Speed Up Your APEX Apps with JSON and Handlebars

Speed Up Your APEX Apps with JSON
and Handlebars
Marko Gorički
BiLog

About BiLog
• small IT company focused on consulting and business solution development
(using Oracle technologies)
• big APEX company ≈ 25 APEX developers
• our APEX products:
HRMb - HR management software
www.bilog.hr

About Me
• started with Oracle Forms and Reports
• working 8 years with APEX
• APEX related blog - apexbyg.blogspot.com
• @mgoricki

It depends
There are only five questions about the database:
• The answer to the first three questions is “use bind variables.”
• The answer to the fourth question is “do not use bind variables.”
• The answer to the fifth question is “it depends”.
If you know those answers, you can answer any question about the database!
– Tom Kyte
• In APEX: “it depends”

JSON
• JavaScript Object Notation – lightweight data interchange format that consists
of name-value pairs
• key features:
• easy to read and write
• easy to generate and parse
• language independent
• subset of JavaScript notation

JSON format
• {“name”: value, “name”: value…}
• key elements
• Name
• Value
• Object (unordered collection)
• Array (ordered collection)
Name/key/attribute
Value
Object
Array

Value
• string - double quotes(“”), backslash escapes ()
• number - decimal notation (possibly signed and possibly including a decimal
exponent)
• no date data type
• null different to SQL null

Object
• unordered set of name/value pairs
• begins and ends with brace - {…}
• name/string/attribute/key followed by colon
• separated by comma

Array
• ordered collection of values
• begins and ends with brackets - […]
• separated by comma

*Please, don’t use this in your CV !! 

JSON vs XML
JSON XML
Predefined data types
Typless or based on XML Schema or document type
definition (DTD)
Structured data Structured and semi-structured data
Data-centric Data or document-centric
Data representation language Document markup and data representation language

Generate JSON
• prior to APEX 5:
• by manually concatenating strings
• apex_util.json_from_*
• PL/JSON

Generate JSON
• with APEX 5 - APEX_JSON API package

Generate JSON
• Other solutions
• Oracle REST Data Services (ORDS)
• node.js

SQL source
• why short column alias (x, a, b and c)?
• JSON size:
• 500 rows - 29.1KB vs 43.3KB
• less readable vs ≈30% smaller size

SQL source
With short aliasWithout alias

Generate JSON
• Manually by concatenating strings
• apex_util.json_from_*
• PL/JSON library
• APEX_JSON package
• ORDS

Manually by concatenating
strings
• using sys.htp package
• CONS:
• hard to maintain and develop
• manually escape values
• manually define value types
• easy to make mistakes
• no parsing
• PROS
• customizable
• it can be fast

Using apex_util.json_from*
• procedures: *_sql, *_array, *_items, *_string
• CONS:
• “not documented”
• no null, true and false values
• hard to create nested JSON objects
• no parsing
• security issue: passing string into json_from_sql
• PROS:
• simple and easy to develop
• auto escaping
• recognizes some value types (number)
• available before APEX 5

PL/JSON
• open source library (2009.)
• DB types: JSON (object) and JSON_LIST (array)
• CONS
• complex
• lack of real documentation
• performance issues
• PROS
• can be stored in DB
• parsing
• supports all value types
• open source
• available before APEX 5

APEX_JSON API
• PROS:
• native
• generating and parsing
• can be used as standalone (CLOB)
• light footprint
• easy conversion from/to xmltype
• CONS:
• only in APEX 5.0+

APEX_JSON API
• Simple JSON Array
apex_json.open_array;
for emp in (select *
from emp
where deptno = p_deptno)
loop
apex_json.write(emp.ename);
end loop;
apex_json.close_array;

Nested JSON object - with cursor
declare
cur_dept sys_refcursor;
begin
open cur_dept for
select d.dname
, d.loc
, cursor (select e.ename
, e.job
, e.sal
, (select m.ename from emp m where m.empno = e.mgr) manager
, decode(e.comm, null, 'false', 'true') as hasCommision
from emp e
where d.deptno = e.deptno) as emps
from dept d
where d.deptno = nvl(p_deptno, d.deptno);
apex_json.open_object;
apex_json.write('DEPTS',cur_dept);
apex_json.close_object;
end;

