Access Manager API for PubNub Kotlin SDK

PubNub Access Manager (PAM) allows you to enforce secure controls for client access to resources within the PubNub network. With PAM, your servers can grant their clients access to individual PubNub resources for a limited duration, with the ability to extend access or add permissions for additional resources.

As soon as PAM is enabled, no publish/subscribe operations can be done without first explicitly providing an authorization token to the PubNub object. If an invalid token is provided, the requesting client will receive a Forbidden error.

For more information about PAM, refer to Managing Permissions with Access Manager.

Calling Kotlin methods

Most PubNub Kotlin SDK method invocations return an Endpoint object, which allows you to decide whether to perform the operation synchronously or asynchronously. You must choose one of these or the operation will not be performed at all.

For example, the following code is valid and will compile, but the publish won't be performed:

pubnub.publish(
    message = "this sdk rules!",
    channel = "my_channel"
)

To successfully publish a message, you must follow the actual method invocation with whether to perform it synchronously or asynchronously, for example:

pubnub.publish(
    message = "this sdk rules!",
    channel = "my_channel"
).async { result, status ->
    if (status.error) {
        // handle error
    } else {
        // handle successful method result
    }
}

Grant

Requires Access Manager add-onRequires that the Access Manager add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

The grant method allows you to grant permissions for one or more resources to one or more authKeys. You may need to make multiple grant calls with an authKey so that you can specify explicit permissions for each channel, channelGroup and uuid resources. For common permissions, you can normally use a single request.

Privileges specifically granted to an application's subscribeKey always take precedence over privileges granted to channel or auth_key. Therefore an application that requires authentication at the user level should not grant access at either the Application or Channel levels. View the Grant Levels section for more details.

Permissions

The grant request allows your server to securely grant access for your clients on the following resources within the platform. Each resource allows a limited set of permissions that control the operations that can be performed by the clients. For permissions and API operations mapping information, refer to Managing Permissions with Access Manager

Resource	Permissions
channel	read, write, get, manage, update, join, delete
uuid	get, update, delete
channelGroup	read, manage

Wildcard Permissions

To make granting access on multiple channels and channel groups more efficient, you can use the wildcard notation. It doesn't, however, apply to the uuid resource and you can only go one level deep using wildcards.

• * grants access on all channels
• a.* grants access on all channels that begin with a.
• a.b.* doesn't work. If you grant on a.b.*, the grant treats a.b.* as a channel name, not a wildcard

Grant Levels

When a user attempts to access a PubNub resource, PAM will evaluate any existing rules using the following order of precedence before access to a channel is granted to the user:

1. Application Level - PAM privileges are always evaluated first at the Application level. If either read or write attribute is set to true for a subscribeKey, PAM will immediately grant access for that attribute without proceeding to check permissions at either Channel or User levels. If an attribute is set to false at the Application level, PAM proceeds to evaluate the attribute at the next most granular level.
2. Channel Level - After first verifying an attribute at the Application level, PAM evaluates the attribute at the Channel level. If an attribute is set to true for a combination of subscribeKey, and channel, PAM grants access for that attribute at the Channel level without proceeding to check whether there may be user level permissions.
3. User Level (Recommended) - As a final step PAM evaluates the attributes at the User level. If an attribute is set to true for subscribeKey, channel and auth_key, access is granted for that attribute. Similarly, user level grants also allow you granting an auth_key access to channelGroups and uuids. User level grants require auth_key and are the recommended approach if you need to manage permissions for individual users within your application. Each user should be assigned a unique auth_key and securely passed back to the user to perform operations on the platform.

Method(s)

To Grant Permissions on a Channel you can use the following method(s) in the Kotlin V4 SDK:

this.pubnub.grant(
    authKeys: List<String>,
    channels: List<String>,
    channelGroups: List<String>,
    write: Boolean,
    read: Boolean,
    manage: Boolean,
    delete: Boolean,
    ttl: Int
).async { result, status -> }

Parameter	Type	Required	Default	Description
authKeys	List<String>	Optional		Specifies authKey to grant permissions to. It's possible to specify multiple auth keys. You can also grant access to a single authKey for multiple channels at the same time. Zero or more channels with zero or more auth tokens are allowed.
channels	List<String>	Optional		Specifies the channels on which to grant permissions. If no channels/channelGroups are specified, then the grant applies to all channels/channelGroups that have been or will be created for that publish/subscribe key set. Furthermore, any existing or future grants on specific channels are ignored, until the all channels grant is revoked. It's possible to grant permissions to multiple channels simultaneously. Wildcard notation like a.* can be used to grant access on channels. You can grant one level deep. - a.* - you can grant on this. - a.b.* - grant won't work on this. If you grant on a.b.*, the grant will treat a.b.* as a single channel with name a.b.*.
channelGroups	List<String>	Optional		Specifies the channelGroups to grant permissions. If no channels/channelGroups are specified, then the grant applies to all channels/channelGroups that have been or will be created for that publish/subscribe key set. Furthermore, any existing or future grants on specific channelGroups are ignored, until the all channelGroups grant is revoked. It's possible to grant permissions to multiple channelGroups simultaneously.
write	Boolean	Optional	false	Write permission
read	Boolean	Optional	false	Read permission
manage	Boolean	Optional	false	Manage permission
delete	Boolean	Optional	false	Delete permission
ttl	Long	Optional	Not set	Time in minutes for which granted permissions are valid. Setting ttl to 0 will apply the grant indefinitely, which is also the default behavior.
sync	PNAccessManagerGrantResult?	Optional		Fires the request, locks the thread, and throws an exception if something goes wrong.
async	{PNAccessManagerGrantResult?, PNStatus} ->	Optional		Fires the request asynchronously and reports back with a callback.

