All Databases Inside Mac - Basic Toolbox

Interapplication Communication

The interapplication communications architecture provides support for

• automated copy and paste between applications

• sending and receiving events between applications

• reading and writing blocks of data between applications

The Edition Manager, Apple Event Manager, Event Manager, and

PPC Toolbox provide these features, and the Figure below shows their

relationships.

The managers constituting the interapplication communications architecture

The IAC architecture is built on communication and cooperation between

applications. Apple has defined important standards to help ensure that

communication between applications is effective. Using the Clipboard,

applications can share static data by allowing the user to copy and paste data

between documents. Using the Edition Manager, applications can support

dynamic data sharing and allow users to perform automatic copy and paste

between documents. Applications that support dynamic data sharing allow users

to copy data from one document to another and receive automatic updating of

the information when the data in the original document changes. The verbs

publish and subscribe describe this form of dynamic data sharing.

You can let users publish and subscribe among many documents by using the

Edition Manager and implementing the Create Publisher and

Subscribe To menu commands. This is a form of high-level communication

between applications; actually, the communication is in direct, as the

Edition Manager provides the interface that allows applications to share

dynamic data.

Your application can publish and subscribe with applications and documents

on a local disk or across a network. In general, anything that you allow the

user to copy or paste you should also allow the user to publish or subscribe to.

See Sharing Data Among Applications below for more information on

using the publish and subscribe features in your application.

Using the Apple Event Manager, applications can send Apple events to each

other to request services or information. These types of events are often the

result of a user request, or they can be specific events that your application

sends to another application. Apple events provide a standard way in which

your application can communicate with many other applications. Other

high-level events are for applications that choose to use a protocol other than

the Apple Event Interprocess Messaging Protocol (AEIMP). Applications can

use the Event Manager to send high-level events that follow their own

protocol.

The Program-to-Program Communications Toolbox(PPC Toolbox) is a set

of low-level routines that allow applications to communicate on the local

computer or over a network. Using the PPC Toolbox, applications can

exchange blocks of data with each other by reading and writing low-level

message blocks. The PPC Toolbox provides a method of communication

between applications that is more useful for applications that are closely

integrated, specifically designed to work together, or dependent on each other

for information. The PPC Toolbox is typically more useful for code that is

not event-based.

Your application can use the PPCBrowser function to allow the user to

choose another application to which to send high-level events or low-level

message blocks. The PPCBrowser function provides a standard user interface

for choosing an application to communicate with, much like the

Standard File Package provides a standard user interface for opening a

file.

All these forms of interapplication communication are based on the premise

that applications cooperate with each other. Both the application sending the

high-level event or low-level message block and the application receiving it

must agree on the protocol of communication.

The Figure below shows that your application can use the

Edition Manager to publish and subscribe to data. Your application can use

the Apple Event Manager to send and process Apple events and the

Event Manager to send and receive high-level events. Your application can

use the PPC Toolbox to read and write low-level message blocks. Your

application can use any of these methods to communicate with other

applications located on the same computer or across a network.

As the Figure below shows, managers in the IAC architecture can use the

services of other managers. For example, the Apple Event Manager uses the

communication services of the Event Manager. The Event Manager

in turn uses the PPC Toolbox on behalf of applications.

The Figure below shows how two different applications can use the

Edition Manager to publish and subscribe, and how they can use the

routines provided by the Apple Event Manager, the Event Manager, or

the PPC Toolbox to communicate with each other.

The next sections describe the three parts of the IAC architecture: the

Edition Manager, the Apple Event Manager and Event Manager, and

the PPC Toolbox.

Using interapplication communication

Applications using interapplication communication

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