Parsing simple JSON object
declare
v_json_object varchar2(100) := '{"dname":"ACCOUNTING","loc":"NEW YORK"}';
begin
apex_json.parse(v_json_object);
dbms_output.put_line(
apex_json.get_varchar2('dname')
);
end;

Parsing nested JSON object
declare
v_json_object clob := ‘{…}’;
begin
apex_json.parse(v_json_object);
apex_json.get_varchar2('DEPTS[1].EMPS[2].ENAME')
);
apex_json.get_varchar2(p_path => 'DEPTS[%d].EMPS[%d].ENAME’
, p0 => 1
, p1 => 2)
);
end;

Oracle REST Data Services (ORDS)
• easy to develop modern REST interfaces
• ways to use it:
• APEX GUI
• SQL Developer (auto-rest)
• PL/SQL API
• Simple Oracle Document Access (SODA) API over REST
• URL format:
• protocol://host:port/ords-name/apex-workspace-name/uri-template/bind-value
• https://apex.oracle.com/pls/apex/mgoricki/dept/10

Oracle Rest Data Services (ORDS)
• CONS
• little slower
• you need ORDS
• PROS
• declarative and simple
• many options
• easy to create nested JSON objects

Best method?
• It depends! 

657.80
1574.00
287.00
332.80
254.70
0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00 1600.00 1800.00
ORDS
PL/JSON
apex_json
apex_util.json_from_sql
Manually
Average execution time (ms)

29.90
29.30
29.30
29.30
29.30
29.00 29.10 29.20 29.30 29.40 29.50 29.60 29.70 29.80 29.90 30.00
ORDS
PL/JSON
apex_json
Manually
Average JSON size (KB)

JSON and Oracle12c
• native support from 12.1.0.2
• store JSON data (with VARCHAR2, CLOB or BLOB data types), index,
query…
• parse JSON data with SQL

JSON and Oracle12c
• storing JSON data
create table my_json(
json_col clob
);
alter table my_json add constraint valid_json
check (json_col is json);
insert into my_json
values ('{"dname":"ACCOUNTING","loc":"NEW YORK"}');

JSON and Oracle12c
• parsing JSON data
SQL> select json.json_col.dname from my_json json;
DNAME
---------
ACCOUNTING

Using JSON
• APEX use it (IR, Page designer)
• New APEX 5.1 grid
• Oracle JET
• fetch asynchronously data with AJAX
• communicate with Web services (REST API - Twitter, Flickr, Google
Apps)
• easy to use with JavaScript

Old HTML way
HTTP Request
HTML page
Client / Browser Server / DB

AJAX partial page
AJAX Request
HTML part

Client side templates
AJAX Request
JSON
HTML Template

• light weighted JavaScript templating engine (Mustache.js,
AngularJS, Backbone.js, Ember.js, Marko.js…) used for client-side
data binding
• subset of Mustache.js + minimal logic
• works by expanding tags in a template using values provided by
JSON object
• tags can be replaced with value, nothing or series of values
Handlebars.js

Handlebars.js templates
• tags start and end with double braces (mustaches) {{…}}
• two simple types of tags:
• variables - basic tag type
{{title}}
• sections/block expressions - render block of text one or more times
{{#posts}}…{{/posts}}

In APEX
• Add JS library
• Create template item

• Define HTML object where to put result
• Fetch JSON and run render function
In APEX
Example

578.80
657.80
1574.00
287.00
332.80
254.70
0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00 1600.00 1800.00
Report region
ORDS
PL/JSON
apex_json
Manually
Average execution time (ms)

122.00
29.90
29.30
29.30
29.30
29.30
0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00
Report region
ORDS
PL/JSON
apex_json
Manually
Average JSON size (KB)

Real-life example
Generation time: 2 minutes
Response time: 2.3 MB
Only first 700 rows

Real-life example
Generation time: 2.9s vs 2 minutes
Response time: 500KB vs 2.3 MB
All 2422 rows vs 700 rows

Speed Up Your APEX Apps with JSON and Handlebars

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