Exchanging Message Blocks Between Programs

meet the needs of most applications for program-to-program communication.

However, for low-level control or to get services not provided by the

The PPC Toolbox lets you send larger amounts of data to other applications

located on the same computer or across a network. The

PPC Toolbox can also be used by pieces of code that are not event- driven.

The PPC Toolbox is usually called by the Operating System; device drivers,

desk accessories, or other code modules can also use it.

Using the PPC Toolbox to send data between programs requires that both

your program and the program you're communicating with are open at the

same time. To initiate communication, one program opens a port and requests a

session with another program. The target program must also open a port and

accept the request. Once a session is established, the two programs can read and

write low-level message blocks.

See the PPC Toolbox for information on reading and writing low-level

message blocks between programs.

Remote Data Access

Using the Data Access Manager, your application can communicate with

databases or other data sources running on a Macintosh computer or on a

remote host computer. For example, your application can use high-level

routines to open a document containing commands to be sent to a remote data

server; initiate communication with the remote data server; send the

commands to the server; and (after the server executes the commands)

retrieve the requested data from the server. You can also use the

Data Access Manager to send data to a remote database or other data source.

If your application knows how to create commands for a remote data server,

then your application can use low-level routines to send these commands and

data directly to the data server.

The Figure below shows how a user in San Francisco might use a spreadsheet

application to request data from a company database in New York. The

spreadsheet application can use the Data Access Manager to request the data

from the database. The database application in New York sends back the

requested data, and the spreadsheet application can use this data to generate a

graph of the information.

Requesting data from a remote database

See the Data Access Manager for information on sending and retrieving

information from a remote database or other data source.

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