S1A - Web Programming with eRPG

Transcription

Essential eRPG
Bradley V. Stone
www.bvstools.com
Essential eRPG
• The Basics
HTML, JavaScript, Stylesheets, Cookies, SSI, The IFS
• The Function
How does eRPG work?
• The Core
Working with Input, Output and More
• The Misunderstandings
Hype, Lies, and the real power of eRPG
• The Examples
Examples of sites using eRPG
• The Resources
Resources for eRPG Application Development and Administration
© 2007 Cozzi Productions, Inc.
The Basics
Any web application team requires
knowledge of the following:
• Server Configuration
• HTML
• JavaScript
• Stylesheets (CSS)
• Cookies
• Server Side Includes (SSI)
• The IFS
The Basics
Server Configuration
Contains commands that:
• Specify the port
• Restrict and grant access to
certain locations on the machine
• “Hide” physical location of
documents
• Specify location of CGI
applications
• Control other aspects of the
server (directory indexes, server
side includes, etc.)
The Basics
Server Configuration Cont…
Listen xx.xx.xx.xx:80
DocumentRoot /www
DirectoryIndex index.html
CGIConvMode %%EBCDIC/EBCDIC%%
ScriptAliasMatch ^/cgi-bin/(.*)
/qsys.lib/as400cgi.lib/$1.pgm
<Directory />
Options None
AllowOverride None
order deny,allow deny from all
</Directory>
<Directory /www>
AllowOverride None
order allow,deny
allow from all
<FilesMatch "\.html(\..+)?$">
Options +Includes
SetOutputFilter Includes
</FilesMatch>
</Directory>
<Directory
/qsys.lib/as400cgi.lib>
allow from all
order allow,deny
Options +ExecCGI +Includes
</Directory>
The Basics
Sever Configuration Cont…
Web Request
• www.mysite.com
• www.mysite.com/faq.html
• www.mysite.com/docs/erpg
.html
• www.mysite.com/cgibin/listorder
• /images/logo.jpg
Actual file served
• /www/index.html
• /www/faq.html
• /www/docs/erpg.html
• Program LISTORDER
in library AS400CGI
• ?
The Basics
Server Configuration Cont…
<img src=“/images/logo.jpg” border=“0”>
Actual location:
/www/images/logo.jpg
The Basics
HTML
Why is HTML important?
The Basics
HTML
• Hypertext Markup
Language
• The “Building Blocks”
of web pages
• Used for static and
dynamic content
• Without it, web clients
would be “lost”
The Basics
HTML Cont…
Main HTML Components
• Text
• Hyperlinks
• Images
• Tables
• Input fields and objects
The Basics
HTML Cont…
http://www.bvstools.com/download.html (local)
The Basics
JavaScript
• Makes pages more
Interactive
• Gives control over
web page objects
• Client-side data
validation
The Basics
JavaScript Cont…
<SCRIPT>
function Validate(form) {
if (form.dept.value=="") {
alert("Please enter a department.");
return false;
}
return true;
}
</SCRIPT>
The Basics
JavaScript Cont…
http://www.bvstools.com/erpg/erpgv2/examples/formvalidation1.html
(local)
The Basics
Stylesheets (CSS)
• Used to control the look and feel
of web page
• Allow you to “externalize” the
web page formatting
• Allow for easy, quick and
localized web page style
changes
The Basics
Stylesheets Cont…
•
•
•
•
Stylesheets apply “styles” to web objects
Stylesheets “cascade”
Stylesheets can be internal or external
Using Stylesheets allows you to change
attributes for all web objects in one place
body
{background-color: #FFFFFF;
font-size: 70%; font-family: arial}
td
{font-size: 80%; background-color: #FFFFFF;
text-align: left; vertical-align: top}
td.right {text-align: right}
The Basics
Stylesheets Cont…
The Basics
Stylesheets Cont…
The Basics
Cookies
What are Cookies?
The Basics
Cookies
• Cookies allow you to store
information to identify a visitor, order,
or other information
• Cookies allow “easy” persistent web
programming
• Cookies themselves are not
“dangerous”
• Cookies should not contain sensitive
data
• Some “bugs” in browsers allow(ed)
access to cookies they shouldn’t
have
The Basics
Cookies Cont…
Cookies are placed into
the web page
headers in the form:
Set-Cookie: NAME=VALUE;
expires=DATE; path=PATH;
domain=DOMAIN_NAME;
secure
• Cookies are stored
locally on the client’s
machine
• Cookies values are
retrieved using the
HTTP_COOKIE
environment variable
The Basics
Cookies Cont…
http://www.bvstools.com/erpg/erpgv2/examples/testcookie.html
The Basics
Server Side Includes (SSI)
• Server Side Includes (SSI)
allow you to build your web
pages in smaller pieces, like
puzzle
• SSI allows you to change
reused pieces on every page in
one step
• SSI content can be either static
or dynamic
The Basics
SSI Cont…
Web Page Source:
SSIData.html Source:
<html>
<body>
The following will be
inserted using an SSI
directive.
<hr>

