TweetFollow Us on Twitter

Cyberdog Intro
Volume Number:12
Issue Number:2
Column Tag:OpenDoc

Cyberdog, the OpenDoc

Internet Components

The future of Internet surfing is OpenDoc

by Stephen Humphrey, VP Engineering, Acorde Corporation

Cyberdog is the code name for Apple Computer’s OpenDoc-based Internet components. This article provides a 10,000-foot view of the Cyberdog architecture and a cursory introduction to the most important parts of its API.

Cyberdog will include components which provide Web browsing, SMTP and POP mail, Usenet News, FTP, Gopher, and Telnet. These components provide the sort of functionality one expects from Internet apps today, plus strong mutual integration with one another, and with a universal log, which keeps a historical record of the user’s actions, and a notebook, which stores pointers to the user’s favorite places and people. For instance, Cyberdog’s integrated SMTP and POP mail system (see Figure 1) is fully MIME-capable; addresses may be stored in the notebook for easy access; and any CyberItem may be sent as an enclosure. The News reader shows the familiar display of newsgroups and messages (see Figure 2), and any icon can be dragged to the notebook. Cyberdog is designed to improve the Internet experience for MacOS users by closely integrating the various

Figure 1. A Mail window

Figure 2. The News reader

components with each other, with other applications, and with the desktop. Apple will encourage third-party developers to extend and replace the base Cyberdog components by fully documenting the Cyberdog API and architecture.

As I write this article, Apple plans to distribute a sneak preview of the shared libraries which make up Cyberdog on the OpenDoc Developer Release 4 CD [in this issue]; the end-user release of the Cyberdog components is currently scheduled for May 1996.

The Cyberdog components factor their Internet responsi-bilities into three major areas: Viewers, Services, and Context facilities. Viewers are responsible for displaying the myriad data types commonly found on the Net, like JPEG and HTML. Services manage the protocols used for transporting the data types. Context facilities hold the history of the user’s interaction and help the users keep track of their favorite sites, newsgroups, and mail addresses.

Viewers are OpenDoc Part Editors

One of the most exciting aspects of Cyberdog is its extensive use of OpenDoc. Cyberdog depends fully on the OpenDoc architecture for displaying and interacting with Net-borne data. In fact, every part of Cyberdog that has a user interface(UI) is implemented as an OpenDoc part. Even those components which do not have a UI are implemented as SOM objects, so again they behave similarly to OpenDoc components. This dependence on OpenDoc means that a Cyber-aware Viewer you write will automatically benefit from the strengths of the OpenDoc architecture. So, for example, if you write a Cyberdog-savvy Stock Ticker, your users will be able to display dynamically-updating information about their portfolios in any OpenDoc container.

Cyberdog viewers are first and foremost OpenDoc viewers. To show a data type in Cyberdog, you first implement an editor based on ODPart. All of a regular OpenDoc part’s methods are required, and the part editor uses the standard OpenDoc event, layout, and storage facilities. To add the functionality of Cyberdog, you add an extension to your editor which inherits from CyberPartExtension.

CyberPartExtension is a virtual class which provides the methods with which the other Cyberdog components will interact with your viewer. You will write an extension which inherits the base functionality of CyberPartExtension but which also knows about the particular details of interacting with your editor. So for example, if you have already written a JPEG display part using OpenDoc, you will write a CyberJPEGExtension which provides your part with the additional capabilities of retrieving the JPEG data from the Net instead of just from your OpenDoc StorageUnit. CyberPartExtension is a standard ODExtension, so you will provide your extension to Cyberdog via the standard ODPart::HasExtension() and ODPart::GetExtension() mechanisms. After your part is initialized but before you create your first display frame, Cyberdog will tell your editor to use a CyberService to retrieve its data.

CyberServices Encapsulate Internet Protocols

A CyberService is the base class which manages a single Internet protocol. The basic Cyberdog components include CyberService implementations for HTTP, FTP, Gopher, Telnet, and the local file system. Notice that CyberServices represent transport protocols and not data types, so there is an FTPService, not a JPEGService. A CyberService’s most important role is as a manager of a few other classes of objects which actually implement a full Internet protocol, particularly the CyberItem and the CyberStream.

