Miscellaneous Configuration Options of Oracle REST Data Services

4 Miscellaneous Configuration Options of Oracle REST Data Services

This section explains how to configure Oracle REST Data Services for connecting to multiple databases for routing requests, and it refers to other documentation sources for other configuration information.

Note:

You must restart Oracle REST Data Services after making any configuration changes. For ensuring High Availability, Oracle recommends that you use a load balancer in front of multiple ORDS instances, so that rolling restarts can be achieved.

Topics:

Support for Oracle RAC Fast Connection Failover

Oracle REST Data Services support the Fast Connection Failover (FCF) feature of Oracle Real Application Clusters (Oracle RAC).

Oracle REST Data Services runs with the Universal Connection Pool (UCP) in all the Application Server environments that it supports, such as WebLogic, Tomcat. UCP in turn supports Fast Connection Failover . To enable FCF, Oracle Notification Service (ONS) must to be enabled. To enable ONS, add entries to the list of properties in the Oracle REST Data Services settings.xml configuration file as shown in the following code snippet:

<entry key="jdbc.enableONS">true</entry>
<entry key= "jdbc.ONSConfig">nodes=racnode1:4200,racnode2:4200\nwalletfile=/oracle11/onswalletfile</entry>

ONS is the messaging facility used to send the Fast Application Notification (FAN) events. When ONS is enabled, Oracle REST Data Services automatically enables FCF. To Enable specific FCF capabilities such as fail over or other advanced FCF capabilities such as load balancing, you need to add entries in the configuration file for the custom connection as shown in the following code snippet:

<entry key="db.connectionType">customurl</entry>
<entry key="db.customURL">jdbc:oracle:thin:@(DESCRIPTION=(FAILOVER=ON)(ADDRESS_LIST=
		(LOAD_BALANCE=ON)(ADDRESS=(PROTOCOL=TCP)(HOST=prod_scan.example.com)(PORT=1521)))
		(CONNECT_DATA=(SERVICE_NAME=ISPRD)))|</entry>

After updating the defaults.xml configuration file, Oracle REST Data Services need to be restarted for the changes to take effect.

UCP supports Fast Connection Failover. FCF listens and responds to FAN events to deal with the following two scenarios:

Unplanned outages: When RAC detects an instance failure, it generates a FAN Down event which FCF picks up. FCF then terminates all connections to the failed instance and directs all future requests to the surviving RAC instances.
Planned outages: For instance, when a Database Administrator (DBA) wants to gracefully shut down a RAC instance for performing some maintenance activity. The instance shutdown generates a FAN Planned Down event which FCF picks up. FCF then directs all new requests to other RAC instances and drains or allows currently active transactions to complete.

Note:

Long running transactions may need to be terminated forcefully.

Configuring ORDS with Kerberos Setup

This section explains how ORDS can be configured to reference a Kerberos file-based ticket cache and make a connection to an Oracle Database Kerberos authenticated user with the ORDS Runtime Privilege.

To configure ORDS with Kerberos setup, perform the following steps:

Create a new user using external authentication
Set up the environment variables
Provide a valid ticket
Add ORDS pool settings

Create a New User using External Authentication

Create a new Oracle Database user using external authentication (Kerberos) and provision the user as an ORDS runtime user.

CREATE USER ORDS_PUBLIC_KRBUSER IDENTIFIED EXTERNALLY AS '<kerberos_principal_name>';
GRANT CONNECT TO "ORDS_PUBLIC_KRBUSER";
BEGIN
     ORDS_ADMIN.PROVISION_RUNTIME_ROLE(
         p_user => 'ORDS_PUBLIC_KRBUSER',
         p_proxy_enabled_schemas => TRUE);
END;
/

Set up the Environment Variables
Note:
Ensure that you have a Kerberos configuration file krb5.conf and a file-based ticket cache
Set up the following environment variables:
```
export KRB5_CONFIG=<path to krb5.conf>
export KRB5CCNAME=<path to credential cache>
```
Provide a Valid Ticket
Provide a valid ticket in the ticket cache to get authenticated when connecting to the Oracle Database.
kinit <principal>
Add ORDS Pool Settings
Add the following pool settings to the pool.xml file using the ticket in the ticket cache:
```
<entry key="oracle.net.authentication_services">(KERBEROS5)</entry>
<entry key="oracle.net.kerberos5_mutual_authentication">true</entry>
```
Run the following command when ORDS is starting up:

-Djava.security.krb5.conf="<path to krb5.conf>"

For example, to run ORDS in standalone mode with Kerberos, execute the following command:

java -Djava.security.krb5.conf=$KRB5_CONFIG -jar ords.war

Authorizing Oracle REST Data Services to Access Oracle Data Guard Protected Users

To access the database schema objects that are protected by an Oracle Data Vault Realm, it is necessary to grant a proxy user authorization to the Oracle REST Data Services Public User.

