Sending Events Between Applications

The Macintosh Operating System provides routines that allow your

application to send and receive events using the Apple Event Manager

and Event Manager. The Event Manager provides a general method for

communication between applications. The Apple Event Manager provides a

standard method of communication between applications using the Apple Event

Interprocess Messaging Protocol. (The PPC Toolbox can be used to read and

write low-level message blocks and is more useful for applications that are

closely integrated or perform coordinated tasks.)

events to other applications to request services or information. You can send

these events between applications on the same computer or between

applications located on different computers on a network. The

Apple Event Manager uses the services of the Event Manager to send and

receive Apple events. The Event Manager uses the communication services of

the PPC Toolbox on behalf of your application to send and receive events.

For high-level events and Apple events, the applications involved must agree

on what they can ask each other and on the action that should be taken in each

situation. Both the application sending the event and the application receiving

the event must agree on the protocol of communication.

Your application should support at least the required set of Apple events sent

by the Operating System. If you plan to implement publish and subscribe

capabilities, your application should also support the Apple events sent by the

Edition Manager. You can also implement other common Apple events or

design your own customized Apple events. In addition, sets of Apple events exist

for many specific categories of applications (for example, word processors or

spreadsheets).

If your application acts on an Apple event, it should perform the standard

action requested by that event. This helps ensure that other applications (and

eventually users) can send an event to a particular type of application and

expect the other application to understand and act on the event in a standard

way.

In most cases, you should use Apple events to communicate with other

applications. However, if necessary, you can implement your own protocol for

high-level events. The Figure below shows how two applications might use

high-level events. For example, a user might need to update the telephone

numbers of everyone in the marketing department. To accomplish this, the

user might use a word-processing application to send a

high-level event with the new telephone numbers across a network to a

directory application running on a Macintosh computer at the company's

headquarters. When the telephone directory application receives the

high-level event, it updates its directory with the new telephone numbers.

See the Event Manager for information on how to send and receive

high-level events. See the Apple Event Manager for information on the

Apple Event Interprocess Messaging Protocol.

Sending events to other applications

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