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ECOMP is a trademark and service mark of AT&T Intellectual Property. =============== APPC User Guide =============== APPC Overview and Architecture ============================== The Application Controller (APPC) is one of the components of the ONAP platform. It is responsible for handling the Life Cycle Management (LCM) of Virtual Network Functions (VNFs). This document provides an overview of the APPC components that enable the LCM operations. Implementation -------------- The APPC infrastructure is implemented on virtual machines in an OpenStack cloud in the Amsterdam release. APPC is created on top of the OpenDaylight (ODL) platform The following diagram represents a non-redundant APP-C deployment. |image0| Features -------- The APPC HTTP API supports Life Cycle Management (LCM) commands, allowing users to manage virtual applications and their components via other ONAP components. Refer to Architecture section for further details. Interface --------- The Application Controller Dashboard interacts with the controller using REST APIs and performs actions on VNF/VNFC/VMs, such as snapshot, lock, sync, and health-check. Dashboard ~~~~~~~~~ To open the Application Controller dashboard, go to: |image1| Navigate to the available LCM commands by clicking on **appc-provider-lcm**: |image2| Click on the URI of the desired action to open a frame with information about the action and an option to try it out. For example, to send the action, add the request body as the input parameter value, and click **Try it out!** The following figure shows an example body of a LCM restart request: |image3| If the request is accepted, you should see the following response: |image4| APPC Architecture ----------------- This section discusses the APPC internal components in detail. **APPC High Level Architecture** |image5| Northbound REST Layer ~~~~~~~~~~~~~~~~~~~~~ This layer is responsible for interfacing with APPC clients, such as SO or SDC and others, exposing YANG-based API via REST HTTP and/or DMaaP messaging (see the Interfaces Summary section for details). In addition, it exposes APPC OAM (Operation Administration Management) APIs, enabling ONAP Operations Manager (OOM) or TechOps portal to perform APPC lifecycle operations APPC Provider ~~~~~~~~~~~~~ The APPC Provider module exposes the endpoints for each action supported by APPC. This module uses the YANG model to define the YANG Remote Processing Call (RPC) and data model, in other words, the input and output parameters for each action. The Provider module is responsible for validating the RPC input and for rejecting any malformed input. After successful validation, the APPC Provider calls the Dispatcher to continue the request processing. LCM API ~~~~~~~ The APPC exposes an HTTP API to support the Life Cycle Management (LCM) commands sent from ONAP components such as SO, SDC, and the Portal. These commands enable the components to request APPC to perform actions such as to control, modify, start, or stop virtual applications and/or their components.  A virtual application is composed of the following layers. A Life Cycle Management command may affect any number of these layers. - Virtual Network Function (VNF) - Virtual Network Function Component (VNFC) - Virtual Machine (VM) APP-C supports two types of LCM requests, as described below. **Note:** For further information about LCM API, including details of all the commands currently supported in APP-C and examples of the request and response format see the ONAP Application Controller (APPC) API Guide.  LCM over REST ^^^^^^^^^^^^^^ LCM command requests over REST are sent to the APPC using an HTTP POST request. APPC returns one or more responses for each LCM request.  The APP-C LCM API provides a POST HTTP API endpoint per command.  An **asynchronous** command, containing an authorized and valid request, results in at least two discrete response events: - an ACCEPT (a synchronous HTTP response) to indicate that the request is accepted and will be processed, and - a final asynchronous response for the command containing an execution status is sent via DMaaP An unauthorized or invalid request would result in a single ERROR response.  