This data was inserted using an
SSI directive.<br>
Isn't that cool?<br>

The Basics
SSI Cont…
The Basics
SSI Cont…
“View Source” results:
<html>
<body>
directive.
<hr>

This data was inserted using
an SSI directive.<br>
Isn't that cool?<br>

<hr>
</body>
</html>
• SSI Statements
insert content at run
time
• Content inserted
can be static or
dynamic
• HTTP server must
be configured to
“recognize” SSI
statements
The Basics
SSI Cont…
Web Page Source:
<html>
<body>
directive.
<hr>
<!--#exec cgi="/erpg/ssi1" ->
<hr>
</body>
</html>
The Basics
SSI Cont…
Source for SSI1 eRPG
Program
The Basics
SSI Cont…
<Directory /www>
AllowOverride None
order allow,deny
allow from all
<FilesMatch "\.html(\..+)?$">
Options +Includes
</FilesMatch>
</Directory>
<Directory /qsys.lib/cgilib.lib>
allow from all
order allow,deny
Options +ExecCGI +Includes
</Directory>
The Basics
The IFS
• Different from the Library/File
file system we are used to
• Similar to Windows or Unix file
systems
• Used to store static web pages,
JavaScript, Stylesheets, etc.
• Used to store Apache
configuration files
• Access through green screen,
FTP, Windows Explorer
The Basics
The IFS Cont…
The IFS Contains:
• QSYS.LIB file system
• QDLS file system
• QOpenSys file
system
• “Root” File System
• Others…
IFS Commands
• Work With Object
Links (WRKLNK)
• Display File (DSPF)
• Edit File (EDTF)
• Copy to Stream File
(CPYTOSTMF)
• Copy to Import File
(CPYTOIMPF)
• Others…
The Basics
The IFS Cont…
Basic IFS Structure for web applications.
Port 80 (Production)
• /www
[html]
– /Images
– /Stylesheets
– /Javascript
– /Templates
– /SSI
Port 8080 (Devo/Test)
• /wwwtest
[html]
– /Images
– /Stylesheets
– /Javascript
– /Templates
– /SSI
The Function
•
•
•
•
•
•
What is “eRPG”?
How does eRPG Work?
What Languages are Used?
What about the Web Server?
Environments
eRPG Benefits
The Function
What is “eRPG”?
Simple, an easier way
to say:
• RPG/CGI
• CGI/RPG
• CGI Programming
with RPG
The Function
How does eRPG work?
• Client makes a request
• Server decides what it needs to
return
• Static pages are returned “as is”
• Dynamic pages are built using a
eRPG program
Examples:
http://www.myserver.com/index.html
(static)
http://www.myserver.com/cgi-bin/sales.pgm
(dynamic)
The Function
•
•
•
•
•
•
RPG
COBOL
Net.Data
Perl
Active Server Pages (ASP)
Java (Servlets, Java Server Pages, etc)
The Function
Basic Requirements for each language:
• RPG/COBOL/Net.Data – “Powered by
Apache” HTTP Server
• Perl – 3rd party or native Perl Interpreter
and “Powered by Apache” HTTP Server
• Active Server Pages (ASP) – Microsoft
Internet Information Services (IIS) Server
• Java – WebSphere or other Java Web
Service (such as Tomcat)
The Function
What about the Web Server?
• In the beginning, there was the
“Classic HTTP Sever”
• Then a choice, “Classic” or the new
“Powered By Apache” HTTP
Server
• V5R3 and higher, no longer a
choice, only the “Powered by
Apache” HTTP Server is available
• WebSphere is NOT required
The Function
Environments
• It is useful to set up at least two
environments, possibly three
– Production
– Testing
– Development
The Function
Environments Cont…
Each environment should contain:
• A web server using a separate IP address/port
• A web configuration
• A directory to hold files, templates, images, JavaScript,
etc
• A programming library
The Function
eRPG Benefits
•
•
•
•
•
•
•
Very small learning curve for RPG shops
Available learning media
Available toolkits (CGIDEV2, eRPG SDK)
Existing RPG skills used
No extra software is needed
Excellent performance
Fewer system resources used overall
The Core
•
•
•
•
•
•
•
•
User Profiles
Library List
APIs
Output
Input
Record Selection
Debugging
Toolkits
The Core
User Profiles
• Your eRPG programs run in
jobs just like any other
application
• Jobs normally run under
user profiles QTMHHTTP
and QTMHHTP1
• Knowing this helps with
problem solving such as
disabled profiles, authority
