# DataSource peers configuration (part 2) Here are the rest of the DataSource configuration items that define a DataSource application’s connections to its DataSource peers. **📌 NOTE**\ "_this DataSource application_" means the DataSource application for which you are defining the configuration. _"DataSource peer_" or "_peer_" means a DataSource application that this DataSource application communicates with. More DataSource-peer configuration items can be found in [DataSource peers configuration (part 1)](datasource-datasource-peers-configuration-part-1.md). ## add-apikey Introduced in platform 8, DataSource supports using an API key to authenticate and authorise adapters. This allows the Liberator or Transformer to control whether to accept a peer connection and which dynamic services to allow it access to. The adapter uses the [add-peer:apikey](datasource-datasource-peers-configuration-part-1#apikey) configuration option to specify an API key for a connection, and the Liberator or Transformer uses [add-apikey](#add-apikey) to assign roles to that API key. The first value provided to `add-apikey` is the SHA-256 hash of the API key. A value for this can be generated using the `**sha256sum**` command-line tool available on Linux machines. The second value is a comma-separated list of security roles to grant to the API key. The following security roles are available: | Role | Description | | --- | --- | | ds-connect | Allow a peer to connect | | ds-dynamic-fields | Allow a peer to supply and receive field codes | | ds-dynamic-peer | Allow a peer to connect dynamically | | ds-dynamic-service | Allow a peer to supply data-service configuration | **Since:** DataSource 8 **Use in:** C **Syntax**: `add-apikey "[,...]"` **Type**: string array **Default value:** _none_ **Example**: ``` add-apikey f9912b266474a1805205454548fa6e4f80f5f688a379481d14976bdbea25e047 "ds-connect,ds-dynamic-fields,ds-dynamic-peer,ds-dynamic-service" ``` ## datasrc-batch-time `datasrc-batch-time` specifies the time period in seconds for this DataSource application to batch together messages sent to a peer. As an example, if `datasrc-batch-time` time is 0.2 seconds, when the DataSource application needs to send a message to the peer and there are no outgoing messages already in the queue, it queues the message and waits 0.2 seconds. Any subsequent outgoing messages are also queued until 0.2 seconds have elapsed, and then all the queued messages are sent to the peer in one batch. Batching messages in this way can improve performance when there is a high rate of data updates being sent to the peer. If datasrc-batch-time is set to `0.0`, messages are not batched. **Use in:** C **Syntax**: `datasrc-batch-time ` **Type:** float **Default value:** `0.01` (seconds) **Values accepted:** `0.0` -- `10.0` ## datasrc-default-obj-hash-size `datasrc-default-obj-hash-size` specifies the default number of entries in the hashtable that holds information about this DataSource application’s [active subscriptions](datasource-active-subscription-model.md). **Use in:** C **Syntax:** `datasrc-default-obj-hash-size ` **Type:** integer **Default value:** `16384` objects ## datasrc-heartbeat-slack-time When this DataSource application doesn’t receive an expected DataSource heartbeat from a peer, it waits `datasrc-heartbeat-slack-time` seconds before disconnecting from the peer and trying to reconnect to it. `datasrc-heartbeat-slack-time` applies to all dynamic peers, and static peers that do not have `heartbeat-slack-time` configured. If [`add-peer::heartbeat-slack-time`](datasource-datasource-peers-configuration-part-1.md#heartbeat-slack-time) is set, it takes precedence over `datasrc-heartbeat-slack-time`. After modifying any of the heartbeat configuration items, restart both the DataSource application and its peers for the change to take effect. **Available from:** DSDK 7.1.16 (Liberator 7.1.15, Transformer 7.1.10), DS.NET 7.1.16, DataSource for Java 7.1.13 **Use in:** C, Java **Syntax:** `datasrc-heartbeat-slack-time ` **Type:** float **Default value:** `5.0` ## datasrc-heartbeat-time The two peers involved in a DataSource connection exchange heartbeat messages at regular intervals so that each of the DataSource applications can check that the other is still present, and take appropriate action if it is not (such as attempt to