Apple Newton Internet Enabler Especificaciones descargar pdf (Pagina 8)

June 1996 Newton Technology Journal

• the DNSGetMailServerNameFromDomainName

function translates a domain name into the domain name for a mail

server that serves that domain.

• the DNSGetNameFromAddressfunction translates an

Internet address into its corresponding domain name.

You must supply a

clientContext

and

clientCallback

parameter to

each of the DNS functions, just as you do for the link controller functions.

However, the DNS callback functions are called with different parameters

than are the link controller functions.

The callback function for DNSCancelRequests receives no

parameters.

The callback function for all of the other DNS functions receives two

parameters: an array of DNS results frames and a result code. Each results

frame contains a number of slots that describe the DNS operation that was

performed. For example, the DNSGetAddressFromName

function is declared as follows:

DNSGetAddressFromName(addr, clientContext, clientCallback)

An example of a callback for this function is shown here:

myApp.DNSGetAddrcallback := func(results, error)

begin

if error or length(results) < 1 then

begin

print("DNS error: " && error);

// do something with the error

return;

end;

// save the resolved address

myRemoteIpAddr := results[0].resultIPAddress;

end;

Each results frame contains a type slot and at least one result slot. Most

results frames contain the

targetDomainName

slot; however, this is not

guaranteed. Table 1-2 shows which slot is guaranteed to be valid for each

DNS operation.

Table 1-2: Result slots for each DNS operation

DNS operation Results frame slot

DNSGetAddressFromName resultIPAddress

DNSGetNameFromAddress resultDomainName

DNSGetMailServerNameFromDomainName

resultDomainName

DNSGetMailAddressFromName resultIPAddress

For example, the DNSGetAddressFromName function

returns a results array that looks something like this:

[ {

type: kDNSAddressType,

targetDomainName: "newton.apple.com.",

resultIPAddress: [155,227,54,3]

} ]

In contrast, the DNSGetNameFromAddress function

returns a results array that looks something like this

[{

type: kDNSDomainNameType,

targetDomainName: "newton.apple.com.",

resultIPAddress: [155,227,54,3]

} ]

Some DNS operations return a results array that contains more than one

results frame. For example, a mail exchange operation can generate

multiple mail exchange results frames.

USING THE NEWTON INTERNET ENABLER OPTIONS

You configure the Newton Internet Enabler links with communications

options. Send these options down with your endpoint method calls, as

you do for other communications tools. Table 1-3 describes the Newton

Internet Enabler options, including which options to send with which

endpoint methods.

Table 1-3: Newton Internet Enabler options

Option name Description When to use

Expedited data For expedited Set this option with an

transfer

('iexp')

transmission of data Output call to

over a TCP link. transfer data on a TCP

endpoint.

Physical link To identify the link ID to use. Set this option at endpoint

identifier

('ilid')

instantiation time.

Local port To set the local port number Set this option if you are

('ilpt')

for TCP binds. binding to do a Listen

(at endpoint instantiation

or bind time). You don’t

need to set this option for

a Connect.

To set the local port number Set this option at endpoint

for UDP binds. instantiation or bind time.

To retrieve the local port Retrieve the value of this

number used for TCP option when you are

or UDP. connecting, sending, or

receiving data.

TCP remote socket To set the socket to which Set the value of this option

('itrs') TCP connects. at before using the

connection (at endpoint

instantiation, bind, or

connect time).

To retrieve the sender Get the value of this option

address for data received when listening for data on

over a TCP link. a TCP connection.

Transport service To set the transport Set this option at endpoint

type ('itsv') service type (TCP or UDP). instantiation time.

UDP destination To set the destination Set this option when

socket ('iuds') address for data being sending data with a UDP

sent over a UDP link. connection.

To retrieve the destination Get this option when

address for data received listening for data on a UDP

over a UDP link. connection.

UDP source socket To retrieve the source Get the value of this option

('iuss') address for data received when listening for data on

over a UDP link. a UDP connection.

NEWTON INTERNET ENABLER: PROVIDING CONVENIENT CONNECTIVITY

To summarize, the Newton Internet Enabler makes it easy for you to

provide Internet connectivity in your NewtonScript applications. If you

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