A Natural Extension: Using the Com-plete HTTP Server for Web-Enablement

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A Natural ExtensionUsing the Com-plete HTTP
Server for Web-Enablement

• David Wimberly
• Project/Program Director, University of Arkansas
• wdw_at_uark.edu

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Presentation Overview

• The Com-plete HTTP server
• A Natural tool for web enablement
• Web-Enablement at the University of Arkansas
• Enhancing existing applications with web
  technologies
• Implementation considerations
• Tips and techniques
• Examples

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The Com-plete HTTP Server

• A Natural tool for web-enablement
• Com-plete 6.1 architecture
• Natural and the HTTP server
• Natural programmers view
• System view
• Advantages of this native MVS web and application
  server

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Com-plete 6.1 Architecture
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Natural and the HTTP Server
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Natural Programmers View

• Simple CALL interface

Read user input from the web CALL HAANUPR
CGI-STATUS / Return code and reason code
CGI-ACTION / GET-DATA or PUT-DATA
FIELD-NAME / HTML form field name
FIELD-VALUE / User input value
FIELD-LENGTH / Length anticipated/returned SEPAR
ATE FIND EMPLOYEE WITH
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System View

• Natural programs
• Run in the buffer pool
• Access ADABAS and other resources
• Call external module HAANUPR
• To read HTML form inputs and controls (GET or
  POST)
• To send dynamically generated HTML to the browser
• Configuration parameters for default user ID,
  library, buffer sizes, etc.
• Automatic EBCDIC/ASCII translations and url
  encoding/decoding

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Native MVS Web and Application Server
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Web-Enablement with the Com-plete HTTP Server

• Enhancing existing applications with web
  technologies
• Objectives
• Background
• Web session examples

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U of As Objectives

• To enhance and extend our mainframe applications
• Reach new audiences
• Employees and vendors
• Enhance the presentation of information
• Consolidate information and dress it up
• Simplify access for infrequent users
• Not to replace all or even most 3270 functions
• Not to literally move a 3270 application to the
  web

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U of A Background

• Natural and ADABAS mainframe shop since 1986
• BASIS Business Administrative Strategic
  Information Systems
• Custom inhouse developed applications
• Everything but student systems
• Separate groups doing Java web development and
  screen scraping web deployment
• Preference for Natural application code
• Timing was right for the Com-plete HTTP Server

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Logon
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Menu
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Browse PO selection screen
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Help for Date-Close-Anticipated
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Help for PO status, selection
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Help for PO status, window
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PO status returned
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Budgetary Unit help
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BU help search
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Browse PO for Status and BU by Date
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Browse result and PO selection
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View of PO, top
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View of PO, bottom
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Select a PO to Browse Invoices for PO
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Browse Invoices for PO
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View Invoice
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Select a PO to e-mail
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E-mail the PO
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PO list, vendor help
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Vendor name search
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Select vendor
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PO search by vendor and date, initiated
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PO search by vendor and date, results
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Main menu, select pay activity
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Browse pay activity
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View earnings statement
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Main menu, select addresses
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3270 Addresses, etc. equivalent
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Addresses, etc
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Enter changes, view errors and previous values
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Correct errors and update
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Update confirmation screen
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Logoff screen
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Implementation Considerations

• How to maintain state
• Back button
• Back button vs Return
• Data security
• Configuration
• Essential JavaScript
• Techniques for generating HTML
• Coding tips, debugging tips, and more
• Example HTML and Natural code

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How to Maintain State

• The web is stateless
• Each interaction (submission) is self contained
• No provision for a continuous user session
• To maintain state
• Use conversational mode, or
• Create a session ID (TIMESTMP)
• Place it on the form as a hidden field
• Save and restore user session information using
  ADABAS

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Back Button

• Can subvert your state information
• User reappears not from where you left him
• We considered
• Disabling it
• Running in a window without the toolbar or
  menubar
• Issuing errors if they used it
• Limit the state information you maintain
• Not the active position within a READ loop
• Instead, hide the first and last ISN on a page
• Have one entry point -- a dispatcher program
• actionuwowdis

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Back Button vs Return
Browse A objects at level 1
Browse B objects at level 2
Browse C objects at level 3
As 1 - 10
Bs 1 - 10
Cs 1 - 10
Object selection or Paging
Cs 11 - 20
Bs 11 - 20
Back button
Return
Bs 21 - 30
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How to Return