Basic Usage

Grant PAM Permissions for channel and auth_key

pubnub.grant(
    channels = listOf("ch1", "ch2", "ch3"), //channels to allow grant on
    channelGroups = listOf("cg1", "cg2", "cg3"), // groups to allow grant on
    authKeys = listOf("key1", "key2", "key3"), // the keys we are provisioning
    write = true, // allow those keys to write (false by default)
    manage = true, // allow those keys to manage channel groups (false by default)
    read = true, // allow keys to read the subscribe feed (false by default)
    delete = true, // allow keys to delete messages (false by default)
    ttl = 12337 // how long those keys will remain valid (0 for eternity)
).async { result, status ->
    // result is a parsed and abstracted response from server
}

Returns

The grant() operation returns a PNAccessManagerGrantResult? which contains the following operations:

Method	Type	Description
level	String	Permissions level, one of subkey, subkey+auth, channel, channel-group, channel-group+auth level.
subscribeKey	String	The subscribeKey.
channels	Map<String, Map<String, PNAccessManagerKeyData>?>	Access rights per channel. See PNAccessManagerKeyData for more details.
channelGroups	Map<String, Map<String, PNAccessManagerKeyData>?>	Access rights per channel group. See PNAccessManagerKeyData for more details.

PNAccessManagerKeyData

Method	Type	Description
readEnabled	Boolean	Is true if read rights are granted
writeEnabled	Boolean	Is true if write rights are granted
manageEnabled	Boolean	Is true if manage rights are granted
deleteEnabled	Boolean	Is true if delete rights are granted

Caution

PAM grant or revoke requests must be less than ~32KiB at a time, or the client will return an error. For requests greater than 32KiB, break them into smaller batched requests. When the message size exceeds 32KiB the server returns the HTTP Error code 500, instead of the correct error code 414.

Warning

For NTP synchronization, please ensure that you have configured NTP on your server to keep the clock in sync. This is to prevent system clock drift leading to 400 Invalid Timestamp error response.

https://support.pubnub.com/hc/en-us/articles/360051973331-Why-do-I-get-Invalid-Timestamp-when-I-try-to-grant-permission-using-Access-Manager-

Other Examples

1. Grant subscribe access to a channel only for clients with a specific auth_key with a 5 minute ttl:

   pubnub.grant(
       channels = listOf("my_channel"),
       write = false,
       read = true,
       authKeys = listOf("my_ro_authkey"),
       ttl = 5
   ).async { result, status -> }
   

   The above code returns the following response to the client:

   if (!status.error) {
       result!!.ttl // 5
       result.level // user
   } else {
       // handle error
       status.exception?.printStackTrace()
   }
   

2. Allow access to a specific channel for Presence:

   pubnub.grant(
       channels = listOf("my_channel-pnpres"),
       write = true,
       read = true
   ).async { result, status -> }
   

3. Grant PAM Permissions for channel group:

   pubnub.grant(
       channelGroups = listOf("cg1", "cg2", "cg3"), // groups to allow grant on
       authKeys = listOf("key1", "key2", "key3"), // the keys we are provisioning
       write = true, // allow those keys to write (false by default)
       manage = true, // allow those keys to manage channel groups (false by default)
       read = true, // allow keys to read the subscribe feed (false by default)
       ttl = 12337 // how long those keys will remain valid (0 for eternity)
   ).async { result, status -> }
   

   The above code returns the following response to the client:

   if (!status.error) {
       result!!.ttl // 12337
       result.level // user
   } else {
       // handle error
       status.exception?.printStackTrace()
   }
   

4. Allow access to all channel groups using wildcard:

   To perform a first level wildcard grant for channel groups you need to specify : (colon) as the parameter for channelGroups. This will ensure that users can read or manage all channel groups.

   pubnub.grant(
       channelGroups = listOf(":"),
       read = true,
       manage = true
   ).async { result, status -> }
   

5. Application Level Grant

   Use application level grants with caution

   When access is granted on an application level, all channels and users will have access.

   Application level grants can also happen due to a bug in your code. For example, Null parameters for channels and auth-keys can cause accidental application level grants.

   pubnub.grant(
       write = true,
       read = true
   ).async { result, status -> }
   

6. Channel Level Grant

   pubnub.grant(
       channels = listOf("my_channel"),
       write = true,
       read = true
   ).async { result, status -> }
   

7. User Level Grant

   pubnub.grant(
       channels = listOf("my_channel"),
       authKeys = listOf("my_authkey"),
       write = true,
       read = true,
       ttl = 5
   ).async { result, status -> }