TweetFollow Us on Twitter

March 93 - Front-ending in MacApp

Front-ending in MacApp

Paul Ens

For those of us who see a Macintosh Plus as little more than a paper-weight with a power supply, the days when the dumb terminal ruled the cutting edge seem as ancient as the rule of the dinosaur. However, despite the recent hardware and software advancements in microcomputing, the dumb terminal is still widely used for the day to day business of many of today's corporations. These companies continue to live with the limitations of character-based technology because the advantages of an object-oriented graphical user interface does not outweigh their existing investment in mainframe hardware and software development.

The Macintosh boasts an array of applications that emulate VT100, 3270, and 5250 terminals. These applications allow corporations to give their employees access to the latest in word processing, spreadsheet and electronic mail applications, while continuing to use mainframe-based corporate databases and in-house applications. Unfortunately, these applications tend to pale when compared to Macintosh applications. It doesn't take long for users to expect the Macintosh look-and-feel from their mainframe applications.

BLACKSMITH

The desire to take advantage of today's user-interface technology without losing investment in existing mainframe systems has spawned a new genre of personal computer software called "Front-Ends".

A "Front-End" is a microcomputer application that provides a user-interface for one or more applications on a remote host system. The front-end accesses the host through communications hardware attached to the workstation or its network. Since the front-end's interface hides the host application's screens from the user, the front-end must be capable of interacting with the host in the ways that a user normally would.

Creating a front-end application is usually quite straight-forward. Once all of the screens and functions of the host application have been identified, a Macintosh interface should be designed that will easily and intuitively allow the user access to the same information and functionality. This interface can then be created and tested using the existing MacApp class library.

Once the interface exists, the user's actions and requests need to be relayed to the host system. A product called BLACKSMITH from CEL Corporation provides a set of tools to enable developers to interact with various host systems. The core of BLACKSMITH is a driver. It is accompanied by interfaces to 4th Dimension, Hypercard, Omnis 7, Pascal, C and MacApp. Interfaces to Prograph and Serius are also in the works.

Opening a Session

The core of BLACKSMITH's MacApp interface is the TBSmithSession class. This object class represents a single connection to a host system and provides a number of methods designed specifically for developing sophisticated front-end applications.

Once a TBSmithSession object is created, the developer must select a connection method and initiate communication with the host:

TBSmithSession * mySession = new TBSmithSession;
mySession->IBSmithSession();
mySession->OpenMethod(b_Netway);
mySession->OpenSession(&port, b_PoolName, luName, key
                                b_NewSession, b_ModelAny,
                                b_TerminalSession, returnName);

BLACKSMITH supports virtually all major Macintosh 3270 and 5250 communications hardware products, including MacIrma, MacMainframe, Netway, SNA•ps, NetAxcess, TokenAxcess, TCPAxcess and VT100. Modules for Novell, TN5250, TN3270 and TNVT100 are in the works.

Also supported is a "Dummy" access method which simulates a connection to a host based on screens saved during an actual connection. This "Dummy" method can save significantly on dial-in charges when development or testing must be done remotely. It is also useful for doing demonstrations or proof-of-concept presentations in locations where physical connection to the host is unavailable.

Host Interaction

Reading and Writing Data In order for a front-end to present data from its host applications and to feed the user's action to the host, TBSmithSession maintains a "Presentation Space". This block of memory is the equivalent to the characters of the display of a dedicated terminal. All user activity is expressed through modifications to this presentation space, while all host activity is reflected in the presentation space.

TBSmithSession provides two methods for reading the text of the presentation space: ReadPS and ReadBlockPS. ReadPS reads a number of characters from the presentation space, starting from a specified position. ReadBlockPS reads the block of text from the presentation space enclosed by a set of row and column coordinates. Similarly, WritePS and WriteBlockPS insert text into the presentation space.

A typical host application is designed to accept text input ending with a control key prompting the host to accept the data and perform an action. This style of interaction is accomplished with TBSmithSession through the WriteKeys method. This method sends a string of characters to the host as literal key strokes. Control characters like PF keys, tab and enter keys are designated by a set of character combinations, such as "@T" for tab. The following example would type "User Name", then a tab, "password" and then enter:

mySession->WriteKeys("\pUser Name@Tpassword@E",&sent);

Fields

Most host applications format the presentation space by dividing it into a number of fields. These fields can be either protected, or unprotected. Protected fields cannot be changed by the user and are typically used for displaying text labels or unchangeable data. Unprotected fields are intended for user input.

On a standard terminal, attempting to type into a protected field causes the terminal to go into an "input inhibited" mode. In this mode, further keystrokes cannot be processed until the terminal is reset. It is important for a front-end to be fully aware of the current field layout of the presentation space to avoid such terminal locking.

