COBOL Servlet Programming

COBOL Servlet option (OOP) : COBOL Servlet Programming

COBOL Servlet Programming

Following you will find an explanation about how to develop a simple COBOL servlet that builds an HTML page using a header.htm page and a footer.htm page, filling them with the correct message and sending a text string between them, the string is "Hello world from isCOBOL!".

The Web Servlet container used for this example is Tomcat 7.

This program needs to take the following steps:

•

Create a folder called doctest with the following structure:

doctest/

        WEB-INF/

                classes

                lib

•

Create a file called web.xml in doctest/WEB-INF folder with the following content:

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">

  <display-name>isCOBOL EIS</display-name>

  <welcome-file-list>

    <welcome-file>Hello.htm</welcome-file>

  </welcome-file-list>

  <filter>

        <filter-name>isCOBOL filter</filter-name>

        <filter-class>com.iscobol.web.IscobolFilter</filter-class>

  </filter>

  <filter-mapping>

        <filter-name>isCOBOL filter</filter-name>

        <url-pattern>/servlet/*</url-pattern>

  </filter-mapping>

  <servlet>

        <servlet-name>isCobol</servlet-name>

        <servlet-class>com.iscobol.web.IscobolServletCall</servlet-class>

  </servlet>

  <servlet-mapping>

        <servlet-name>isCobol</servlet-name>

        <url-pattern>/servlet/*</url-pattern>

  </servlet-mapping>

  <listener>

   <listener-class>com.iscobol.web.IscobolSessionListener</listener-class>

  </listener>

</web-app>

•

Create a Hello.htm web form to call a COBOL servlet called HELLO:

<HTML><HEAD><TITLE>Doc isCOBOL Example</TITLE></HEAD>

<BODY>

<H2>Doc isCOBOL Example.</H2>

<H3>This example shows how easily you can compose an HTML page with an isCOBOL program running on the web server. The HTML page is composed by two parts an header and a footer. In every part of the HTML page, the isCOBOL program moves a message and between the two sends the text: "Hello world from isCOBOL".</H3>

<HR size="2">

<FORM method="post" action="servlet/isCobol(HELLO)">

    <p><input type="submit" value="Invoke isCOBOL HELLO program" /></p>

</FORM>

Note that in POST method of HTML form there is the call of the COBOL Servlet called HELLO.

•

Create a Header.htm as follow:

<HTML>

<HEAD><TITLE>CGI Header</TITLE></HEAD>

<BODY>

<CENTER>

<H1>This is the Header HTM form of this isCOBOL example</H1>

<H2>This is the message sent by the isCOBOL program: %%opening-message%%</H2>

<HR>

Note that this form displays the top of the HTML page that the program HELLO.cbl will build; as we can see, the <HTML>, <BODY> and <CENTER> tags are not closed, and there is the string %%opening-message%% that will be managed and replaced by the COBOL servlet program.

•

Create a Footer.htm web form as follow:

</CENTER>

<BR>

<HR>

This is the footer HTML page of this isCOBOL example.

<H2>This is the message sent by the program: %%closing-message%%</H2>

</BODY></HTML>

Note that this form displays the bottom of the HTML page that the program HELLO.cbl will build. Here the tags <HTML>, <BODY> and <CENTER> are closed and there is the string %%closing-message%% that will be managed and replaced by the COBOL servlet program.

•

Create a HELLO.cbl COBOL Servlet program as follows:

       PROGRAM-ID. HELLO initial.

       CONFIGURATION SECTION.

       REPOSITORY.

       class web-area as "com.iscobol.rts.HTTPHandler"

           .

       WORKING-STORAGE SECTION.

       01  hello-buffer pic x(40) value "Hello World from isCOBOL!".

       01  rc pic 9.

       01  html-header-form identified by "Header".

            05  identified by "opening-message".

                10 opening-message pic x(40).

       01  html-footer-form identified by "Footer".

            05  identified by "closing-message".

                10  closing-message pic x(40).

       LINKAGE SECTION.

       01 comm-area object reference web-area.

       PROCEDURE DIVISION using comm-area.

       MAIN-LOGIC.

           move "This is the header" to opening-message

           set rc = comm-area:>processHtmlFile (html-header-form).

           comm-area:>displayText  (hello-buffer).

           move "Bye Bye by isCOBOL" to closing-message

           set rc = comm-area:>processHtmlFile (html-footer-form).

           goback.