issues and finding job logs
The Core
Library List
• Library Lists are handled a bit
differently with web applications
• The library list cannot be
manipulated using job
descriptions (at least previous to
V5R3)
• The library the web application
is running in is “automatically” in
the library list
• Any other libraries must be
manually added or removed
The Core
APIs
•
•
•
•
•
Read input
Write output
Retrieve environment variables
Convert web data to a usable format
Located in service program QZHBCGI in
library QHTTPSVR
The Core
Output
• Basic function of eRPG
programs is output
• Normally in the form of HTML
• This is why understanding
HTML is so important
• Can also be text, XML, other
types of data
The Core
Output Cont…
• QtmhWrStout API is used
• Create a string, pass it to this API
• Data is written to “Standard Output”
– “Data” is normally HTTP Headers + HTML
• Standard Output in this case is a web
browser
• Example (local)
• Example Source
The Core
Input
• Interaction requires Input from the
user
• Text fields, text areas, selection
lists, bullets, check boxes
• Using the proper input type is
critical to design
• Data validation
The Core
Input Cont…
Environment Variables
GET or POST Data
•
•
•
•
•
• Dependant on form
“Method”
• Each type uses a
different API to read
data
• Data is always in the
same form:
IP address
User ID (when available)
Browser Type
POST Data Length
Data from a form using
the “GET” method
• Cookie data
• Many more!
var1=value1&var2=value2&
….
The Core
Input Cont…
Input is read using one of the following APIs:
• QtmhGetEnv – For reading “Query Strings”
(GET)
• QtmhRdStin – For reading “Standard Input”
(POST)
• QzhbCGIParse – Returns data by field name
(either GET or POST)
The Core
Input Cont…
• QtmhCvtDB API is
used to convert input
to a “usable” format
• A physical file is used
by the QtmhCvtDB
API to “pair” fields to
determine size and
data type
Data:
NAME=Brad&AGE=36
Physical File:
NAME 30(A)
AGE 5,0(P)
Results:
NAME = “Brad”
AGE = 36
The Core
Input Cont…
• QzhbCGIParse API
simplifies reading
data
• Build the command
string
• Call the API
• Data is always
returned as character
• Can also retrieve the
nth instance of a
variable
Command String:
-value NAME
Returns:
Brad
Command String:
-value AGE
Returns:
34
Command String:
-init
Returns:
QUERY_STRING=NAME=Brad&Age=3
4
The Core
Input Cont…
• GET Example (Source)
• POST Example (Source)
• QzhbCGIParse Example (Source)
The Core
Input Cont…
• Data validation is very important
• At least server side
• Both client and server side is
ideal
• How errors are displayed is also
crucial
The Core
Input Cont…
• When possible, don’t display a page with
errors only, asking to use the “Back”
Button
• Instead, display errors on the screen,
close to the fields in error.
(source)
• Server Side Error Example
The Core
Record Selection
• To display data, you
must retrieve data from
your database files
• “Native” methods (ie.
READx, CHAIN)
• Open Query File
(OPNQRYF)
• SQL (Embedded or
Dynamic)
The Core
Record Selection Cont…
Native Methods (ie READx, CHAIN, SETxx)
• eRPG Programs function exactly like
green screen/report programs
• Accessing data is no different
• Main issue is library list
The Core
OPNQRYF (Open Query File)
• Normally done inside RPG Programs
• Statement can’t be built interactively
• Outdated method, but still may be more
comfortable to some
• Main issues are library lists, overrides,
manual file opens
The Core
Embedded or Dynamic SQL
• SQL is more common to other platforms
• Programmers not familiar with RPG may
be able to help with SQL
• Dynamic SQL is more “friendly” for certain
applications
• Main issue is learning curve
The Core
• Creating functional SQL statements
requires breaking up the SQL statement
into logical clauses
– The “SELECT” Clause
– The “WHERE” Clause
– The “ORDER BY” Clause
The Core
• The “SELECT” clause is used to specify
which fields to retrieve from the database
