AS400 CGI with external HTML CSS & Forms

Hello Friends,

In our previous few post, we have been looking into CGI concept from AS400. But all those example were raw HTML inside RPGLE. That really concerns because we really do not want in that fashion since we cannot really compile the program again and again if we want to change the content of our HTML.

So the best way is take it out the HTML content and put it outside the program. If we think outside RPGLE we have two things,

1. Physical File
2. An IFS file

Physical file:

The idea is to store the HTML in the physical file. We can use sequence number as key field to retrieve the data in sequence and write it into browser.

The RPGLE code will look like this.

Pros: By this way we do not want to compile the program again and again. We can simply add data into Physical File and see the result in the browser.

Cons: Maintaining the PF is difficult. We need to make sure the data retrieved in the proper sequence. And we cannot really make sure of it.

To resolve this we have the next solution, IFS path.

I assume most of you guys are familiar with IFS path and reading & writing the data into IFS.

IFS path:

We just need to have our HTML inside a IFS folder. Then with a simple RPGLE we can read the whole content and write it to browser.

RPLGE code will look like this.

Output 1 from IFS path:

Change the IFS HTML content:

Output 2:

Pros: Yes, we are having our HTML outside the code, so we can get rid of dependency of compiling the RPGLE. And importantly we can change our HTML as like we want. Just add any HTML code inside the IFS file in a readable format and this will be displayed in your browser.

Cons: I have one but I will be explaining at the end of this article.

Now, let’s jump into something interesting.

Hope you would remember our last post about listing order details in the form of HTML table. But it was done by getting input from browser URL and parsing it inside RPGLE and display the corresponding data. Now, how to get the same done from a HTML Form?

The idea is to create HTML form to get Order number. And when we hit submit we should be able to redirect to our ORDLIST program and catch this inputted order number and show the result(order detail of this order) in HTML browser.

Step 1: Creating HTML form

With our IFS html concept, it is pretty straight forward. You are just going to create HTML with CSS and place the stylish front end in IFS path. (Learn about CSS here) https://www.w3schools.com/css/

E.g.:

Step 2: Redirect to Order List program

We can redirect to other HTML page using action keyword in form tag. But there are two methods, either “get” or “post”.

<form method="get" action="/cgi/ordlist">

(or)

<form method="post" action="/cgi/ordlist">

Let us see how our ordlist program behaves for each method.

1. With "get" Action

Since my input tag field name is "order"

i.e.: <input type="number" name="order" min="0" max="999999999">

We are seeing re-directed URL as /cgi/ordlist?order=123

But it seems our OrdList program is not recognizing this.

Do you remember our correct URL input for ORDLIST program is /cgi/ordlist/123

Because currently it thinks order number will come after “/ordlist/”. So it is not recognizing /cgi/ordlist?order=123

Thus, we need to change the program little to parse this order number from this URL.

2. With "post" action

Using post action, the parameter values will not be passed in the URL. Instead it will be converted as standard input.

This standard input (coming from browser) can be obtained using QtmhRdStin procedure.

Code to read from standard input :

The input will be saved RtnBuffer variable.

Putting it all together:

Now to test both “get” & “post” I am going to write a simple program which receives the input and displays in browser.

This program name is ordinput.  So we need to change our re-direct action such as

<form method="get" action="/cgi/ordinput">

The below outcome is clear, we got the parameters in URL and no standard input is read.

<form method="post" action="/cgi/ordinput">

Here we go..!!! the URL contains nothing. But standard input got value “order=123” due to post action.

One final touch:

I have quickly modified my ordlist program to get the input from Standard input (rather than from URL) and changed my re-direction to /cgi/ordlist with method as "post" and below is my result

What next?

Do you remember I have stated one cons with IFS external HTML. Yes, that is exactly the output we see here. The front end was looking nice with CSS styling but the output is again the plain HTML.

If we want to move this output as external IFS, we have a problem on how do we change the HTML data dynamically from RPGLE? Because the Table may grow or shrink based on input but we need some way to change the IFS HTML itself dynamically.

The good news is, we can do it by CGIDEV2 tool. And my next post will be based on that. Until then…

Have fun…!!! Happy coding…!!!

AS400 & HTML

Hello Friends,

To all my friends who just started AS400 learning/working or having few years of experience on it, this article is going to give you some basics of how we can combine AS400 with HTML. After reading this article you guys may get awesome ideas and explore more on this by your own.

This article is indented for people who know basics of HTML and AS400.

Where to store our HTML:

            AS400 IFS path is the place you write your own HTML and store it. Either you can write it in physical file and copy it to IFS or just a simple notepad and upload (or FTP) the file into your IFS directory.

Sample file: Do note the IFS path I have stored the file

Starting Apache server:

Yes, AS400 (version >= V4R5) comes with in build Apache server. This will be used to handle HTTP request coming into AS400. Use below command to check if your HTTP server is already running.

WRKACTJOB SBS(QHTTPSVR)

If not start it using below command

STRTCPSVR *HTTP HTTPSVR(*ADMIN)

Use this command to start Apache Default server

STRTCPSVR SERVER(*HTTP) HTTPSVR(APACHEDFT)

Now just point your AS400 IP in your browser and look for index.html

E.g. http://yourip/index.html

Apache Config:

/www/apachedft/conf/httpd.conf is the configuration file for apache and make sure below piece of code is available in it

It states all the documents are from /www/apachedft/htdocs so the index.html should be inside this directory. And any html file we create in this path will be accessible in your browser.

So let’s view our welcome.html (from htdocs path)

How to retrieve HTML from different IFS path:

So it is not restricted that we have to place our entire HTML inside document root path. Instead we can use Alias match and assign specific IFS folder for document retrieval.

Just edit the httpd.conf file of apachedft and add these lines.

So if anything comes as /mydocs/ in url will look for files from /Home/Devyus directory.

e.g.: http://yourip/mydocs/welcome.html

before we test this we have to restart our APACHEDFT server since we have modified the config file

STRTCPSVR SERVER(*HTTP) RESTART(*HTTP) HTTPSVR(APACHEDFT)

After restart check it in browser using above example url

What Next?

So till now it is not a big deal because we are just showing some static HTML page available from AS400 IFS. What is really interesting will be, how to use this functionality as front end and which calls RPGLE program based on inputs and RPGLE returns output back to browser. Looks great is it…

Yes, It is possible using CGI programming in AS400. I shall come back soon with some basic example of how CGI works and how to build our first web based application which integrates with our RPGLE business logic and DB2 database and produces result back on the web. Until then…

Have Fun…!!! Happy coding..!!!