<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Research and Development of the API for Personal Health Record</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Anzhelika Parkhomenko</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Ivan Tyshchenko</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Vanderslab Ltd</institution>
          ,
          <addr-line>Zaporizhzhia</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Zaporizhzhia National Technical University</institution>
          ,
          <addr-line>Zaporizhzhia</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>The problems of electronic personal health record development and application are considered in this paper. The features of popular on the market software for working with patients` medical information have been analyzed. It is shown that the main restrictions on the usage of the considered solutions in Ukraine are: the orientation towards integration with the state medical systems of another countries, the absence of localizations, the limited functions of searching the necessary data in previously downloaded information, closed API and the lack of documentation. Therefore, this work is devoted to the research and development of public API for Personal health record as well as its documentation based on the OpenAPI specification.</p>
      </abstract>
      <kwd-group>
        <kwd>informatization of medicine</kwd>
        <kwd>personal health record</kwd>
        <kwd>application programming interface</kwd>
        <kwd>web-application</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        Thanks to modern information technologies, medicine acquires completely new
features today. The widespread introduction of computer technology and specialized
software leads to significant changes in medical theory and practice, as well as in the
training of healthcare professionals. [
        <xref ref-type="bibr" rid="ref1 ref2 ref3">1-3</xref>
        ].
      </p>
      <p>Today, a significant number of medical institutions of various forms of ownership
provides Ukrainians with a wide range of services, especially in large cities. Due to
the fact that the majority of private medical institutions are relatively small, they are
usually specialized in certain healthcare sectors, that generally leads to the usage of
several unrelated clinics by citizens. As a result, patients have medical documents
(advisory opinions, research results, prescriptions, etc.) in various formats and forms.
Therefore, the patient’s medical information is kept distributed and most often
inaccessible to the person himself. This makes difficulty in changing the place of
medical services receiving and increases the number of examinations that have to be
repeated. The lack of a holistic "history" of the patient increases the risk of incorrect
diagnoses and reduces the effectiveness of the treatment as a whole.</p>
      <p>
        All this factors contribute to the direct interest of people in the availability of their
own medical information, regardless of the medical institution. Especially the
collection and processing of medical information is complicated for people who travel
frequently or change their place of residence, which is quite common in the modern
world. Thus, a personalized electronic medical record can provide the patients with
the possibility to more closely monitor their health status and have access to the
necessary health information at anytime, anywhere, from any platform. Moreover, it
can be not only a medical history or medical examination data, but various
information related to human health (physiological parameters and features of a
healthy person’s development, dietology issues, healthy lifestyle, medical bills, etc.)
[
        <xref ref-type="bibr" rid="ref4 ref5 ref6 ref7">4-7</xref>
        ].
      </p>
      <p>
        Today, a significant number of software systems are offered on the market for
creating a personalized electronic medical record and working with it. Each solution
has its own characteristics of implementation and usage. The selecting of an
appropriate software is a complex task, because it requires to take into account the
peculiarities of the process of informatization of medicine in Ukraine, the issues of
personal data protection and reliable information storage [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ].
      </p>
      <p>
        Therefore, this work is devoted to the study of methods and ways of organizing
personalized electronic medical records that will ensure the effective storage and
retrieval of information about patient’s health.
2 State-of-the-Art
As studies have shown, in [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] several important definitions are given related to the
electronic information about the patients’ health:
 Electronic Medical Record (EMR) is the electronic information related to the
health of the patient, which is created, stored, maintained and used by certified
medical professionals and staff in one medical institution.
 Electronic Health Record (EHR) is the electronic information related to the health
of the patient, complying with national interoperability standards, which is created,
maintained and used by certified medical professionals and staff of more than one
medical institution.
 Personal Health Record (PHR) is the electronic information related to the health of
the patient, complying with national interoperability standards, obtained from
various sources, which the patient self-manages, controls and provides access to it
[
        <xref ref-type="bibr" rid="ref9">9</xref>
        ].
      </p>
      <p>Thus, EMR, EHR and PHR are the sets of information about the health of a
particular person, differing from each other in terms of the collection of information
and the way it is managed. These three concepts indirectly determine the most
important areas of health care system informatization:
 Informatization of specific medical organizations.
 Creation of integration projects for the information exchange between medical
organizations, at the national and international levels, that means the creation of a
single information space for physicians (professionals).
