DPA client to server communications
Desktop and Process Analytics client machines send data to the server through HTTP soap messages. The amount of data transferred depends on the activity level on the client machine. If the client machine is idle, only a small amount of data is sent to the server. The soap packets in the messages are compressed. The compression algorithm (lz-based run length encoding) makes the size of traffic much smaller than it would be with uncompressed data grams, especially when the same windows and applications are reused.
Fired triggers (where configured)
When a trigger fires, a maximum of 2 KB of data is sent from the client machine to the server. Typically, the size of data sent from the client machine is much smaller. The size depends on the length of UserName, ComputerName, Application, WinText, and on the number and size of pass-back values. The data size can be as low as 200 Bytes per fired trigger. This data is stored and sent within the PC Usage data transfer, where it is compressed and encoded.
Loss of connection or no network
If the client does not detect a server or does not connect to the remote server, then the soap transfer packet is left locally on the client machine. For each transfer interval that the network connectivity remains lost, another soap transfer packet is stored locally. To limit data buildup on the local machine, once the local store reaches seven days of data, the earliest soap packets are over-written with new ones.
Local storage uses MSMQ. The credentials used to run the logging client only have write access to these queues. The credentials used to run the DPA transport service have read and write access to these queues.
Regaining a connection or network established
Once a network connection is detected, if the client has some older soap packets from a time period without connectivity, it sends the current soap packet first. Then, starting with the oldest, it sends up to 10 of the older packets from its store. This process limits the bandwidth used on the network after a disconnection period.
Client shutdown or workstation log off
The DPA transport service continues to run independently of the logged in session. If a client logs off, but the workstation remains powered on, the service continues to send all client data off disk. A user does not need to be logged in for the DPA transport service to send data off the workstation. If the workstation is shut down when the user is logged off, a small amount of data can remain on the local disk. This data remains on the client desktop until the system is next powered on.
Server-side notification data
Clients typically fire triggers on the client workstation. No additional transport mechanism is used to fire the trigger and all data concerning this trigger firing is contained within the standard soap packets. However, if configured, the client can send a WFO notification call to the server machine. This call is sent on port 80/443 and is similar in bandwidth to typical logged trigger data.