• Save program hierarchy information in hidden
  fields
• Our browse functions stack for each level
• Program ID
• Search type in effect
• ISN and MU/PE occurrence of first record on the
  screen
• Whether page back was valid
• A Return
• Pops one of these from the stack
• Executes the program and re-initiates the browse

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Data Security

• Sensitive data requires encryption
• Com-plete HTTP server does not do SSL
• Proxy server introduced to do all encryption and
  decryption
• To avoid mixing document types and client side
  warnings
• Style sheets and graphics are delivered from a
  separate web server using HTTPS

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U of As Environment
HTTPS
HTTP
Proxy Server for SSL encryption
IBM OS/390 running ADABAS, Natural, and Com-plete
6.1
Client with SSL enabled Web Browser
Web Server for .gif and .css files
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Com-plete HTTP Server Configuration

• HAANCONF
• SERVPOOLYES
• Uses a shared logon or session
• NATLIBdefault library
• Natural CGI programs in other libraries require
  an implicit logon
• HTTPUSERdefault user ID
• URL processing user exit
• Restrict access to specific hosts or domains

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Essential JavaScript

• Cursor placement
• Selection processing and linking to different
  services
• Set hidden form element to selected value
• Submit form
• Window management
• Open and Close windows
• Pass and return values

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Techniques for Generating HTML

• Output your HTML to the Source Work Area
• Use Natural ISPF macros
• But macros cannot be invoked directly as a
  Natural CGI program
• Use Natural
• DEFINE PRINTER (1) OUTPUT 'SOURCE'
• FORMAT (1) PS0 LS133
• EJECT OFF (1)
• SET CONTROL 'Z
• WRITE (1) NOTITLE
• Send the generated HTML to the browser
• HNANCGIP is provided, but limited to 72 character
  lines
• Create your own using longer lines via the
  USR1035N interface

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Coding Tips

• Develop an architecture and generate your Natural
  CGI programs using Natural ISPF macros
• Fast delivery of new functions
• Consistent
• Easy to implement changes -- REGEN
• To simplify making changes in page appearance
• Use copy code, subprograms, constants defined in
  an LDA, and an external style sheet
• HTML form fields can have dashes, but javascript
  cannot reference them
• Translate them to under-scores

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HAANUPR Tips

• Field names
• Must end with a blank character
• Field values
• Are not blank filled, reset them before your CALL
• Field length
• Passed in the largest value you will receive
• Returned the actual size of the field entered
• CALL HAANUPR
• CGI-STATUS / Return and reason code
• CGI-ACTION / GET-DATA or PUT-DATA
• FIELD-NAME / HTML form field name
• FIELD-VALUE / User input value
• FIELD-LENGTH / Length anticipated/returned

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Debugging Tips

• You cant sprinkle WRITEs into your code
• You cant run the Natural debugger
• Trap and log errors on a data base file
• Note ERROR-TA always starts as HNANERR and can
  only be changed by an assignment statement
• Output your debugging information with your web
  page using HTML
• This may mean holding information until you reach
  the page ltbodygt

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Code Reuse

• Develop a Natural subprogram to output the core
  HTML document for an object (Purchase Order,
  Earnings Statement, etc.)
• Call from your Com-plete web application (Natural
  CGI program)
• Call from online 3270 session to generate an HTML
  e-mail attachment
• Read the source work area and send to SMTP using
  ESS PROCESS WRITE-SPOOL
• Call from batch to generate an HTML e-mail
  attachment

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HTML for UWOMENU, part 1
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HTML for UWOMENU, part 2
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Natural code, UWCSBH
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Natural code, output Action
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Natural code, output table of Services
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Natural code, read HTML form fields
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Enhancement Proposal 958

• Efficient browsing of ADABAS data (no wasted I/O)
• Forward or backward (descending)
• Possible due to STARTING WITH ISN
• Regular descriptors
• MU type descriptors
• Unique PE type descriptors
• It is not possible with non-unique PE type
  descriptors!
• Vote for FIND DESCENDING, enhancement proposal 958

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Presentation Review

• The Com-plete HTTP server
• A great run time environment for Natural, and now
  an enabler for Natural based web applications
• Web-Enablement at the University of Arkansas
• Examples of what can be done with the Com-plete
  HTTP server
• Implementation considerations
• Tips and examples from the University of Arkansas

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Thank You!