A CyberItem represents the address of a piece of data on the Net. In its simplest form, it can be thought of as an objected-oriented wrapper for a URL. In practice, there is nothing to stop much more advanced capabilities in a CyberItem, such as complete database queries. CyberItems are portable; they can be saved in your StorageUnit and reinstantiated later. If you are implementing a viewer which can contain one or more links to outside data, such as an HTML viewer, you will save CyberItems in your StorageUnit as part of your own content model, retrieving them when necessary based on action from the user. CyberItems have no inherent UI, so they inherit from SOMObject instead of ODPart.

A simple example of a CyberItem’s behavior is shown by a CyberButton, a simple Cyber-savvy viewer which comes with Cyberdog. A CyberButton is an OpenDoc part which behaves as a button (surprise!); it can be displayed in any OpenDoc container, can display a title or a picture on its face, and can be clicked on by the user. Internally, a CyberButton holds one CyberItem. When the user clicks on the CyberButton, the button calls the CyberItem’s Open() method. This is a fire-and-forget call; the CyberButton is not responsible for any additional interaction with the CyberItem. The CyberItem is free to take any appropriate action, the most common of which is to open a viewer to display the data pointed to by the CyberItem.

As a Cyber-savvy viewer, you become interested when the SetCyberItem() method of your CyberPartExtension is called. This tells you that you are being opened because the user fired a CyberItem, and you are provided a reference to that CyberItem. Your most common action then will be to ask the CyberItem to create a CyberStream through which you will get the data to display; to do this, call the CyberItem’s CreateCyberStream() method, and it will return a CyberStream.

CyberStreams Provide Clean Data to Viewers

A CyberStream implements the actual passing of data from a protocol to a viewer. After receiving a CyberStream from a CyberItem, you will tell the CyberStream to either Open() or OpenWithCallback(). This call tells the CyberStream that it should immediately begin downloading the data. It is the CyberStream’s responsibility to begin retrieving the data asynchronously and to store it until you ask for it.

If you opened the CyberStream by calling Open(), you will poll it for data by calling its GetStreamStatus() method. The most interesting replies are kDataAvailable and kDownloadComplete. If you opened the CyberStream by calling its OpenWithCallback() method, then the CyberStream will notify you whenever data is available by calling the notification method you register.

Any time the CyberStream has data available, you can request a chunk of data from the stream with the call GetBuffer(). When you are finished processing the data, you must call ReleaseBuffer(). If you are using a callback method to notify you when data is available, you must remember that this notification may happen at interrupt time; you will not be able to allocate memory, draw to the screen, or perform any other action which is not interrupt-safe. However, it is okay to set an internal state which will get and process the data later, such as at idle time. The CyberStream may only have a limited number of buffers, so it is a good idea to release them as soon as you are able to. You will continue calling GetBuffer() and ReleaseBuffer() until the CyberStream reports it is finished downloading.

CyberStreams are responsible for parsing the data stream and removing any protocol-specific headers or similar data blocks in the stream. This has the advantage of providing the viewer with a consistent stream of data regardless of the data’s transfer protocol on the Net. So for example, your JPEGViewer need not care whether the CyberItem it receives is really a GopherItem, an FTPItem, or a FileItem; regardless of the protocol the user chose, the JPEG stream you receive will be the same.

One limitation of the method described above is that sometimes a CyberItem doesn’t know what kind of viewer it should open. For example, a WebItem cannot open an appropriate viewer until it knows the kind of data at which it is pointing, that is, until it parses the HTML and finds an appropriate data-type tag. In this case, the CyberItem will actually open the CyberStream and start it downloading even before the real viewer is opened. The CyberItem will also open a special OpenerPart that will display the download status until the real viewer can be determined and opened. However, as a viewer you will not know or care that the stream has already been opened; you will ask the CyberItem to create a CyberStream, ask the CyberStream to open, and begin polling as usual.