TBSmithSession provides a number of methods to search for fields and provide information about them. For example:

TBSmithSession::FindField( short findType, short *pos, short *len,
                                    short *wLen, short *attr);

The findType determines if the search is to move forward or backward from the specified position, and if the search is to include protected fields, unprotected fields, or both. FindField returns the position and length of the found field. It also returns an attribute byte which tells you if the field is protected or not, as well as its color and other display characteristics.

Other methods for finding the location of screen elements include FindString, FindFieldList (providing a list of all screen fields) and FindFieldIndex.

Status Line

Dedicated terminals have a status line (called the Operator Information Area, or OIA) containing a string of symbolic characters which provide information about the status of the user's session. The OIA reports when the session is waiting, when it is locked (input inhibited) and other session conditions.

It is important for a Front-End to monitor the state of the session in order to recover from errors, or to provide feed-back to the user. The status line can be read using the ReadOIA method:

TBSmithSession::ReadOIA (Str255 oia);

Screen Traversal

While the read, write and find methods of TBSmithSession are useful for dealing with individual host screens, another important element of a robust front-end application is screen traversal. Screen traversal involves identifying the current screen, and navigating the host from there to another screen, as well as dealing with exception handling and complex timing issues.

Pattern Matching

Before a front-end can navigate somewhere, it must know where it is. Even if the front-end is the only user of a session, it can be dangerous to make assumptions about its "location". Most host systems include features like time-outs and information broadcasts which can change your session's location without warning. In order to positively identify the current screen, a front-end needs to check the presentation space for the presence or absence of certain elements.

TBSmithSession provides a powerful pattern matching system to facilitate screen identification. The base of this system is the PatternMatch method:

TBSmithSession::PatternMatch (Str255 pattern,  short* matched);

A pattern is a group of strings which are searched for at specific locations of the presentation space. If the PatternMatch is successful, matched will be returned with a value of zero. If the session is busy when PatternMatch is called, it will return -1. Otherwise, an index to the first element of the pattern to fail will be returned.

A pattern string contains a number of components delimited by ¶ (option 7) or • (option 8). The first component is the pattern type. Currently, only a pattern of type 1 has been defined. Additional components describe an area of the screen followed by a string (or strings) to check for within that area. A pattern's second component must contain a list of indexes to the screen area descriptions. The search area can be specified to be a particular row, a block of text, a cursor-relative area or the entire screen.

For example, if one of your host screens contains the string "Enter Command:" somewhere on the screen, you could detect it with the following pattern: "1•3•0•Enter Command:". The "3" in the second component tells TBSmithSession that the third component is the only screen area description. The zero in the third component means that the string should be searched for anywhere on the entire screen. The fourth component is the string to search for.

While this pattern structure can be quite confusing at first, the complexity is outweighed by its flexibility and power. This flexibility is especially apparent for more complex screens. Consider the following pattern:

"1•3,6•1•Main Menu•File Menu•5,10,1,20,15•Save Changes"

As indicated by the "3,6" in the second component of the pattern, PatternMatch will be checking in two regions. One check will take place in the region described in component three, the other in the r1egion described in component six. The "1" in component three means to search for strings on row 1. So, if either the string "Main Menu" or "File Menu" appear in row 1, the pattern can succeed. Component six describes the block of characters enclosed by row 10, column 1, row 20 and column 15. If this area contains the text "Save Changes", then the pattern can match.

Another TBSmithSession method, DoReady, accepts a list of patterns and returns an index to the first matching pattern. With this command, a front-end can rapidly check the current screen against a large database of possible patterns.

Traversing

Once the current screen has been identified, a front end can execute the appropriate key-strokes to navigate to its desired screen. This is generally done using WriteKeys to send a sequence of text and control keys to the session.

Once the data has been sent, the session will be busy for a period of time processing the request. If the front-end needs to continue traversing once the session has completed the request, it must monitor the session's status until it is free. Once it is free, the front-end should again check the current location to ensure no errors took place, and then take appropriate action based on the new location.

Much of this monitoring can be accomplished by using the TBSmithSession method DoWaitTillReady. DoWaitTillReady accepts a list of patterns, along with a tolerance and settle time, and waits for one of the patterns to match. If one of the patterns successfully matches for at least as long as the specified settle time, the index to that pattern is returned. If none of the patterns match within the specified tolerance time, an error is returned.

Example: Logging In

Most host systems begin a session with some sort of title screen and log-in sequence. Logging in to a host is a typical front-ending task. A front-end application would provide a friendly method for a user to identify themself and enter their password. It would then use this data to automatically navigate through the host's log-on sequence.

