Transaction Monitoring – Network Appliances

Yet another way to implement Transaction Monitoring solutions is via a Network Appliance. This approach is defined here as any approach that collects data by non intrusive "Network Sniffing". Two good examples of vendors that provide this type of solution are B-Hive and Correlix.

How it Works

Network appliance solutions usually connect to a port mirror in order to collect the traffic, and then try and re-construct the entire transaction. Information needs to be collected directly from every node that is of interest.

Applications

• Any application where transaction latencies need to be monitored in a production environment
  
• Managing SLAs
  
• Systems which cannot be tempered with at all and need a "plug and play" solution
  

Advantages

• Zero Overhead
  
• Full time monitoring
  
• Immediate installation
  
• Instillation only concerns the network administrator
  
• There is no risk of crashing the system ( some "Deep Dive" solutions will cause system failure if they are used to monitor too many transaction due to high overhead)
  

Drawbacks

• Uses an algorithmic approach to track transactions which limits accuracy of metrics, latencies are not right, you do not know the accurate flow of the transaction through different tiers and so on.
  
• Tracking is not really end-to-end since you cannot see what is actually happening within the servers (cannot achieve full visibility)
  
• Even if you collect data from all nodes, correlating that data into a single transaction path (or topology of the entire transaction) accurately has yet to be done (if you can give a concrete example, then let me know and I will post it)
  
• Receiving data at the network level makes measuring encrypted data close to impossible
  
• Once an event has begun processing, it cannot be controlled (say for resource allocation purposes)
  

Disclaimer

When trying to give an understanding of a general approach to a solution, all potential advantages and drawbacks (which people who develop or promote the specific solution would prefer to ignore) are listed. Comment with any objections (as people have done in the past) and I will at some point post everything.