As of now, CyberStreams are designed primarily to pass data in one direction. This is decidedly unhelpful for some protocols which depend on more interactive communication between the viewer and the stream. For example, the telnet protocol cannot be implemented efficiently using CyberStreams. Thus, when a TelnetItem (a telnet CyberItem) asks a TelnetViewer to open, the TelnetViewer never requests a TelnetStream. Instead, it just fully implements the telnet protocol within the viewer by asking the TelnetItem for its connection information and creating the connection itself. Since no CyberConnection object exists, this means implementing these types of protocols is fairly tedious today. This is a great opportunity for either a future version of Cyberdog or for a smart third-party.

Context Facilities Tie the Parts Together

Cyberdog provides several built-in context facilities which unite the various components into a seamless Internet workspace. These include a common Connect dialog, a Preferences panel, the Log, and Notebooks. Each of these is managed through the single CyberSession object.

The CyberSession is responsible for the overall integration of the Cyberdog components. It is similar in purpose to the OpenDoc session object, ODSession, although it is different in the particular services it provides. There is at most one CyberSession for each ODSession. The CyberSession is the main facility through which Viewers will request various Cyberdog objects. It is also the facility through which standard OpenDoc containers will be able to add the Cyberdog menus to their menu bar. Among its responsibilities, the CyberSession checks the Cyberdog libraries folder to see which CyberServices are available. This is what allows the run-time addition of new services to Cyberdog’s repertoire.

CyberServices may provide a Connect panel. If provided, this part allows the Cyberdog Connect dialog to display protocol-specific fields for any service available to the user. In operation, the Connect dialog is reminiscent of the pre-System 7 Control Panel dialog, with scrolling icons on the left and individual panels on the right. Since the panels are implemented as regular OpenDoc parts, a service which implements a new protocol can easily provide a panel for the CyberSession to display to the user. Such a Connect panel is implemented by adding a CyberPanelExtension to a regular part subclassed from ODPart.

Similarly, any CyberService can provide a Preferences panel that the CyberSession will display in the Cyberdog Preferences Dialog. A Preferences panel, too, is implemented by adding a CyberPanelExtension to a regular part subclassed from ODPart. (This implementation of the Cyberdog dialog boxes provides one of the best non-document uses of OpenDoc to date; it validates OpenDoc as more than just a compound-document architecture.)

To provide an historical context for the user’s actions, Cyberdog provides a universal Log which tracks where the user has been on the Net. The user can show the log, display its items hierarchically, alphabetically, or historically, and return to places in it by simply clicking on the place’s icon (see Figure 3). A Viewer posts a new item on the log by providing a CyberItem (and optionally, its hierarchical parent) to the CyberSession’s AddCyberItemToLog() method.

Figure 3. The Log window

The user may also save one or more Cyberdog Notebooks (see Figure 4). These simple lists of CyberItems have a single-level folder system in which the user can organize favorite places and people. The user identifies a default notebook, and Viewers may add an item to this default notebook by simply telling the CyberSession to AddCyberItemToNotebook(). More typically, Viewers allow the user to drag CyberItems to a Notebook using the OpenDoc drag-and-drop facilities (so the user can drag e-mail addresses, newsgroups, Web sites, Gopher directories, and telnet connections right into a Notebook). Like other parts of Cyberdog, the Notebook is designed to implement the minimum functionality required by a beginning Internet user; it is ripe for replacement by an enterprising third-party.

Figure 4. The Notebook

Where To Go From Here

By the time you read this article, the Cyberdog components and SDK should be available on the OpenDoc DR4 CD. The SDK is quite preliminary, but should be sufficient to get started with developing for Cyberdog (especially if you’re not afraid to bleed a little). Various listservers have been established to facilitate Cyberdog discussion. Mail a message to cdog@apple.com with subject “DEV-INFO” for more information.

Apple has done a commendable job of designing Cyberdog. From its foundation, Cyberdog’s architecture permits and even encourages third-party developers to replace and extend it. Since it is still alpha-quality code, expect some pain. However, developers who learn to walk the ’dog now might discover opportunities and markets that will be harder to find later. If you start early, the ’dog will probably bite you occasionally; but once you’ve learned to handle it, you’ll be able to cuddle up close.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Minecraft 302 - Popular sandbox building...
Minecraft allows players to build constructions out of textured cubes in a 3D procedurally generated world. Other activities in the game include exploration, gathering resources, crafting, and combat... Read more
FotoMagico 5.2b8 - Powerful slideshow cr...
FotoMagico lets you create professional slideshows from your photos and music with just a few, simple mouse clicks. It sports a very clean and intuitive yet powerful user interface. High image... Read more
TeamViewer 11.0.65452 - Establish remote...
TeamViewer gives you remote control of any computer or Mac over the Internet within seconds, or can be used for online meetings. Find out why more than 200 million users trust TeamViewer! Free for... Read more
Dropbox 9.4.49 - Cloud backup and synchr...
Dropbox is an application that creates a special Finder folder that automatically syncs online and between your computers. It allows you to both backup files and keep them up-to-date between systems... Read more
Geekbench 4.0.0 - Measure processor and...
Geekbench provides a comprehensive set of benchmarks engineered to quickly and accurately measure processor and memory performance. Designed to make benchmarks easy to run and easy to understand,... Read more
Nisus Writer Pro 2.1.5 - Multilingual wo...
Nisus Writer Pro is a powerful multilingual word processor, similar to its entry level products, but brings new features such as table of contents, indexing, bookmarks, widow and orphan control,... Read more
Default Folder X 5.0.6 - Enhances Open a...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click on... Read more
Alfred 3.1 - Quick launcher for apps and...
Alfred is an award-winning productivity application for OS X. Alfred saves you time when you search for files online or on your Mac. Be more productive with hotkeys, keywords, and file actions at... Read more
MYStuff Pro 2.0.25 - Create inventories...
MYStuff Pro is the most flexible way to create detail-rich inventories for your home or small business. Add items to MYStuff by dragging and dropping existing information, uploading new images, or... Read more
OmniOutliner Pro 4.6 - Pro version of th...
OmniOutliner Pro is a flexible program for creating, collecting, and organizing information. Give your creativity a kick start by using an application that's actually designed to help you think. It's... Read more

Six! Tips, tricks, and hints for beginne...
There's nothing pretentious about Six!, the latest release from Gram Games. As puzzlers go, it's so unassuming that it took me some time to even realize why it was called what it was. Somewhere, my high school geometry teacher is now sobbing... | Read more »
Mobius Final Fantasy: Multiplayer update...
Up until now, Mobius Final Fantasy has been about as single-player an experience as an RPG can be. Not only do you play solo, but you are literally one among a seemingly unending wave of faceless warriors on the road toward the same goal. [Read... | Read more »
Find out the story behind League of Ange...
If you’re looking for a new thrilling MMORPG to play with your friends then you’ll be excited to hear that there is a sequel to one of the most well known titles in the genre – namely League of Angels 2. With a brand new 3D engine offering... | Read more »
Naruto Shippuden: Ultimate Ninja Blazing...
I'm not sure if it's possible to say you are an anime fan but also never have seen one episode of Naruto. If it is, then I resemble that remark, and if not, I offer a hearty apology. [Read more] | Read more »
5 mobile games that let you explore spac...
No Man's Sky hasn't exactly turned out to be everything it was promised. Though its core concept of exploring an unimaginably vast universe of different planets is an intriguing one, the execution has left many PS4 and PC gamers feeling like they... | Read more »
Mummy madness in new action game Tomb He...
Hot on the tail of Bump Hero, ZPlay is giving gamers another reason to get screen bashing with a brand new release. Tomb Heroes is a challenging action game in which you battle enemies in various tombs around the world. You can select from nine... | Read more »
Siralim 2 (RPG / Roguelike) (Games)
Siralim 2 (RPG / Roguelike) 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Siralim 2 is an old-school monster catching RPG. Summon and customize hundreds of creatures to fight for you as... | Read more »
Clean Text (Productivity)
Clean Text 1.0 Device: iOS Universal Category: Productivity Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Gemini - A Journey of Two Stars (Games)
Gemini - A Journey of Two Stars 1.0.1 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.1 (iTunes) Description: *** SPECIAL LAUNCH SALE: $2.99 (25% off) *** "A mesmerizing and unexpectedly emotional journey." -- Los... | Read more »
How to get four NFL superstars for your...
Even though you're probably well on your way to building a top notch squad for the new season in Madden NFL Mobile, let's say you could beef it up by adding Rob Gronkowski, Antonio Brown, Von Miller, and Todd Gurley to your roster. That's... | Read more »