After creating an instance of TBSmithSession and opening a connection to the host, a front-end would create a list of patterns representing the screens involved in logging on to the host:

splashScreen = "1•3•0•Welcome to the Mainframe";
passwordScreen = "1•3,5•15•Enter your id:•17•Password:";
mainMenu = "1•3•1•Main Menu•File Menu";

TBSmithPatternList * logonList = new TBSmithPatternList;
logonList->IBSmithPatternList();
logonList->Insert(mainMenu);
logonList->Insert(passwordScreen);
logonList->Insert(splashScreen);

Next, it must find out what screen the mainframe is currently on:

short whatPat;
whatPat = mySession->DoWaitTillReady(logonList,120,20);
Once the screen has been identified, the appropriate actions can be taken to arrive at the main menu:
if (whatPat == 3)  {   /* if matched splashScreen */
    err = mySession->WriteKeys("\p@E");    /* Hit Enter */
    logonList->Delete(3);    /* Remove splashScreen from list */
    whatPat = mySession->DoWaitTillReady(logonList,120,20);
            /* do another DoWaitTillReady to see where
                 the session is now. */
};

if (whatPat == 2)   {   /* if matched splashScreen */
    err = mySession->WriteKeys(userName);
    err = mySession->WriteKeys("@T");      /* Hit Tab */
    err = mySession->WriteKeys(password);
    err = mySession->WriteKeys("\p@E");    /* Hit Enter */
    logonList->Delete(2);
    whatPat = mySession->DoWaitTillReady(logonList,120,20);
};

if (whatPat == 1)   /* if matched on main menu */
    success = TRUE;

other features

Terminal Emulation

Developing and testing a front-end application requires regular monitoring of host sessions. Users of front-ends will often need access to the host session in order to use portions of the host applications that are not front-ended. To facilitate these needs, BLACKSMITH provides a fully-functional terminal emulation window encapsulated in the TBSmithTerminal class, a subclass of TWindow.

A TBSmithTerminal can be customized in a number of ways. It provides methods to change the display colors, font and font size. The mapping of the Macintosh keyboard to standard terminal keys is also completely customizable. Individual keys can even be assigned complex macros.

A powerful recording facility is built-in to TBSmithTerminal. This facility allows a developer to record the keystrokes of an experienced user moving through the various screens of a host application. This recording can be played back later for reference during the front-end's development process.

File Transfer

TBSmithSession also provides a number of methods that enable a front-end to transfer files to and from the host. Currently, only IND$FILE transfers on CICS, TMO or CMS host systems is supported.

conclusions

Front-ending is an extremely valuable tool for corporations who rely on mainframe applications. A front-end will decrease the cost of computing by moving host processing to the Macintosh which is much more efficient at user-driven, non-data intensive tasks. While it can sometimes take months to modify a host application, a front-end can be modified very quickly, at any time. It is also possible for different areas of the same organization to customize their front-end to meet the needs of their division without having to alter the original host application.

BLACKSMITH provides first-rate tools for creating powerful front-end applications, including support for most major communications hardware, advanced screen manipulation, pattern matching, full terminal emulation, screen recording and file transfers. These tools, combined with the power of MacApp can allow in-house developers or consultants to give new life to old programs.

A Windows version of BLACKSMITH is expected to ship in February 1993 and support for Bedrock is being planned.

CEL Corporation, the author of BLACKSMITH, can be contacted at (403) 463-9090, P.O. Box 8339, Station F; Edmonton, Alberta; Canada; T6H 4W6, AppleLink: CEL.MKTG. You can also get information about BLACKSMITH from CEL's folder in the Third Party folder on AppleLink.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

BusyContacts 1.0.2 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
Capture One Pro 8.2.0.82 - RAW workflow...
Capture One Pro 8 is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 300 high-end cameras -- straight out of the box. It... Read more
Backblaze 4.0.0.872 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac.With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Little Snitch 3.5.2 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more
Monolingual 1.6.4 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. If you use your computer in only one (human) language, you... Read more
CleanApp 5.0 - Application deinstaller a...
CleanApp is an application deinstaller and archiver.... Your hard drive gets fuller day by day, but do you know why? CleanApp 5 provides you with insights how to reclaim disk space. There are... Read more
Fantastical 2.0 - Create calendar events...
Fantastical is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event details... Read more
Cocktail 8.2 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Direct Mail 4.0.4 - Create and send grea...
Direct Mail is an easy-to-use, fully-featured email marketing app purpose-built for OS X. It lets you create and send great looking email campaigns. Start your newsletter by selecting from a gallery... Read more
jAlbum Pro 12.6 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code!... Read more