reconnect to the peer, or fail over to another peer). `datasrc-heartbeat-time` defines the time in seconds between each DataSource heartbeat. When two DataSource applications connect, they compare their configured heartbeat times and use the lowest. `datasrc-heartbeat-time` applies to all dynamic peers, and static peers that do not have `heartbeat-time` configured. If [`add-peer::heartbeat-time`](datasource-datasource-peers-configuration-part-1.md#heartbeat-time) is set, it takes precedence over `datasrc-heartbeat-time`. After modifying any of the heartbeat configuration items, restart both the DataSource application and its peers for the changes to take effect. **Available from:** DSDK 7.1.16 (Liberator 7.1.15, Transformer 7.1.10), DS.NET 7.1.16, DataSource for Java 7.1.13 **Use in:** C, Java **Syntax:** `datasrc-heartbeat-time ` **Type:** integer **Default value:** `15` ## datasrc-id **📌 NOTE**\ The use of this configuration item is discouraged. Use [datasrc-local-label](#datasrc-local-label) instead. `datasrc-id` specifies the ID number of this DataSource application. You can override this ID for a particular peer connection by adding a [local-id](datasource-datasource-peers-configuration-part-1.md#local-id) option to the [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer) configuration item relating to the connection. **Use in:** C, Java **Syntax:** `datasrc-id ` **Type:** integer **Default value:** `0` ## datasrc-interface `datasrc-interface` binds the DataSource server socket to a single IP address or to a single IP address wildcard. **📌 NOTE**\ Only one DataSource server-socket is supported per DataSource application. If no value is specified (default), then the DataSource server socket is available on all IPv4 and IPv6 addresses on the host. Some system settings affect this functionality; see the two tables below. **❗ IMPORTANT**\ Do not set `datasrc-interface` directly for Liberator. Instead, use the configuration macros `LIBERATOR${THIS_LEG}_DATASRC_INTERFACE` and `LIBERATOR${OTHER_LEG}_DATASRC_INTERFACE`. For more information, see [Deployment Framework’s configuration macros](../deployment-framework/cdf-configuration-macros-and-items.md). The behaviour of `datasrc-interface` differs slightly between C-based and Java-based DataSource applications: **DataSource for C** | Value | Example Value | Result | | --- | --- | --- | | <empty_string> | `""` | [Default] The DataSource server-socket is available on all available IPv4 and IPv6 addresses on the host. IPv6 addresses are supported from DataSource 7. See [footnote 1](#ds4c-1). | | IPv4 address | `192.0.2.1` | The DataSource server-socket is bound to the specified IPv4 address. | | IPv4 wildcard | `0.0.0.0` | The DataSource server-socket is bound to all available IPv4 addresses on the host. | | IPv6 address | `2001:db8:0:0:0:0:0:1` | The DataSource server-socket is bound to the specified IPv6 address. Supported from DataSource 7. | | IPv6 wildcard | `::` | The DataSource server-socket is bound to all available IPv6 addresses on the local machine. Supported from DataSource 7. | | Hostname | `server.example.com` | The DataSource server-socket is bound to the first IP address the hostname resolves to. IPv6 addresses are supported from DataSource 7. See [footnote 2](#ds4c-2). | 1. On dual-stack hosts, setting `datasrc_interface` to `""` causes DataSource for C to open an IPv6 server socket that accepts IPv4-mapped addresses. IPv4 address mapping is enabled by default on Linux, but it can be disabled by the system administrator. See your operating system’s documentation for `/proc/sys/net/ipv6/bindv6only`. 2. From version 7, DataSource for C uses the POSIX function `getaddrinfo` for name resolution, which can return multiple IP addresses for a host. On Linux, `getaddrinfo` returns IP addresses in the order defined in [RFC 3484](https://www.rfc-editor.org/rfc/rfc3484.txt), which gives IPv6 addresses precedence over IPv4 addresses of equal suitability. For more information, see your operating system’s manual entry for the POSIX function `getaddrinfo`. **DataSource for Java** | Value | Example Value | Result | | --- | --- | --- | | <empty_string> | `""` | [Default] The DataSource server-socket is available on all available IPv4 and IPv6 addresses on the host. IPv6 addresses are supported from DataSource 7. See [footnote 1](#ds4j-1). | | IPv4 address | `192.0.2.1` | The DataSource server-socket is bound to the specified IPv4 address. | | IPv4 wildcard | `0.0.0.0` | The DataSource server-socket is bound to all available IPv4 and IPv6 addresses on the host. IPv6 addresses are supported from DataSource 7. See [footnote 1](#ds4j-1). | | IPv6 address | `2001:db8:0:0:0:0:0:1` | The DataSource server-socket is bound to the specified IPv6 address. Supported from DataSource 7. | | IPv6 wildcard | `::` | The DataSource server-socket is bound to all available IPv4 and IPv6 addresses on the host. Supported from DataSource 7. See [footnote 1](#ds4j-1). | | Hostname | `server.example.com` | The DataSource server-socket is bound to the first IP address the hostname resolves to. IPv6 addresses are supported from DataSource 7. See [footnote 2](#ds4j-2). | 1. On dual-stack hosts, by default Java creates IPv6 server sockets that accept IPv4-mapped addresses. To force Java to create IPv4 server sockets instead, set the Java system property `java.net.preferIPv4Stack` to `true`. See Oracle’s [Networking IPv6 User Guide](https://docs.oracle.com/javase/8/docs/technotes/guides/net/ipv6_guide/) for more details. 2. DataSource for Java uses Java’s `java.net.InetAddress` class for name resolution. In the interests of compatibility, Java gives IPv4 addresses precedence over IPv6 addresses of equal suitability. To force a Java virtual machine (JVM) to give precedence to IPv6 addresses, set the JVM option `java.net.preferIPv6Addresses` to `true`. See Oracle’s [Networking IPv6 User Guide](https://docs.oracle.com/javase/8/docs/technotes/guides/net/ipv6_guide/) for more details. **Use in**: C, Java **Syntax:** `datasrc-interface ` **Type:** string **Default value**: `""` (empty string) ## datasrc-local-flags Specifies flags determining the behaviour of this DataSource application when it starts up and establishes connections to peers, or when it reconnects to peers. Overridden by [add-peer:local-flags](datasource-datasource-peers-configuration-part-1.md#local-flags) for specific peer connections. **Syntax:** `datasrc-local-flags __flag__[|__flag__ ...]` **Flags** * `none` or `0`: No special restart/reconnection behaviour. * `recvautoreplay` or `4`: When restarting, this DataSource application must accept replay updates from the peer. **This flag is deprecated.** * `noconnect` or `8`: When this DataSource application starts up, it must not automatically connect to the peer. * `nofields`: Do not send [Dynamic Fields](datasource-field-definitions.md#dynamic-fields) data in the DataSource handshake. Required for a DataSource 8 application to connect to Liberator/DSDK < 7.1.31 or Transformer < 7.1.19. **Example:** `datasrc-local-flags nofields` ## datasrc-local-label `datasrc-local-label` sets a name that uniquely defines this DataSource application within the Caplin Platform installation. Together with the [remote-label](datasource-datasource-peers-configuration-part-1.md#remote-label) option of [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer), it replaces `datasrc-id` and the `remote-id` option of `add-peer`. You can override this label for a particular peer connection by adding a [local-label](datasource-datasource-peers-configuration-part-1.md#local-label) option to the [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer) configuration item relating to the connection (this allows you to implement multiple connections for the same peer). **💡 TIP**\ Here’s an [example](datasource-datasource-peers-configuration-part-1.md#example-of-datasrc-local-label-and-remote-label) of how `datasrc-local-label` and `remote-label` are used together. **Use in**: C, Java **Syntax:** `datasrc-local-label ` **Type:** string **Default value:** `[none]` ## datasrc-name The name of this DataSource application, which the application’s DataSource peers use to identify it. **❗ IMPORTANT**\ The use of [add-peer:local-name](datasource-datasource-peers-configuration-part-1.md#local-name), [add-peer:remote-name](datasource-datasource-peers-configuration-part-1.md#remote-name), and [datasrc-name](datasource-datasource-peers-configuration-part-2.md#datasrc-name) is discouraged. Use [add-peer:local-label](datasource-datasource-peers-configuration-part-1.md#local-label), [add-peer:remote-label](datasource-datasource-peers-configuration-part-1.md#remote-label), and [datasrc-local-label](datasource-datasource-peers-configuration-part-2.md#datasrc-local-label) instead. You can override this name by adding a [local-name](datasource-datasource-peers-configuration-part-1.md#local-name) option to an [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer) entry - the `local-name` is then the name that the DataSource peer defined by the `add-peer` entry uses to identify this application. The name can contain the parameters `%a` and `%h`. At run time, `%a` is replaced by the DataSource [application-name](datasource-run-time-environment-configuration.md#application-name), and `%h` is replaced by the host name of the machine on which the DataSource application is running. **Use in**: C, Java **Syntax:** `datasrc-name ` **Type:** string **Default value:** `%a-%h` ## datasrc-pkt-log `datasrc-pkt-log` specifies the file path of this DataSource application’s packet log file. It can also be used to turn off packet logging. The file path can be relative or absolute. If relative, the file path is relative to the value of [log-dir](datasource-logging-configuration.md#log-dir). To disable the log, set the file path to `/dev/null`. **Supported substitution tokens** | Token | Description | | --- | --- | | %a | The DataSource [application-name](datasource-run-time-environment-configuration.md#application-name). | | %h | The host name of the machine on which this DataSource application is running. | **Use in**: C, Java **Syntax:** `datasrc-pkt-log ` **Type:** string **Default value:** `packet-%a.log` ## datasrc-port `datasrc-port` specifies the network port to listen on for non-WebSocket connections from DataSource peers. The default of `0` means that no connections can be made to this DataSource application (in which case, you’d configure the application so that it initiates the connections to its peers; see the [addr](datasource-datasource-peers-configuration-part-1.md#addr) and [port](datasource-datasource-peers-configuration-part-1.md#port) options of [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer)). To listen for secure (SSL) connections from DataSource peers, you must specify the configuration item [datasrc-ssl-port](datasource-datasource-secure-sockets-layer-ssl-configuration.md#datasrc-ssl-port). **Use in**: C, Java **Syntax:** `datasrc-port ` **Type:** integer **Default value:** `0` (No connections can be made.) ## datasrc-public-addresses `datasrc-public-addresses` specifies a list of network addresses at which this DataSource component’s DataSource port ([datasrc-port](#datasrc-port)) is available to peers and Discovery. These addresses, together with the DataSource component’s hostname as reported by the OS or as set by [datasrc-interface](#datasrc-interface), are registered by the DataSource with Discovery during the Discovery-DataSource handshake. Discovery and peers attempting to connect to this DataSource try addresses in `datasrc-public-addresses` first before trying the DataSource component’s hostname. Network addresses may be specified as hostnames, fully-qualified domain names, or IP addresses. **Use in**: C (DSDK 7.1.27+, Liberator 7.1.27+, Transformer 7.1.17+), Java (DataSource for Java 7.1.20+) **Compatibility**: Discovery 7.1.4 **Syntax:** `datasrc-public-addresses __address__ ...` **Type:** string array **Default value:** __none__ **Example:** `datasrc-public-addresses liberator1 liberator1.example.com` ## datasrc-ws-port `datasrc-ws-port` specifies the network port to listen on for WebSocket connections from DataSource peers. The default of `0` means that no WebSocket connections can be made to this DataSource application (in which case, you’d configure the application so that it initiates the WebSocket connections to its peers; see the [addr](datasource-datasource-peers-configuration-part-1.md#addr), [port](datasource-datasource-peers-configuration-part-1.md#port), [websocket](datasource-datasource-peers-configuration-part-1.md#websocket) and [websocket-path](datasource-datasource-peers-configuration-part-1.md#websocket-path) options of [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer)). Unlike [datasrc-port](#datasrc-port) there is no separate port for secure connections. This port listens for secure (SSL) connections from DataSource peers if [datasrc-ssl-enable](datasource-datasource-secure-sockets-layer-ssl-configuration.md#datasrc-ssl-enable) is `TRUE`. **Use in**: C, Java **Since**: DSDK 7.1.30 (Liberator 7.1.30, Transformer 7.1.18), DataSource for Java 7.1.22, Discovery 7.1.5 **Syntax:** `datasrc-ws-port ` **Type:** integer **Default value:** `0` (No connections can be made.) ## datasrc-ws-path `datasrc-ws-path` specifies the path to listen on for WebSocket connections from DataSource peers. See the [websocket-path](datasource-datasource-peers-configuration-part-1.md#websocket-path) option of [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer) when configuring applications initiating the connection. **Use in**: C, Java **Since**: DSDK 7.1.30 (Liberator 7.1.30, Transformer 7.1.18), DataSource for Java 7.1.22, Discovery 7.1.5 **Syntax:** `datasrc-ws-path ` **Type:** string **Default value:** `/` ## datasrc-reject-new-peers `datasrc-reject-new-peers` when set to TRUE, prevents a peer from connecting to this DataSource application when there’s already a peer connected that has the same label (or the same ID if there’s no label defined for the peer). Setting `datasrc-reject-new-peers` prevents abnormal behaviour if the system is wrongly configured and two peers are inadvertently deployed with the same labels or IDs. By default, if a DataSource peer tries to connect to this DataSource application but there is already one connected with the same label or ID, the current peer is disconnected and the new one is allowed to connect. The first peer could then attempt to reconnect, which would cause the second peer to be disconnected. The second peer would then in turn attempt to reconnect, and so on. This configuration item turns off this default behaviour, so the second DataSource peer is never allowed to connect. The peer’s label is defined in the [remote-label](datasource-datasource-peers-configuration-part-1.md#remote-label) option of this DataSource application’s [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer) configuration entry. The peer’s ID is defined in the [remote-id](datasource-datasource-peers-configuration-part-1.md#remote-id) option of the `add-peer`. **Use in**: C, Java **Syntax:** `datasrc-reject-new-peers ` **Type:** boolean **Default value:** `FALSE` (a new peer with the same label or ID as an existing one is allowed to connect) ## datasrc-tcp-nodelay-off `datasrc-tcp-nodelay-off` specifies whether the DataSource application’s peer connection sockets should have the TCP_NODELAY feature turned off. The default is `FALSE`, which means TCP_NODELAY is enabled. Setting this configuration item to `TRUE` _disables_ TCP_NODELAY. **Use in**: C, Java **Syntax:** `datasrc-tcp-nodelay-off ` **Type:** boolean **Default value:** `FALSE` (TCP_NODELAY is disabled) ## peer-accept-wait-time `peer-accept-wait-time` specifies the time in seconds to wait for an information packet when accepting a connection from a peer. **Use in**: C **Syntax:** `peer-accept-wait-time ` **Type:** float **Default value:** `10.0` seconds ## peer-debug-metrics-interval `peer-debug-metrics-interval` specifies the interval in seconds between updates of the following Prometheus metrics: * [`datasource_discard_average`](datasource-prometheus-metrics.md#datasource-discard-average) * [`datasource_discard_count`](datasource-prometheus-metrics.md#datasource-discard-count) * [`datasource_discard_max`](datasource-prometheus-metrics.md#datasource-discard-max) * [`datasource_executor_queue_length`](datasource-prometheus-metrics.md#datasource-executor-queue-length) * [`datasource_netty_bytes_before_writable`](datasource-prometheus-metrics.md#datasource-netty-bytes-before-writable) * [`datasource_bytes_before_unwritable`](datasource-prometheus-metrics.md#datasource-netty-bytes-before-unwritable) * [`datasource_request_average`](datasource-prometheus-metrics.md#datasource-request-average) * [`datasource_request_count`](datasource-prometheus-metrics.md#datasource-request-count) * [`datasource_request_max`](datasource-prometheus-metrics.md#datasource-request-max) **Use in**: Java **Syntax:** `peer-debug-metrics-interval ` **Type:** int **Default value:** `10` seconds ## peer-monitor-interval `peer-monitor-interval` specifies the interval in seconds at which statistics about this DataSource application’s connection to its DataSource peers are read and transferred to the application’s [JMX