=Paper=
{{Paper
|id=Vol-3041/387-392-paper-71
|storemode=property
|title=Walt Platform for Web Application Development
|pdfUrl=https://ceur-ws.org/Vol-3041/387-392-paper-71.pdf
|volume=Vol-3041
|authors=Vladimir Korenkov,Sergey Kuniaev,Sergey Semashko,Ivan Sokolov
}}
==Walt Platform for Web Application Development==
https://ceur-ws.org/Vol-3041/387-392-paper-71.pdf
Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
WALT PLATFORM FOR WEB APPLICATION
DEVELOPMENT
V.V. Korenkov, S.V. Kuniaev, S.V. Semashko, I.A. Sokolov a
Joint Institute for Nuclear Research, 6 Joliot-Curie St., Dubna, 141980, Russia
E-mail: a isokolov@jinr.ru
The article describes the Web Application Lego Toolkit (WALT), which is a template-oriented
platform designed for the development of web applications of various degrees of complexity. Unlike
some other platforms, which represent a "magic black box", the main idea of WALT is to provide
transparent, extensible, and modifiable tools for solving some specific problems that arise when
developing web applications. WALT is primarily intended for use by individual full-stack developers
or small groups of developers. The article depicts the WALT architecture and provides examples of its
use for the development of JINR corporate web applications.
Keywords: web application, service, template, platform, java, request
Vladimir Korenkov, Sergey Kuniaev, Sergey Semashko, Ivan Sokolov
Copyright © 2021 for this paper by its authors.
Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
1. Introduction
Currently, there is a great variety of platforms for the development of web applications:
Django, ASP.NET Core, Express, Angular, etc. [1, 2, 3, 4]. These platforms provide developers with a
rich set of tools and libraries, which allows them to create advanced web applications. As a rule, a
relatively large team of developers works on a project in large or medium-sized IT companies. At the
same time, there is a division within the team according to the nature of the work: design, frontend
web development, backend development, testing. Listed above platforms are well suited for such a
web development organization.
However, in the scientific field and in our real life, very often only one or two people are
engaged in the development of a web application, they are essentially full-stack developers. In
addition, often the same people simultaneously work on other projects and support applications which
are already in operation. Thus, the development process follows the principles of Agile
Programming.[5].
The WALT platform presented in the article is very effective for such organization of work
and can be successfully used for the development of web applications of various complexity by a
small team. It also allows expanding and modifying the functionality of the application during its
operation. Web applications developed using WALT are characterized by high performance and
humble server resource requirements. The platform is easy to learn. To start using it, it is enough for a
developer to have basic layout skills (HTML + CSS), be able to administer a DBMS, master the SQL
query language, learn the WALT template language, and get acquainted with the existing set of
WALT services.
2. Project overview
WALT is implemented as a Javatm class library [6], but it does not require Java proficiency
from the developer to perform typical tasks. WALT is a template-oriented platform. A simple
language and corresponding interpreter were developed to use templates. This language allows to
customize the output HTML code, SQL queries to the database, as well as to modify the processing
route in run-time depending on the particular user request and intermediate results. In other words,
template says to the Java-program what to do using a very laconic language and the Java-program
does it. So, templates define the main part of the web application logic and behavior.
WALT makes it possible to combine the functionality of frontend and backend parts within a
module and freely move the functionality from the frontend to the backend and vice versa. It is
compatible with modern frontend tools like JQuery, Bootstrap, etc. This allows the developer to
choose the optimal distribution of functionality between the frontend and backend right during the
project implementation.
Unlike many others, WALT is a transparent and easily extensible platform.
2.1 WALT architecture
The WALT architecture is shown in Fig. 1. It is based on Java servlet technology [7]. Some
kind of a servlet container (Servlet engine) is needed to run it. Apache Tomcat [8] is well suited and
free. The Servlet engine receives an HTTP request from the client and passes it to the WALT
application servlet. In the servlet, the request goes through several general initial stages of processing:
creating and launching a separate thread to execute the request, extracting input data from the request
and forming a list of parameter values, connecting to the database, authenticating the user, etc. After
going through the general steps, based on the obtained information, servlet selects a specific module
with templates and launches the corresponding service. The service extracts necessary information
from the module templates and performs necessary actions based on the client’s request, namely,
exchanging data with the database, preparing a response to the client, and other actions on the server-
side. At the end of processing, the servlet sends the generated response to the client.
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
Figure 1. WALT architecture
2.2 Main WALT services
The WALT core provides the developer with 21 services. A service is a class written in Java,
designed to perform a specific kind of tasks (working with data from a database, file operations,
sending emails, image processing, etc.). The basic root service is the Java-class
dubna.walt.service.Service. It is used as a parent class for all other services. Also Service itself
together with corresponding modules can process many common tasks like execute a set of SQL-
queries to database, prepare output HTML code, make some file operations etc. Other most frequently
used services are:
● TableServiceSimple, TableServiceSortable, TableServiceComplex, TableServiceSpecial –
different kinds of table-oriented services that can execute an SQL query to the DB and process
the obtained recordset (typically, output results to the client, but other operations like update
data can also be performed)
● CrossTabService – executes an SQL query and creates a cross-tab report similar to EXCEL’s
Pivot table
● CommandExecutor – executes a native host command and obtains the result
● ServiceUploadFile – uploads a file to the server
● ServiceBinaryData – sends data to the client in a binary form for downloading data as a file or
for some other processing
● SendMailService – sends an email
● ServiceImportData, ServiceCopyData – copies data from a database to another one
Usually, the core services allow to solve at least 95% of the tasks within a web application. In
rare cases, when the existing services cannot cope with some very specific tasks, or it is necessary to
modify the processing, WALT makes it possible to expand the functionality. To do this, it is necessary
to implement a new service based on the existing one. However, it requires some Java programming
skills from the developer.
