately closed.
Depending on what is returned, a mapping of the data to
a return HL7 message is performed through the inclusion
of data elements in the adequate message template. The
message is included in a send queue and sent when a
connection to the HL7 partner can be established [10].
3.1.2. HL 7 Clients
Any system that implements HL7 v.3.0 messaging can
act as a client, from native HL7 clients to HL7-compliant
equipment or other software can connect through adap-
tors. Even web-based applications can rely on the
HL7Server: in this case the web-server acts as an HL7
client and implements HL7 messages whenever data has
to be retrieved or stored.
The client/server communication between non HL7-
compliant legacy systems and the server has to be medi-
ated by adaptors, which translate the output of these sys-
tems to HL7 syntax and back. These adaptors work and
are employed in the same way as do database wrappers.
In programming, a wrapper is a component, which
changes the interface of an existing component in order
to increase its compatibility with various other systems,
so we called our adaptors HL7 wrappers. HL7 wrappers
can be implemented in two different ways, depending on
how much access one has to the legacy system:
HL7 extension wrappers can be implemented when
access to the source code is possible and the legacy
platform supports implementing TCP/IP communica-
tion. In this case, an extension to the code of the leg-
acy system or an external library can be developed
and used to compose, send, receive and parse HL7
HL7 external wrappers can be employed whenever
access to the source code is not available or the plat-
form of the legacy system does not support network-
ing programming. In this case, file-based communi-
cation is performed with an external wrapper process,
that monitors a directory tree or local database where
the legacy system records its actions.
3.1.3. Message Rep osit ory and Database Abstraction
Due to the complexity of HL7 messages, which could be
considered a limiting factor in the development of wrap-
pers and communication routines, an HL7messagetem-
plate was generated for each messages supported by the
HL7Server [10]. A message template is an XML docu-
ment containing special comments that indicate which
information has to be filled in each HL7 message ele-
ment. This allows an adaptor developer to abstract from
the syntax of the message and to focus on the semantics
of the message elements. The HL7Server manages a dy-
namicrepository of HL7 message templates and links to
their associated stored procedures, as shown in Figure 1,
which allows the vocabulary to be dynamically extended
during runtime, without restarting the server. A stored
procedure is a set of SQL commands that has been com-
piled and stored on the database server.
Once it has been “stored”, client applications can exe-
cute it over and over again without sending it to the
DBMS again and without compiling it. These aspects of
the architecture also provide an abstraction from the ac-
tual database, since the database is visible only through
the vocabulary implemented by the HL7Server.
Additionally, the HL7Server uses a Data Mapping
module, which employs XML documents to relate mes-
sage elements to fields and stored procedures of a given
database, as shown in Figure 1.
3.2. Performance Evaluation
In order to compare the performance of this interopera-
bility bus against a traditional architecture we employed
two different test settings that emulate the behavior of
our EHR system [11]. One system operated directly on
the PACS database and another routed all communica-
tion through the HL7Server. In order to measure the la-
tency time between request and response, we defined
four different network bandwidths (128 kbps, 400 kbps,
1 Mbps and 1 Gbps). Each request represents a set of 100
accesses into the database and was sent in batch mode for
image retrieval and patient data storage.
For a better performance evaluation under different
kinds of data compositions, we selected four different
examination modalities for each of the batches of 100
access requests, presenting different image sizes and
quantity: Computed Tomography (CT): 25 examinations,
containing approximately 48 slices each; Nuclear Medi-
cine (NM): 25 examinations, containing approximately
six images each; Electrocardiogram (ECG): 25 examina-
tions, containing approximately two images each; Endo-
scopy (SC): 25 examinations, containing approximately
two images each.
For guarantee most similar database access times for
both settings, the HL7Server was installed in the same
machine as the web server.
3.2.1. Se t #1: Without HL 7Middleware
In this scenario we simulate various browsers accessing
and querying our system in a controlled manner. We de-
veloped an HTTP client for the purposes of this valida-
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tion experiment. This client emulates a browser access-
ing the HTTP server, as shown in detail in Figure 2, and
send 100 examination result access requests under each
of the four bandwidths.
The processing sequence in Figure 2 is:
1) Request examination data: sends examination ID
from the examination list to the web server. The exami-
nation list contained 100 IDs from 4 different modalities;
2) SQL request to DB: a PHP procedure at the web
server opens a connection to the database, composes and
performs an SQL query;
3) Sends result: result of the SQL query is sent to the
web server;
4) Retrieve infos: the web server retrieve results, de-
codes and generates local files for each image. Resulting
data is sent as HTML data to HTTP client.
3.2.2. Set #2: Using the HL7Middleware
For the tests using the HL7Middleware, we employed a
web server that contained an embedded HL7 client, im-
plemented in PHP, responsible for the communication
with the HL7Server. The data requests were performed
by the same HTTP client, which sent 100 examination
IDs under each of the four bandwidths, emulating a web
browser. Figure 3 shows the communication during this
test in detail.
