What Exactly is the BMC Remedy AR System Mid Tier?

At its core, the Mid Tier acts as an intermediary. Think of it as a translator and a traffic controller. It sits between your powerful, data-rich AR System server (the “backend”) and the end-user’s web browser (the “frontend”).

• Client of the AR System Server: The Mid Tier communicates directly with the AR System server, requesting data, submitting changes, and retrieving application definitions. It doesn’t hold all the data itself but fetches what’s needed from the server.
• Server to the Browser: On the other end, the Mid Tier serves up the information and user interface to the browser. It translates the AR System’s backend language into a format that web browsers understand (HTML, CSS, JavaScript), allowing users to interact with applications like Change Management, Incident Management, or Knowledge Management directly from their web browser without needing dedicated client software.

Essentially, the Mid Tier democratizes access to your AR System applications, making them accessible from any device with a web browser, regardless of whether it’s running on a desktop, laptop, or even a tablet. This is a cornerstone of modern ITSM, enabling self-service portals, mobile access, and a more flexible IT support environment.

Real-world example: Imagine your IT support team needs to quickly update an incident record while on the go. Instead of rushing back to their desk to use the User Tool, they can simply open a web browser on their laptop or mobile device, navigate to the Mid Tier URL, log in, and update the incident directly. The Mid Tier makes this seamless interaction possible.

The Command Center: The Mid Tier Configuration Tool

Managing the Mid Tier’s behavior and ensuring it communicates effectively with your AR System server is done through a dedicated web-based tool: the Mid Tier Configuration Tool. This is your primary interface for fine-tuning various settings without needing to directly edit configuration files on the server, although understanding the underlying configuration files is also beneficial.

You can access this tool by navigating to a specific URL in your web browser. The exact URL will depend on your server’s hostname, the port it’s listening on, and the context path defined during installation. A common format looks like this:

http://hostname:port/contextPath/shared/config/config.jsp

For instance, if your server is named ‘remedy-server’ and runs on the default port 8080 with the context path ‘arsys’, the URL would be:

http://remedy-server:8080/arsys/shared/config/config.jsp

This tool provides a user-friendly interface for a wide range of critical configurations, including:

• AR System Server Information: Defining and managing the connection details for one or more AR System servers. This is vital if you have a clustered environment or multiple AR System instances.
• Configuration Passwords: Setting and changing passwords required for the Mid Tier to authenticate with the AR System server, especially for administrative tasks.
• Cache Policy Information: This is arguably one of the most critical aspects of Mid Tier configuration, directly impacting performance and stability. We’ll delve into cache modes shortly.
• User Authentication: Configuring how users are authenticated, whether through AR System’s native authentication or integrated solutions like LDAP.
• Web Services: Specifying settings related to web services integration.

There’s also a specific URL for cache-related configurations:

http://localhost:8080/arsys/shared/config/config_cache.jsp

This emphasizes the importance of cache management within the Mid Tier.

Understanding Mid Tier Cache Modes: The Performance Engine

Caching is fundamental to the Mid Tier’s performance. It stores frequently accessed data and application definitions locally, reducing the need to constantly query the AR System server. This significantly speeds up response times for users. However, how this caching behaves during administrative operations is controlled by two distinct modes: Production Cache Mode and Development Cache Mode.

Production Cache Mode (Default)

This is the default and recommended mode for most live environments. The primary goal here is to ensure that end-users experience minimal disruption, even when administrators are making changes or performing maintenance.

• How it works: When an administrative operation (like deploying a form change, modifying an active link, or updating an escalation) is initiated, the Mid Tier doesn’t immediately lock out all users. Instead, it intelligently creates a temporary, “administrative copy” of its cache. This allows other application users to continue using the existing, shared cache without interruption. Once the administrative changes are fully processed and the new cache is ready, it’s seamlessly swapped in.
• Key characteristics:
  • Definition Change Check Interval: In this mode, this value is set to GREATER than 0. This interval determines how often the Mid Tier checks the AR System server for definition changes. A value of, say, 300 seconds (5 minutes) means it will poll the server for changes every 5 minutes.
  • Sync Cache Feature: The Sync Cache feature is fully functional. This allows administrators to manually force the Mid Tier to synchronize its cache with the AR System server, immediately applying any changes that have been made.
  • Best for: Environments with a large number of active users where any downtime or performance degradation due to administrative tasks is unacceptable. Think production environments supporting hundreds or thousands of users.