Appy to Have Known You - Lee Hamlet Look...
Being at 148Apps these past 2 years has been an awesome experience that has taught me a great deal, and working with such a great team has been a privilege. Thank you to Rob Rich, and to both Rob LeFebvre and Jeff Scott before him, for helping me... | Read more »
MLB Manager 2015 (Games)
MLB Manager 2015 5.0.14 Device: iOS Universal Category: Games Price: $4.99, Version: 5.0.14 (iTunes) Description: Guide your favorite MLB franchise to glory! MLB Manager 2015, officially licensed by MLB.com and based on the award-... | Read more »
Breath of Light (Games)
Breath of Light 1.0.1421 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.1421 (iTunes) Description: Hold a quiet moment. Breath of Light is a meditative and beautiful puzzle game with a hypnotic soundtrack by... | Read more »
WWE WrestleMania Tags into the App Store
Are You ready to rumble? The official WWE WrestleMania app, by World Wrestling Entertainment, is now available. Now you can get all your WrestleMania info in one place before anyone else. The app offers details on superstar signings, interactive... | Read more »
Bio Inc's New Expansion is Infectin...
Bio Inc., by DryGin Studios, is the real time strategy game where you infect a human body with the worst virus your evil brain can design. Recently, the game was updated to add a whole lot of new features. Now you can play the new “Lethal”... | Read more »
The Monocular Minion is Here! Despicable...
Despicable Me: Minion Rush, by Gameloft, is introducing a new runner to the mix in their latest update. Now you can play as Carl, the prankster minion. Carl has a few new abilities to play with, including running at a higher speed from the start.... | Read more »
Dungeon of Madness (Games)
Dungeon of Madness 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: Dungeon of Madness is an action game where you rotate tiles to create our own route. Help the hero by connecting the... | Read more »
Filters for iPhone (Photography)
Filters for iPhone 1.0 Device: iOS iPhone Category: Photography Price: $.99, Version: 1.0 (iTunes) Description: | Read more »
Jump'N'Shoot Attack (Games)
Jump'N'Shoot Attack 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: A mobile game for gamers! Join Louise Lightfoot, the legendary "Master of Jumping and Shooting", on her mission to save... | Read more »
Space Bounties Inc. (Games)
Space Bounties Inc. 1.4 Device: iOS Universal Category: Games Price: $1.99, Version: 1.4 (iTunes) Description: SuperGameDroid: 4/5 "Satisfying futuristic RPG combat, high replay value, and a heavy dose of nostalgia make Space... | Read more »

Price Scanner via MacPrices.net

iMacs on sale for up to $205 off MSRP
B&H Photo has 21″ and 27″ iMacs on sale for up to $205 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $1019 $80 off - 21″ 2.7GHz iMac: $1189 $110 off - 21″ 2.9GHz... Read more
Färbe Technik Offers iPhone Battery Charge LI...
Färbe Technik, which manufactures and markets of mobile accessories for Apple, Blackberry and Samsung mobile devices, is offering tips on how to keep your iPhone charged while in the field: •... Read more
Electronic Recyclers International CEO Urges...
Citing a recent story on CNBC about concerns some security professionals have about the forthcoming Apple Watch, John Shegerian, Chairman and CEO of Electronic Recyclers International (ERI), the... Read more
Save up to $380 with Apple refurbished iMacs
The Apple Store has Apple Certified Refurbished iMacs available for up to $380 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $2119 $... Read more
Logitech Says MX Master Is Its Most Advanced...
Logitech’s new MX Master Wireless Mouse incorporates the best of Logitech’s many computer mouse innovations into a striking hand-sculpted design. The company claims that the MX Master creates a new... Read more
Save up to $300 on a new Mac, $30 on an iPad,...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
Apple refurbished 2014 MacBook Airs available...
The Apple Store lowered prices on Apple Certified Refurbished 2014 MacBook Airs recently, with models now available starting at $679. An Apple one-year warranty is included with each MacBook, and... Read more
Mac Notebook Evolution; A Desktop Replacement...
More often than not right from the beginning, Apple’s Macs have tended to skew toward small. The original Macs were called “compacts,”, and notwithstanding a few exceptions like the honking Big Mac... Read more
13-inch 1.4GHz/128GB MacBook Air (Apple refur...
The Apple Store has Apple Certified Refurbished 2014 13″ 1.4GHz/128GB MacBook Airs available for $759 including free shipping plus Apple’s standard one-year warranty. Their price is $240 off original... Read more
YEP! Alternative Browser for iOS Now Supports...
Pfaeffikon, Switzerland based Power App AG has announced the release of an update to their Yep! Web Browser (v1.3.0) for iOS8 iPhone and iPad. Yep! hit the App Store shortly after the release of iOS... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Lead *Apple* Solutions Consultant - Retail...
**Job Summary** Job Summary The Lead ASC is an Apple employee who serves as the Apple business manager and influencer in a hyper-business critical Reseller's store Read more
*Apple* Pay - Site Reliability Engineer - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.