24
Wed, Apr
0 New Articles

TechTip: Be a Web Wiz

Web Languages
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

The Apache Web server, included free on iSeries machines, contains a powerful feature, known as mod_rewrite, that can convert URLs from their original versions (as requested by a Web browser or other client) to any format you find more useful.

This article offers a small taste of what URL Rewriting can do. The possibilities are limitless. The solutions can get complex, too!

Note: Readers are assumed to have some familiarity with Apache.

What It Can Do

URL Rewriting helps make your Web sites and applications more secure and more accessible to users, other applications, and search engines. It allows these improvements without forcing you to change your site or application.

Essential Directives

These directives go in your configuration file (httpd.conf), which you might edit using the iSeries Web-based Web administrator.

  • RewriteEngine—Tells Apache whether you wish to use rewriting. Turn rewriting on with the RewriteEngine On directive.
  • RewriteCond—An optional directive that restricts the execution of any directives that follow consecutively. Its syntax is RewriteCond TestString CondPattern, where TestString is the string or variable to test and CondPattern is a regular expression (powerful search-and-replace string) that represents the test to perform.
  • RewriteRule—The workhorse of rewriting. Its syntax is RewriteRule Pattern Substitution, where Pattern is a regular expression to match the incoming URL and Substitution is the resulting URL you want.
     

Enhance Security

URL Rewriting can enhance security in many ways, such as showing the public an architecture that hides your server's true directory structure. Another security measure is to require that all users access the site using SSL encryption. Here is how we can enforce SSL encryption:

RewriteEngine On
RewriteCond %{SERVER_PORT} !^443$
RewriteRule ^/(.*) https://%{SERVER_NAME}/$1 [NC,R,L]

If the server port is not 443 (the port normally used for SSL encryption, represented in the browser by the "https" prefix), we run a rewrite rule that redirects the browser to the same site but with an "https" prefix. The RewriteRule takes any path information (matched by the wildcard "(.*)"), substitutes it into the result by the symbol /$1, and prefixes it with "https" and the server name. The bracketed options mean the following: NC=not case sensitive; R=ask the browser to redirect to the new URL; L=last request (don't execute any more rewriting rules for the current request).

Example: The original URL is http://www.mytestsite.com. Apache redirects to https://www.mytestsite.com (notice the "s" in "https").

Simplify the URL of Your Home Page

The URL of a dynamically generated home page can be complex. Some software tools require several parameters. This example is from a major retailer's Web site, its name disguised:
http://www.rdfrederick.com/cgibin/xyzweb?procfun+homeproc01+pghome+rdf+eng.

We should be able to reach the home page by a simple domain name (e.g., http://www.rdfrederick.com). The usual solution is to create a "dummy" home page, reached at the domain name, that uses JavaScript or metatags to redirect to the dynamic page. The "redirection" approach is slow and awkward. URL rewriting provides a better answer.

RewriteEngine On
RewriteRule ^/$ /cgi-bin/xyzweb?procfun+homeproc01+pghome+rdf+eng [PT,L]

The ^/$ indicates an empty string. The rule finds a match when a simple domain name is used, without any further path or file data. The rule, having been matched, will substitute the second parameter (/cgi-bin...). Inside the brackets, there is no "R," so no redirection takes place. The substitution of the longer URL occurs inside the Web server. Although the proper program (xyzweb with parameters) is called, the user's browser just shows http://www.rdfrederick.com. Note: the "PT" ("Pass through") inside the brackets is important; it passes the rewritten result through to any other processing that the Web server might have to do.

Fit a Long URL on a Short Screen

The Client Access 5250 emulator provides an easy way to integrate Internet content, such as Web pages and images, with text-based 5250 screens. By default, Client Access recognizes when a URL is displayed, converting it to a clickable link. Clicking a link launches the associated content in the default Web browser. One problem: If the URL is longer than the screen width, which by default is 80 characters (or a 24 x 80 screen), some of the URL will be cut off.

For example, our Web-based invoice software could require a long URL that looks like this:
http://www.myinvsite.com/qsys.lib/wwwcgi.lib/softweb.pgm?procfun+myproc+func001+ dev+eng+funcparms+stdrentry(A0010):Y+account(A0100):12345+ invoice(A0050):22222+line(A0060):43.

That's a mouthful! We can reduce it to this dainty (and more readable) URL:
http://www.myinvsite.com/account=12345/invoice=22222/line=43

The conversion is managed with the following directives:

 

RewriteEngine On
RewriteRule /account=(.*)/invoice=(.*)/line=(.*) /qsys.lib/wwwcgi.lib/softweb.pgm?procfun+myproc+func001+dev+eng+funcpar

ms+stdrentry(A0010):Y+account(A0100):$1+invoice(A0050):$2+line(A0060):$3 [PT,L]

Notice the three wildcards "(.*)", which are saved and substituted for the "$1," "$2," and "$3" symbols in the replacement URL. Apache pulls the three values out of the original URL and places them in the replacement URL. The user and Client Access see the short URL, while the Web server processes the long one.

Incidentally, search engines seem to prefer simple URLs over complex ones. A site with long, complex URLs might improve its search engine rankings by simplifying its URLs using this technique.

More Ideas and Information

Many inspiring "Practical Solutions" can be found in the URL Rewriting Guide. The study of regular expressions will aid the aspiring Web wizard, as will this tutorial and the official mod_rewrite documentation.

Readers who have questions, comments, or suggestions about URL Rewriting are encouraged to post comments into the forums discussion located at the end of this article. Share your own wizardry if you like.


 

Alan Seiden
  Alan Seiden founded Seiden Group to help IBM i shops design and implement high-performance web and mobile applications using PHP, DB2, RPG business logic and Zend Framework best practices. Alan and his team work closely with some of the best minds at both Zend and IBM on behalf of their clients.With a passion for open source and community, Alan co-developed the popular PHP Toolkit with IBM. He was one of the first Zend Framework certified engineers; co-founder of the NYC Zend Framework Meetup; charter member of IBM/COMMON's PHP Advisory Board; and a consultant for IBM's manual PHP: Zend Core for i5/OS. An award-winning speaker, Alan has been called "the performance guru of PHP on IBM i." He shares his expertise regularly at conferences and user groups such COMMON, ZendCon, the RPG & DB2 Summit, OMNI, the Northeast Users Group Conference, OCEAN and WMCPA. He also mentors other developers within the Club Seiden forum.In his spare time, Alan plays the trombone and studies and teaches the Feldenkrais Method® of Somatic Education.Subscribe to Alan’s monthly newsletter PHP on IBM i Tips.  Follow Alan on Twitter: @alanseiden and LinkedIn: www.linkedin.com/in/alanseidenMore on Alan
BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$0.00 Raised:
$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: