TweetFollow Us on Twitter

ObjectWare

Volume Number: 13 (1997)
Issue Number: 6
Column Tag: Openstep

ObjectWare

by Michael Rutman, independent consultant

Selling your technology to developers as a drop-in

What is ObjectWare?

As functionality in different applications start to overlap, many programmers are forced to reinvent existing technology. Most modern word processors have drawing packages built into them, and most modern drawing packages have word processors built into them. Normally, each developer must create both a word processor and a drawing package. With ObjectWare, the philosophy is to create a great word processor object, which can be dropped into any application and then sell it to application developers.

Why is ObjectWare a philosophy rather than a technique? There are many techniques to add technology to an application, ranging from shared libraries to publicly sold source code. ObjectWare differs in the process. If an application is already object oriented, and you can isolate the objects needed to use a technology, then those objects can be easily bundled and resold. Not only can you sell your application to end users, but you can sell your technology to other application developers. Using shared libraries is a technique for doing ObjectWare.

OPENSTEP's support of ObjectWare is done through custom palettes for InterfaceBuilder. A palette is a bundle of object files, interface files, and any other resource that InterfaceBuilder would need to add the technology to an application. Once loaded into InterfaceBuilder, all the functionality of the custom objects are accessable as if NeXT had bundled them into InterfaceBuilder in the first place.

NeXT provides a wonderful tutorial, called CustomPalette.rtfd. I have been assured that this documentation will become available to all Macintosh developers soon. Many of the details, as well as source code, for implementing custom palettes, which are the user interface to an ObjectWare package, are located in that tutorial.

The code in this article is built using NEXTSTEP 3.3 for the development, and all coding is done in Objective-C. OPENSTEP is slightly different, and Rhapsody has not been fully defined as of the writing of this article.

How do I use ObjectWare?

Under OPENSTEP, ObjectWare is easier than ever before. Adding a new technology to your application can be as easy as a double-click and drag and drop. Bundled objects are built with palettes and then can be loaded into InterfaceBuilder. Once loaded into InterfaceBuilder, they can be dragged into your UI just like any existing OPENSTEP object. At that point, there is no difference between adding a button, a graph or any other object to your application. To load the libraries, just drag and drop the library into your project, and it's ready for compilation.

Unfortunately, as a developer you will probably have to write some code. Not always, though, as there are some Objects that just work and require no setup. A graphing object, for example, will probably require some custom code to interact between the user and the application. On the other hand, an ObjectWare package of pretty buttons could be hooked up to your application using InterfaceBuilder without any code changes.

Related to ObjectWare is loadable bundles. Loadable bundles are functionality that can be added to existing applications at run time. Metrowerks and Adobe Plugins are very similar to loadable bundles.

Creating an ObjectWare Palette

ObjectWare under OPENSTEP requires an InterfaceBuilder palette and a library, both of which are created using ProjectBuilder. When ProjectBuilder creates a new project, it will ask for a project type such as palette, bundle, library or application. When creating a palette, ProjectBuilder will create a folder, a nib (InterfaceBuilder file), and some starting source files.

The starting source files ProjectBuilder creates will be enough to load custom objects into InterfaceBuilder. Unlike Constructor on the Macintosh, these objects are more than placeholders. InterfaceBuilder allows user interfaces to be tested without adding any code. An example of this is the Text Object. Many times OPENSTEP's power has been demonstrated by placing a Text Object in a window and testing it from InterfaceBuilder. Without adding a single line of code, the Text Object is able to spell check, word wrap, place tabs, and many other features found only in more powerful text editors. Likewise, any ObjectWare created will be as full-featured from InterfaceBuilder as from any application they are used in.

The starting source files created by ProjectBuilder are mostly complete. If you are adding only View elements, then you need not edit the starting source files. However, to add non-View object you must first associate it with a View object so InterfaceBuilder has a way to represent the object. This requires your overriding the finishInstantiate() method and adding a line of code to associate each non-view object with a custom view. In other words, if there is a non-graphical object, both the non-graphical object and a custom view representing that object must be created. When the developer grabs the custom view and drags it to where it belongs, InterfaceBuilder will create the correct non-view object instead. The view object is required to draw something to provide feedback in InterfaceBuilder.

