We were looking at some of the search queries that are collected from the community of those using  logs from an identity provider:

Some other interesting events for identity include:

37) cross API calls - in the API sequence across layers such as http filters we discussed how to walk down the chain in the logs to find out which layer responded with an  error. This mention here is for the same layer cross API calls which determine the response from this layer. Sometimes we have the information for responses gatherer via cross api calls and determining their failures requires inspection of the responses formed in this layer.

38) state sharing between APIs - most caller and callee share state or keys for each other and this helps in tracking or studying them in the logs. The count of unique such states indicates the distinct conversations between APIs. In this case we can even re-use this to find out the exact input or output for a particular customer. Often the customerId is shared in the request parameters itself, so listing all APIs by customerId should have covered this case but this is not necessarily true for APIs from different departments that may not follow the same rules. In such cases the translation of customerId to the corresponding key/state helps find the API calls.

39) incorrect API responses  - one of the most notorious failures in the services is when the api fails without an exception. The latter is very helpful for diagnosis and troubleshooting because it determines a point of failure. In its absence reconstructing the point of failure by studying requests and responses at the API become very difficult. For this purpose tracing the api activity may come helpful but because production logs are rarely at debug level, it would behoove the api to log incorrect responses also. In such cases, the results are easier to diagnose and determine when compared with the other successful calls.

40) state pass through - one of the most successful techniques is when apis capture and append state that will be helpful downstream. In the example cited above, the logs were to be enhanced to improve the diagnosability. Here the data speaks for itself. The data carries all the information we need.subsequently and the operation at any particular layer merely has to look at this state.

#codingexercise
Generate the nth Newman Conway Sequence number. This sequence is shown as
1 1 2 2 3 4 4 4 5 6 7 7
It is defined as the recursion :
P(n) = P(P(n - 1)) + P(n - P(n - 1))
and with closure conditions as
P (1) = 1
P (2) = 1

double GetNCS ( double n )
{
if ( n == 1 || n == 2)
      return 1;
else
      return GetNCS (GetNCS (n-1)) + GetNCS (n-GetNCS (n-1));
}
n = 3:
P (P (2))+P (3-P (2))
    = P (1) +P (2) 0= 2
n = 4
P (P (3))+P (4-P (3))
= P (2) +P (2) = 2