 Creation of a common information space for non-professionals (patients and even
those who do not consider themselves to be patients yet), that means the creation of
services and facilities for maintaining medical information and electronic
interaction between doctors and patients.</p>
      <p>
        Informatization of medicine in Ukraine is an important part of the health care
system reforming [
        <xref ref-type="bibr" rid="ref10 ref11">10,11</xref>
        ]. But, as studies have shown, today in Ukraine there are only
attempts to create systems for working with EMR and EHR, with a significant lag of
the third component - PHR. Considering the experience of the United States, Great
Britain and other leading countries in which PHRs are actively used, their
development and implementation is also a key step in the informatization of medicine
in Ukraine.
      </p>
      <p>The analysis of existing on the market software solutions for the PHR allowed to
identify the most popular: Microsoft HealthVault, Zweena, Health Companion,
Healthspek.</p>
      <p>
        Microsoft HealthVault is a popular environment for working with PHR, which
allows to collect, store, use and monitor information about the health of a person and
his family, including medical images. This solution can be called one of the best on
the market due to the well-known name of the developer - Microsoft company and a
fairly large number of platforms on which different versions of HealthVault can be
installed [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ].
      </p>
      <p>The studies have shown that the disadvantages of HealthVault are:
 Glut of functionality, for example, the program combines task manager and
calendar functionality that it is usually more convenient for users to have them as
separate standard applications for their platforms (for example, Google Calendar
for Android smartphones).
 Ultimative approach to interface organization.
 Commercial overtones: the application of this software leads to the usage of the
services of certain companies and promotes certain products that are often
provided by Microsoft partners.
 Restrictions by regional principle: not all countries are available when creating a
profile (for example, Ukraine is not available for selection).
 Lack of speech recognition and optical character recognition (OCR).</p>
      <p>
        Zweena is an environment for working with PHR that supports import from
HealthVault and requires an account and pre-registration to log in. This product has
less functionality than HealthVault, and it can be used both for free and with a
monthly payment [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. Zweena is only available as a website and does not have its
own mobile applications for working with it. The shortcomings that were identified
during analysis of this software are:
 Completely non-adaptive interface, the web site is in no way adapted for use on a
device with the screen size less than 960px.
 Lack of mobile applications.
 Closed API (information about it can be obtained only after contacting the
company on the phone).
 Restrictions of free account (1000 entries maximum).
 Chargeable recognition of scanned documents.
      </p>
      <p>
        Health Companion is a complete and long-term system for working with PHR that
can integrate personal health information from various sources, track medical
financial bills and make preventive health and wellness recommendations based on
personal risk factors [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
      <p>Health Companion has an adaptive web-site. Android and iOS apps are available
for usage free of charge. The interface languages are English or Spanish, so the
applications are oriented for usage in Americas. The system has a lot of integration
with polyclinics and other medical services, and it also meets the requirements of
the USA law.</p>
      <p>The shortcomings of this system revealed during the analysis are:
 Orientation to receive information primarily through integration with other
systems.
 Mobile applications have some issues with compatibility with the latest operating
systems of the platforms which they operate on.
 Closed API.
 Limited search capabilities.</p>
      <p>
        Healthspek is a free system for managing all personal and family health
information in one secure location accessible from multiple devices anywhere in the
world. The system has an adaptive website, Android and iOS applications that are
available for usage for free. Interface language is only English [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ]. The shortcomings
identified during the analysis of this system are:
 Closed API.
 Adaptation problems for countries without insurance medicine.
 Limited information retrieval capabilities.
 Poor support for people with disabilities.
      </p>
      <p>
        Summing up the results of analysis of the functionality and features of popular all
over the world software systems for working with PHR, it can be concluded that most
of them are aimed at integration with certain information providers, as well as the
usage for certain countries. Another important limitation of the considered PHRs is
the lack of documents` recognition as well as full search tools (only in HealthVault
there is a relatively comprehensive search, but it also does not allow finding audio
recordings by content). One of the major drawbacks of all considered software
systems is the closed API. Nevertheless, API is an interface that allows developers to
use ready-made blocks to build a program code and, thus, to speed up software
development and make it more attractive economically [
        <xref ref-type="bibr" rid="ref16 ref17 ref18">16-18</xref>
        ].
      </p>
      <p>Therefore, the task of development of an open API, which will enable the users to
maintain their own electronic PHR, that will combine information from different
sources and provide convenient tools for working with personal data, is relevant.