2.3 WALT template syntax and directives
Templates are grouped into modules, which are plain text files with a specific structure. Each
module is designed to perform some specific task. It is made up of sections containing a code fragment
that performs some part of the whole task. The use of sections allows following the principle “divide
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
and conquer”. Sections can be used both inside the same module and in other modules, which enables
code reuse.
In practice, most of the tasks in web applications are related to database record processing.
WALT enables solving such tasks by writing a simple module with information about necessary
queries to the database and about the output HTML (or any other) code. The rest of the work is done
by a core WALT service.
An important basic element of the template syntax is the “Parameters Substitution”
construction. It is denoted in the code as #name#, where "name" is the name of the parameter whose
value we want to use at this point of the code. In the following sample, the value of a parameter named
“age” is inserted into the code instead of #age#:
Age: #age#
Another important element of the syntax is the “Condition Check” construction. It checks the
fulfillment of the condition after the double question mark, and, if the result is false, the code line is
ignored. In the following sample, the string “Some_line_of_code” is inserted into the code only if the
value of the parameter “ID” is greater than 5 or the value of the parameter “Name” is equal to “Ivan”,
and the value of the parameter “age” is greater than 30:
Some_line_of_code ??ID>5|Name=Ivan&age>30
“Parameters Substitution” and “Condition Check” allow controlling user request processing at
runtime. For instance, they can be used to customize the SQL query template according to the user's
request or to modify the output HTML code depending on the data obtained from the DB.
Another important element of the syntax is the directive. Directives make it possible to
perform some separated completed actions on the backend. Directives extend the Services
functionality and add flexibility. In the template, the directive call starts with the “$” sign. 26
directives are implemented in WALT:
● $INCLUDE – insert some section from this or another module into the code. It enables code
reuse and makes it more compact and readable
● $GET_DATA – get necessary data by executing some SQL script or by other actions (e.g.
read data file)
● $CALL_SERVICE – execute another module inside the parent one. It allows one to divide a
complex task into several simple subtasks, as well as to reuse the code. It gives an opportunity
to implement recursive calls.
● $JS, $JS_BEGIN - $JS_END – use the server-side JavaScript code. It often protects the
developer from having to develop a new Java service.
● $READ_FILE, $COPY_FILE, $MOVE_FILE, $DELETE_FILE, $GET_FILE_SIZE –
common file operations
● $GET_URL – open the specified URL and obtain its response
● And others such as $EXECUTE_LOOP, $IF - $ELSE - $ENDIF, $WAIT, $USE_DB,
$CLOSE_DB, $STORE_PARAMETERS - $RESTORE_PARAMETERS,
$GET_AUTH_URL, $BREAK, $PRINT, $LOG, etc.
The WALT template language is capacious and concise, which enables the creation of a
compact module to solve complex tasks by decomposing it into simple parts and reusing the code.
2.4 Simplest usage sample
The code of a simple module and the result of its work are presented in Fig. 2. This module
selects information about people from the database, as well as allows searching for people by the
beginning of the family name. It contains an indication of the service to be used, templates for the
SQL query to the database and the output HTML code. The rest of the task on fetching data, forming
the HTML table and output to the client is carried out by the specified TableServiceSimple. Thus, the
compact code performs some completed task.
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
Figure 2. Simplest module
2.5 JINR corporate web applications developed using WALT
WALT has been used to develop many JINR corporate web applications of various levels of
complexity. The table below provides a list of them and approximate estimated labour costs in man-
months for the development of the first working version. All these applications are currently in
operation, some of them are evolving.
Table 1. JINR corporate web applications developed using WALT
Application Appointment HR
(man x
months)
ADB2 JINR's management accounting 4
PIN Staff information in various aspects [9] 6
EDMS Electronic storage for administrative activity documents 6
”Documents DB”
NICA EVM Project structure, workplans, expenses, Costbook, reports, etc. 4
EDMS “Dubna” JINR electronic document management system [10] 12
HR JINR Staff information in various aspects 4
Map JINR Basic map of JINR’s sites. Accessible for everyone online without 2
restrictions
Gateway Universal gateway for data exchange between various systems 2
ISSC Scientific attestation support system 3
CERN DB JINR's staff at CERN: trips, accommodation, reports, etc. 4
eco.jinr.ru Structured list of JINR's corporate applications with distributed 0.5
administration
EDMS “Advance Data preparation for business trip accounting reports 5
reports”
Checkpoint lists Lists for access to JINR’s sites in a limited access mode 0.25
It took only one week to twelve man-months to develop and launch a trial of the 1st version of
the application. In addition to the above listed, more than a dozen applications have been developed
using WALT outside of JINR. This confirms the effectiveness of WALT usage.
3. Conclusion
The presented platform with its very small code volume (~650 KB) has many advantages and
can facilitate the development of sophisticated web applications by a small group of developers.
Thanks to the number of available services and the concise and capacious template language, the
developer can promptly perform complex tasks with a minimum amount of code. When very specific
tasks arise, WALT allows the developer to expand or modify the functionality. WALT is compatible
with client tools such as jQuery, AJAX technology, etc., enabling to use them for frontend
development. The effectiveness of the platform is proved by many applications developed using it.
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Proceedings of the 9th International Conference "Distributed Computing and Grid Technologies in Science and
Education" (GRID'2021), Dubna, Russia, July 5-9, 2021
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