When the project is created ProjectBuilder creates a default palette to represent your objects in InterfaceBuilder. You must use InterfaceBuilder to modify this palette to populate it with whatever interface elements are necessary for the ObjectWare package. Palettes can contain custom views, menus, windows, or objects with no interface element. Each element must have a subclass of view created and placed in the palette window.

Basic palettes don't require any special code to make them work, but more sophisticated palettes might. For example, your palette might have an Inspector panel where various attributes, such as initial settings, can be set. These attributes should probably be saved as the application is being built. Use of the Inspector and reading and writing attributes require custom code. OPENSTEP provides objects to help perform these tasks. One such object is typed streams, which are an interesting mechanism for saving and restoring objects with disk files.

Typed Streams

Typed streams are a private data format for archiving objects. Each object declares the types in the stream, then writes those types. An object can declare another object, and write that object to the stream. In practice, it is usually easiest to write the document object to a stream, and have the document object's write method declare all other objects. Listing 1 shows sample code that archives some integers and subsidiary objects. One of the powers of typed stream is not having to worry about big endian/little endian issues. Typed streams work correctly with everything but bit fields.

Listing 1:
- read:(NXTypedStream*)stream
{
	[super read:stream];
	NXReadTypes( stream, "ii", &total, &stepSize );
	helperObject = NXReadObject( stream );
	return self;
}

- write:(NXTypedStream*)stream
{
	[super write:stream];
	NXWriteTypes( stream, "ii", &total, &stepSize );
	NXWriteObject( stream, helperObject );
	return self;
}

Typed streams are very easy to implement, but they do have some drawbacks. Each written stream must be read correctly. In the read method, the code has to specify that it is reading integers. If the stream and the code don't match, then the read will raise an exception. Typed streams support versioning, though, and each object can specify that objects version. So, if only one object changes, then that object would up its version number without any changes outside of that object.

Another drawback of typed streams is the lack of random access. Typed streams are meant to be read in their entirety. Each object is created in turn. Deferred loading of part of a document would be difficult.

The final problem I have had with typed streams is lack of portability. Despite OPENSTEP running on Intel, HP, Sun, and now Macintosh hardware, some people still need Windows applications. Some developers also need the file format to be the same across their Windows and OPENSTEP applications. This just isn't going to work.

Inspectors

Most objects will require an inspector to examine and modify attributes of the object in InterfaceBuilder. The inspector code is only used by InterfaceBuilder, but it is still important. There are 4 inspectors for each object, Attribute, Connection, Size, and Help. Default inspectors are provided automatically if custom inspectors are not created. Custom Connection and Help inspectors are rarely used.

Custom palette objects are identified by adding one or more of the following factory methods to the object:

getInspectorClassName
getConnectInspectorClassName
getSizeInspectorClassName
getHelpInspectorClassName

Factory methods are, for all intensive purposes, the same as C++ static methods. There are some differences, but most of those are implementation details. Here, factory methods are used to retrieve global objects.

Each custom inspector object must be added to the palette project. There is no theoretical limit on the number of custom objects that can be placed in a palette of a project, as each custom object identifies which custom objects apply. Likewise, a custom inspector object can inspect multiple objects.

Each custom inspector is an object and a nib file. Interface Builder has a command for creating the nib and object templates. Unlike the palette object, the inspector objects require some code, but not much.

The inspector object inherits from IBInspector, which has outlets for connecting to the inspector. Once these outlets are hooked up, then the object is able to communicate with InterfaceBuilder.

There are four methods that need to be overridden. The first is the init method. The init method is called automatically by InterfaceBuilder and is responsible for loading the nib file. As well as the nib file, the init method can instantiate any helper objects it will require.

The second method required is the wantsButtons method. InterfaceBuilder will call each custom Inspectors wantsButtons to determine if an OK and Revert button are needed. If the inspector is doing live updating, then there is no reason for the OK and Revert buttons to be present. Most objects don't do live updating, but wait for the OK button to be hit.

The last two methods are OK and Revert. These methods are automatically called when the user clicks on the OK and Revert buttons. Both of these methods must access the API created for the custom object to set and retrieve values. InterfaceBuilder saves settings by writing objects into a nib file. When an application loads a nib file, the retrieval method unarchives the objects. In reality, every object displayed in InterfaceBuilder is an instantiation of the object that will appear in the application.

