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Chapter 3 Clusters

Netscape Application Server: Process Automation Edition (PAE) associates a configuration directory, a corporate user directory, a relational database, an Enterprise Server and one or more Netscape Application Servers into a cluster. Applications are deployed to a cluster and are copied to all Netscape Application Servers in the cluster. All applications in a cluster access the same set of shared components: database, directories, and Netscape Application Servers.

Each Netscape Application Server that is part of PAE is associated with one and only one particular cluster. When designers deploy a new application, they must identify which cluster it belongs to. PAE replicates all applications across all Netscape Application Servers in a cluster and the administrator can manage all applications from any Process Administrator in the cluster.

This chapter discusses these topics:


About Clusters
A cluster associates these components:

The initial cluster includes one Netscape Application Server. Later you can join additional Netscape Application Servers to an existing cluster as needed. Note that each Netscape Application Server can only belong to one cluster, and you must have a cluster available in order to use PAE.

Each PAE-enabled Netscape Application Server has its Process Administrator. You can use any Process Administrator and get the same view of a cluster because all applications are fully replicated to all Netscape Application Servers in a cluster.

As the PAE administrator, you can perform these tasks that relate to clusters:


Creating a Cluster
You administer PAE through the Process Administrator interface on an Enterprise Server. The first time you access Process Administrator's home page after installing PAE, Process Administrator detects that this Netscape Application Server is not yet associated with any cluster and immediately prompts you to create or join a cluster.

Note. The database user who is creating the cluster and all the other database users for applications (if any) should be ordinary users with create table/view permissions. None of them should be the dbo of the database.

To create a cluster, follow these steps:

  1. Launch your web browser.

  2. Go to your local Process Administrator's home page at

    3. http://yourServer/Administrator.apm

    This initializes Process Administrator and displays the Create or Join Cluster page. This step may take longer the first time you initialize Process Administrator after installing or restarting your server.

    Figure 3.1    The Create or Join Cluster page

  3. Click the "Create a New Cluster" link. This displays the Create Cluster page.

  4. Enter information about these components (For details, see the next section, New Cluster Information):

  5. Click Create Cluster when you are done.

    6. A series of diagnostic messages are displayed onscreen as the cluster is created. The last few lines contain instructions for modifying the Process Builder preferences.ini file.

  6. Copy the lines from the onscreen messages and paste them into the preferences.ini file. This file identifies to the Process Builder which Directory Server to use as the corporate user directory and where one or more clusters are located in the configuration directory. You need to do this before a designer can access this cluster from Process Builder.

    7. The Process Builder's preferences.ini file is located in the Process Builder root folder. This is the serverRoot/builder folder by default.


Once you've completed these steps, designers can deploy applications to a cluster.

New Cluster Information
The administrator must provide information about a new cluster. The only general restriction is that you cannot use double quotation marks (").

Figure 3.2    The Create Cluster page

 General Cluster Information

Cluster DN. The full distinguished name for your cluster. That is, the directory path for the cluster data. For example, cn=PM Cluster, o=NetscapeRoot. For more information about what LDAP attributes to enter here, see Directory Server Terms and Attributes.

Cluster Display Name. The display name you choose for your cluster. (Optional)

Description. A more meaningful description of the cluster. (Optional)

Figure 3.3    The directory information sections

 For further information on Directory Server terminology, see LDAP Terms.

Corporate User Directory Information

Host Name. The full host name for your corporate user directory. For example, corporate.airius.com.

Port Number. The port number for this directory. This defaults to 389 if you are using a Netscape Directory Server.

Base DN. The base distinguished name for the directory. For example, o=mcom.com. For more information about what LDAP attributes to enter here, see Directory Server Terms and Attributes.

Bind DN. (Optional) A valid user ID for a user of this directory. Leave this blank if PAE will be accessing the corporate directory as an anonymous user, which is the default. This allows read-only access.

Bind Password. (Optional) The password for this directory user. Leave this blank if PAE will be accessing the corporate directory as an anonymous user.

Figure 3.4    The configuration directory information section

 Configuration Directory Information

Host Name. The full host name for the Directory Server that you plan to use for your cluster and application configuration. For example, netscape.mcom.com.