Note: For in-depth details on specific parameters related to Production Cache Mode, refer to the BMC Remedy AR System Configuration documentation, typically found in the “after installation” sections.

Development Cache Mode

This mode is designed for development and testing scenarios, where direct control and immediate visibility of changes are more critical than uninterrupted user access.

• How it works: In stark contrast to Production mode, administrative operations in Development mode do not create a separate copy. Instead, they effectively lock other users out of the shared cache. The administrative thread must wait for all current users accessing that cache to complete their operations before it can proceed with applying changes. This can also include waiting for long-running server-side processes like escalations and archive jobs to finish.
• Key characteristics:
  • Definition Change Check Interval: This value is set to 0. A value of 0 typically means the Mid Tier will only check for definition changes when explicitly told to, or when a user manually forces a refresh, rather than on a scheduled interval. This can lead to changes taking longer to appear if not manually synced.
  • Sync Cache Feature: The Sync Cache feature cannot be used effectively in this mode. Manual synchronization is either disabled or behaves in a way that doesn’t provide the immediate, “safe” update seen in Production mode.
  • Incompatibility with Long-Running Tasks: Potentially long-running tasks such as active escalations, BMC Atrium Integration Engine jobs, and complex queries are incompatible with administrative thread changes in this mode. If an administrator attempts to deploy changes while such a task is running, it can lead to extremely long delays or even timeouts, as the admin thread waits for these processes to complete.
  • Best for: Development, testing, or sandbox environments where downtime or temporary lockouts for a small group of testers are acceptable, and immediate reflection of changes is prioritized.

Note: Again, the official BMC Remedy AR System Configuration guide provides granular details on these settings.

Configuring Key Settings: A Practical Guide

Beyond cache modes, several other configurations are crucial for the Mid Tier’s operation. Let’s look at how to manage them, focusing on a common need: changing the configuration password.

Changing the Configuration Password

The configuration password is used by the Mid Tier to authenticate with the AR System server for certain administrative operations. It’s good practice to change this periodically or if there’s any suspicion of compromise. There are a few ways to approach this, but the most direct and recommended method is through the Mid Tier Configuration Tool.

1. Access the Mid Tier Configuration Tool: Open your web browser and navigate to the configuration URL (e.g., http://hostname:port/contextPath/shared/config/config.jsp).
2. Locate Password Settings: Within the configuration tool, look for a section related to “AR System Server Information,” “Connection Settings,” or “Security.” The exact labeling might vary slightly based on your Mid Tier version.
3. Modify the Password: You should find fields where you can enter the current password and then the new password. Enter your new password carefully and confirm it.
4. Save Changes: Click the “Save,” “Apply,” or “Update” button to store your changes.
5. Restart Mid Tier (if necessary): Depending on your specific configuration and Mid Tier version, a restart of the Mid Tier web server (e.g., Tomcat, WebSphere) might be required for the password change to take full effect. Check the confirmation message or documentation for guidance.

Alternative Configuration Methods (and why they are less preferred for password changes):

• ar.cfg (AR System Server Configuration File): While the ar.cfg file on the AR System server contains many important settings for the server itself, it generally doesn’t directly store the Mid Tier’s configuration password. The Mid Tier maintains its own configuration, which is why the Mid Tier Configuration Tool is the primary interface. Directly editing ar.cfg is more for AR System server-level parameters.
• User Tool: The User Tool is the classic thick client for AR System. While it’s used for many administrative tasks, it doesn’t have direct access to change the Mid Tier’s internal configuration password. Its focus is on interacting with AR System server data and definitions, not the Mid Tier’s middleware settings.

Other Important Configuration Areas via the Tool:

• Server List: Adding, removing, or prioritizing multiple AR System servers. This is crucial for load balancing and high availability.
• Cache Management: Beyond the modes, you can often configure cache expiration times, size limits, and whether to enable/disable specific caching mechanisms.
• Session Management: Settings related to user sessions, such as timeout durations.
• Logging: Configuring the level of detail for Mid Tier logs, which is invaluable for troubleshooting.