monitoring module](datasource-datasource-monitoring-and-management.md). You can override this item for a specific peer by adding a [monitor-interval](datasource-datasource-peers-configuration-part-1.md#monitor-interval) option to this DataSource application’s [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer) configuration item for the peer. **Use in**: C **Syntax:** `peer-monitor-interval ` **Type:** float **Default value:** `30.0` seconds ## peer-request-timeout `peer-request-timeout` is a higher-precedence alias of [`source-request-timeout`](#source-request-timeout). Peer-request timeout precedence (highest first): [`add-peer::request-timeout`](datasource-datasource-peers-configuration-part-1.md#request-timeout) > `peer-request-timeout` > [`source-request-timeout`](datasource-datasource-peers-configuration-part-2.md#source-request-timeout). **Use in**: C **Syntax:** `peer-request-timeout ` **Type:** float **Default value:** `-1.0` (no timeout) ## peer-thread-pool-size `peer-thread-pool-size` specifies the maximum number of pooled connection threads allocated to handle the DataSource application’s peer connections that don’t have an explicitly named thread. If you configure more than 30 peers, you should define `peer-thread-pool-size`. For more about `peer-thread-pool-size` and the thread-name option of `add-peer`, see [Configure threads for peer communication](datasource-configure-threads-for-peer-communication.md). If this item is configured, the DataSource application creates a pool of threads that are used to handle peer connections. The item specifies the maximum number of threads in the pool. When a peer connection doesn’t have a named thread configured for it (see the [thread-name](datasource-datasource-peers-configuration-part-1.md#thread-name) option of the [add-peer](datasource-datasource-peers-configuration-part-1.md#add-peer) item), communication with the peer is handled on one of the pool threads. However, if `peer-thread-pool-size` is 0 or not defined, an unnamed thread is created and dedicated to that peer. If `peer-thread-pool-size` is less than the number of peer connections with no explicitly named thread, these connections share threads from the pool. **Use in**: C **Syntax:** `peer-thread-pool-size ` **Type:** integer **Default value:** `-1` (no pool configured - see explanation below) ## source-request-timeout `source-request-timeout` specifies a timeout in seconds for a DataSource peer’s response to a request (for example, a subscription request) sent to it by this DataSource application. If the peer doesn’t respond within this time, the requested object is assumed to be not available and the application sends a discard message for the object to the peer. Peer-request timeout precedence (highest first): [`add-peer::request-timeout`](datasource-datasource-peers-configuration-part-1.md#request-timeout) > [`peer-request-timeout`](datasource-datasource-peers-configuration-part-2.md#peer-request-timeout) > `source-request-timeout`. A request to a peer in the context of a data-service is also subject to the data-service’s request timeout. For more information, see [`add-data-service::request-timeout`](datasource-data-services-configuration.md#request-timeout) and [`service-request-timeout`](datasource-data-services-configuration.md#service-request-timeout). **Use in**: C **Syntax:** `source-request-timeout ` **Type:** float **Default value:** `-1.0` (no timeout) --- **See also:** * Reference: [DataSource peers configuration (part 1)](datasource-datasource-peers-configuration-part-1.md) * Reference: [Data services configuration](datasource-data-services-configuration.md) * Reference: [DataSource Secure Sockets Layer (SSL) configuration](datasource-datasource-secure-sockets-layer-ssl-configuration.md) * [DataSource configuration reference: Introduction](datasource-datasource-configuration-reference-introduction.md) * How can I... [Use timers in DataSource applications](datasource-use-timers-in-datasource-applications.md) * How can I... [Enable heartbeats between DataSource applications](datasource-enable-heartbeats-between-datasource-applications.md) * How can I... [Configure threads for peer communication](datasource-configure-threads-for-peer-communication.md) * How can I... [View packet logs using logcat](datasource-view-packet-logs-using-logcat.md)