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bounding box MBR, and tile size and format. Click Submit to create the map tile layer. You can also define the map cache properties in XML by clicking XML.
■
Managing map tile layers for Oracle Maps
Click Manage Map Caches, then Manage. Then do any of the following: To refresh map caches, click Refresh.
To edit a map tile layer, under Existing Map Tile Layers, select the data source. At the cache level, you can delete the cache, view cache details, and place the cache
offline or online. At the tile level, you can perform operations such as clearing, prefetching, and refreshing the tiles, specifying the zoom level, and specifying the
bounding box.
To check the status of a request, enter the request ID and click Submit.
1.6 Oracle Real Application Clusters and MapViewer
When the database is an Oracle Real Application Cluster Oracle RAC, you cannot create MapViewer data sources that directly connect to it. Instead, MapViewer must
connect to an Oracle RAC database through the data source of the J2EE container. To enable MapViewer to connect to an Oracle RAC database, you must do the following:
1.
Create a JDBC data source that connects to the Oracle RAC database at the OC4J level, as explained in
Section 1.6.1 . The data source can then be used by
applications such as MapViewer through JNDI lookup.
2.
Configure the OC4J instance so that it publishes the JNDI location of the Oracle RAC data source so that MapViewer can access it, as explained in
Section 1.6.2 .
3.
Define a MapViewer data source that reuses the container data source through the JNDI location in its configuration file, as explained in
Section 1.6.3 .
4.
Restart MapViewer.
1.6.1 Creating a Container Oracle RAC Data Source
With either a full Oracle Fusion Middleware or standalone OC4J installation, use Oracle Enterprise Manager to create a data source that connects to the Oracle RAC
database. For example, if using Oracle Application Server release 10.1.3 or later, you can log in to Enterprise Manager, navigate to the OC4J instance that contains the
MapViewer server, click the Administration tab, and click the JDBC Resources Go to Task
link to start creating a new data source, as shown in Figure 1–12
.
Introduction to MapViewer 1-39
Figure 1–12 Administration Tab for Creating Oracle RAC Container Data Source
For more information about creating a data source to connect to an Oracle RAC database, see Oracle Application Server Administrators Guide.
After creating the data source, you should test the connection using Enterprise Manager, by clicking the Test Connection icon for the connection, as shown in
Figure 1–13 .
Figure 1–13 Testing the Connection for the Data Source
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Be sure to note the JNDI Location value which is jdbcmvdemods in Figure 1–13
, because you will need this value when you create the MapViewer data source
explained in Section 1.6.3
.
1.6.2 Adding the userThreads Option to the OC4J Container
You must specify the userThreads option to tell the OC4J instance to publish the JNDI locations, such as the one for the newly created data source, to all user threads.
Without this option, MapViewer cannot access the JNDI location that references the data source, because by default OC4J makes such JNDI locations available only to the
main thread within which OC4J itself is running. MapViewer, however, is started in a separate user thread.
The mechanism for specifying the userThreads option depends on whether you re using a standalone OC4J instance or a full Oracle Fusion Middleware installation.
1.6.2.1 Adding userThreads for a Standalone OC4J Instance
With a standalone OC4J instance, you must start the OC4J instance with the -userThreads option, as in the following example:
java –jar oc4j.jar –userThreads
1.6.2.2 Adding userThreads for a Full Oracle Fusion Middleware 10gR3 Installation
With a full Oracle Fusion Middleware 10gR3 installation, the Java startup parameters are defined in the OAS_HOMEopmnconfopmn.xml configuration file. opmn is
the master process that starts and stops various Oracle Fusion Middleware 10gR3 components, such as OC4J instances.
In this file you can specify Java JVM startup parameters for the OC4J instance running MapViewer. For example, if you deployed MapViewer to the home OC4J instance, add
the text -Doc4j.userThreads=true, as shown in the following example:
ias-component id=OC4J process-type id=home module-id=OC4J status=enabled
module-data category id=start-parameters
data id=java-options value=-server -Djava.security.policy=ORACLE_HOMEj2eehomeconfigjava2.policy
-Djava.awt.headless=true -Dhttp.webdir.enable=false -Doc4j.userThreads=true
category ...
After editing and saving the opmn.xml file, you must restart the OC4J instance for the userThreads option to take effect; and if that does not work, restart Oracle Fusion
Middleware 10gR3. For information about restarting the OC4J instance or Oracle Fusion Middleware 10gR3, see Oracle Application Server Administrators Guide.
1.6.3 Creating a MapViewer Data Source
Create a new MapViewer data source that enables it to connect to the Oracle RAC database, by using the container_ds attribute of the MapViewer data source.
Specifically, you must add an entry like the following in the mapViewerConfig.xml file:
map_data_source name=mvdemo container_ds=jdbcmvdemods
number_of_mappers=7
Introduction to MapViewer 1-41
In the preceding example:
■
The name attribute specifies the MapViewer data source name, which is needed for map requests.
■
The value for the container_ds attribute must match the JNDI Location string that you noted when you created the container Oracle RAC data source see
Section 1.6.1 .
■
The number_of_mappers attribute specifies the maximum number of supported concurrent map requests that can target this data source.
For more information about the name and number_of_mappers attributes, see Section 1.5.2.14
. After adding the data source definition, you must restart MapViewer to have the new
data source created. After you do this, whenever you request a map from this data source, MapViewer obtains the necessary database connections from the container
before proceeding.
1.7 High Availability and MapViewer
MapViewer users can benefit from the high availability features of Oracle Database and Oracle Fusion Middleware.
1.7.1 Deploying MapViewer on a Multiprocess OC4J Instance
You can safely deploy MapViewer in an OC4J instance of Oracle Fusion Middleware that has multiple processes. Oracle Fusion Middleware lets you configure the number
of actual processes JVMs that can be started for each OC4J instance. On a multiprocessor host, starting multiple processes for a single OC4J can better utilize the
system resources. Releases of MapViewer before 10g Release 2 10.1.2 could not take advantage of this feature and thus could not be deployed on such OC4J instances.
When MapViewer is deployed to an OC4J instance with multiple processes, each process has a MapViewer server running inside it. These MapViewer servers all reside
on the same host but in different Java processes. Map requests sent to this OC4J instance are automatically dispatched to the individual MapViewer servers. Each
MapViewer server generates map image files according to a unique naming scheme, with the names coordinated when the different MapViewer servers are first started
that is, when the containing OC4J instance is started. This avoids the possibility of two MapViewer servers generating map files in the same sequence with the same file
names.
1.7.2 Deploying MapViewer on a Middle-Tier Cluster
OC4J instances in different Oracle Fusion Middleware 10gR3 installations can be clustered into an island. This provides a middle-tier fail-safe option. MapViewer can
be deployed to an OC4J island. You must take care, however, about how the generated
Note: This section is intended for advanced users who want to take
full advantage of the high availability features of Oracle Fusion Middleware with MapViewer. You must have a strong understanding
of high availability features, which are described in Oracle Fusion Middleware High Availability Guide.
