Creating entity ACLs

This page explains how to construct an ACL (access control list) component in Unity. They’re used to control which workers have read and write access to an entity’s components.

For background on the concept of ACLs, see Understanding write access.

EntityBuilder

This page is about building an ACL on its own. For information about creating an ACL when you’re using EntityBuilder to create an entity template, see the Using EntityBuilder section on the Creating and deleting entities page.

Create an entity ACL

To create entity ACLs in Unity, use the entity ACL builder. Import this class using the statement using Improbable.Unity.Core.Acls;.

To build an ACL:

1. Define the worker attributes you want to reference.
2. Define the worker requirements: which worker attributes you need for a particular use.
3. For each component, give write access to a particular attribute.
4. For the whole entity, give read access (on all components) to a particular attribute.
5. Add the ACL to the entity template.

To see how this works in practice, see the example below.

Reference

To build an ACL from scratch, start with Acl.Build(), for example:

var myAcl = Acl.Build();

Worker attributes

You can find which attributes a worker has in the bridge section of its worker configuration file. Usually, a UnityWorker will have the attribute “physics”, and a UnityClient will have the attribute “visual”.

To build a WorkerAttributeSet, use this static method on Acl:

• public static WorkerAttributeSet MakeAttributeSet(string attribute1, params string[] attributeSet)

  For example, var unityWorkerAttributeSet = Acl.MakeAttributeSet("physics");

The CommonAttributeSets class contains shortcuts for commonly used worker attribute sets:

• public static WorkerAttributeSet Physics is the same as Acl.MakeAttributeSet("physics");

  For example, var unityWorkerOnlyRequirement = Acl.MakeRequirementSet(CommonAttributeSets.Physics);

• public static WorkerAttributeSet Visual is the same as Acl.MakeAttributeSet("visual");

  For example, var workerOrClientRequirement = Acl.MakeRequirementSet(CommonAttributeSets.Physics, CommonAttributeSets.Visual);

• public static WorkerAttributeSet SpecificClient(string clientId);

  For example, var specificClientRequirement = Acl.MakeRequirementSet(CommonAttributeSets.SpecificClient(clientWorkerId));

Worker requirements

To build a WorkerRequirementSet, use this static method on Acl:

• public static WorkerRequirementSet MakeRequirementSet(WorkerAttributeSet attribute1, params WorkerAttributeSet[] attributes)

  For example, var unityWorkerOnlyRequirement = Acl.MakeRequirementSet(unityWorkerAttributeSet);

The CommonRequirementSets class contains shortcuts for commonly used worker requirements:

• public static WorkerRequirementSet PhysicsOnly is the same as Acl.MakeRequirementSet(CommonAttributeSets.Physics);

  For example, acl.SetWriteAccess<Position>(CommonRequirementSets.PhysicsOnly);

• public static WorkerRequirementSet VisualOnly is the same as Acl.MakeRequirementSet(CommonAttributeSets.Visual);

  For example, acl.SetReadAccess<Position>(CommonRequirementSets.VisualOnly);

• public static WorkerRequirementSet PhysicsOrVisual is the same as Acl.MakeRequirementSet(CommonAttributeSets.Physics, CommonAttributeSets.Visual);

  For example, acl.SetReadAccess(CommonRequirementSets.PhysicsOrVisual);

• public static WorkerRequirementSet SpecificClientOnly(string clientId);

  For example, acl.SetWriteAccess<Position>(CommonRequirementSets.SpecificClientOnly(clientWorkerId));

Setting read and write access

To set read and write access, use these methods:

• public Acl SetWriteAccess<TComponent>(WorkerRequirementSet requirement) where TComponent : IComponentMetaclass

  For example, acl.SetWriteAccess<Position>(unityWorkerOnlyRequirement);

• public Acl SetWriteAccess(uint componentId, WorkerRequirementSet requirement)

  For example, acl.SetWriteAccess(Position.ComponentId, unityWorkerOnlyRequirement);

• public Acl SetReadAccess(WorkerRequirementSet requirement)

  For example, acl.SetReadAccess(workerOrClientRequirement);

Common ACLs

Acl provides the following static methods to generate completely some common types of ACL for an entity:

• public static Acl GenerateServerAuthoritativeAcl(Entity entity);

  This returns an entity ACL that has read access set to UnityClient or UnityWorker, and write access set to UnityWorker only, for all components that exist on the given entity.

• public static Acl GenerateClientAuthoritativeAcl(Entity entity, string workerId);

  This returns an entity ACL that has read access set to UnityClient or UnityWorker, and write access set to a UnityClient with the given worker ID, for all components that exist on the entity.

Setting the ACL

You can set the ACL on an Entity object or update it at runtime.

• public EntityAcl.Data ToData()

  For example, exampleTemplate.Add(acl.ToData());

• public EntityAcl.Update ToUpdate()

  For example, exampleTemplate.Send(acl.ToUpdate());

You can also set the ACL directly on the Entity. Remember that this will replace the entire ACL component on the entity, so any components not specified will have their ACLs reset.

• public void Entity.SetAcl(Acl)

  For example, exampleTemplate.SetAcl(acl);

To merge an Improbable.Unity.Core.Acls.Acl into an entity’s existing ACLs, you can use the MergeAcl(Acl aclChanges) helper. Any components whose ACLs are specified in aclChanges will be updated. All other components will remain unchanged.

• public void Entity.MergeAcl(Acl aclChanges)

  For example,

  entityTemplate.SetAcl(baseAcl);       // Sets all ACLs for 'entityTemplate'
  entityTemplate.MergeAcl(updatedAcl);  // Overwrites whichever ACLs are specified in 'updatedAcl'
  

Example

In this example, we want to create an entity with Position and Combat components. Position is defined in the standard schema library; `Combat is defined as follows:

package improbable.general;

component Combat {
  id = 1002;
  uint32 attack_power = 1;
}

Adding the components to the entity template looks like this:

var exampleTemplate = new Entity();
exampleTemplate.Add(new Position.Data(new PositionData(new Coordinates(0, 0, 0))));
exampleTemplate.Add(new Combat.Data(new CombatData(5)));

Before you can create an entity using this template, you must add an entity ACL to it.

In this example:

• both UnityWorkers and UnityClients have read access on both components
• only UnityWorkers have write access, on both components

var unityWorkerAttributeSet = Acl.MakeAttributeSet("physics");
var clientAttributeSet = Acl.MakeAttributeSet("visual");

var unityWorkerOnlyRequirementSet = Acl.MakeRequirementSet(unityWorkerAttributeSet);
var workerOrClientRequirementSet = Acl.MakeRequirementSet(unityWorkerAttributeSet, clientAttributeSet);

var acl = Acl.Build()
             .SetReadAccess(workerOrClientRequirementSet)
             .SetWriteAccess<Position>(unityWorkerOnlyRequirementSet)
             .SetWriteAccess<Combat>(unityWorkerOnlyRequirementSet);

exampleTemplate.SetAcl(acl);

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