/// <summary>
/// Process method checks for presence of a session id and sequence
/// number. If they do not exist then they are initialized in evidence.
/// If they do exist in evidence then the sequence number is incremented
/// and added back to the evidence.
/// </summary>
/// <param name="data">
/// The <see cref="IFlowData"/> instance to process.
/// </param>
/// <exception cref="ArgumentNullException">
/// Thrown if the supplied data instance is null
/// </exception>
protected override void ProcessInternal(IFlowData data)
{
if (data == null)
{
throw new ArgumentNullException(nameof(data));
}
var evidence = data.GetEvidence().AsDictionary();
// If the evidence does not contain a session id then create a new one.
if (evidence.ContainsKey(Constants.EVIDENCE_SESSIONID) == false)
{
data.AddEvidence(Constants.EVIDENCE_SESSIONID, GetNewSessionId());
}
// If the evidence does not have a sequence then add one. Otherwise
// increment it.
if (evidence.ContainsKey(Constants.EVIDENCE_SEQUENCE) == false)
{
data.AddEvidence(Constants.EVIDENCE_SEQUENCE, 1);
}
else if (evidence.TryGetValue(Constants.EVIDENCE_SEQUENCE, out object sequence))
{
if (sequence is int result || (sequence is string seq && int.TryParse(seq, out result)))
{
data.AddEvidence(Constants.EVIDENCE_SEQUENCE, result + 1);
}
else
{
data.AddError(new Exception(Messages.MessageFailSequenceNumberParse), this);
Logger.LogError(Messages.MessageFailSequenceNumberIncrement);
}
}
/// <summary>
/// Check if the given key is needed by the given flowdata.
/// If it is then add it as evidence.
/// </summary>
/// <param name="flowData">
/// The <see cref="IFlowData"/> to add the evidence to.
/// </param>
/// <param name="key">
/// The evidence key
/// </param>
/// <param name="value">
/// The evidence value
/// </param>
private static void CheckAndAdd(IFlowData flowData, string key, object value)
{
if (flowData.EvidenceKeyFilter.Include(key))
{
flowData.AddEvidence(key, value);
}
}