Figure 2. Test set #1—without HL7Middleware.
Figure 3. Test set #2—employing HL7Middleware.
The processing sequence in Figure 3 is:
1) Request examination data: sends examination ID
from the examination list to the web server. The exami-
nation list contained 100 IDs from four different modali-
2) Send message: an HL7 message is composed, a
socket is created and a connection to the HL7Server es-
tablished. Message is sent;
3) Send DB query: server accepts connection, re-
ceives HL7 message and parses it, fills in parameters and
calls the associated stored procedure;
4) Send back processing result of the stored proce-
5) Retrieve data and generate file: parses query re-
sults decodes images and saves in a public directory;
6) Send return message: composes return HL7 mes-
sage and sends to the HL7 client;
7) Extract infos: receives return message, parses
XML and retrieves images from a public directory;
8) Generate file: web server generates local files for
each retrieved image. Resulting data is sent as HTML
data to HTTP client.
3.3. Wrapper Development Effort
In order to acquire data about the effort involved in the
development of HL7 wrappers, we monitored the devel-
opment effort of two different wrappers connecting two
different systems: an external HL7 wrapper connecting
the legacy hospital management system (HMS) to the
HL7Server; an extension HL7 wrapper connecting a
PACS client for Unix/Linux platforms that is used in
different hospitals of the RCTM to acquire image data
from non-DICOM devices, to the HL7Server.
The requirements for wrapper development in these
cases represented what we considered typical examples
for each kind of wrapper: (a) an external wrapper for a
legacy system developed in an obsolete and limited pro-
gramming language using communication through files
and (b) an extension wrapper for a modern but non-HL7
UNIX application developed in C++. We considered that
monitoring the development, tests and deployment effort
associated with these two wrappers should be representa-
tive of the development effort associated with wrapper
implementation for our approach.
The effort was measured through standard software
measurement techniques and quantified in terms of per-
3.3.1. The External Wrapper
In order to implement message sending and receiving in
the HMS, we developed an external HL7 client, running
as an independent process, to perform communication-
with the HL7Server. This was necessary because the
Gupta/Centura platform does not offer support for ex-
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plicit sockets programming. The communication process
is described below and depicted in Figure 4:
Message composition: as Gupta/Centura does not
support XML document manipulation such as XPath,
we use a set of HL7 message templates, where a spe-
cially developed static procedure is responsible for
inserting values at runtime.
Message coding: as the HMS Sybase database em-
ploys the CP-850 encoding scheme to store informa-
tion, it is necessary to translate it to the UTF-8 en-
coding scheme used in HL7 messages. The new mes-
sage generation procedure of the HMS only fills the
message template with adequate values; the HL7 cli-
ent performs the transcoding afterwards.
Message saving and transfer: as the HMS operates
on a different sub networks than the HL7Server, a di-
rectory was created that is constantly monitored by a
process that copies all messages generated by the
HMS on the x.x.10.x subnet to the x.x.160.x subnet in
a directory called “Xmls”;
Message sending and receiving: a special HL7 client
(CycClient) was developed to act as awrapper and
send the messages in XMLs to the HL7Server and
receive responses. For this purpose the CycClient
monitors the Xmls directory and reads, parses and
sends any well formed messaged found there. Mes-
sages received from the HL7Server are either stored
in a directory called “Success” or “Failed”, depending
on if they represent a true response from the server or
an error message.
Figure 4. Steps for communication process between HMS
and HL7Server.
3.3.2. The Extension Wrapper
The CycDCM is an image and video capturing applica-
tion that acts as a Radiological Information System
(RIS)/DICOM client. It codes the captured examination
data together with demographic data informed by the
operator as DICOM objects and sends to a central PACS,
the CycDCM. The server automatically replicates all
demographic data in the EHR database of the STT and
also generates JPEG or MPEG renderings of the exami-
nations and stores in the EHR database. The CycDCM
can also be used as a RIS client for providing on-site
findings reports. In this case, it sends the data directly to
the EHR database employing an SQL query.
Here we implemented an HL7 client as a library. All
data intended for the EHR database will be stored di-
rectly by the HL7Server, instead using the PACS for
direct database access, as shown in Figure 5.
4. Results
The benchmark tests showed the result that the perform-
ance of the HL7Middleware is superior if compared with
traditional database access for larger data volumes and
when the user’s network bandwidth is considerably infe-
rior to the bandwidth of the HL7 server-database connec-
tion. Table 1 shows measured mean latency times when
using traditional database access, comparing to the
HL7Middleware. The traditional database access showed
considerably lower latency times when a Gigabit band-
width was employed. As bandwidth deteriorates, HL7-
Middleware performance becomes comparatively better.
Figure 6 shows the mean total latency times for the
128 kbps, 400 kbps, 1 Mbps and 1 Gbps bandwidths.