3</p>
      <p>
        Architectural Approach and the Methods of Organizing the
API for PHR
The REST implementation was chosen as an architectural style for the API-oriented
development of PHR, which has several advantages over the SOAP approach [
        <xref ref-type="bibr" rid="ref19 ref20 ref21">19-21</xref>
        ].
      </p>
      <p>The developed public API for implementing client applications (mobile, desktop
and web) will provide basic PHR functionality: storing, viewing, and searching of the
health information. In this case, the following possibilities are given to user:
 Creation of profiles for other people (family members).
 Creation of events.
 Storing of information in the form of photos, text and audio records.
 Search among stored information.
 Deletion of the records.
 Export of documents as PDF files.</p>
      <p>Based on the completed assessment of the level of technologies and platforms
development, it was decided to develop the system using the JavaScript programming
language, which provides sufficiently high speed, convenience and performance of
writing code. Node.js was used for the software interface on the server side
development. During the analysis of the development toolkit, it was decided to use a
number of libraries, such as Elasticsearch, Express.js, Mongoose, etc. These solutions
make it possible to reduce the cost of program developing while increasing its quality
parameters, and therefore to increase its competitiveness.</p>
      <p>The Express was chosen as the Node.js framework, which provides easy
maintenance, high speed, relatively cheap hosting and a wide range of hosting
selection. Node.js support is the minimum for most hosting sites, and therefore there
is no need to pay for “exoticism”. The flexibility of the structure and the minimum
amount of time spent on performing routine actions are also typical for it.</p>
      <p>WebStorm from etBrians was chosen as the development environment for the
website. This environment is characterized by convenience and wide functionality. Its
usage reduces time costs and increases programmer productivity. Developed API can
be run on any modern Linux based VPS (Virtual Dedicated Server) server.</p>
      <p>The created project can be divided into the following parts:
 ElasticSearch is the search engine, which provides high search performance among
users` artifacts in the database.
 API documentation that provides developers with information on incoming and
outgoing data for the route.
 API-core is the part of the system that is responsible for user requests routing and
processing.</p>
      <p>The developed API is the application that installs on an ordinary web server with
Node.js 6 (LTS Boron), MongoDB 3.4. *, Elasticsearch 5.6. *. It is available for the
usage by clients via the http / https protocol. JSON data exchange format is used.</p>
      <p>It is necessary to perform the following steps for developed API functions usage.</p>
      <p>Step 1. To form the HTTP request that includes the following data: server address,
the API version (/ api / 1), the controller name (/ users), the action (/ profile).
Parameters can be transmitted both via the URL "? Param = 123" and in the body of
the request.</p>
      <p>Step 2. To send the generated request to the server (at the specified address) via the
GET / POST / PUT / DELETE method: POST https://server-url.com/api/profiles</p>
      <p>
        Step 3. In response, to get the result of the command execution by the server in the
form of JSON:
{
"fullName": "string",
"phone": "string",
"birthday": "string",
"relationship": "string",
"gender": "string",
"height": {
"ft": 0,
"in": 0
},
"weight": "string",
"emergencyContactName": "string"
format for creating documents online. The simplicity and consistency are its
advantages, but the lack of tools developed by the community is its open issue [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ].
      </p>
      <p>
        So, the Swagger was chosen for API documentation organization and management
after the provided analysis [
        <xref ref-type="bibr" rid="ref22">22</xref>
        ]. Swagger User Interface is a small collection of
scripts for creating interactive documentation for APIs of web applications with the
REST architecture.
      </p>
      <p>The main Swagger online documentation page is shown in Fig. 1. There are two
text fields on the top panel. The first field contains the path to the JSON
documentation file. The developed API methods are described in this format. The
second field is the access token that will be used for requests to the API creation with
the usage of Swagger. During the page opening, the value of the token is taken from
the configuration file and the test user is added to the database using migration. If it is
necessary, the access token can be changed with using the documentation. For
example, for several users work simulation in the application, it is necessary to find
the access token of the desired user in the database. Then enter this token in the field
and click the Explore button. The token will be valid until the user exits this page.
The token from the configuration file will be loaded after the page re-opening.</p>
      <p>The documentation page contains the accordion interface element with addresses
which are contained in the API. A brief information about the API (the base URL that
is attached to the server address and the current version of the API) is shown after the
list of display controllers. The list of groups` routes is opened with clicking on its
name (Fig. 2).</p>
      <p>It is possible to find out from the list next data: the method which you can call this
route with (POST / GET / ...), the required URL that is attached to the base and a brief
description of the assignment. Routes are sorted by call method and alphabetical
order. If the method is selected, detailed information about it opens: a text description,
a list of parameters and responses from the server, as well as a “Try it out” button for
creating a request to the server (Fig. 3). The result of calling the API method is
displayed after clicking on the button (Fig. 4).
