Adding first set of apex-pdp document changes

Adding document changes for auth, context, core, model, services & the
main apex-pdp module.

Change-Id: Id0d026baa258f1dc6998978f9911f3c4a73b5b3b
Issue-ID: POLICY-867
Signed-off-by: ramverma <ram.krishna.verma@ericsson.com>

6 files changed, 287 insertions, 0 deletions

diff --git a/src/site-docs/adoc/fragments/apex-intro/configuration-matrix.adoc b/src/site-docs/adoc/fragments/apex-intro/configuration-matrix.adoc
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+//
+// ============LICENSE_START=======================================================
+//  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+// ================================================================================
+// This file is licensed under the CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL LICENSE
+// Full license text at https://creativecommons.org/licenses/by/4.0/legalcode
+// 
+// SPDX-License-Identifier: CC-BY-4.0
+// ============LICENSE_END=========================================================
+//
+// @author Sven van der Meer (sven.van.der.meer@ericsson.com)
+//
+
+== APEX Configuration
+
+An APEX engine can be configured to use various combinations of
+	event input handlers,
+	event output handlers,
+	event protocols,
+	context handlers, and
+	logic executors.
+The system is build using a plugin architecture.
+Each configuration option is realized by a plugin, which can be loaded and configured when the engine is started.
+New plugins can be added to the system at any time, though to benefit from a new plugin an engine will need to be restarted.
+
+.APEX Configuration Matrix
+image::apex-intro/ApexEngineConfig.png[APEX Configuration Matrix]
+
+The APEX distribution already comes with a number of plugins.
+The figure above shows the provided plugins.
+Any combination of input, output, event protocol, context handlers, and executors is possible.
diff --git a/src/site-docs/adoc/fragments/apex-intro/introduction.adoc b/src/site-docs/adoc/fragments/apex-intro/introduction.adoc
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+//
+// ============LICENSE_START=======================================================
+//  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+// ================================================================================
+// This file is licensed under the CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL LICENSE
+// Full license text at https://creativecommons.org/licenses/by/4.0/legalcode
+// 
+// SPDX-License-Identifier: CC-BY-4.0
+// ============LICENSE_END=========================================================
+//
+// @author Sven van der Meer (sven.van.der.meer@ericsson.com)
+//
+
+== Introduction to APEX
+
+APEX stand for Adaptive Policy EXecution.
+It is a lightweight engine for execution of policies.
+APEX allows you to specify logic as a policy, logic that you can adapt on the fly as your system executes.
+The APEX policies you design can be really simple, with a single snippet of logic, or can be very complex, with many states and tasks.
+APEX policies can even be designed to self-adapt at execution time, the choice is yours!
+
+.Simple APEX Overview
+image::apex-intro/ApexSimple.png[Simple APEX Overview]
+
+The Adaptive Policy Engine in APEX runs your policies.
+These policies are triggered by incoming events.
+The logic of the policies executes and produces a response event.
+The __Incoming Context__ on the incoming event and the __Outgoing Context__ on the outgoing event are simply the fields and attributes of the event.
+You design the policies that APEX executes and the trigger and action events that your policies accept and produce.
+Events are fed in and sent out as JSON or XML events over Kafka, a Websocket, a file or named pipe, or even standard input.
+If you run APEX as a library in your application, you can even feed and receive events over a Java API.
+
+.APEX States and Context
+image::apex-intro/ApexStatesAndContext.png[APEX States and Context]
+
+You design your policy as a chain of states, with each state being fed by the state before.
+The simplest policy can have just one state.
+We provide specific support for the four-state link:https://www.researchgate.net/publication/303564082_Apex_An_Engine_for_Dynamic_Adaptive_Policy_Execution[MEDA (Match Establish Decide Act)] policy state model and the three-state link:https://en.wikipedia.org/wiki/Event_condition_action[ECA (Event Condition Action)] policy state model.
+APEX is fully distributed.
+You can decide how many APEX engine instances to run for your application and on which real or virtual hosts to run them.
+
+In APEX, you also have control of the __Context__ used by your policies.
+Context is simply the state information and data used by your policies.
+You define what context your policies use and what the scope of that context is.
+__Policy Context__ is private to a particular policy and is accessible only to whatever APEX engines are running that particular policy.
+__Global Context__ is available to all policies.
+__External Context__ is read-only context such as weather or topology information that is provided by other systems.
+APEX keeps context coordinated across all the the instances running a particular policy.
+If a policy running in an APEX engine changes the value of a piece of context, that value is is available to all other APEX engines that use that piece of context.
+APEX takes care of distribution, locking, writing of context to persistent storage, and monitoring of context.
+
+.The APEX Eco-System
+image::apex-intro/ApexEcosystem.png[The APEX Eco-System]
+
+The APEX engine (AP-EN) is available as a Java library for inclusion in your application, as a microservice running in a Docker container, or as a stand-alone service available for integration into your system.
+APEX also includes a policy editor (AP-AUTH) that allows you to design your policies and a web-based policy management console you use to deploy policies and to keep track of the state of policies and context in policies.
