Advanced Parameters

The advanced parameters of MigratoryData are described below.

RunAsUser

For example, if migratorydata is an existing normal user, then you could configure MigratoryData to run as a normal user as follows:

RunAsUser = migratorydata

Then, start MigratoryData as root (this is necessary to be able to bind on the privileged ports 80 or 443). Please note that while running as root, MigratoryData will not accept any client connections. Then, MigratoryData will drop the root privileges (using the system call setuid) and will automatically switch to the normal user migratorydata. Only at this time, MigratoryData Server will start to accept client connections.

PublishAllowFromAddressList

If this parameter is configured, then MigratoryData will accept message publications only from the clients running on any of the IP addresses defined by this parameter.

If this parameter is not set, message publication will be allowed from any client provided however that the client is allowed by the entitlement rules you define (see the Entitlement parameter).

PublishAllowFromAddressList = 192.168.5.23, 10.0.0.0/24

Native.Ssl

This parameter can have two values: true or false. If set on true, then MigratoryData will use the OpenSSL library for TLS/SSL support. The OpenSSL library provides a better implementation of TLS/SSL in terms of memory and CPU usage compared to the default implementation of Java. While this difference might not be substantial for small or medium MigratoryData deployments, for large MigratoryData deployments with millions of users, it is recommended to use OpenSSL.

MaxCachedMessagesPerSubject

For each subject, the MigratoryData maintains an in-memory cache. Messages are removed continuously from the cache of each subject, however each message is held in the cache up to the number of messages defined by this parameter or at least for the number of seconds defined by the parameter CacheExpireTime, whichever comes first..

This parameter applies only if the Guaranteed Message Delivery feature is enabled, see the parameter ClusterDeliveryMode for more details.

SnapshotExpireTime

The MigratoryData server saves a snapshot message in memory for every subject. By default, the snapshot message is persisted in memory for an indefinite period. However, you can specify a limit on the retention time of the snapshot messages using this parameter.

This feature is especially helpful when new subjects are continuously added to the system, but they are not updated after a certain time. Without a time limit, the snapshot messages of these inactive subjects would accumulate in memory, leading to potential memory issues.

CacheExpireTime

For each subject, the MigratoryData maintains an in-memory cache. Messages are removed continuously from the cache of each subject, however each message is held in the cache up to the number of messages defined by the parameter MaxCachedMessagesPerSubject or at least for the number of seconds defined by this parameter, whichever comes first.

This parameter applies only if the Guaranteed Message Delivery feature is enabled, see the parameter ClusterDeliveryMode for more details.

Workgroups

In order to better scale on multiprocessor hardware the incoming users are separated in groups. This parameter configures the number of groups (every group has a dedicated thread). If not supplied the total CPU cores available is the default value. In most situations it is not recommended to modify the default value.

IoThreads

If not supplied the number of total CPU cores available is the default value. In most situations it is not recommended to modify the default value.

Stats.LogInterval

The minimum value of this parameter is 5 seconds. The format of the stats logs is as follows:

[timespamp] [S] [INFO] [STATS] {
      connectedSessions,\
      connectedSessionsWeb,\
      connectedSessionsMobile,\
      connectedSessionsDesktop,\
      sessionConnectionsPerSecond,\
      sessionDisconnectionsPerSecond,\
      inPublishMessagesPerSecond,\
      outPublishMessagesPerSecond,\
      inBytesPerSecond,\
      outBytesPerSecond,\
      clientInPublishMessagesPerSecond,\
      connectRateRecoverySuccessPerSecond,\
      connectRateRecoveryFailPerSecond,\
      clientPublishFailedPerSecond\
}

MaxBatchingSpace

Batching is the process of collecting messages together for a period of time or until a maximum size is reached before sending them in a single I/O operation to a client.

Once enabled with this parameter MaxBatchingSpace or with MaxBatchingTime, MigratoryData will not send every message individually to the client, instead it will send messages in batches, thus MigratoryData will perform a single I/O network operation for a single batch. The following diagram shows the circulation of messages without batching (left) and with batching (right):

Depending on your use case, especially if subjects are systematically updated at a high frequency (multiple messages per second), then batching can optimize the network I/O.

If this parameter is not configured or configured with the default value 0, then batching by space is disabled.

MaxBatchingTime

Refer to the parameter MaxBatchingSpace to learn about batching.

If this parameter is not configured or configured with the default value 0, then batching by time is disabled.

SslProtocols

For Java 8, the following TLS/SSL protocols are configured by default TLSv1.2, TLSv1.1, TLSv1. You can change the default list of TLS/SSL protocols by using this parameter. For example, to enable only the TLSv1.2 protocol, configure this parameter as follows:

SslProtocols = TLSv1.2

CipherListEnabled

Use this parameter to enable one or more supported ciphers not enabled by default. For example:

CipherListEnabled = \
  TLS_DHE_RSA_WITH_AES_128_CBC_SHA, \
  TLS_DHE_DSS_WITH_AES_128_CBC_SHA

CipherListExcluded

Use this parameter to exclude one or more ciphers enabled by default. For example:

CipherListEnabled = \
  TLS_DHE_RSA_WITH_AES_128_CBC_SHA, \
  TLS_DHE_DSS_WITH_AES_128_CBC_SHA

MaxMessageSize

This parameter specifies the maximum number of bytes a message should have (including the protocol overhead) to be accepted by MigratoryData. A client which sends a message larger than this size will be automatically disconnected.

