Interfaces

Often a pattern emerges that may take advantage of having multiple internal or external implementations. Adaptive Framework declares an Adaptive Interface definition for these patterns in order to formalize and document the related functions and parameters. This allows the core and extensions to follow a contract and work cohesively together through the interface implementation. Refer to the following table for a list of interfaces and their descriptions.

Interface	Description
`afw_extension`	Interface returned from afw_extension_initialize() of an Adaptive Framework environment extension module. Additional information about an extension is found in object /afw/_AdaptiveManifest_/<extension_id>.
`afw_adaptor_factory`	Factory to create an instance of an afw_adaptor.
`afw_adaptor`	Adaptor interface.
`afw_adaptor_object_type_cache`	Adaptor object type cache interface. This interface is used by afw_adaptor_get_object_type().
`afw_adaptor_session`	Adaptor session interface.
`afw_adaptor_transaction`	Adaptor session transaction interface.
`afw_adaptor_impl_index_cursor`	Adaptor implementation index cursor interface.
`afw_adaptor_key_value`	Adaptor implementation of key value interface.
`afw_adaptor_impl_index`	Adaptor implementation index interface.
`afw_authorization_handler_factory`	Factory to create an instance of an afw_authorization_handler.
`afw_authorization_handler`	Adaptive framework authorization handler interface.
`afw_content_type`	Adaptive Content Type.
`afw_content_type_object_list_writer`
`afw_data_type`	Adaptive Data Type.
`afw_list_setter`	Adaptive list setter interface.
`afw_list`	Adaptive value list interface.
`afw_log_factory`	Log factory.
`afw_log`	Log.
`afw_object_setter`	This is interface used to set properties and meta of an adaptive object. See interface afw_object method get_object_setter for more information.
`afw_object`	This is interface used to access the properties of an adaptive object.
`afw_server`	Adaptive framework server interface.
`afw_service_type`	Adaptive framework service type interface. Each instance is registered in the environment with type of "service_type" and id of the service type id.
`afw_object_associative_array`	This is interface for an object associative array.
`afw_request_handler_factory`	Create an instance of an afw_request_handler.
`afw_request_handler`	Adaptive framework request handler interface.
`afw_connection`	Adaptive Framework connection. This has not yet been developed.
`afw_request`	Adaptive framework request interface.
`afw_xctx`	Adaptive Framework Execution Context (xctx) interface. An execution context holds common information related to a unit of work in Adaptive Framwork. This unit of work runs in a single thread of a single-threaded or multi-threaded process. In a multi-threaded process, the main thread has the global execution context. Other threads have their own execution context and required the appropriate mutexes or queued work to access memory in the global execution context. The type of execution contexts can be "server", "request_session', etc. A execution context's pool, properties, and object cache will last for the life of the execution context. An execution context's parent will always have a longer life.
`afw_stream`	An interface for a stream.
`afw_pool`	Adaptive framework pool interface.
`afw_adaptor_journal`	Adaptor journal interface.
`afw_value`	Adaptive value.
`afw_variable_handler`	Adaptive variable handler.
`afw_writer`	An interface for a writer.

The following sections describe a few interfaces that are significant to discussion of the Adaptive Framework architecture. For a more comprehensive list, refer to the Developer Guide.

Request Handlers

Request Handlers control how client requests are handled to by implementing the afw_request_handler interface. Currently, the only Request Handler provided by Core is the Adaptor Request Handler, which allows clients to retrieve and store objects in configured Adaptor(s). In time, additional request handlers may be added to provide functionality, such as XACML.

Content Types

Both core and extensions may register Content Types, which provide Adaptive Objects with an external representation. These Content Types are useful for translating adaptive objects between adaptors and storing them in ways that are convenient and useful. They allow you to encode and decode all properties of an Adaptive Object, including their Adaptive Values. The following content types are provided by core:

Content Type	Description
JSON	Javascript Object Notation
XML	Extensible Markup Language
UBJSON	Universal Binary JSON
YAML	YAML Ain't Markup Language

Adaptors

Adaptors implement several afw_adaptor_ interfaces in order to provide your Adaptive Framework application with a way to store and retrieve Adaptive Objects. There are several adaptors that are included with the Adaptive Framework:

Adaptor	Description
File	File-based object storage
LDAP	Lightweight Directory Access Protocol
LMDB	Lightning Memory-Mapped Database
Model	Model Adaptor
VFS	Virtual File System

Logs

Logs implement the afw_log interface and allow for messages produced by Adaptive Framework to be routed to an external destination for viewing. There are currently two Logs available:

Log	Description
Standard	Logging to standard output
Syslog	Logging to syslog

Journals

Journals implement the afw_adaptor_journal interface and allow for object events to be journaled into a persistent queue. Journals must maintain cursors into this queue to track clients (or Provisioning Peers) who are producing or consuming journal entries. Currently, two adaptors also support the Journal interface:

Journal	Description
File	File-based journal
LMDB	Lightning Memory-Mapped Database journal

Authorization Handlers

Authorization Handlers implement the afw_authorization_ interfaces in order to provide Adaptive Framework Core with a way to request and enforce authorization decisions when clients make requests for resources. There is currently one Authorization Handler provided by Core:

Authorization Handler	Description
Script	Adaptive-Script based authorization