Troubleshooting Common Mid Tier Issues

Like any complex piece of software, the Mid Tier can sometimes throw curveballs. Here are some common issues and how to approach them:

1. Users Unable to Access Applications via Browser

• Check Mid Tier Service: Is the Mid Tier web server (e.g., Tomcat) running? Check its status.
• Verify URL: Is the URL correct (hostname, port, context path)? Try accessing the Mid Tier Configuration Tool itself as a test.
• AR System Server Reachability: Can the Mid Tier server reach the AR System server?
  • Check network connectivity (ping, telnet to the AR System server’s port).
  • Verify AR System server details in the Mid Tier Configuration Tool.
  • Ensure the AR System server is running and accessible.
• Authentication Issues: Are user credentials valid? Check authentication methods configured in both Mid Tier and AR System.
• Firewall Issues: Are there any firewalls blocking communication between the Mid Tier and the AR System server, or between the user’s browser and the Mid Tier?

2. Slow Performance or Unresponsive Applications

• Cache Mode: Confirm you’re in Production Cache Mode for a live environment.
• Cache Contents: Is the cache becoming too large or filled with stale data? Sometimes clearing or flushing the cache (if the option is available and appropriate) can help.
• Definition Change Check Interval: If set too low in Production mode, frequent checks might cause overhead. If set too high, changes might not appear promptly.
• AR System Server Load: The Mid Tier’s performance is directly tied to the AR System server’s responsiveness. Check the AR System server’s CPU, memory, and database performance.
• Network Latency: High latency between the Mid Tier and AR System server, or between users and the Mid Tier, can cause perceived slowness.
• Browser Cache: Sometimes, clearing the user’s browser cache can resolve display issues.

3. Errors During Administrative Operations

• Configuration Password: Ensure the configuration password used by the Mid Tier to connect to the AR System server is correct.
• Permissions: Does the user performing the administrative operation have the necessary permissions on the AR System server?
• Cache Mode: In Development mode, long-running tasks can cause failures.
• Mid Tier Logs: Examine the Mid Tier’s log files for detailed error messages. These are often the most valuable resource for diagnosing issues.

Interview Relevance: What Interviewers Look For

Understanding the Mid Tier is crucial for any role involving BMC Remedy administration, development, or support. Interviewers want to gauge your practical knowledge and ability to manage this critical component.

Common Interview Questions About the Mid Tier:

• “Can you explain the role of the Mid Tier in a BMC Remedy architecture?”
• “What’s the difference between Production Cache Mode and Development Cache Mode? When would you use each?”
• “How do you access and configure the Mid Tier?”
• “What are some common performance issues with the Mid Tier, and how would you troubleshoot them?”
• “How would you change the password that the Mid Tier uses to connect to the AR System server?”
• “What is the ‘Definition Change Check Interval’ and why is it important?”
• “What happens if you try to deploy changes to AR System while a long-running escalation is active, and how does the Mid Tier’s cache mode affect this?”

What Makes a Good Answer:

• Clarity and Conciseness: Clearly define its role as a bridge.
• Practical Understanding of Cache: Go beyond just naming the modes; explain the implications for users and administrators. This is a frequent differentiator.
• Hands-on Experience: Mentioning the Mid Tier Configuration Tool and its URL shows practical familiarity.
• Troubleshooting Prowess: Articulating common issues and systematic approaches to resolving them demonstrates problem-solving skills.
• Awareness of Best Practices: Emphasizing Production Cache Mode for live environments shows maturity.

Conclusion

The BMC Remedy AR System Mid Tier is more than just a technical component; it’s the gateway that unlocks the full potential of your AR System applications for your end-users. By understanding its architecture, mastering its configuration through the Mid Tier Configuration Tool, and being aware of the critical impact of its cache modes, you’re well-equipped to ensure a stable, performant, and accessible ITSM experience.

Whether you’re a seasoned administrator or embarking on your journey into the world of BMC Helix ITSM, a solid grasp of the Mid Tier is an investment that pays dividends in system efficiency and user satisfaction. Keep exploring, keep configuring, and most importantly, keep your users connected!