13
Thu, Jun
4 New Articles

Server with a Smile

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

A Web server is a set of programs that responds to requests coming from another program—a Web browser such as Netscape Navigator or Microsoft Internet Explorer. Having thrown its hat into the Web server ring, the AS/400 Web server development team has made steady strides in bringing the AS/400 into a respectable position. The AS/400’s Web server features include the following: an HTTP server that provides Web page content for Web browser users; a Workstation Gateway (WSG) server that delivers AS/400 5250 data stream content; and a server-side program execution gateway that calls a program on the server to interact with a Web browser user.

An HTTP server program transmits data representing an HTML document to a requesting host computer. The receiving computer reads the transmitted data into a Web browser. The Web browser is capable of interpreting the data into a display consisting of lines of text, artwork, sounds, and so on. For some applications, there must also be support for programs running on the server that collect data provided by the user (CGI programs, for example). As seen in Figure 1, the client/server structure upon which HTTP is built places part of the mechanism on the client and part on the server. The browser program resides on the client and acts as a general-purpose instruction interpreter. HTML data contains instructions that tell the client’s browser how to behave, plus textual and multimedia content.

The AS/400’s HTTP server support is capable of running more than one set of server programs at one time. Each set of the running programs is called an instance of the server. Normally, you want to run only a single default instance of the server. Each instance of the server must have its own port to use—no two TCP/IP server programs can use the same port at the same time. The well-known port for HTTP services is port 80, and this is where the Web browsers of the world send requests. Any other instance of the server has to use another port number, and, to avoid conflict with standard TCP/IP utilities, that port number should be above 1023. (Port numbers 1-1023 are reserved for common TCP/IP utilities such as FTP or Telnet.)

HTTP Server Configuration

An HTTP server, such as Apache for UNIX operating systems or the one that comes with OS/400, is a complex application capable of a variety of tasks. A server is designed to be


flexible in its operations, and the price of this flexibility is complexity in the program’s configuration.

HTTP Configuration Precedence

HTTP configuration information has five setting levels. Figure 2 shows the levels of configuration for HTTP and the associated methods—either a CL command or an HTTP administration form—you use to set values. As you might suspect, you can configure the AS/400’s HTTP server in two ways. Using Operations Navigator (OpsNav), however, is not one of them. You can perform most HTTP configuration tasks from an AS/400 5250 session by using CL commands such as Change HTTP Attributes (CHGHTTPA) and Work with HTTP Configuration (WRKHTTPCFG), which runs a special HTTP configuration editor in a green-screen session.

A more meaningful interface to the complex tasks attendant to HTTP configuration is available through a configuration utility made available by IBM.

The HTTP server Configuration and Administration utility groups related pieces of configuration details into a series of forms that makes the task easier. The IBM utility is a Java applet that runs on your Java-enabled Web browser. The applet is a program that interacts with the user to present and accept HTTP configuration information for the AS/400. As seen in Figure 3, the configuration applet has, on the left-side menu, a series of categories that are opened to allow access to the specifics. The specifics are presented in forms on the right-side panel.

The HTTP administration server groups configuration tasks into the following categories:

• Global server parameters apply to all instances of the HTTP server.

• Server instances create, delete, and manage server instance configurations.

• Configurations set details of server request processing.

• Internet users add, change, and remove Internet user entries. (An Internet user entry defines only an HTTP server user—not an AS/400 user as is defined with an AS/400 user profile.)

• Access control lists define access authority at the file level within a directory. A request for file access is evaluated by file name, request method, and user name.

Starting the HTTP Configuration Utility

The HTTP administration server runs over port 2001 and is not normally started automatically. You can start the HTTP configuration and administration server from a 5250 command line with CL command STRTCPSVR SERVER(*HTTP) HTTPSVR(*ADMIN) or with OpsNav. Allow the server time to start (you can check with WRKACTJOB for the status) and then access the utility from a PC Web browser.

To start the HTTP configuration applet (*IOSYSCFG system authority is required), start your Web browser. In the location/address box, specify the URL http://Your.AS400Host.AndDomain:2001/. If all is well, a welcome page will appear. Clicking on IBM HTTP Server for AS/400 starts the Configuration and Administration utility seen in Figure 3. (If you click on Related task information from this display, you bring up the IBM AS/400 Information Web page over the Internet at www.as400.ibm.com/anchor/MRI2924/anchhome.htm. This page gives you easy access to the HTTP server documentation as well as other related IBM manuals.)

