NCIP

The NCIP module is an extensible API that allows developers to create applications that communicate via the NCIP protocol.

It includes an API to create, configure, and manage NCIP applications, connections, and messages. It also provides a simple user interface for listing and modifying default NCIP settings as well as application and provider-specific settings.

About NCIP
National Information Standards Organization (NISO) Circulation Interchange Protocol (NCIP) is a protocol for the exchange of messages between and among computer-based applications to enable them to perform functions necessary to lend and borrow items, to provide controlled access to electronic resources, and to facilitate cooperative management of these functions.

API, classes, and objects
The NCIP module provides an API for creating and managing NCIP applications, connections, and messages:

• An application initiates or responds to connections to communicate with other applications
• A connection is a collection of HTTP requests between two applications
• A message is an XML document encoded according to UTF-8 specifications and streamed as-is over a connection

Each of these have their respective classes in the /ncip/lib folder, used to build objects that interact with each other to implement the NCIP protocol. The three classes are:

• NCIPApplication objects manage a collection of connections and stores specific properties of the application, such as the supported NCIP version, “from” agency and system ID, and other message header options for authentication and application profile type.
• NCIPConnection objects belong to an NCIPApplication object and are of a particular type specifying whether it is initiating or responding. These objects facilitate the transport of messages to and from applications, and store specific properties of the connected application, such as its “to” agency and system ID and other message header options for authentication.
• NCIPMessage objects should belong to an NCIPConnection object, but in rare situations, they may not. These objects manage the content of an XML document, allowing it to be edited in a more intuitive manner and transformed to and from an XML string, SimpleXMLElement object, DOMDocument object, or NCIPMessage object.

Implementation
On its own, the NCIP module does not implement any NCIP services (or verbs); it only builds the foundation necessary to communicate over this protocol in Drupal. Other modules must then take advantage of the NCIP module's features and API to construct or parse messages sent or received to and from NCIP applications. An example of such module is the NCIP Provider module, included with the Drupal Toolkit.

Features
The module currently can create applications only with initiating connections that expect a response after messages have been sent via HTTP. It supports all current versions of the NCIP protocol.

Future
In the future, the NCIP module may support both an initiating and responding connections, connect via TCP, or make use of implementation profiles.