# Configuring ts_salobj¶

## Environment Variables¶

Environment variables used by ts_salobj for configuration. If setting these via os.environ please be sure to set these to string values, even if they are parsed as integers or floats.

Used by Vortex OpenSplice, and thus indirectly by Domain:

• ADLINK_LICENSE points to directory containing your Vortex OpenSplice license. Required if using the licensed version of Vortex OpenSplice; ignored otherwise. Example value: /opt/ADLINK/Vortex_v2/Device/VortexOpenSplice/6.10.3/HDE/x86_64.linux/etc
• LSST_DDS_DOMAIN_ID (optional) is used to set the DDS domain: an integer. ADLink recommands the domain ID be in range 0 <= ID <= 230 for “maximum interoperability” (based on case 00020758 asking about a possible error in their configuration guide, which recommended 0 < ID < 230). DDS participants in different domains cannot see each other at all, and all telescope and site nodes use the default domain, so you should rarely have any reason to set this. If supported, it will be part of the OpenSplice configuration file pointed to OSPL_URI.
• OSPL_HOME (required) directory of the Vortex OpenSplice software. This directory should contain subdirectories bin, include, lib, etc. Example: /opt/OpenSpliceDDS/V6.9.0/HDE/x86_64.linux.
• OSPL_MASTER_PRIORITY (optional) is used to set the Master Priority in ts_sal 4.2 and later. Nodes with higher Master Priority are more eager to become master (the primary source of late joiner data). Ties are broken by systemId, a random number handed out when a node is created. Every time a new node takes over as master, the entire system is must be “aligned”, which is expensive, so it is best to assign the highest Master Priority to one or a few nodes that will be created early. Valid values are 0-255. 0 is used for SAL Scripts, because they should never be master. 256 means “use the legacy method for choosing the master”; do not use it. A default value is used if this environment variable is not specified, and that default is guaranteed to be >0 and <255. OSPL_MASTER_PRIORITY is specific to Vera Rubin Observatory. If supported (ts_sal 4.2 and later), it will be part of the OpenSplice configuration file pointed to OSPL_URI. Constant lsst.ts.salobj.MASTER_PRIORITY_ENV_VAR is available to make this easier to set from Python.
• OSPL_URI (required) points to the main DDS configuration file. Example: file:///home/saluser/tsrepos/ts_opensplice/OpenSpliceDDS/v6.9/HDE/x86_64.linux/etc/config/ospl.xml

Used by SalInfo:

• LSST_DDS_PARTITION_PREFIX (required): a prefix for DDS partition names. This is read by SalInfo so that different instances of SalInfo (thus different Remotes and Controllers) can communicate with different DDS partitions, even though all share the same Domain. See SalInfo for DDS partition name details.
• LSST_DDS_DOMAIN (deprecated): a deprecated alias for LSST_DDS_PARTITION_PREFIX that is used if LSST_DDS_PARTITION_PREFIX is not defined.
• LSST_DDS_HISTORYSYNC (optional): time limit (sec) for waiting for historical (late-joiner) data. If, and only if, you are running DDS without a durability service then set this negative to avoid waiting for historical data.

Used by AsyncS3Bucket:

• S3_ENDPOINT_URL: The endpoint URL for the S3 server, e.g. http://foo.bar:9000. You must specify a value in order to use an S3 service that is not part of Amazon Web Services (AWS). Eventually we hope that endpoint_url can be defined in ~/.aws/config. Once that is supported you can leave this environment variable unset, and we can deprecate it.

## Other Configuration¶

In addition to the environment variables described above, you will need the following Python packages:

• ts_ddsconfig for OpenSplice DDS configuration.
• ts_idl for the IDL files that define SAL topic schemas, and associated enum modules.
• ts_sal to build IDL files and to run ts_salobj unit tests.

DDS topic schemas are defined by OMG IDL files, which are contained in the idl directory of the ts_idl package. You may generate new IDL files using the make_idl_files.py command-line script in the ts_sal package.