Port Number. The port number for this directory, which defaults to 389 because this is a Netscape Directory Server.

Bind DN. A valid user ID for a user of this directory. This user must have full Directory Server privileges. For example, the installation default is cn=Directory Manager. For more information about what LDAP attributes to enter here, see Directory Server Terms and Attributes.

Bind Password. The password for this directory user.

Figure 3.5    The database information section

 Database Information

Database Server Type. The type of database you are using from the drop-down list. The choices are Oracle and Sybase.

Database Server Identifier. The database server name that you used when you installed the database. See Databases for more information about databases.

Database. For Oracle, leave this blank. For Sybase, use the name for the database that Process Administrator should use for creating tables and views. Note: On Sybase, this database must already exist.

User ID. The user ID for a valid user for this database. The user must have enough privileges to create tables and write to them.

Password. The password for this database user.

Note. If you are using Sybase on Windows NT, be sure that your DSQuery system environment is set to point to the correct sybase database server. If not, you will not be able to connect to the database.

Figure 3.6    The mail server information section

Mail Server Information

SMTP Server. (Optional) The mail server associated with the cluster.

SMTP Port. (Optional) The mail server port.

SMTP Reply To. (Optional) The reply-to address that appears on notifications sent to users by PAE applications. This address could be set to the PAE administrator's email address, so that the administrator would be the one handling any notification replies users send.

What Happens at Cluster Creation
When you create a new cluster, Process Administrator performs these operations:


Joining an Existing Cluster
The initial cluster includes one Netscape Application Server, but you can add additional servers at any time. Whenever you access Process Administrator for the first time from a new Netscape Application Server, Process Administrator checks which cluster that server belongs to. If it is not associated with a cluster, you are prompted to create a cluster or join one of the clusters that already exists.

To join an existing cluster, follow these steps:

  1. Go to your local Process Administrator's home page at http://yourServer/Administrator.apm. This displays the Create or Join Cluster page.

  2. Click the "Join an Existing Cluster" link. This displays the Join Cluster page.

  3. Enter information about these components (For details, see the next section, Existing Cluster Information):

  4. Click Join Cluster when you are done.
This operation creates a cluster definition file in the PAE folder on your local machine, at

serverRoot/bpm/PMExtensionManager.properties

Existing Cluster Information
The administrator must provide this information about an existing cluster. The only general restriction is that you cannot use double quotation marks (").

Figure 3.7    The Join Cluster page

 General Cluster Information

Cluster DN. The full distinguished name for your cluster. This is the directory path for the cluster data. For example, you could enter cn=PM Cluster, o=airius.com. For more information about what LDAP attributes to enter here, see Directory Server Terms and Attributes.

Configuration Directory Information

Host Name. The full host name for the Directory Server you plan to use for your cluster and application configuration. For example, sample.airius.com.

Port Number. The port number for this directory, which defaults to 389 because this is a Netscape Directory Server.

Bind DN. A valid user ID for a user of this directory. This user must have full Directory Server privileges. For example, you could enter cn=Directory Manager. For more information about what LDAP attributes to enter here, see Directory Server Terms and Attributes.

Bind Password. The password for this directory user.

What Happens at Cluster Joining
When you join an existing cluster, Process Administrator performs these operations:


Managing a Cluster
Process Administrator provides a main Cluster Management page at the Cluster Management tab.

This section includes these topics:

Changing Cluster Information
As server administrator, you can change some cluster information. You can change the cluster's name and description and you can change which corporate user directory you include in the cluster You cannot switch to use a different configuration directory or database in this cluster.

Note
If you change the corporate user directory, you may wish to update the Process Builder preferences.ini file with its LDAP URL. When Process Builder designers want to revise a deployed application, if they define the application's corporate directory as cluster-based, then the new user directory is automatically used. Designers need to check that their group and role assignments are still valid whenever the corporate user directory changes.

You must also change the corporate directory on your Enterprise Server to match that of the LDAP URL. You can change this in the dbswitch.conf file.

