bvstone

Building JSON with RPG and YAJL and Writing to Standard Output

Posted:

Building JSON with RPG and YAJL and Writing to Standard Output

This example is meant to explain how to use the YAJL toolkit from Scott Klement, RPG, and the Apache server to easily create JSON and write it out to standard output.  This sort of functionality is nice if you're creating a web service for others to consume.

The HTTP Server Configuration

First, we need to set up an Apache server configuration.  This is really simple and would look similar to this:

Listen x.x.x.x:80

CGIConvMode %%EBCDIC/EBCDIC%%

<Directory />
   Options None
   Order Deny,Allow
   Deny From all
</Directory>

<Directory /www/bvsdemo/html>
   Order Allow,Deny
   Allow From all
   <FilesMatch "\.html(\..+)?$">
       Options +Includes
       SetOutputFilter Includes
  </FilesMatch>
</Directory>

ScriptAliasMatch ^/cgi-bin/(.*) /qsys.lib/bvsdemo.lib/$1.pgm

<Directory /qsys.lib/bvsdemo.lib>
   allow from all
   order allow,deny
   Options +ExecCGI +Includes
   SetOutputFilter Includes
</Directory>

With this configuration we are basically telling the Apache server to run any program requested to the /cgi-bin directory.  The actual library the program is in will be BVSDEMO.

The RPG Program

Next, we need the program (caution... full free format following!)

**free
ctl-opt DFTACTGRP(*NO) ACTGRP('BVSDEMO') BNDDIR('YAJL') DECEDIT('0.');

// Imports
/include yajl_h

// Global Definitions
dcl-ds CSTMSTDS extname('CSTMSTPF') end-ds;

// Work Variables
dcl-s yajl_errMsg varchar(500) inz('');

//**********************************************************************
yajl_genOpen(*ON);
yajl_beginObj(); //main JSON object

exsr $Data;

yajl_endObj(); // Main JSON Object

// Write JSON to Standard Output
yajl_writeStdout(200:yajl_errMsg);

if (yajl_errMsg <> '');
   // handle error
endif;

yajl_genClose();

*inlr = *on;

//***************************************************************
//* Build JSON
//***************************************************************
begsr $Data;

  exec SQL declare C1 cursor for
      select email, bname, name, add1, add2,
             city, state, zip
        from CSTMSTPF;

  exec SQL open C1;
  exec SQL fetch next from C1 into
      :email, :bname, :name, :add1, :add2,
      :city, :state, :zip;

  yajl_beginArray('customerList');

  dow (sqlCode = 0);
    yajl_beginObj();  //Customer Object
    yajl_addChar('email':%trimr(email));
    yajl_addChar('bname':%trimr(bname));
    yajl_addChar('name':%trimr(name));
    yajl_addChar('add1':%trimr(add1));
    yajl_addChar('add2':%trimr(add2));
    yajl_addChar('city':%trim(city));
    yajl_addChar('state':%trimr(state));
    yajl_addChar('zip':%trimr(zip));
    yajl_endObj();  //Customer Object

    exec SQL fetch next from C1 into
        :email, :bname, :name, :add1, :add2,
        :city, :state, :zip;
  enddo;

  exec SQL close C1;

  yajl_endArray(); //customerList

endsr;

As show by this program, we simply build the JSON using YAJL and then use the yajl_WritestdOut() function to output that JSON to the browser.

The Results

An example of this exact program can be seen here by clicking here.

Related Articles:


Last edited 07/12/2019 at 10:50:43



Latest Posts:

G4MSMAIL Now Allows Wildcard Attachments G4MSMAIL Now Allows Wildcard Attachments
Posted by June 10, 2021
BVSTools >> BVSTools Announcements >> GreenTools for Microsoft Apps (G4MS) Specific Announcements
G4G Update for Uploading Large Files G4G Update for Uploading Large Files
Posted by May 28, 2021
BVSTools >> BVSTools Announcements >> GreenTools for G Suite (Google Apps) (G4G) Specific Announcements
Can We Purchase License Keys for More Than One Year at a Time? Can We Purchase License Keys for More Than One Year at a Time?
Posted by May 21, 2021
BVSTools >> BVSTools Announcements
JOBWATCH 5.10 Released with New Feature to Monitor CPU Percentages JOBWATCH 5.10 Released with New Feature to Monitor CPU Percentages
Posted by May 10, 2021
BVSTools >> BVSTools Announcements >> Job Watch (JOBWATCH) Specific Announcements
Iseries Access data transfer Iseries Access data transfer
Posted by April 29, 2021
IBM Power Systems >> (QGPL) IBM i
YAJL - Parsing YAJL - Parsing
Posted by April 4, 2021
Programming >> RPG Programming
Create LPAR partition and install OS Create LPAR partition and install OS
Posted by March 24, 2021
IBM Power Systems >> (QGPL) IBM i
G4MS Now Allows User/Password Authentication Option G4MS Now Allows User/Password Authentication Option
Posted by March 16, 2021
BVSTools >> BVSTools Announcements >> GreenTools for Microsoft Apps (G4MS) Specific Announcements
IPDS printer file using CHRSIZ IPDS printer file using CHRSIZ
Posted by February 25, 2021
Programming >> RPG Programming
How to Correctly Send the Display Machine Information (DSPMCHINF) Data to BVSTools for Key Generation How to Correctly Send the Display Machine Information (DSPMCHINF) Data to BVSTools for Key Generation
Posted by February 9, 2021
BVSTools >> BVSTools Software Discussion
G4MS Updated to v7.10 - Required Update for All G4MS Users G4MS Updated to v7.10 - Required Update for All G4MS Users
Posted by November 12, 2020
BVSTools >> BVSTools Announcements >> GreenTools for Microsoft Apps (G4MS) Specific Announcements
MAILTOOL Errors with Microsoft Office 365 (2020) MAILTOOL Errors with Microsoft Office 365 (2020)
Posted by September 3, 2020
BVSTools >> BVSTools Software Discussion >> Email Tools (MAILTOOL) Specific Discussion
Using MAILTOOL With Office 365 and Two Factor Authentication (2FA or MFA) Using MAILTOOL With Office 365 and Two Factor Authentication (2FA or MFA)
Posted by August 17, 2020
BVSTools >> BVSTools Software Discussion >> Email Tools (MAILTOOL) Specific Discussion
Updating DNS With Dynamic IP Addresses After a Router Reboot/Power Outage Updating DNS With Dynamic IP Addresses After a Router Reboot/Power Outage
Posted by August 16, 2020
Programming >> Proof of Concept (POC)
GETURI v10.10 Released with New ILE Functions GETURI v10.10 Released with New ILE Functions
Posted by August 12, 2020
BVSTools >> BVSTools Announcements >> Get URI (GETURI) Specific Announcements

Reply




Copyright 1983-2020 BVSTools
GreenBoard(v3) Powered by the eRPG SDK, MAILTOOL Plus!, GreenTools for Google Apps, jQuery, jQuery UI, BlockUI, CKEditor and running on the IBM i (AKA AS/400, iSeries, System i).