AS1Sender Module

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The AS1Sender component implements an AS1 / EDI-INT client, capable of sending EDI messages over electronic mail.

Syntax

nsoftware.IPWorksEDI.As1sender

Remarks

The AS1Sender component is used to send EDI or other messages over SMTP/S, using the AS1 protocol specified in RFC 3335. The class is also used to retrieve and verify server responses.

A typical AS1 transaction is as follows:

(1) The sender sends an EDI document to the receiver using SMTP or SMTPS. Typically the document will be signed and encrypted (particularly if TLS/SSL is not used). A signed receipt will also be requested.

(2) The receiver decrypts the message and verifies the signature.

(3) The receiver sends a signed receipt back to the client. The signature is over the hash of an MDN, which contains a hash of the received message.

When sending an EDI message, the client should specify, at a minimum, From and SendTo, MailServer, and Data and EDIType. The Send method should then be invoked.

To secure the EDI transmission, the message may be signed and/or encrypted by setting the appropriate certificates. By default, the class will apply message security if the appropriate certificates are specified. To sign the data set SigningCert. To encrypt, set RecipientCerts.

TLS/SSL will also be used if SSLStartMode is set. In case your trading partner is using a self-signed certificate with their mail server it will be necessary to set SSLAcceptServerCert or trap the SSLServerAuthentication event to accept the certificate.

The message may also be compressed by setting CompressionFormat.

To request a receipt, or Message Disposition Notification (MDN), simply set the MDNTo property. The MDN will be returned in a separate email response. The MDNOptions property may be used to customize the request. By default, the class will request a signed MDN over an SHA1 hash.

Validating AS1 MDNs

AS1 MDNs are returned asynchronously in a separate email. Generally MDNs will not be returned immediately.

The class supports the use of the POP/S protocol for receiving e-mail. To receive an MDN, set the MailServer, User, and Password properties, and call Connect. At this point you may search your mailbox using the MailMessage properties; when you have found the appropriate message you should invoke ReadReceipt, which will set MDNReceipt. If the receipt is indeed an MDN it will also be parsed (although not verified) and MessageId will be set. If the message is not an MDN an exception will be thrown.

You should then use the values of From and MessageId to look up your trading partner's certificates, the MDNOptions requested, and the OriginalContentMIC calculated when you sent the original message (you must store this value externally to verify signed receipts). Finally, invoke VerifyReceipt.