To change a cluster's information, follow these steps:

  1. Go to Process Administrator's home page at http://yourServer/Administrator.apm.

  2. Click the Cluster Management tab.

  3. Click the Change Cluster Information button. This displays the Change Cluster page.

  4. You can enter information about these cluster components (For details, see the next section, New Cluster Information):

  5. Click Apply Changes when you are done.

    6. Figure 3.9    The Change Cluster Information page

New Cluster Information
The administrator can modify the following information about an existing cluster. The only general restriction is that you cannot use double quotation marks (").

Cluster Name. The user-defined display name for the cluster.

Cluster Description. Text describing the cluster.

User Directory Host Name. The server name for the corporate user directory.

User Directory Port. The port number for the corporate user directory. This defaults to 389 for Netscape Directory Servers.

User Directory Base DN. The directory suffix (or "base DN") for the corporate user directory. For more information about what LDAP attributes to enter here, see Directory Server Terms and Attributes.

User Directory Bind DN. (Optional) The user ID for a user of this directory server. Leave this blank if PAE will be accessing the corporate directory as an anonymous user.

User Directory Bind Password. (Optional) The password for this directory user. Leave this blank if PAE will be accessing the corporate directory as an anonymous user.

Database Password. The database user's password.

SMTP Server Host. The mail server associated with the cluster.

SMTP Server Port. The mail server port.

SMTP Reply To. The reply-to address that appears on notifications sent to users by PAE applications. This address could be set to the PAE administrator's email address, so that the administrator would be the one handling any notification replies users send.

Accessing Directory Server Information
You can access Directory Server information by clicking one of the LDAP directory links on the Cluster Management page.

Viewing the Process Administrator Logs
You can view the Process Administrator logs by clicking the View Logs button.

Figure 3.10    A sample Process Administrator's log

 If Process Administrator is not available, you can access the Process Administrator logs (error.html, info.html, and security.html) at this location:

serverRoot/bpm/admin/logs

Unjoining From a Cluster
You can unjoin an application server from a cluster. This revises the entries in the configuration directory and removes the applications that are stored on that server machine.

To unjoin an application server from a cluster, follow these steps:

  1. Go to Process Administrator's home page at http://yourServer/Administrator.apm.

  2. Click the Cluster Management tab.

  3. Scroll down on the Cluster Information page.

  4. Click the "Unjoin from Cluster" button.
After you unjoin the server from its cluster, the next time you access Process Administrator, you will be prompted to create or join a cluster.

When you unjoin a server from a cluster, Process Administrator performs these operations:

Deleting a Cluster
You can delete a cluster that you no longer need. When you delete a cluster, Process Administrator deletes the cluster entry in the configuration directory and deletes the local application server copy of the PMExtensionManager.properties file. You can also choose to delete the database tables.

Note
When you delete a cluster, you need to inform designers using Process Builder that the cluster's entry in the Process Builder preferences.ini file is no longer valid. If they do not not want to delete the references to the cluster in the preferences.ini file, the cluster appears in their Select An Application window with a red X through it, indicating that it is unavailable.

To delete a cluster, follow these steps:

  1. Go to Process Administrator's home page at http://yourServer/Administrator.apm.

  2. Click the Cluster Management tab.

  3. Scroll down on the Cluster Information page.

  4. Click Delete Cluster. This displays the Delete Cluster page.
Note
You can choose to delete the application data for all cluster applications, which also deletes the application-specific database tables. This is not recoverable. If you are not sure whether you want to do this, even for an old unused cluster, first archive the application data. For details, see the section Exporting and Deleting Data.

Figure 3.11    The Delete a Cluster page

  1. If you want to keep the application data, select the "Keep the data in the database" radio button.

    2. If you want to delete the application data, select the "Delete the data in the database" radio button.

  2. Click Delete Cluster to delete the cluster (and your user data if you chose that option).
If you try to delete a cluster that still has other active servers running, Process Administrator first removes the other servers, then it removes your local server and deletes the cluster. Note that this also removes the PMExtensionManager.properties file from your local server, so the next time you try to access Process Administrator, you are "initializing" it again and you will have to create a new cluster.

 

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