Price Scanner via MacPrices.net

Apple refurbished 12-inch iPad Pros available...
Apple has Certified Refurbished 12″ iPad Pros available for up to $160 off the cost of new iPads. An Apple one-year warranty is included with each model, and shipping is free: - 32GB 12″ iPad Pro... Read more
Tim Cook Posts Open Letter To The Apple Commu...
Apple Inc. CEO Tim Cook has posted an open letter commenting on the European Commission’s bizarre demand that Apple pay more than $14 billion in allegedly underpaid back taxes on its Irish... Read more
Streetwise Drivers Club App Now Features Open...
Streetwise Drivers Club, an app that rewards drivers with deals on everything from dining and gift cards to tires and insurance, has announced the launch of a new enhancement connecting app users... Read more
15-inch Retina MacBook Pros on sale for up to...
B&H Photo has 15″ Retina Apple MacBook Pros on sale for up to $200 off MSRP. Shipping is free, and B&H charges NY tax only: - 15″ 2.2GHz Retina MacBook Pro: $1799 $200 off MSRP - 15″ 2.5GHz... Read more
RESCUECOM 2016 Semi-Annual Computer Reliabili...
The beginning of a new school year is upon us again, in which students and parents have some very important choices to make, often including the purchase of a computer or tablet. Whether you are... Read more
VRS Design Damda Glide Series iPhone 7 and 7...
What makes the Damda Glide Series for the iPhone 7 and iPhone 7 Plus special? Case maker VRS Design says its Damda Glide Series is the first mobile case to incorporate a semi-automatic mechanism for... Read more
Apple refurbished iMacs available for up to $...
Apple has Certified Refurbished 2015 21″ & 27″ iMacs available for up to $350 off MSRP. Apple’s one-year warranty is standard, and shipping is free. The following models are available: - 21″ 3.... Read more
Clearance 2015 13-inch MacBook Airs available...
B&H Photo has clearance 2015 13″ MacBook Airs available for $350 off original MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 1.6GHz/4GB/128GB MacBook Air (MJVE2LL/A): $829... Read more
Check Apple prices on any device with the iTr...
MacPrices is proud to offer readers a free iOS app (iPhones, iPads, & iPod touch) and Android app (Google Play and Amazon App Store) called iTracx, which allows you to glance at today’s lowest... Read more
Save $120 with Apple refurbished Time Capsule...
Apple has certified refurbished Time Capsules available for $120 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $179, $120 off (not... Read more

Jobs Board

*Apple* Solutions Consultant - Apple (United...
Apple Solutions ConsultantJob Number: 51218534Pleasant Hill, California, United StatesPosted: Aug. 18, 2016Weekly Hours: 40.00Job SummaryAs an Apple Solutions Read more
*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 51218354 Fredericksburg, Virginia, United States Posted: Aug. 18, 2016 Weekly Hours: 40.00 **Job Summary** As an Apple Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* /Mac Support Engineer - GFI Digital,...
FI Digital, Inc. is currently seeking candidates for a full time Apple Support Engineer to add to our Maryland Heights, Missouri IT team. Candidates must be dynamic Read more
*Apple* Solutions Consultant - Apple (United...
Apple Solutions ConsultantJob Number: 51218534Pleasant Hill, California, United StatesPosted: Aug. 18, 2016Weekly Hours: 40.00Job SummaryAs an Apple Solutions Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.