SeisComP plugins

Scope

This chapter describes the general use of plugins in SeisComP.

Overview

Plugins expand the functionality of applications. They are C++ shared object libraries which are dynamically loaded at runtime into an application.

Typical plugins provide access to:

• Databases

• Recordstream implementations

• Locator routines

• Amplitude and magnitude types

• Waveform quality.

The plugin files themselves are located in share/plugins.

By just loading a plugin an application does not change it’s way to function magically. Common plugins just implement a certain interface (see e.g. messaging or RecordStream) and exhibit that functionality by adding a new entry to the internal interface factory. As an example an application makes use of interface DatabaseInterface. Technically it creates a new object implementing a certain interface by calling the C++ method:

db = DatabaseInterface::Create("mysql");

Without having a plugin loaded the returned object will be NULL or to put it in other words, there is not implementation for mysql available.

Once the plugin dbmysql is loaded into the application, an implementation for type mysql is added and will be available to the application. It is still required for the application to explicitly ask for a particular interface. That is most likely left to the user by adding a corresponding configuration option to the configuration file.

That means, if an application loads two plugins, e.g. dbmysql and dbpostgresql that does not mean that it will not read from two database at a time. It means the user has now the option to either use a MySQL database or a PostgreSQL database. He still needs to make his choice in the configuration file.

Trunk plugins are only supported as shared object libraries and therefore are required to be written in C++. Implementations for all available interfaces can be added. An incomplete list of SeisComP C++ interfaces:

• Messaging

• Database

• RecordStream

• Record formats

• Map projections

• Time domain filters

• Importer

• Exporter

• Amplitude processors

• Magnitude processors

This is just a subset of available extensible interface factories. The emphasized entries refer to the factories which are most commonly extended.

Location and Configuration

Plugins are located in $SEISCOMP_ROOT/share/pugins. In order to make a plugins available for a module it must be added to the configuration of plugins of the global parameters of a module or in Module Configuration.

Configuring plugins with the name of a plugin will let the exclusively use this plugin and no other ones, e.g. default plugins. Example:

plugins = evrc

In order to add a plugin to the default plugins or plugins loaded by before, e.g. by the global configuration, load these