For each image retrieved from de database, the
HL7Server converts de data from base64 representation
to binary, creates, stores a file in a public directory and
includes a link into the return message sent to the HL7
client. The client system must access the image and copy
it locally. The bandwidth represents an additional bottle-
neck that is not present when using the traditional data-
base approach because the DB client performs this proc-
ess locally after the data is received.
Figure 5. Steps in the communication process between
ycDCM and HL7Server. C
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Table 1. Comparing HL7Middleware with traditional database access.
Modality Bandwidth HL7Middleware Traditional Difference Ratio
128 kbps 19.66 47.15 27.49 0.42
400 kbps 8.38 15.33 6.95 0.55
1 Mbps 5.30 6.67 1.37 0.80
1 Gbps 0.51 0.09 0.41 5.54
128 kbps 8.60 18.93 10.33 0.45
400 kbps 3.92 6.03 2.11 0.65
1 Mbps 2.61 2.42 0.19 1.08
1 Gbps 0.20 0.05 0.16 4.47
128 kbps 10.01 23.07 13.06 0.43
400 kbps 4.34 7.34 2.99 0.59
1 Mbps 2.86 2.97 0.11 0.96
1 Gbps 0.18 0.05 0.13 3.82
128 kbps 1.36 1.00 0.35 1.35
400 kbps 0.79 0.28 0.50 2.79
1 Mbps 0.67 0.08 0.60 8.75
1 Gbps 0.13 0.01 0.12 21.57
With HL7Middleware Traditional
Figure 6. Mean total latency times.
Table 2. Development effort to implement the wrappers.
System Kind Effort Description
HMS Legacy application + HL7Wrapper 182 man/hour
150 man/hour by develop the CycClient;
20 man/hour for build the messages;
12 man/hour for deployment and testing
CycDCM Legacy application + HL7Wrapper 46 man/hour 16 man/hour for build the messages;
30 man/hour for development the library.
STT HL7ClientApplication 30 man/hour For develop an application of HL7Client attributes.
Since the HL7Server is connected to the database
through our local gigabit network, the database response
time to queries from the HL7Server is considerably
lower. Even with the additional processing generated by
HL7 messaging, the HL7Serverperformance exceeds
direct access to the database by users connected through
bandwidths such as 1 Mbps or 400 kbps.
The HL7Server converts the images to the final binary
format and the images are sent in base64 encoding. This
explains why connections using the HL7Middleware
were faster, even if more processing is involved. The
traditional database access was faster only when DB cli-
ent/DBMS bandwidth was similar to the HL7 client/
HL7Server bandwidth.
In order to quantify the effort of the integration of a
legacy system using the HL7Middleware, we recorded
the development and deployment time of this wrapper.
The total effort to develop and deploy the necessary
connection software has been about 182 persons/hour.
About 150 persons/hour of this effort were considered to
be directly reusable on the integration of other services at
the hospital. This process indicates a probable progres-
sive reduction of the integration of further services or
subsystems in an organization. Table 2 shows the neces-
sary effort to be developing the wrapper.
5. Discussion and Conclusions
In many clinics, hospitals and large health care networks,
which have a quite old computer process and grow
wildly, to change these systems is not easy. Due to the
large amount of heterogeneous systems, the difficulty in
the change and also other services that are essential and
can not be stopped, connecting these different systems is
a major challenge of computer systems. An advantage of
the healthcare domain is to possess a general-purpose of
a communication channel represented by the HL7 standard.
We consider the better practical path to be an integration
approach for such legacy systems. Traditional HL7-based
solutions are intended to be peer-to-peer solutions.
We developed a slightly different HL7-based client-
server model expressed as an HL7 interoperability bus,
where all communications between systems are routed
through a central server and also key information can be
centrally stored for common access. This approach offers
a general-purpose interface where legacy systems can be
connected. Wrappers that monitor these systems or, when
possible, are invoked to perform integration of legacy
systems, and make possible also the systems integration
where source code is not available and modifications
cannot be performed on the system. The test results
showed that the performance of the HL7Middleware
model is satisfactory. But an unexpected side effect was
achieved. Due to the more compact image-encoding
scheme used, the communication was faster using the
HL7Middleware when bandwidth represented a bottle-
The time spent on the wrapper development and de-
ployment was considered low because of the benefits
provided by the standardization of database access. HL7
Middleware architecture allows for programming lan-
guage, database and operating system independence. The
interoperability bus also allows the integration with
medical equipment that already uses the HL7 standard
and heterogeneous healthcare systems interoperability.
From the necessary effort point of view, it is important
to observe that the external HL7 wrapper CycClient that
had to be developed is a generic HL7 client tool able to
read XML document files composed by legacy systems.
This client sent HL7 messages to an HL7 server using
the HL7 application protocol. The development was
necessary for the integration between the STT and the
HL7Server, but the 150 persons/hour efforts involved in
its development must not be spent again to the imple-
mentation of further communication channels. Only the
32 persons/hour effort for the coding of additional mes-
sages would be necessary to implement more services.
This turns out to be a very interesting effort.
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