merGeo: Integration Platform For Linked Data Management Tools

BSc thesis, available at: https://pergamos.lib.uoa.gr/uoa/dl/object/2075232

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Α) Installation notes

Due to some backend services, merGeo can only be supported on Linux systems. Follow the next steps and install the required applications/modules in order to successfully deploy merGeo on Tomcat.

1. Apache Tomcat (http://tomcat.apache.org/)

Apache Tomcat can be downloaded here: (https://tomcat.apache.org/download-90.cgi), depends on the operating system and its distribution. You can find installation instructions here (http://tomcat.apache.org/tomcat-9.0-doc/setup.html). After installation, you can point your browser at this location (http://localhost:8080/) to verify that the deployment succeeded. You can find information of how-to deploy an application here: (http://tomcat.apache.org/tomcat-9.0-doc/deployer-howto.html).

Important! In order to create folders and edit files inside Tomcat location, we have to change the permissions to Tomcat folder and to all its sub-folders. This can be done through the graphical interface of our operating system, on “tomcat” folder:

Right-Click->Permissions and change everything to “Create and delete files”.

Otherwise, through command line you can run:

$> sudo chmod –R 777 /tomcat

(We know it’s not quite safe to change the permissions in 777, this is going to be fixed in the next updates)

2. Installing PostgreSQL and PostGIS

1 -- Install PostgreSQL 9.0 or higher. More information can be found at http://www.postgresql.org/download/

$> sudo apt-get install postgresql-9.5

2 -- Install PostGIS 2.2 or higher. More information can be found at http://postgis.refractions.net/download/

$> sudo apt-get install postgresql-9.5-postgis-2.2

3 -- Provide a password for default user (postgres)

$> sudo -u postgres psql -c "ALTER USER postgres WITH PASSWORD 'postgres';"

Creating a spatially enabled database

Spatially-enabled databases permit the use of spatial function calls. MonetDB creates spatially-enabled databases by default if you have enabled the geom module. More information on how to create a spatially-enabled database in PostGIS can be found at http://postgis.refractions.net/docs/.

1 -- Set postgis-2.2 path.

$> POSTGIS_SQL_PATH=`pg_config --sharedir`/contrib/postgis-2.2

2 -- Create the spatial database that will be used as a template.

$> createdb -E UTF8 -T template0 template_postgis -U postgres

3 -- Add PLPGSQL language support.

$> createlang -d  template_postgis plpgsql -U postgres

Load the PostGIS SQL routines

$> psql -d template_postgis -f $POSTGIS_SQL_PATH/postgis.sql                                                                
$> psql -d template_postgis -f $POSTGIS_SQL_PATH/spatial_ref_sys.sql

Allow users to alter spatial tables

$> psql -d template_postgis -c "GRANT ALL ON geometry_columns TO PUBLIC;"
$> psql -d template_postgis -c "GRANT ALL ON geography_columns TO PUBLIC;"
$> psql -d template_postgis -c "GRANT ALL ON spatial_ref_sys TO PUBLIC;"

Perform garbage collection

$> psql -d template_postgis -c "VACUUM FULL;"
$> psql -d template_postgis -c "VACUUM FREEZE;"

Allows non-superusers the ability to create from this template

$> psql -d postgres -c "UPDATE pg_database SET datistemplate='true' WHERE datname='template_postgis';"
$> psql -d postgres -c "UPDATE pg_database SET datallowconn='false' WHERE datname='template_postgis';"

Create a spatially-enabled database named endpoint

$> createdb endpoint -T template_postgis

<!> Notice: In some psql commands you may need to add: –U postgres <!>

<!> Notice 2: In WebController.java, in line 35, you have to change the variable:

// TODO - Change this folder to one folder inside your Computer where the Strabon App will be already deployed
// so as to take its content and use it as the default deploying endpoint application
    
public static String endpointFolder = "/opt/tomcat/endpoint/strabon-endpoint-3.3.2-SNAPSHOT/."

B) Additional info

Default Strabon Endpoint info:

Strabon Endpoint version    : strabon-endpoint-3.3.2-SNAPSHOT.war
Hostname    ("localhost");
Port        ("5432");
Dbengine    ("postgis");
Dbname      ("endpoint");
Username    ("postgres");
Password    ("postgres");
Cp_username ("endpoint");
Cp_password ("3ndpo1nt");