+Context handling (AP-CTX) is integrated into the APEX engine and policy deployment (AP-DEP) is provided as a servlet running under a web framework such as link:http://tomcat.apache.org/[Apache Tomcat].
diff --git a/src/site-docs/adoc/fragments/apex-intro/policy-matrix.adoc b/src/site-docs/adoc/fragments/apex-intro/policy-matrix.adoc
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+//
+// ============LICENSE_START=======================================================
+//  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+// ================================================================================
+// This file is licensed under the CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL LICENSE
+// Full license text at https://creativecommons.org/licenses/by/4.0/legalcode
+// 
+// SPDX-License-Identifier: CC-BY-4.0
+// ============LICENSE_END=========================================================
+//
+// @author Sven van der Meer (sven.van.der.meer@ericsson.com)
+//
+
+== APEX Policy Matrix
+
+APEX offers a lot of flexibility for defining, deploying, and executing policies.
+Based on a theoretic model, it supports virtually any policy model and allows to translate legacy policies into the APEX execution format.
+However, the most important aspect for using APEX is to decide what policy is needed, what underlying policy concepts should be used, and how the decision logic should be realized.
+Once these aspects are decided, APEX can be used to execute the policies.
+If the policy evolves, say from a simple decision table to a fully adaptable policy, only the policy definition requires change.
+APEX supports all of that.
+
+The figure below shows a (non-exhaustive) matrix, which will help to decide what policy is required to solve your problem.
+Read the matrix from left to right choosing one cell in each column.
+
+.APEX Policy Matrix
+image::apex-intro/ApexPolicyMatrix.png[APEX Policy Matrix]
+
+The policy can support one of a number of stimuli with an associated purpose/model of the policy, for instance:
+
+* Configuration, i.e. what should happen.
+	An example is an event that states an intended network configuration and the policy should provide the detailed actions for it.
+	The policy can be realized for instance as an obligation policy, a promise or an intent.
+* Report, i.e. something did happen.
+	An example is an event about an error or fault and the policy needs to repair that problem.
+	The policy would usually be an obligation, utility function, or goal policy.
+* Monitoring, i.e. something does happen.
+	An example is a notification about certain network conditions, to which the policy might (or might not) react.
+	The policy will mitigate the monitored events or permit (deny) related actions as an obligation or authorization.
+* Analysis, i.e. why did something happen.
+	An example is an analytic component sends insights of a situation requiring a policy to act on it.
+	The policy can solve the problem, escalate it, or delegate it as a refrain or delegation policy.
+* Prediction, i.e. what will happen next.
+	An example are events that a policy uses to predict a future network condition.
+	The policy can prevent or enforce the prediction as an adaptive policy, a utility function, or a goal.
+* Feedback, i.e. why did something happen or not happen.
+	Similar to analysis, but here the feedback will be in the input event and the policy needs to something with that information.
+	Feedback can be related to history or experience, for instance a previous policy execution.
+	The policy needs to be context-aware or be a meta-policy.
+
+Once the purpose of the policy is decided, the next step is to look into what context information the policy will require to do its job.
+This can range from very simple to a lot of different information, for instance:
+
+* No context, nothing but a trigger event, e.g. a string or a number, is required
+* Event context, the incoming event provides all information (more than a string or number) for the policy
+* Policy context (read only), the policy has access to additional information related to its class but cannot change/alter them
+* Policy context (read and write), the policy has access to additional information related to its class and can alter this information (for instance to record historic information)
+* Global context (read only), the policy has access to additional information of any kind but cannot change/alter them
+* Global context (read and write), the policy the policy has access to additional information of any kind and can alter this information (for instance to record historic information)
+
+The next step is to decide how the policy should do its job, i.e. what flavor it has, how many states are needed, and how many tasks.
+There are many possible combinations, for instance:
+
+* Simple / God: a simple policy with 1 state and 1 task, which is doing everything for the decision-making.
+	This is the ideal policy for simple situation, e.g. deciding on configuration parameters or simple access control.
+* Simple sequence: a simple policy with a number of states each having a single task.
+	This is a very good policy for simple decision-making with different steps.
+	For instance, a classic action policy (ECA) would have 3 states (E, C, and A) with some logic (1 task) in each state.
+* Simple selective: a policy with 1 state but more than one task.
+	Here, the appropriate task (and it's logic) will be selected at execution time.
+	This policy is very good for dealing with similar (or the same) situation in different contexts.
+	For instance, the tasks can be related to available external software, or to current work load on the compute node, or to time of day.
+* Selective: any number of states having any number of tasks (usually more than 1 task).
+	This is a combination of the two policies above, for instance an ECA policy with more than one task in E, C, and A.
+* Classic directed: a policy with more than one state, each having one task, but a non-sequential execution.
+	This means that the sequence of the states is not pre-defined in the policy (as would be for all cases above) but calculated at runtime.
+	This can be good to realize decision trees based on contextual information.
+* Super Adaptive: using the full potential of the APEX policy model, states and tasks and state execution are fully flexible and calculated at runtime (per policy execution).
+	This policy is very close to a general programming system (with only a few limitations), but can solve very hard problems.