HTTP Directive Statements


Traditionally, Web service functions take place under utilities (such as Apache) that run on a UNIX operating system. To make the AS/400 more appealing to the traditional UNIX market, the AS/400 Web server developers extended an effort to make its interface more UNIX-like. Configuring a server is done via special instruction statements called directives.

Directives to the AS/400 HTTP server program are plain-text statements that the system administrator maintains.

You can maintain multiple sets of directive statements, each corresponding to an instance of the HTTP server. Each set is stored in its own member. When shipped, the AS/400 is preconfigured with a default set of directives residing in the member named CONFIG. The directive statements contained in the CONFIG member are mostly comments as designated by the number sign (#). The comments provide information about directives and are worth reading.

With a rudimentary IBM-supplied editor (somewhat similar to SEU), you can also edit a set of directive statements from an AS/400 5250 session. You invoke the editor with the CL command WRKHTTPCFG. The default configuration member is brought up for editing with WRKHTTPCFG CFG(CONFIG).

You usually edit directive statements with the less direct but more meaningful access that the HTTP Configuration and Administration utility provides.

Directive statements are a capricious little language of their own, and only the statements required for minimal configuration will be presented here. (See the HTTP Server for AS/400 Webmaster’s Guide V4R4 for complete information.) However, it is important to understand that the interpretation of some directive statements is done in mutual exclusion. That is, when a directive statement within a group is found that matches given criteria in a top-down search, the rest of the statements in the group are ignored. HTTP character interpretation is case-sensitive, and often some specifications are entered twice—once in uppercase and once in lowercase.

Directive statements are grouped by the following categories:

• General directives apply to a particular instance of the server as a whole.

• Mapping directives cross-reference incoming requests to actual resource locations.

• File name suffix directives bind incoming requests for a file with a particular extension to MIME content types or subtypes.

• Directory list directives control how the contents of a specified directory are made available to the requester.

• Welcome directives map requests without an explicit page reference to a default, or welcome, page (index.html, for example).

• Logging directives control HTTP access and error logging.

• Accessory program directives determine which CGI program to call when an incoming request for program execution cannot be mapped to a program.

• Timeout condition directives establish a timeout value for requests from the browser, the server, or an executing program.

Essential HTTP Directives

Only a few directive statements are required for basic HTTP configuration. Enable and Disable are general directives that enable or disable a connection request. Pass is a mapping


directive that redirects incoming URL requests to actual system directories or libraries. Exec is a mapping directive that indicates that the server may execute a CGI program and specifies where the program may be found.

The Enable and Disable Directive Statements

The Enable and Disable statements instruct the server program to accept or reject a specified type of connection request. The basic types of connection method requests are as follows:

• GET requests a retrieval of Web page content or output from an executable program.

• HEAD requests a connection. (The HEAD method causes the server to return an HTTP document header without the document body. Generally, you use this method for testing.)

• POST indicates that the input to the CGI program will be passed in a standard input stream format, which is required for some types of HTML form processing.

• OPTIONS allows a client to determine the options and requirements associated with an object or determine the capabilities of a server without having to retrieve the object.

• TRACE causes the server to echo the request message sent by the client. (This method is used for testing.)

The default settings enable the GET, HEAD, OPTIONS, and TRACE methods and disable the POST method. (If you are going to allow form processing, you must specify the Enable POST directive.)

Pass Directive Statements

The Pass directive replaces a matched string coming from a browser within a URL request with a replacement string. The string that is to be matched and replaced is called the template. Pass is the directive statement used to map an incoming request for page content to the actual directory and file name. You may have multiple Pass directives; when a template match is found, the search is ended. The format of the Pass directive is as follows:

Pass request-template [file-path] [IP-address-template]

In this format, request-template is the incoming string that is to be matched, file- path (optional) is the directory and file name (an asterisk (*) indicates that file names will be passed as they are), and IP-address (optional) is the server address that the client connected to.

As I mentioned, your AS/400 is preconfigured with several Pass directives entered in the default configuration member CONFIG. (Do not make any changes to the ADMIN configuration member. There are no directive statements anyway because all parameters are correct as defaults.)

Figure 4 shows these two preconfigured Pass directives (highlighted). The first Pass directive instructs the HTTP server to route URL requests that do not include a specific file request (for example, www.myas400.com) to the AS/400 Integrated File System (AS/400 IFS) directory/QIBM/ProdData/ HTTP/Public/TC1/ICSS/ HTML/. And in that directory, you will find the HTML document Welcome.html, which is to be served by default. (Welcome.html is an IBM-supplied page that is provided as a sample.)