Library

The last step is to distribute the object files for application programmers to use. Unfortunately, the palette is only usable in InterfaceBuilder. Fortunately, the same objects used in the palette can be used in the library.

The best mechanism, but the least used, is to distribute the source code. Of course, every programmer wants to be able to fix bugs in other programmer's libraries, but giving away your source code is rarely used.

If there is only one custom object, then distributing the object file created by gcc will work. The object file can be included in a project without any problems. If there are many objects, then the objects can be linked into a library. ProjectBuilder can create libraries as easily as creating palettes or applications. Each directory can only hold one project, so a second directory will have to be created.

The standard way of creating the libraries is to bundle the objects with any nib files needed. Again, ProjectBuilder can create Bundles automatically. Bundles are a collection of objects and, nib files, and other resources that can either linked in or loaded at run-time. Shipping as a bundle allows applications to load functionality as needed.

Conclusion

With ObjectWare, not only can developers market their technologies for other developers to use, but they can incorporate the latest technologies without re-inventing the them. OPENSTEP's architecture and development tools make bundling technology simple. There is no set source code language, any resources can be included, any call made by an application can be made by the custom objects. Furthermore, developers that are testing their interfaces in InterfaceBuilder using the custom palettes will see the objects live instead of an abstract box that might work once the application is done.

Overall, ObjectWare under OPENSTEP opens possibilities that other platforms have long struggled to achieve.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Printopia 3.0.4 - Share Mac printers wit...
Run Printopia on your Mac to share its printers to any capable iPhone, iPad, or iPod Touch. Printopia will also add virtual printers, allowing you to save print-outs to your Mac and send to apps.... Read more
Tinderbox 7.3.1 - Store and organize you...
Tinderbox is a personal content management assistant. It stores your notes, ideas, and plans. It can help you organize and understand them. And Tinderbox helps you share ideas through Web journals... Read more
ExpanDrive 6.1.6 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Printopia 3.0.4 - Share Mac printers wit...
Run Printopia on your Mac to share its printers to any capable iPhone, iPad, or iPod Touch. Printopia will also add virtual printers, allowing you to save print-outs to your Mac and send to apps.... Read more
Tinderbox 7.3.1 - Store and organize you...
Tinderbox is a personal content management assistant. It stores your notes, ideas, and plans. It can help you organize and understand them. And Tinderbox helps you share ideas through Web journals... Read more
ExpanDrive 6.1.6 - Access cloud storage...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
VOX 3.0.1 - Music player that supports m...
VOX just sounds better! The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all audio formats you should ever need.... Read more
Merlin Project 4.3.3 - $289.00
Merlin Project is the leading professional project management software for OS X. If you plan complex projects on your Mac, you won’t get far with a simple list of tasks. Good planning raises... Read more
Mac DVDRipper Pro 7.1 - Copy, backup, an...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
iMazing 2.5.2 - Complete iOS device mana...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more

Latest Forum Discussions

See All

148Apps' Ultimate Guide to Black Fr...
Black Friday is here, and there are a whole lot of discounts running right now for folks on the lookout for new mobile devices, accessories, and yes, even games. Here's a helpful rundown of what you'll find both in stores and online. Happy... | Read more »
The best Black Friday mobile game deals
Black Friday's upon us, and if you've happened to nab a fancy new phone during the week's big savings, you might be searching for some new games to fill up space on your new gadget. There are a lot of great games on sale right now for Black Friday... | Read more »
The best mobile games to play while your...
Thanksgiving is a time to reconnect with loved ones, eat lots of food, and all of that jazz, but once the festivities start to wind down, folks tend to head to the couch to watch whatever football is happening for Turkey Day. | Read more »
The best Black Friday deals for Apple ga...
Black Friday is hours away at this point, but many popular retailers are getting a jump on things with plenty of pre-Black Friday sales already available. Many of those early bird sales including some sharp discounts on the latest Apple phones... | Read more »
The Inner World 2 (Games)
The Inner World 2 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Solve mind-bending puzzles in a world full of mystery and save the family of the flute-noses! Their dynasty has been... | Read more »
warbot.io wants you for the robot wars
Fans of epic gundam-style battles will find a lot to love in warbot.io, the first game for up and coming developer Wondersquad. The game saw a lot of success when it first launched for browsers and Facebook, and now even more people are getting the... | Read more »
Uncover alien mysteries in cross-genre s...
If the Alien franchise taught us anything, it’s that landing on a strange planet at the behest of a faceless corporation is probably asking for trouble. And Eldritch Game’s Deliria doesn’t prove otherwise. In 2107, Dimension LG7 is rich with... | Read more »
The best mobile games to play during dre...
| Read more »
Animal Crossing: Pocket Camp beginner...
Animal Crossing: Pocket Camp, was just announced yesterday, but it's already in soft launch in Australia. No matter where you are in the world, you can still get access to the soft launch on iOS, so we've devised a few beginner tips for folks who... | Read more »
The mobile gamer's guide to Black F...
We're starting to catch wind of some exciting deals in the mobile gaming space for Black Friday. There are big discounts on mobile phones and accessories cropping up already, so you might want to get a move on things ahead of the big day. It's... | Read more »