Nowadays Ukraine is only at the beginning of informatization process of medicine.
Considering the experience of the United States, Great Britain and other advanced
countries, the implementation of PHR is a relevant task and it can be considered as an
important step in the informatization of medicine, together with the introduction of
EMR and EHR. Therefore, the problems considered in this paper are relevant, and the
proposed solution is seemed to be promising. As a work result, an open API was
created, which simplifies the development of mobile and web applications for the
necessary platform for working with PHR, and it also provides visual documentation
according to the OpenAPI specifications.</p>
      <p>Acknowledgements. This work is carried out partly with the support of Erasmus + KA2
project BIOART «Innovative Multidisciplinary Curriculum in Artificial Implants for
BioEngineering BSc/MSc Degrees» (586114 – EPP – 1 – 2017 – 1 – ES - EPPKA2 – CBHE – JP)</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          1.
          <string-name>
            <surname>Kachmar</surname>
            ,
            <given-names>V.O.</given-names>
          </string-name>
          :
          <article-title>Medical information systems - the state of development in Ukraine</article-title>
          .
          <source>Ukrainian Journal of Telemedicine and Medical Telematics</source>
          ,
          <volume>8</volume>
          (
          <issue>1</issue>
          ),
          <fpage>12</fpage>
          -
          <lpage>17</lpage>
          (
          <year>2010</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          2.
          <string-name>
            <surname>Churpiy</surname>
            ,
            <given-names>I.K.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Churpiy</surname>
            ,
            <given-names>N.V.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Skripko</surname>
            ,
            <given-names>V.D.</given-names>
          </string-name>
          <article-title>Current state of informatization in medicine</article-title>
          .
          <source>Bukovinsky medical bulletin</source>
          ,
          <volume>15</volume>
          (
          <issue>1</issue>
          ),
          <fpage>171</fpage>
          -
          <lpage>173</lpage>
          (
          <year>2011</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          3.
          <string-name>
            <surname>Nazarenko</surname>
            ,
            <given-names>G.I.</given-names>
          </string-name>
          , Guliyev,
          <string-name>
            <given-names>Ya.I.</given-names>
            ,
            <surname>Ermakov</surname>
          </string-name>
          ,
          <string-name>
            <surname>D.E.</surname>
          </string-name>
          :
          <article-title>Medical information systems: theory and practice</article-title>
          ,
          <source>general editor G.I. Nazarenko</source>
          ,
          <volume>320</volume>
          p.
          <source>FIZMAT-LIT</source>
          , Moscow (
          <year>2005</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          4.
          <string-name>
            <surname>Bates</surname>
            ,
            <given-names>D.W.</given-names>
          </string-name>
          :
          <article-title>Physicians and ambulatory electronic health records Health Aff</article-title>
          , Millwood,
          <volume>24</volume>
          (
          <issue>5</issue>
          ),
          <fpage>1180</fpage>
          -
          <lpage>1189</lpage>
          (
          <year>2005</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          5.
          <string-name>
            <surname>Menachemi</surname>
            ,
            <given-names>N.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Perkins</surname>
            ,
            <given-names>R.M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Durme</surname>
            ,
            <given-names>D.J.:</given-names>
          </string-name>
          <article-title>Examining the adoption of electronic health records and personal digital assistants by family physicians in Florida</article-title>
          .
          <source>Inform. Prim. Care</source>
          ,
          <volume>14</volume>
          (
          <issue>1</issue>
          ),
          <fpage>1</fpage>
          -
          <lpage>9</lpage>
          (
          <year>2006</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          6.
          <string-name>
            <surname>Miller</surname>
            ,
            <given-names>R.H.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sim</surname>
            ,
            <given-names>I.</given-names>
          </string-name>
          :
          <article-title>Physicians' use of electronic medical records: barriers and solutions</article-title>
          .
          <source>Health Aff, Millwood</source>
          ,
          <volume>23</volume>
          (
          <issue>2</issue>
          ),
          <fpage>116</fpage>
          -
          <lpage>126</lpage>
          (
          <year>2004</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          7.