The following example authorizes the Oracle REST Data Services Public User, ORDS_PUBLIC_USER to proxy the database HR user:

begin
  DBMS_MACADM.AUTHORIZE_PROXY_USER('ORDS_PUBLIC_USER','HR');
end;
/

Configuring REST-Enabled SQL Service Settings

This section explains how to configure the REST- Enabled SQL service.

Note:

Enabling the REST- Enabled SQL service enables authentication against the Oracle REST Data Service enabled database schemas. This makes the database schemas accessible over HTTPS, using the database password. Oracle highly recommends that you provide strong secure database passwords

REST- Enabled SQL service is a feature of Oracle REST Data Service. By default, the REST Enabled SQL service is turned off. To enable the REST- Enabled SQL service and the REST- Enabled SQL Export service, perform the following steps:

Run the following command:
ords --config <configuration_folder> config [--db-pool <pool_name>] set restEnabledSql.active true
Restart Oracle REST Data Services.

Configuring the Maximum Number of Rows Returned from a Query

To configure maximum number of rows returned from a query, perform the following steps:

Run the following command:
ords --config <configuration_folder> config set [--db-pool <pool_name>] misc.pagination.maxRows <number>

Note:
The default value for misc.pagination.maxRows is 10000.
Restart Oracle REST Data Services.

Configuring ICAP Server Integration for Virus Scan

This section explains how to configure ORDS to integrate with ICAP server for virus scan.

ORDS PL/SQL gateway supports the offloading of virus scanning responsibilities to an Internet Content Adaptation Protocol (ICAP) compliant virus scan server when the files are uploaded. The hostname and port of the virus scan server is specified in the icap.server, icap.port, and icap.secure.port global configuration properties.

APEX uses ORDS PL/SQL gateway. Once configured, this ICAP integration is also applied to file uploads in APEX.

To configure ORDS to integrate with ICAP server, perform the following steps:

Run the following command:
ords --config <configuration_folder> config [--db-pool <pool_name>] set icap.port <number> ords --config <configuration_folder> config [--db-pool <pool_name>] set icap.server <name_or_ip>
Restart Oracle REST Data Services.

ICAP server must support the following requirements:

ICAP version 1.0
Antivirus service named AVSCAN
Antivirus service that supports action=SCAN
Previews of at least 4 bytes
Return header named X-Infection

Once configured, when a file is uploaded through PL/SQL Gateway, ORDS makes a request similar to the following:

RESPMOD icap://<icap_server>:<icap_port>/AVSCAN?action=SCAN ICAP/1.0
Host: <icap_server>:<icap_port>
Preview: 4
Allow: 204
Encapsulated: req-hdr=0 res-hdr=153 res-body=200

Configuring the Custom Error Pages

This section explains how to configure a custom error page instead of the error page generated by Oracle REST Data Services.

To configure a custom error page,

Run the following command:

ords --config /path/to/conf config set error.externalPath /path/to/error/pages/folder/

Where:

/path/to/error/pages/folder is the path to a folder containing files that define the error pages. The files are stored in {status}.html format. Where, {status} is the HTTP status code for which you want to create a custom error page.
Restart Oracle REST Data Services

Example 4-1 Configuring custom error page for “HTTP 404” status code

To configure a custom error page for the “HTTP 404 – Not Found” status, perform the following steps:

Create a file named 404.html.
Save it under /usr/local/share/ords/error-pages/ folder.
Configure the error.externalPath parameter to point to /usr/local/share/ords/errro-pages/ folder.
Restart Oracle REST Data Services.

Managing ORDS Administrator Privilege

Access to the ORDS_ADMIN PL/SQL package is provisioned through the ORDS_ADMINISTRATOR_ROLE. This role can be provisioned through the ORDS_ADMIN package to create additional ORDS administrators.

Provisioning ORDS_ADMINISTRATOR_ROLE to a User

This section describes how to provision ORDS_ADMINISTRATOR_ROLE role to a user.

You can provision ORDS_ADMINISTRATOR_ROLE role to a user by using either the database GRANT command or through the ORDS_ADMIN.PROVISION_ADMIN_ROLE PL/SQL method (as an ORDS Administrator).

Example 4-2 Using Grant command

GRANT ORDS_ADMINISTRATOR_ROLE TO HR_ADMIN;

Example 4-3 Using ORDS_ADMIN package method

BEGIN
  ORDS_ADMIN.PROVISION_ADMIN_ROLE(
    p_user => 'HR_ADMIN');
END;
/

Unprovisioning ORDS_ADMINISTRATOR_ROLE from a User

This section describes how to unprovision ORDS_ADMINISTRATOR_ROLE from a user.

