Write data

The Sequential Data Store (SDS (Sequential Data Store)) REST API (REpresentational State Transfer - Application Programming Interface)s provide programmatic access to write data to SDS (Sequential Data Store). All writes rely on a stream's key or primary index. The primary index determines the order of events in the stream. Secondary indexes are updated, but they do not contribute to the request. All references to indexes are to the primary index.

When working in .NET, convenient SDS (Sequential Data Store) Client libraries are available. The ISdsDataService interface, accessed using the SdsService.GetDataService() helper, defines the available functions.

Single stream writes

The following methods support writing a single or multiple values:

• Insert Values inserts a collection of events.

• Patch Values updates specific fields for a collection of events.

• Replace Values replaces a collection of events.

• Remove Values deletes the events based on the request parameters.

• Update Values add or replaces a collection of events.

Request body format

With the exception of Remove Values, all single stream write calls require a request body containing the events to insert or modify. The events must be formatted as a serialized JSON (JavaScript Object Notation) array of the stream's type. JSON (JavaScript Object Notation) arrays are comma-delimited lists of a type enclosed within square brackets. The following code shows a list of three WaveData events that are properly formatted for insertion.

For samples, see the CONNECT data services code samples in GitHub (https://github.com/AVEVA/AVEVA-Samples-CloudOperations/).

[

{

"Order":2,

"Tau":0.25722883666666846,

"Radians":1.6162164471269089,

"Sin":1.9979373673043652,

"Cos":-0.090809010174665111,

"Tan":-44.003064529862513,

"Sinh":4.8353589272389,

"Cosh":5.2326566823391856,

"Tanh":1.8481468289554672

},

{

"Order":4,

"Tau":0.25724560000002383,

"Radians":1.6163217742567466,

"Sin":1.9979277915696148,

"Cos":-0.091019446679060964,

"Tan":-43.901119254534827,

"Sinh":4.8359100947709592,

"Cosh":5.233166005842703,

"Tanh":1.8481776000882766

},

{

"Order":6,

"Tau":0.25724560000002383,

"Radians":1.6163217742567466,

"Sin":1.9979277915696148,

"Cos":-0.091019446679060964,

"Tan":-43.901119254534827,

"Sinh":4.8359100947709592,

"Cosh":5.233166005842703,

"Tanh":1.8481776000882766

}

]

You can serialize your data using one of many available JSON (JavaScript Object Notation) serializers available at Introducing JSON.

Indexes

SDS (Sequential Data Store) writes rely on the primary index for positioning within streams and locating existing events. Most writes use the index as specified by the value; however, for deletes, indexes are specified as strings in the URI (Uniform Resource Identifier), or, when using the SDS (Sequential Data Store) Client Libraries, the index may be passed as-is to DELETE methods that take the index type as a generic argument. For more details about working with indexes, see Indexes.

To specify compound indexes in the URI (Uniform Resource Identifier), specify each field that composes the index, in the specified order, separated by the pipe character, |.