For commands such as Restart, Start, and Stop, the asynchronous response is sent over DMaaP. A **synchronous** command, for example Lock or Unlock, results in a single response, which is either SUCCESS or ERROR. For this type of request, the first response is a synchronous HTTP response.. For the ONAP Amsterdam release, APPC supports the HTTPS protocol, whereas the plain HTTP requests are blocked.. Endpoint format:  ``://:/restconf/operations/appc-provider-lcm:`` LCM over Message Bus (DMaaP) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ APPC is capable of receiving LCM command requests as messages on the DMaaP bus. In this case, APPC returns one or more responses for each LCM request, similar to LCM over REST, while both are communicated over DMaaP. Configure the Read/Write topics for the DMaaP as described in APPC Deployment, APPC Available Properties. APPC client library, embedded into APPC client’s (for example, SO) code, intends to simplify communication over DMaaP by eliminating topic provisioning at the client site. Refer to http://onap.readthedocs.io/en/latest/ for more details on the APPC Client Library. For further information about the request and response format, see the APPC API Guide at http://onap.readthedocs.io/en/latest/ Dispatcher ~~~~~~~~~~ The APPC Dispatcher component processes requests received by the Request Handler from other ECOMP components. The Dispatcher checks the conditions are sufficient for performing the request and selects the correct Direct Graph (DG) workflow for execution or rejects the request. When the DG execution is complete, the Dispatching function is responsible for notifying the initiator of the operation with the request execution result (Success/Error) and updates the VNF Orchestration state in Active and Available Inventory (A&AI). The detailed responsibilities of the Dispatcher are as follows: - Upon receiving the operation request, the Dispatcher performs the synchronous part of the execution: - Starts the operation's time-to-live countdown - Queries A&AI to get the VNF type and its current orchestration state - Checks VNF\_type-specific rules in the LCM State machine for whether to allow or reject the requested command execution - Allocates and initiates an appropriate DG workflow by invoking the Service Logic Interpreter (SLI) framework to start the asynchronous part of the execution - Returns a response to the initiator: OK or reject (for example, if the State Machine blocks the operation, no DG or time-to-live, or bad parameters) - If the operation is rejected, the Dispatcher generates an appropriate Audit log for the Event and Error Logging Framework (EELF) and the Local Event Journal - Upon workflow completion, the Dispatcher: - Receives the execution results from the DG from the SLI framework - Publishes the execution result over DMaaP (success or error) - Updates VNF status in A&AI - Generates an Audit log for EELF and Local Event Journal Request Handler ^^^^^^^^^^^^^^^ The Request Handler manages incoming requests and locks APPC for new requests, as needed for operations with a specific command execution sequences. Lifecycle Management ^^^^^^^^^^^^^^^^^^^^ The Lifecycle Management VNF State Machine enables the Dispatching function to determine the validity of the requested operation (desired state) as a function of the current VNF state, acquired from the A&AI. The State Machine maintains its data (states and valid operations) in-memory. At the point of APPC initialization, the State Machine constructs a matrix based on the metadata of the current operation and the valid desired state.  Command Executor ^^^^^^^^^^^^^^^^ Manages command execution queue. State Machine ~~~~~~~~~~~~~ The VNF State machine enables the Dispatching function to determine the validity of the requested operation (desired state) as a function of the current VNF state, acquired from the A&AI. The State machine maintains its data (states and valid operations) in-memory. At the point of APP-C initialization, the State Machine constructs a matrix based on the metadata of the current operation and the valid desired state.  The Service Logic Interpreter (SLI) Framework ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The SLI framework is responsible for executing Directed Graphs (DGs). The Dispatcher invokes the SLI framework to execute a specific DG, based on the input action. The SLI executes the DG and the sub-DG and returns a success or failure response to the caller along with the context variables used to exchange data with the calling body (for example, the Dispatcher). The caller can use the SLI context to specify data required for DG execution. The DG returns the same context when execution completes. Currently, there is a combination of input action specific and/or VNF type specific DG’s as well as a DGOrchestrator DG which is action and VNF type agnostic. The DGOrchestrator approach consists of the following: - DGOrchestrator DG which: - Accepts request from the Dispatcher and converts it into DG context format - Calls A&AI to retrieve the inventory for the VNF instance - Calls a Sequence Generator for start/stop actions which generates a workflow sequence containing a set of start or stop VM requests - Auto-generates a workflow for other requests with a single step - Executes each step in the workflow by invoking DG’s to