          <string-name>
            <surname>Mark</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Hall</surname>
            ,
            <given-names>J.D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Kevin</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Schulman</surname>
          </string-name>
          , M.D.: Ownership of Medical Information, JAMA,
          <volume>301</volume>
          (
          <issue>12</issue>
          )
          <fpage>1283</fpage>
          (
          <year>2009</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          8.
          <string-name>
            <surname>Gravanova</surname>
          </string-name>
          , Yu.:
          <article-title>Features of the storage of medical information</article-title>
          . http://www.cnews.ru/reviews/free/national2006/articles/safe/
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          9.
          <string-name>
            <given-names>Defining</given-names>
            <surname>Key Health Information Technology Terms</surname>
          </string-name>
          . http://www.hitechanswers.net/wpcontent/uploads/2013/05/NAHIT-Definitions2008.pdf
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          10.
          <article-title>Decree of the President of Ukraine No. 187/2012 The National plan of actions for 2012 on the implementation of the program of economic reforms for 2010-2014. "Prosperous Society, Competitive Economy, Efficient State"</article-title>
          . https://zakon.rada.gov.ua/laws/show/187/2012
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          11.
          <article-title>Draft Order of the Ministry of Health of Ukraine "On approval of the concept of informatization of the healthcare of Ukraine on 2013-2018 years"</article-title>
          http://uacm.kharkov.ua/download/2013_10/
          <fpage>148</fpage>
          -154_Konzepziya_10_sc_P.pdf
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          12.
          <string-name>
            <surname>Healthvault</surname>
          </string-name>
          . https://international.healthvault.com
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>13. Zweena Health. https://www.pinterest.com/zweenahealth/</mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>14. Health Companion. https://www.healthcompanion.com</mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          15.
          <string-name>
            <surname>Healthspek</surname>
          </string-name>
          . https://www.healthspek.com
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          16. Anuff, Ed.:
          <article-title>APIs are Different then Integration</article-title>
          . https://pages.apigee.com/rs/apigee/images/APIs-not
          <string-name>
            <surname>-</surname>
          </string-name>
          integration-ebook-05-2014.pdf
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          17.
          <string-name>
            <surname>Poliakov</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Larionova</surname>
            ,
            <given-names>T.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Tabunshchyk</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Parkhomenko</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Henke</surname>
            ,
            <given-names>K.</given-names>
          </string-name>
          :
          <article-title>Remote laboratory for teaching of control systems design as an integrated system</article-title>
          .
          <source>In: The XIІІ international conference on Remote engineering and virtual instrumentation</source>
          , Madrid, Spain, pp.
          <fpage>333</fpage>
          -
          <lpage>340</lpage>
          (
          <year>2016</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          18.
          <string-name>
            <surname>Parkhomenko</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Gladkova</surname>
            ,
            <given-names>O.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sokolyanskii</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Shepelenko</surname>
            ,
            <given-names>V.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Zalyubovskiy</surname>
            ,
            <given-names>Y.</given-names>
          </string-name>
          :
          <article-title>Implementation of reusable solutions for remote laboratory development</article-title>
          .
          <source>International Journal of Online Engineering</source>
          .
          <volume>12</volume>
          (
          <issue>7</issue>
          ),
          <fpage>24</fpage>
          -
          <lpage>29</lpage>
          (
          <year>2016</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref19">
        <mixed-citation>
          19.
          <string-name>
            <surname>Why Should We Choose REST (Client-Server</surname>
          </string-name>
          ) Model to Develop Web Apps? https://medium.com/@audira98/
          <article-title>why-should-we-choose-rest-client-server-model-todevelop-web-apps-c3bb2451b13a</article-title>
        </mixed-citation>
      </ref>
      <ref id="ref20">
        <mixed-citation>
          20.
          <article-title>Types of HTTP requests and REST philosophy</article-title>
          . http://habrahabr.ru/post/50147/
        </mixed-citation>
      </ref>
      <ref id="ref21">
        <mixed-citation>21. W3C. SOAP Specification. https://www.w3.org/TR/soap/</mixed-citation>
      </ref>
      <ref id="ref22">
        <mixed-citation>
          22.
          <string-name>
            <surname>Maltseva</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          <article-title>Why use Swagger for creating and documenting APIs</article-title>
          . https://dev.to/dianamaltseva8/why
          <article-title>-use-swagger-for-creating-and-documenting-apis-115l</article-title>
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>