7.2.4 Registering Java Functions

This section explains how to register Java functions and store Java applications.

This procedure must be performed each time a Java function is created.

Registering Java Functions

Connect to the database
As the instance administrator, connect to the database that corresponds to the container that was created using the psql command or pgAdmin.
Register the function in the database
Java functions run on sessions that are not dependent on the caller session. To operate a Java function using the caller session, use the SET statement to set the plextjava.separate_session parameter to "off" and then register it.
```
SET plextjava.separate_session=off
```
This section explains the CREATE FUNCTION statement used when registering a function in the database.
Syntax:
```
CREATE  [ OR  REPLACE ]  FUNCTION
    name  ( [ IN ] argtype [, ...] )
    [ RETURNS  rettype ]
    AS  'definition'
    LANGUAGE  lang_name
```
name
Specify the name of the Java function.
The name of the Java function does not need to match the name of the Java application method.
A qualified schema name can be used. Create the schema in advance.
argtype
Specify the data type of the Java function argument.
rettype
Specify the data type of the Java function return value.
definition
Specify "packageName.className. methodName" or "className.methodName" of the Java application.
Do not specify the method arguments as they will be invalid.
lang_name
Specify "plextjavau".
Example
If the schema name is "javatest", the Java function name is "java_addOne", and the "packageName.className.methodName" of the Java application is "org.postgresql.plextjava.example.Parameters.addOne"
```
db01=# CREATE FUNCTION javatest.java_addOne(INTEGER)
                   RETURNS INTEGER
                   AS 'org.postgresql.plextjava.example.Parameters.addOne'
                   LANGUAGE plextjavau;
```
See
- Refer to "Relationship between the Java Function Data Type and Application Data Type" in the Application Development Guide for information on data types.
- Refer to "CREATE FUNCTION" under "Reference" in the PostgreSQL Documentation for details.
Set privileges for users connecting to the database
Grant privileges to users for database objects (such as tables, columns, and views) that will be accessed when accessing the database from the Java application. Use the GRANT statement to grant privileges.
Example
Grant privileges to user name "user01" to add data to table "table01"
```
db01=# GRANT INSERT ON table01  to user01;
```
Set privileges for Java functions
Grant execution privileges for Java functions to users who call Java functions. Use the GRANT statement to grant privileges.
Note
Grant execution privileges for a Java function only to users who have permission to access the resources accessed by that functions, otherwise the users may inadvertently be granted improper access to those resources via the function.
Example
Grant privileges to user "user04" for the Java function "java_addOne"
```
db01=# GRANT EXECUTE ON FUNCTION javatest.java_addOne(INTEGER) to user04;
```
Disconnect from the database.

See

Refer to "Reference" in the PostgreSQL Documentation for information on the GRANT statement.

Storing Java applications

Copy the Java application
Manually copy the Java application in jar format to the directory below.
```
domainRoot\plextjava\databaseName
```