GISBReceiver Component

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The GISBReceiver component is used to process EDI messages and generate receipts.

Syntax

nsoftware.InEDI.Gisbreceiver

Remarks

The GISBReceiver implements server-side processing of EDI messages, as specified in versions 1.4 and 1.6 of the GISB/NAESB specification. It can be used to decrypt and verify incoming messages; in version 1.6, it may additionally be used to generate signed receipts. The component is designed to be easily incorporated into an HTTP server, and features custom functionality for server environments such as ASP.NET.

Basic Operation

The ProcessRequest method is used to process incoming messages and generate responses. ProcessRequest will parse the form data, determine DataFrom and DataTo, and then attempt to process any signed or encrypted data using PGP.

The PGP operations may be performed by an external implementation such as GnuPG or an internal implementation within the component. The PGPProviderType setting specifies which implementation is used. This property is only applicable when using an external implementation.

By default the external implementation is used, and component does not by itself implement PGP, instead it uses the provider pattern to interface with external cryptography libraries. A PGP provider is a simple module that allows the component to offload PGP operations to the PGP software of your choice. The interface is designed to be generic in its ability to include various PGP software and is limited to only the bare minimum capabilities required for a GISB message exchange. We include a PGP provider implementation for GnuPG which may be used as a reference to implement other providers.

A PGP provider is simply a class called "IPWorksGISBPGPProvider" that should have the following methods. The component uses reflection to access the methods of the provider.

    public void SetParam(string name, string value);
    public byte[] Encrypt(byte[] data);
    public byte[] Decrypt(byte[] data);
    public byte[] Sign(byte[] data);
    public byte[] SignAndEncrypt(byte[] data);
    public bool VerifySignature(byte[] signature, byte[] signedData);

The SetParam method is used to specify the parameters required by the PGP provider to perform the PGP operation. Although the parameters needed may vary in different providers, we expect the following set to be necessary. The reference GnuPG provider interprets the following parameters.

The following parameters are only applicable when sending data and PGPProviderType is set to 1 (internal).

The component expects the encryption to return an ASCII armored output and the signing to compute a detached signature.

Note: GnuPG is the Free Software Foundation's implementation of OpenPGP. It is free software and is recommended by NAESB (in version 1.6 of the EDM specification) for use in GISB/NAESB applications.

GnuPG is not included with this package, so you should download the latest version from http://www.gnupg.org. You might use GnuPG (or other software) to import your trading partners' public keys, and to import or generate a private key for yourself. These operations are outside the scope of this software, so please see the GnuPG documentation for details.

Finally, the component will generate a Response which you may send to the client with SendResponse.

The most important part of the Response is the RequestStatus; this property will contain either "ok" or an error message to be returned to the requesting client. By default the component will accept any post that conforms to the standard. If you want to be more restrictive you should first invoke ParseRequest to determine the sender, check the message security used, and extract the EDI data. If there is a problem you may then set RequestStatus to an error before calling CreateResponse. Please see the RequestStatus property for a list of standard error messages.

If you use version 1.4 of the GISB/NAESB protocol, the response will be a simple HTML reply. If you use version 1.6 the sender has the option of requesting a signed receipt. In all cases the response may be created with CreateResponse and sent with SendResponse.

To create log files, set LogDirectory prior to invoking ProcessRequest. This will log all incoming and outgoing data, and will also write the received EDI files to disk.

Additional Server-Side Functionality

When used in a server environment such as ASP, ASP.NET, etc., the component may be used to interface directly with the underlying HTTP context. If Request is not set by the user ParseRequest and ProcessRequest will first get the request from the underlying HTTP environment, if possible. SendResponse will send the reply in this environment if able; otherwise the reply will be directed to standard out.