Note that the COBOL servlet does the following steps:

•

Move the value "This is the header" to the variable opening-message of the structure prepared for Header.htm

•

Add to the HTML page source (that currently is empty) the Header.htm form replacing the string %%opening-message%% by the opening-message variable value

•

Add to the HTML page the text "Hello world from isCOBOL!"

•

Move the value "Bye Bye by isCOBOL" to the variable closing-message of the structure prepared for Footer.htm

•

Add to the HTML page source the Footer.htm form replacing the string %%closing-message%% by the closing-message variable value

at the exit of the program, the page HTML will be sent to the Web Server.

•

Compile HELLO.cbl without particular option and copy HELLO.class under doctest/WEB-IF/classes folder

•

Create a iscobol.properties file under doctest/WEB-IF/classes folder with a property to inform isCOBOL EIS framework of the path of all HTML useful files:

iscobol.http.html_template_prefix=webapps/doctest

•

Create a war file to be deployed in Tomcat called doctest.war that includes all files of doctest folder. It can be done with the following command:

jar -cfv doctest.war *

Once doctest.war file is deployed correctly in Tomcat servlet container, we can try it using http://127.0.0.1:8080/doctest, assuming to have Tomcat running on localhost using default 8080 port.

By pressing the "Invoke isCOBOL Hello program" button, the result is:

doctest/ WEB-INF/ classes lib

<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> <display-name>isCOBOL EIS</display-name> <welcome-file-list> <welcome-file>Hello.htm</welcome-file> </welcome-file-list> <filter> <filter-name>isCOBOL filter</filter-name> <filter-class>com.iscobol.web.IscobolFilter</filter-class> </filter> <filter-mapping> <filter-name>isCOBOL filter</filter-name> <url-pattern>/servlet/</url-pattern> </filter-mapping> <servlet> <servlet-name>isCobol</servlet-name> <servlet-class>com.iscobol.web.IscobolServletCall</servlet-class> </servlet> <servlet-mapping> <servlet-name>isCobol</servlet-name> <url-pattern>/servlet/</url-pattern> </servlet-mapping> <listener> <listener-class>com.iscobol.web.IscobolSessionListener</listener-class> </listener> </web-app>

<HTML><HEAD><TITLE>Doc isCOBOL Example</TITLE></HEAD> <BODY> <H2>Doc isCOBOL Example.</H2> <H3>This example shows how easily you can compose an HTML page with an isCOBOL program running on the web server. The HTML page is composed by two parts an header and a footer. In every part of the HTML page, the isCOBOL program moves a message and between the two sends the text: "Hello world from isCOBOL".</H3> <HR size="2"> <FORM method="post" action="servlet/isCobol(HELLO)"> <p><input type="submit" value="Invoke isCOBOL HELLO program" /></p> </FORM>

<HTML> <HEAD><TITLE>CGI Header</TITLE></HEAD> <BODY> <CENTER> <H1>This is the Header HTM form of this isCOBOL example</H1> <H2>This is the message sent by the isCOBOL program: %%opening-message%%</H2> <HR>

</CENTER> <BR> <HR> This is the footer HTML page of this isCOBOL example. <H2>This is the message sent by the program: %%closing-message%%</H2> </BODY></HTML>

PROGRAM-ID. HELLO initial. CONFIGURATION SECTION. REPOSITORY. class web-area as "com.iscobol.rts.HTTPHandler" . WORKING-STORAGE SECTION. 01 hello-buffer pic x(40) value "Hello World from isCOBOL!". 01 rc pic 9. 01 html-header-form identified by "Header". 05 identified by "opening-message". 10 opening-message pic x(40). 01 html-footer-form identified by "Footer". 05 identified by "closing-message". 10 closing-message pic x(40). LINKAGE SECTION. 01 comm-area object reference web-area. PROCEDURE DIVISION using comm-area. MAIN-LOGIC. move "This is the header" to opening-message set rc = comm-area:>processHtmlFile (html-header-form). comm-area:>displayText (hello-buffer). move "Bye Bye by isCOBOL" to closing-message set rc = comm-area:>processHtmlFile (html-footer-form). goback.

iscobol.http.html_template_prefix=webapps/doctest

jar -cfv doctest.war *

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