+
+The final step is to select a response that the policy creates.
+Possible responses have been discussed in the literature for a very long time.
+A few examples are:
+
+* Obligation (deontic for what should happen)
+* Authorization (e.g. for rule-based or other access control or security systems)
+* Intent (instead of providing detailed actions the response is an intent statement and a further system processes that)
+* Delegation (hand the problem over to someone else, possibly with some information or instructions)
+* Fail / Error (the policy has encountered a problem, and reports it)
+* Feedback (why did the policy make a certain decision)
diff --git a/src/site-docs/adoc/fragments/apex-intro/resources.adoc b/src/site-docs/adoc/fragments/apex-intro/resources.adoc
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+//
+// ============LICENSE_START=======================================================
+//  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+// ================================================================================
+// This file is licensed under the CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL LICENSE
+// Full license text at https://creativecommons.org/licenses/by/4.0/legalcode
+// 
+// SPDX-License-Identifier: CC-BY-4.0
+// ============LICENSE_END=========================================================
+//
+// @author Sven van der Meer (sven.van.der.meer@ericsson.com)
+//
+
+== Resources
+
+* APEX Documentation hosted on Github: link:https://ericsson.github.io/apex-docs[]
+* APEX source code repo hosted on Github: link:https://github.com/Ericsson/apex[]
+* Issue Management (source and documentation): link:https://github.com/Ericsson/apex/issues[]
+* List of APEX publications: link:https://ericsson.github.io/apex-docs/apex-publications.html[]
diff --git a/src/site-docs/adoc/fragments/apex-intro/upee-clustering.adoc b/src/site-docs/adoc/fragments/apex-intro/upee-clustering.adoc
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+//
+// ============LICENSE_START=======================================================
+//  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+// ================================================================================
+// This file is licensed under the CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL LICENSE
+// Full license text at https://creativecommons.org/licenses/by/4.0/legalcode
+// 
+// SPDX-License-Identifier: CC-BY-4.0
+// ============LICENSE_END=========================================================
+//
+// @author Sven van der Meer (sven.van.der.meer@ericsson.com)
+//
+
+== Flexible Clustering
+
+APEX can be clustered in various ways.
+The following figure shows a few of these clustering options.
+Cluster, engine and (policy) executors are named UPec (universal policy cluster), UPe (universal policy engine, APEX engine) and UPx (universal policy executor, the APEX internal state machine executor).
+
+.APEX Clustering Options
+image::apex-intro/UpeeClusterOptions.png[APEX Clustering Options]
+
+[loweralpha]
+. Single source/target, single UPx
+	* Simple forward
+. Multiple sources/targets, single UPx
+	* Simple forward
+. Single source/target, multiple UPx
+	* Multithreading (MT) in UPe
+. Multiple sources/targets, multiple UPx instances
+	* Simple forward & MT in UPe
+. Multiple non-MT UPe in UPec
+	* Simple event routing
+. Multiple MT UPe in UPec
+	* Simple event routing
+. Mixed UPe in UPec
+	* Simple event routing
+. Multiple non-MT UPec in UPec
+	* Intelligent event routing
+. Multiple mixed UPec in UPec
+	* Intelligent event routing
+
+["loweralpha", start=11]
+. Mix of UPec in multiple UPec
+	* External intelligent event routing
+	* Optimized with UPec internal routing
diff --git a/src/site-docs/adoc/fragments/apex-intro/upee-deployment.adoc b/src/site-docs/adoc/fragments/apex-intro/upee-deployment.adoc
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+//
+// ============LICENSE_START=======================================================
+//  Copyright (C) 2016-2018 Ericsson. All rights reserved.
+// ================================================================================
+// This file is licensed under the CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL LICENSE
+// Full license text at https://creativecommons.org/licenses/by/4.0/legalcode
+// 
+// SPDX-License-Identifier: CC-BY-4.0
+// ============LICENSE_END=========================================================
+//
+// @author Sven van der Meer (sven.van.der.meer@ericsson.com)
+//
+
+== Flexible Deployment
+
+APEX can be deployed in various ways.
+The following figure shows a few of these deployment options.
+Engine and (policy) executors are named UPe (universal policy engine, APEX engine) and UPx (universal policy executor, the APEX internal state machine executor).
+
+.APEX Deployment Options
+image::apex-intro/UpeeDeploymentOptions.png[APEX Deployment Options]
+
+[loweralpha]
+. For an interface or class
+	* Either UPx or UPe as association
+. For an application
+	* UPx as object for single policies
+	* UPe as object for multiple policies
+. For a component (as service)
+	* UPe as service for requests
+	* UPec as service for requests
+. As a service (PolaS)
+	* One or more UPe with service i/f
+	* One or more Upec/UPec with service i/f
+	* One or more Upec/UPec with service i/f
+. In a control loop
+	* UPe as decision making part
+	* UPec as decision making part
+. On cloud compute nodes
+	* Nodes with only UPe or Upec
+	* Nodes with any combination of UPe, UPec
+. A cloud example
+	* Left: 2 UPec managing several UPe on different cloud nodes
+	* Right: 2 large UPec with different UPe/UPec deployments