MaxBandwidthRate

This parameter specifies the maximum bandwidth rate – in bytes per second (B/s) – that the MigratoryData server is allowed to consume from the available network bandwidth capacity to push messages to clients. If zero is specified, the bandwidth rate will not be limited (this is the default value).

This parameter is particularly useful for use cases where, occasionally, the outgoing message throughput is higher than the available network bandwidth capacity. Suppose the MigratoryData server is installed on a machine with a network bandwidth capacity of 1 Gbps (i.e. 125 MB/s), and supposing there are one or more large messages to be delivered to a large number of users, producing an outgoing data volume of 1250 MB. By configuring this parameter at 125 MB/s ( MaxBandwidthRate=1000000000 ), the assumed available network capacity, the MigratoryData server will be able to deliver that volume of data during 10 seconds, and then operate normally, with low message latency. Otherwise, without configuring this parameter, the system might be severely impacted - as the capacity of the kernel’s socket buffers could be exhausted.

Note that configuring this parameter could be useful not only for the use cases discussed above. It can be used as a protection against the deliberate or accidental exceeding of the available network bandwidth capacity for any other use case.

For most cases, this parameter should be configured to be equal to the available network bandwidth capacity.

Extension.InteractivePublishing

The interactive publishing add-on is preinstalled in the MigratoryData server, but it is disabled by default. To enable it, set this parameter on true.

Extension.InteractivePublishing.Token

In a MigratoryData cluster, the interactive publishing add-on of a cluster node communicates with the interactive publishing add-ons of the other cluster nodes, as well as with the interactive publishers of the MigratoryData cluster using a number of meta-subjects, subjects which start with the following subject prefix:

/__migratorydata__/ipub/

If the parameter Entitlement is set on Basic or None, then configure this parameter with the value of the parameter EntitlementAllowToken. If the parameter Entitlement is set on JWT, then configure this parameter with a JWT token that includes in the list all under its section permissions, the following wildcard subject /__migratorydata__/ipub/*. Finally, if the parameter Entitlement is set on Custom, then configure this parameter with any entitlement token, provided that your entitlement rules authorize it for subscriptions and publications on all subjects which start with the prefix /__migratorydata__/ipub/.

Extension.Presence

Set this parameter on true to enable the presence extension built with the Server Extensions API for Presence and deployed under the folder extensions of your MigratoryData installation.

Extension.Presence.Subject

Whenever a user connects to or disconnects from a cluster member or changes its list of subscribed subjects (by subscribing to and unsubscribing from them), a presence event is provided to the presence extension of that cluster member. Furthermore, this presence event propagates across the entire MigratoryData cluster, ensuring that each cluster member’s presence extension receives this presence event.

Internally, MigratoryData uses its client library to replicate presence updates across the cluster. Each cluster member subscribes to the subject defined by this parameter. Whenever a user connects to or disconnects from a cluster member, that cluster member publishes a presence event on the subject defined by this parameter.

Extension.Presence.EntitlementToken

As detailed in the description of the parameter Extension.Presence.Subject, MigratoryData replicates presence events across the cluster.

The default value of this parameter is the value of the parameter EntitlementAllowToken. In this way, if the value of the parameter Entitlement is Basic or None, then there is no need to configure this parameter. Simply use its default value.

Otherwise, if the value of the parameter Entitlement is Custom or JWT, then your custom entitlement rules should entitle subscriptions and publications on the subject defined by the parameter Extension.Presence.Subject for the connections using the entitlement token defined by this parameter.

Extension.Audit.Access

Set this parameter on true to enable the audit access logs from your custom audit extension. If your custom audit extension built with the Server Extensions API for Audit and deployed under the folder extensions of your MigratoryData installation is not already enabled, then configuring this parameter on true will also enable your custom audit extension.

Alternatively, set this parameter on log4j to load the ready-made Log4j audit extension pre-installed under the folder addons of your MigratoryData installation.

Extension.Audit.Cache

Set this parameter on true to enable the audit cache logs from your custom audit extension. If your custom audit extension built with the Server Extensions API for Audit and deployed under the folder extensions of your MigratoryData installation is not already enabled, then configuring this parameter on true will also enable your custom audit extension.

Alternatively, set this parameter on log4j to load the ready-made Log4j audit extension pre-installed under the folder addons of your MigratoryData installation.

Extension.Audit.Message

Set this parameter on true to enable the audit message logs from your custom audit extension. If your custom audit extension built with the Server Extensions API for Audit and deployed under the folder extensions of your MigratoryData installation is not already enabled, then configuring this parameter on true will also enable your custom audit extension.

Alternatively, set this parameter on log4j to load the ready-made Log4j audit extension pre-installed under the folder addons of your MigratoryData installation.

Extension.Audit.Stats

Set this parameter on true to enable the audit stats logs from your custom audit extension. If your custom audit extension built with the Server Extensions API for Audit and deployed under the folder extensions of your MigratoryData installation is not already enabled, then configuring this parameter on true will also enable your custom audit extension.

Alternatively, set this parameter on log4j to load the ready-made Log4j audit extension pre-installed under the folder addons of your MigratoryData installation.