interact with the VNF, OpenStack, or Ansible/Chef servers. These DG’s which are specific to the protocol and possibly action. Some DG’s may update A&AI (such as for Configure) or retrieve the VNF running configuration. - Returns success/failure status to the Dispatcher. In the future, all action/VNF type specific DG’s will be migrated to the DGOrchestrator approach. The following diagram shows the Amsterdam Release DGOrchestrator architecture |image6| Westbound Layer ~~~~~~~~~~~~~~~ A&AI ^^^^ A&AI is an ONAP component, which maintains information about VNF instances. APPC uses A&AI as a source of the true VNF status, topology and operational data. In addition, at the end of each operation, APPC updates the VNF changes that result from the operation: for example, VNFC record(s) are added after configuration. The VNF orchestration status is not updated for read-only operations such as Sync or Audit. In the case of the VNF Terminate operation, APPC removes the terminated VNF from A&AI by deleting its Virtual Machines (VMs).  The Dispatching function and operation-specific DGs manage access to the A&AI using the A&AI Adapter.   Southbound Layer ~~~~~~~~~~~~~~~~ Southbound VNF Adapters ^^^^^^^^^^^^^^^^^^^^^^^ APPC uses several adapters to communicate with VNFs. The Interface as a Service (IAAS) adapter is part of the OpenDayLight (ODL) platform, while other adapters have been added by the ONAP development. Restconf Adapter ^^^^^^^^^^^^^^^^^ The Adapter is responsible for configuration tasks, using JSON format, for VNFs supporting Restconf API. **Using the Restconf Adapter** The restconf adapter is normally called from a directed graph. An "execute" node block should be used in the directed graph to the "org.onap.appc.adapter.rest.RestAdapter" plug-in. There are several methods available to use: - commonGet - commonDelete - commonPost - commonPut There are several parameters that the RestAdapter plug-in takes org.onap.appc.instance.URI The url that the rest request will be made to org.onap.appc.instance.requestBody The body of the rest request org.onap.appc.instance.headers The header of the rest request org.onap.appc.instance.haveHeader true/false value which specifies if a header is present. (Should be set to "true" if the org.onap.appc.instance.headers parameter is defined, or set to "false" if the headers parameter is not defined) There are several parameters returned back to the DG from the RestAdapter org.onap.rest.result.code An http code representing if the request completed. Will always be 200 if the request completes. See the below parameter for the exact http code that gets returned. org.onap.rest.agent.result.code The http code returned from the rest request. org.onap.rest.agent.result.message The status or body returned from the rest request. An example execute node: :: Netconf Adapter ^^^^^^^^^^^^^^^ The Adapter is responsible for configuration tasks, using XML format, for VNFs supporting Netconf API. IAAS Adapter  ^^^^^^^^^^^^^ The IAAS Adapter connects APPC with the OpenStack controllers to perform various operations on VMs and VNFs such as Restart, Migrate, and Rebuild. The IAAS Adapter integrates as a DG plugin, while the DGs call the services exposed by the adapter. SSH (XML/CLI) Adapter ^^^^^^^^^^^^^^^^^^^^^ A custom adapter that enables connection to a VNF using an SSH session. It is designed to support CLI and XML protocols, including Netconf. It is used to load configurations and retrieve the running configuration. Chef Adaptor ^^^^^^^^^^^^ This adaptor incorporates a client for an external Chef server, which connects to VNF NB APIs. The adaptor enables APPC to operate cookbooks (Chef recipes) to perform various LCM operations over VNFs, connected to the Chef server. Ansible Adapter ^^^^^^^^^^^^^^^ This adaptor incorporates a client for an external Ansible server, which connects to VNF NB APIs. The adaptor enables APPC to operate playbooks to perform various LCM operations over VNFs connected to the Ansible server. Cross Cutting Components ~~~~~~~~~~~~~~~~~~~~~~~~ The Cross Cutting Component services operate across all APPC modules. Configuration ^^^^^^^^^^^^^ Used to configure operational parameters of APPC modules based on function-specific configuration files, for example: - ``log4j.properties`` for the logging service - ``appc.properties`` for core APPC-related configuration - ``dblib.properties`` for managing APPC database-related configuration - ``aaiclient.properties`` for managing A&AI-related configuration KPI Service ^^^^^^^^^^^ This Cross Cutting component manages KPI measurement, storage and reporting. Enable matrix logs to log the number of hits of the configured method of APPC, by configuring the following properties in ``appc.properties:``:: metric.enabled= schedule.policy.metric.start.time=