Module org.apache.sis.referencing
Package org.apache.sis.referencing.factory.sql

Class InstallationScriptProvider

Object
InstallationResources
InstallationScriptProvider
public abstract class InstallationScriptProvider extends InstallationResources
Provides SQL scripts needed for creating a local copy of a dataset. This class allows Apache SIS users to bundle the EPSG or other datasets in their own product for automatic installation when first needed. Implementations of this class are discovered automatically by EPSGFactory if they are declared in module-info​.java as providers of the org​.apache​.sis​.setup​.Installation­Resources service.

How this class is used

The first time that an EPSGData­Access needs to be instantiated, EPSGFactory verifies if the EPSG database exists. If it does not, then:
  1. EPSGFactory​.install(Connection) searches for the first instance of Installation­Resources (the parent of this class) for which the set of authorities contains "EPSG".
  2. The license may be shown to the user if the application allows that (for example when running as a console application).
  3. If the installation process is allowed to continue, it will iterate over all readers provided by open­Script(String, int) and execute the SQL statements (not necessarily verbatim; the installation process may adapt to the target database).
Since:
0.7

  • Field Details

    • PREPARE

      protected static final String PREPARE
      A sentinel value for the content of the script to execute before the SQL scripts provided by the authority. This is an Apache SIS build-in script for constraining the values of some VARCHAR columns to enumerations of values recognized by EPSGData­Access. Those enumerations are not required for proper working of EPSGFactory, but can improve data integrity.
      See Also:

    • FINISH

      protected static final String FINISH
      A sentinel value for the content of the script to execute after the SQL scripts provided by the authority. This is an Apache SIS build-in script for creating indexes or performing any other manipulation that help SIS to use the dataset. Those indexes are not required for proper working of EPSGFactory, but can significantly improve performances.
      See Also:

  • Constructor Details

    • InstallationScriptProvider

      protected InstallationScriptProvider(String authority, String... resources)
      Creates a new provider which will read script files of the given names in that order. The given names are often filenames, but not necessarily (it is okay to use those names only as labels).
      Typical argument values
      Authority Argument values
      EPSG {PREPARE, "EPSG_Tables.sql", "EPSG_Data.sql", "EPSG_FKeys.sql", FINISH}
      Parameters:
      authority - the authority (typically "EPSG"), or null if not available.
      resources - names of the SQL scripts to read.
      See Also:

  • Method Details

    • getAuthorities

      public Set<String> getAuthorities()
      Returns the identifiers of the dataset installed by the SQL scripts. The values currently recognized by SIS are:
      • "EPSG" for the EPSG geodetic dataset.
      The default implementation returns the authority given at construction time, or an empty set if that authority was null. An empty set means that the provider does not have all needed resources or does not have permission to distribute the installation scripts.
      Specified by:
      get­Authorities in class Installation­Resources
      Returns:
      identifiers of SQL scripts that this instance can distribute.

    • getResourceNames

      public String[] getResourceNames(String authority) throws IOException
      Returns the names of all SQL scripts to execute. This is a copy of the array of names given to the constructor. Those names are often filenames, but not necessarily (they may be just labels).
      Specified by:
      get­Resource­Names in class Installation­Resources
      Parameters:
      authority - the value given at construction time (e.g. "EPSG").
      Returns:
      the names of all SQL scripts to execute.
      Throws:
      Illegal­Argument­Exception - if the given authority argument is not the expected value.
      IOException - if fetching the script names required an I/O operation and that operation failed.

    • openScript

      public BufferedReader openScript(String authority, int resource) throws IOException
      Returns a reader for the SQL script at the given index. Contents may be read from files in a local directory, or from resources in a JAR file, or from entries in a ZIP file, or any other means at implementer choice. The Buffered­Reader instances shall be closed by the caller.

      EPSG case

      In the EPSG dataset case, the iterator should return Buffered­Reader instances for the following files (replace <version> by the EPSG version number and <product> by the target database) in same order. The first and last files are provided by Apache SIS. All other files can be downloaded from https://epsg.org/.
      1. Content of PREPARE, an optional data definition script that define the enumerations expected by EPSGData­Access.
      2. Content of "EPSG_<version>.mdb_Tables_<product>.sql", a data definition script that create empty tables.
      3. Content of "EPSG_<version>.mdb_Data_<product>.sql", a data manipulation script that populate the tables.
      4. Content of "EPSG_<version>.mdb_FKeys_<product>.sql", a data definition script that create foreigner key constraints.
      5. Content of FINISH, an optional data definition and data control script that create indexes and set permissions.
      Implementers are free to return a different set of scripts with equivalent content.

      Default implementation

      The default implementation invokes open­Stream(String) – except for PREPARE and FINISH in which case an Apache SIS build-in script is used – and wrap the result in a Line­Number­Reader. The file encoding is UTF-8 (the encoding used in the scripts distributed by EPSG since version 9.4).
      Specified by:
      open­Script in class Installation­Resources
      Parameters:
      authority - the value given at construction time (e.g. "EPSG").
      resource - index of the SQL script to read, from 0 inclusive to get­Resource­Names(authority)​.length exclusive.
      Returns:
      a reader for the content of SQL script to execute.
      Throws:
      Illegal­Argument­Exception - if the given authority argument is not the expected value.
      Index­Out­Of­Bounds­Exception - if the given resource argument is out of bounds.
      File­Not­Found­Exception - if the SQL script of the given name has not been found.
      IOException - if an error occurred while creating the reader.

    • openStream

      protected abstract InputStream openStream(String name) throws IOException
      Opens the input stream for the SQL script of the given name. This method is invoked by the default implementation of open­Script(String, int) for all scripts except PREPARE and FINISH.

      Example 1

      if this Installation­Script­Provider instance gets the SQL scripts from files in a well-known directory and if the names given at construction time are the filenames in that directory, then this method can be implemented as below: 
           protected InputStream openStream(String name) throws IOException {
         return Files.newInputStream(directory.resolve(name));
     }

      Example 2

      if this Installation­Script­Provider instance rather gets the SQL scripts from resources bundled in the same JAR files than and in the same package, then this method can be implemented as below: 
           protected InputStream openStream(String name) {
         return MyClass.getResourceAsStream(name);
     }
      Parameters:
      name - name of the script file to open. Can be null if the resource is not found.
      Returns:
      an input stream opened of the given script file.
      Throws:
      IOException - if an error occurred while opening the file.