Hi @hiroyuki.endo,

The Thomson Reuters Market Data System you connect into offers real time market data. That is, when there are changes in the market, such as trades and quotes, you have the option of registering interest in receiving these changes. The changes come through as updates. If you are interested in receiving updates, you register your market data item as a streaming request within the API. When you register interest in receiving streaming updates, you will always receive a refresh message, followed by zero or more update messages. Alternatively, you can decide to not receive updates by registering your market data item as a non-streaming request. In this scenario, you will only receive a refresh, or what is commonly referred to as a snapshot.

The default behavior within the API is to receive streaming updates.

Regarding the three message processing callbacks:

• onRefreshMsg()

This callback will be invoked when you request for a valid streaming or non-streaming market data item.

• onUpdateMsg()

This callback will be called when you request for a valid streaming market data item and that item updates in real time.

• onStatusMsg()

This callback will be called when there are general status events related to your consumer item registration. For example, if you request for an invalid market data item, you will be notified here that your item requested is invalid.

Refer to the series of tutorials offered within the Elektron API for a walkthrough of how the API works.