I need to invoke journey in journey builder while new data insert/updated in Data extension, each data entry - journey has to invoke immediately ? is that possible ? For that I tried with API event as a entry source
You can trigger a journey from a cloud page by invoking the journey builder fire event REST API.
See the example here
This will insert the data into the entry source DE as well as trigger the journey at the same time
You can use below steps to do this.
Use CloudPages to Admit Contacts into Journey Builder Use a CloudPages Smart Capture form and Journey Builder to admit Marketing Cloud contacts into a journey using the CloudPages Form Submit Event.
Create at least one Smart Capture form in CloudPages before you use this entry source.
Drag CloudPages onto the canvas. Click CloudPages. Choose a Smart Capture form and click Next. When a customer submits the Smart Capture form, that customer is automatically added to a data extension and queued to enter this journey. Build the rest of the journey, and click Activate to begin admitting contacts who submit the designated Smart Capture form.