File, as well as which database file to
process
Eval Select = ‘Select ITITEM,
ITDESC, ITQTY from ITEMPF’
Eval Select = ‘Select * from
ITEMPF’
The Core
• The “WHERE” clause is used to specify
which records to select from the database
file
Eval Where = ‘WHERE ITITEM = ‘’’ +
%trim(MyItem) + ‘’’ AND ITQTY > 10’
The Core
• The “ORDER BY” clause is used to
specify the order in which the data is
returned
Eval OrderBy = ‘ORDER BY ITQTY, ITITEM’
The Core
• Combine all three pieces to create your
completed SQL statement!
Eval DynSQL = %trim(Select) + ‘ ‘ +
%trim(Where) + ‘ ‘ +
%trim(OrderBy)
Select ITITEM, ITDESC, ITQTY from
ITEMPF WHERE ITITEM = ‘MYITEM’ AND
ITQTY > 10 ORDER BY ITQTY, ITITEM
The Core
• Dynamic SQL Example
• Source
The Core
Debugging
• Problem solving involves
“playing computer”
• Sometimes debugging is the
only way to track down a
problem
• eRPG Debugging is similar to
Batch RPG debugging
The Core
Debugging Cont…
eRPG Debugging Steps
• Find the correct job
• Start a service job
• Start debug on the application
• Add breakpoints
• Run application from browser and debug
The Core
Debugging Cont…
Finding the correction job – Method 1 (V5R4
and up)
1. End the HTTP Server
2. Restart the HTTP Server with
parameters “minat 1 maxat 1”
3. There should only be one CGI job now
that you can use for debugging (job won’t
start until you run a CGI program)
The Core
Debugging Cont…
Finding the Correct Job – Method 2 (V5R3
and down)
1. View the HTTP Server Jobs using
WRKACTJOB
2. Restart Statistics with F10
3. Run CGI Application from web client
4. Refresh HTTP Server Jobs Screen and
look for CGI job that the CPU % changed
on
The Core
Debugging Cont…
The Core
Debugging Cont…
The Core
Debugging
• Start Debug on the Application:
STRDBG PGM(AS400CGI/LISTORDER)
UPDPROD(*YES)
• Add Breakpoints
• Run application from browser
• Program will break in the location you set,
debug as your normally do green screen
applications
The Core
Debugging Cont…
Debugging Tips
•
•
•
•
Debug in a Test or Development
Environment
Find the correct job to start a service job
on
Make sure breakpoints are in the proper
places
Clean, well-commented code makes
debugging easier!
The Core
Toolkits
•
•
•
•
Use existing skill set
Very small learning curve
Easy on resources
Split up business and
presentation layers
• No more hard-coding
HTML!
• Not just for web pages!
The Core
Toolkits Cont…
• Templates are external from program
• Use ILE functions to “replace” data and
build web page
• CGIDEV2 – www.easy400.net
• eRPG SDK – www.erpgsdk.com
The Core
Toolkits Cont…
• Example (local)
• Template
• RPG Source
The Misunderstandings
•
•
•
•
•
•
•
•
•
It’s “Legacy” Technology!
It’s Slow!
It’s Resource Intensive!
It’s Hard to Learn!
There Aren’t Any Resources, Toolkits or IDEs
Available!
Our Web Programmers Don’t Know RPG!
WebSphere Makes “Prettier” Web Pages!
IBM Doesn’t Promote It!
Quotes from eRPG Users
“It’s Legacy Technology!”
“A legacy system is an antiquated computer system or
application program which continues to be used
because the user (typically an organization) does
not want to replace or redesign it.” - Wikipedia
• Scare term used to sell the flavor of the month
• Will those “flavors” ever become legacy (ie, will they
be around long enough?)
• Always ask yourself, “What do those who call RPG
legacy have to gain by you not using it, and what do
you have to lose?”
“It’s Slow!”
•
Believe it or not, some people (including IBM reps and
popular figures in the iSeries community) have told people
other technologies such as Java and WebSphere are
faster and more efficient than RPG for web applications!
•
RPG Web applications should not be any slower than
green screen applications. Native DB access is a big plus
when it comes to performance.
•
Trust your experience with a technology that’s been around
long enough to be called “legacy”.
“It’s Resource Intensive!”