Price Scanner via MacPrices.net

Apple Black Friday sale for 2017: $150 Apple...
BLACK FRIDAY Apple has posted their Black Friday deals for 2017. Receive a $150 Apple gift card with the purchase of select Macs and up to $100 with various iPads, iPhones, and Apple Watches. The... Read more
Black Friday 2017: Where to find the best dea...
B&H Photo has 15″ and 13″ MacBook Pros on sale for up to $200 off MSRP as part of the Black Friday and Holiday sale. Shipping is free, and B&H charges sales tax for NY & NJ residents only... Read more
Black Friday 2017: Where to find the best dea...
B&H Photo has 12″ MacBooks on sale for $150 off MSRP as part of the Black Friday and Holiday sale. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 12″ 1.2GHz... Read more
Black Friday 2017: Where to find the best dea...
B&H Photo has 10.5″ iPad Pros in stock today and on sale for up to $130 off MSRP. Each iPad includes free shipping, and B&H charges sales tax in NY & NJ only: – 10.5″ 64GB WiFi iPad Pro... Read more
Black Friday 2017: Where to find the best dea...
B&H Photo has 13″ MacBook Airs on sale for up to $150 off MSRP as part of the Black Friday and Holiday sale. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″... Read more
Black Friday 2017: Where to find the best dea...
B&H Photo has 27″ and 21″ iMacs on sale for up to $200 off MSRP as part of the Black Friday and Holiday sale. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 27... Read more
Black Friday 2017: Where to find the best dea...
B&H Photo has Mac minis on sale for $100 off MSRP as part of their Black Friday sale, each including free shipping plus NY & NJ sales tax only: – 1.4GHz Mac mini: $399 $100 off MSRP – 2.6GHz... Read more
Black Friday 2017: Find the best deals and lo...
Scan our exclusive price trackers for the latest Black Friday 2017 sales & deals and the lowest prices available on Apple Macs, iPads, and gear from Apple’s authorized resellers. We update the... Read more
Black Friday: 27″ 3.4GHz iMac for $1599, save...
Amazon has the 27″ 3.4GHz Apple iMac on sale for $1599.99 as part of their Black Friday sale. That’s $200 off MSRP, and shipping is free. Their price is currently the lowest price available for this... Read more
Black Friday: 13″ 2.3GHz/256GB MacBook Pro fo...
Amazon has the 13″ 2.3GHz/256GB Apple MacBook Pro on sale for $1299.99 as part of their Black Friday sale. Shipping is free: – 13-inch 2.3GHz/256GB Space Gray MacBook Pro (MPXT2LL/A): $1299.99 $200... Read more

Jobs Board

Business Development Manager, *Apple* Pay -...
# Business Development Manager, Apple Pay Job Number: 112919084 Santa Clara Valley, California, United States Posted: 18-Aug-2017 Weekly Hours: 40.00 **Job Summary** Read more
Digital Marketing Media Planner, *Apple* Se...
# Digital Marketing Media Planner, Apple Services Job Number: 113080212 Culver City, California, United States Posted: 03-Oct-2017 Weekly Hours: **Job Summary** Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Business Development Manager, *Apple* Pay -...
# Business Development Manager, Apple Pay Job Number: 112919084 Santa Clara Valley, California, United States Posted: 18-Aug-2017 Weekly Hours: 40.00 **Job Summary** Read more
*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 56553863 North Wales, Pennsylvania, United States Posted: 17-Jun-2017 Weekly Hours: 40.00 **Job Summary** Are you passionate Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.