As an ORDS administrator, you can unprovision ORDS_ADMINISTRATOR_ROLE from a user by either using the database REVOKE command or through the ORDS_ADMIN.UNPROVISION_ROLES PL/SQL method.

Example 4-4 Using REVOKE command

REVOKE ORDS_ADMINSTRATOR_ROLE FROM HR_ADMIN;

Example 4-5 Using ORDS_ADMIN package method

BEGIN
  ORDS_ADMIN.UNPROVISION_ROLES(
    p_user => 'HR_ADMIN',
    p_administrator_role => TRUE);
 END;
 /

Managing ORDS Runtime Privilege

The ORDS_RUNTIME_ROLE database role allows a user to act as a runtime user. A runtime user can manage and configure the runtime connection resources required by an ORDS service instance. The ORDS_PUBLIC_USER is one such database user. When additional runtime users are provisioned, it is possible to configure discrete ORDS service instances with different destination addresses and connection pools but hosted on the same Oracle database container.

It is recommended not to re-use a runtime user for any other purpose as it accumulates the grants necessary to proxy to other users. A runtime user only requires the CREATE SESSION privilege in addition to the ORDS_RUNTIME_ROLE role.

Provisioning ORDS_RUNTIME_ROLE to a User

This section describes how to provision ORDS_RUNTIME_ROLE role to a user.

As an ORDS administrator, you can provision ORDS_RUNTIME_ROLE role to a user by using either the database GRANT command or through the ORDS_ADMIN.PROVISION_ADMIN_ROLE PL/SQL method.

Example 4-6 Using Grant command

GRANT ORDS_RUNTIME_ROLE TO ORDS_PUBLIC_USER_2;

Example 4-7 Using ORDS_ADMIN package method

BEGIN
  ORDS_ADMIN.PROVISION_RUNTIME_ROLE(
    p_user => 'ORDS_PUBLIC_USER_2');
END;
/

Unprovisioning ORDS_RUNTIME_ROLE from a User

This section describes how to unprovision the ORDS_RUNTIME_ROLE role from a user

As an administrator, you can unprovision the ORDS_RUNTIME_ROLE from a user, by either using the database REVOKE command or through the ORDS_ADMIN.UNPROVISION_ROLES PL/SQL method.

Example 4-8 Using REVOKE command

REVOKE ORDS_RUNTIME_ROLE FROM ORDS_RUNTIME_USER_2;

Example 4-9 Using ORDS_ADMIN package method

BEGIN
  ORDS_ADMIN.UNPROVISION_ROLES(
    p_user => 'ORDS_RUNTIME_USER_2',
    p_runtime_role => TRUE);
 END;
 /

Using OAuth2 in Non-HTTPS Environments

RESTful Services can be protected with the OAuth2 protocol to control access to nonpublic data. To prevent data snooping, OAuth2 requires all requests involved in the OAuth2 authentication process to be transported using HTTPS. The default behavior of Oracle REST Data Services is to verify that all OAuth2 related requests have been received using HTTPS. It will refuse to service any such requests received over HTTP, returning an HTTP status code of 403 Forbidden.

This default behavior can be disabled in environments where HTTPS is not available as follows:

Locate the folder where the Oracle REST Data Services configuration is stored, for example: /path/to/conf
Execute the following command:
ords --config /path/to/conf config set security.verifySSL false
Restart Oracle REST Data Services if it is running.

Note that it is only appropriate to use this setting in development or test environments. It is never appropriate to use this setting in production environments because it will result in user credentials being passed in clear text.

Note:

Oracle REST Data Services must be restarted after making configuration changes. See your application server documentation for information on how to restart applications.

Configuring ORDS Metadata Cache

This section explains how to configure the ORDS Metadata Cache.

As the number of REST services grow, the overhead of querying the database for corresponding metadata can have a negative impact on the overall service performance and throughput. Overtime, the queries for ORDS_METADATA views take longer time to complete. These queries are executed for every request. The ORDS metadata cache can help improve the overall response time for REST services when the number of services grow to an extent that querying the ORDS_METADATA views for every request becomes expensive. The ORDS metadata cache can temporarily hold a copy of privilege and module metadata in memory to reduce the number of database queries performed when a REST service request is received. The cache is disabled by default so that the changes made to the metadata are applied immediately for any subsequent request.

Table 4-1 Configuration Properties for ORDS Metadata Cache

Property	Data Type	Default Value	Description
`cache.metadata.enabled`	Boolean	`false`	Specifies a setting to enable or disable metadata caching.
`cache.metadata.timeout`	Duration	`30s`	Specifies a setting that determines for how long the metadata record remains in the cache. Longer the duration, it takes longer to view the applied changes.