• Yes, the same people calling RPG slow also
claim RPG to be more resource intensive than
applications created with tools like WebSphere!
• Anyone who has spent any time using
WebSphere knows that this couldn’t be further
from the truth!
• Most small to mid sized machines are crippled
just by starting the WebSphere Application
Server.
“It’s Hard to Learn!”
•
The hardest part of using any web solution is the basics
such as HTML, JavaScript, Stylesheets, Server Side
Includes, and Cookies.
•
These topics are required for ANY web solution.
•
With the use of a toolkit such as CGIDEV2 or the eRPG
SDK, the learning curve is even lower!
•
Compare that to the months or years needed to learn how
to use WebSphere and Java effectively!
“There Aren’t any Resources Available!”
• Actually, there are plenty of resources available!
Check out www.bvstools.com/erpg/ for a list of
books and training manuals on the subject!
• Sign up on the Web400-L mailing list at
www.midrange.com for discussions on the subject!
• Toolkits such as CGIDEV2 and the eRPG SDK are
readily available! The only IDEs you really need are
SEU (to edit RPG) and a good text editor or HTML
editor! Especially with the use of a toolkit!
“Our Web Programmers Don’t Know RPG!”
• Your web programmers can help your RPG
programmers with the HTML, JavaScript, and other
web topics!
• Split up your web application design into
presentation and business groups! Let your web
programmers design the web pages, and your RPG
programmers handle the business programming!
• With the use of a toolkit, splitting the work is even
easier!
“WebSphere Makes ‘Prettier’ Web Pages!”
• How “pretty” a web page looks relies entirely on the
web page design.
• Web pages are made up of the same “stuff” no
matter what web tool is used!
• There is nothing “Magical” about any web tool that
will make your web pages look better! It’s all
dependant on how the programmers design them!
• As always, please practice function before form!
“IBM Doesn’t Promote It!”
• Why should they, it’s virtually a free technology!
• IBM pushes WebSphere because they make money
not only on the product, but once you realize the
system and programming resources needed, you’ll
be looking for bigger hardware, consulting and
training!
• Sometimes what makes the most sense is the
obvious choice, even if it differs from the opinions of
IBM and System i “pundits”.
Quotes from eRPG Users
““I have found that using [WebSphere] the learning curve is
great, the costs are great, the recourses both on the PC
and the AS/400 is great and it is extremely slow
compared to using RPG and the CGIDEV2 tools.” –
Jason Baker, K&M Tire, Inc.
Quotes Cont…
“eRPG has a particular advantage for companies
with experienced RPG people who already have
experience with the local data and business
rules.” – Martin Cytryn, Midrange Systems
Quotes Cont…
“WebSphere was initially offered for free as part of the OS.
It was promoted by IBM as a way to easily transform
Client Access screens into web usable pages. It was
more costly trying to implement this, "free" software than
if I had purchased a program. It did not come close to
working as advertised and every time IBM revised the
program it would wipe out the code we wrote to work
around WebSphere's problems. To add insult to injury
IBM then tiered WebSphere into various feature levels
for purchase. We luckily found eRPG. It works as stated
and my RPG programmers can actually see and
understand all the code. WebSphere is a Trojan horse
for consultants and IBM. Get CGIDEV2 instead. ” –
Edward Gallucci, Jeunique International
The Examples
•
•
•
•
BVS/Tools (www.bvstools.com)
Jeunique (Distributor’s Page 1052427)
Jeunique (Online Orders)
Spartan Insurance (Insurance Quote – Zip
code 78701/Austin)
The Resources
• www.bvstools.com/erpg/
• www.easy400.net
• www.rpgiv.com

S1A - Web Programming with eRPG

Transcription

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