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I was not familiar with SIP states during the integration of VoIP products such as twilio, plivo and sinch. I am still confused about the state changes after reading documents. Here try to visualize the state change and help me to remember it. The state chart is based on my understanding. It is not necessarily correct. It is just for my reference. QueuedInitiatedRingingAnsweredInProgressCompletedBusyNoAnswerCanceledFailed

Measurement Physical properties SI Units Other Common Units Common measuring apparatus Name Symbol time second s hour (h) minutes(min) day digital stopwatch analogue stopwatch mass kilogram kg gram(g) tonne(t)

PlantUML Diagram Class diagram—​Relations between Class: Type Sysmbol Extension <!-- Composition *-- Aggregation o-- Asciidoc UML sample Class01Class02Class03Class04Class05Class06Class07Class08Class09Class10 PlantUML sample Class01Class02Class03Class04Class05Class06Class07Class08Class09Class10

Asynchronization is very hard. It brings benefits with several catches for backend programming. Here is serveral catches and respective solutions. However all those will increase the cost of developments. Hard to debug and trace As the process breaks down to serveral asynchronious subprocesses, it is very difficult to relate all information of the process when something goes wrong. An extra overhead correlation Id is needed to adopt to ameliorate this issue.

I read a lot of blogs. However I rarely wrote my blogs about my thoughts and learning experiences as I thought those are lack of originality. I changed my mind after I learned more than ten thousand words using anki and memrise in the past 2 years. A writing can serve multiple purposes even lack of originality and thorough thought. Here is a list of those purposes: Deepen my understanding in the topics and improve efficiency of learning

Ditaa 0 start1 q scans from start to end.....endrest of theallocated memory.....n

I always thought SaaS are based shardig, load balance and multiple-tenant. In the past several days, I re-read Dynamo and DynamoDB papers to figure out some key info to share with my colleages to find a common ground about DynamoDB. One thing is mentioned many times in DynamoDB is token-bucket. Suddenly a thought popped out my mind when I walked back after lunch with my colleague that token-bucket algorithm should be a component of SaaS and multiple-tenant.

When I was preparing a slides to recommend broad usage of JsonSchema, somethings I thought are good to have for general public usage. Those things troubled me for a while during I authored a JsonSchema. Versioning Currently there is no standard way how to define a version for a schema. I might use a version property for that. SemVer is good fit for the version content schema. Use if and else for different version.