The other highlighted Pass directive redirects all requests to the directory /sample/* to the real directory /QIBM/ProdData/HTTP/Public/TC1/ICSS/ HTML/*. The asterisk (*) is a wild card character meaning “any file.” With these directives in place, a browser user could reference the URL http://s101901r.evergreen.com/ with no further identification of a


desired document, and the HTTP server would deliver the file Welcome.html. References within Welcome.html to resources (such as artwork files) in the directory /sample/ are likewise mapped to the real directory. You might consider replacing these preinstalled Pass statements (comment them out) with your own to point to your welcome page (usually named index.html) so your users will access your page, rather than IBM’s, when none is specified.

The directive Pass /www/* /webpage/* converts requests to www (the directory published to the world) to a real directory named webpage. The actual directory name is hidden from the browser user, thereby enhancing security. However, here is an important note: Specifying Pass /* (with no replacement string after it) is a serious security exposure. Specifying Pass /* disables any further access control that the server would impose. Using this directory, though, does not override any object-level security that you have in place.

Exec Directive Statements

The Exec directive indicates that the server may execute a CGI program and specifies where the program may be found. (All AS/400 CGI programs must reside in a regular library such as QGPL.LIB.) After a match to the template string is found, the request string is not compared with any other templates.

The format of the Exec directive is as follows:

Exec template program-path [ IP-address ]
[ CGI-conversion-code ]

Here, template is the request string that you want your server to accept and respond to by executing a CGI program; program-path is the name of the AS/400 library (in QSYS.LIB format) where the CGI programs are located; IP-address (optional) is the IP address of the HTTP server to which the client is connected (when HTTP servers represent themselves with more than one address); and CGI-conversion-code specifies the conversion coded character set IDs (CCSIDs) that are to be used (None is the default).

For example, the Exec directive statement Exec /cgi-bin/* /QSYS.LIB/MYCGI.LIB/* directs requests for program execution that refer to directory /cgi-bin/ to the real AS/400 library MYCGI. (Enabling an HTTP server for execution of CGI programs also requires the general directive Enable POST.)

It’s Your Server

The AS/400 Web server gives your users access to current AS/400 data and allows you to collect data from the users with an ordinary PC browser—altogether, an applications solution with very compelling potential.

References and Related Materials

• AS/400 TCP/IP Handbook. Chris Peters. Carlsbad, California: MC Publishing Co., 1999

• HTTP Server for AS/400 Webmaster’s Guide V4R4 (GC41-5434, CD-ROM QB3AEO04)

• IBM AS/400 Information Web site: www.as400.ibm.com/anchor/MRI2924/anchhome.htm
• OS/400 TCP/IP Configuration and Reference V4R4 (SC41-5420, CD-ROM QB3ANL03)


Web Browser

PC Database Applet Support

HTTP Server Program

HTML Documents

Other Page Content, Artwork,

Multimedia, Applets AS/400 Database

CGI Programs

Figure 1: In a Web server/browser arrangement, the server program delivers text, artwork, multimedia, and applet content to a browser program for interpretation and display.

HTTP server configuration item If using the HTTP configuration If using an AS/400 CL command (listed in ascending priority) and administration form access
Server defaults n/a n/a
Global server parameters Global server parameters form CHGHTTPA HTTP server directives in the Multiple forms in the
configuration file instance configuration section WRKHTTPCFG Instance configuration parameters Instance configuration form n/a Parameters specified when the Instance startup form HTTPSVR parameter on HTTP server instance is started STRTCPSVR command

Figure 2: There are five setting levels for HTTP configuration information, and the values can be set using either a CL command or an HTTP administration form.


Server_with_a_Smile07-00.png 397x363

Figure 3: HTTP server configuration may be performed through the IBM- supplied HTTP Server Configuration and Administration applet in a Web browser.

Server_with_a_Smile07-01.png 397x351

Figure 4: Pass directive statements align incoming requests for services with real AS/400 resources.


Chris Peters has 32 years of experience with IBM midrange and PC platforms. Chris is president of Evergreen Interactive Systems, a software development firm and creators of the iSeries Report Downloader. Chris is the author of i5/OS and Microsoft Office Integration Handbook, AS/400 TCP/IP Handbook, AS/400 Client/Server Programming with Visual Basic, and Peer Networking on the AS/400. He is also a nationally recognized seminar instructor and a lecturer in the Computer Science department at Eastern Washington University. Chris can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..


MC Press books written by Chris Peters available now on the MC Press Bookstore.

i5/OS and Microsoft Office Integration Handbook i5/OS and Microsoft Office Integration Handbook
Harness the power of Office while exploiting the i5/iSeries database.
List Price $79.95

Now On Sale

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: