Get started with SdsStreamViews

To work with stream views, you first need to have types, streams, and streams data defined. The following is a simplified procedure for working with a stream view. For code examples, see Indexes outside of .NET framework and Indexes in .NET framework.

1. Create a type that will be the source type.

2. Create a stream that is of the type defined in the previous step.

3. Write data into the stream that was created in the previous step.

4. Read data from the stream to verify.

5. Create another type that will be the target type.

6. Create a stream view using the source type (step 1) and the target type (step 5).

   • The mapping between the source and the target type happens automatically if you do not specify it in Stream views.

7. Get Stream views to see how properties are mapped.

8. Read data from the stream with the stream view to verify. For more information, see Read data.

Work with SdsStreamViews outside of .NET framework

When working with stream views, invoke HTTP directly or use some of the sample code. Both Python and JavaScript use SdsStreamView definitions.

The following JSON is a simple mapping between a source type with identifier Simple and a target type with identifier Simple1.

{

"Id":"StreamView",

"Name":"StreamView",

"SourceTypeId":"Simple",

"TargetTypeId":"Simple1"

}

The following is the corresponding SdsStreamViewMap.

{

"SourceTypeId":"Simple",

"TargetTypeId":"Simple1",

"Properties":[

{

"SourceId":"Time",

"TargetId":"Time"

},

{

"SourceId":"State",

"TargetId":"State"

},

{

"SourceId":"Measurement",

"TargetId":"Value",

"Mode":4

}

]

}

Work with SdsStreamViews in .NET framework

When working in .NET, use the Sequential Data Store (SDS) client libraries method ISdsMetadataService.

Given the following:

public enum State

{

Ok,

Warning,

Alarm

}

public class Simple

{

[SdsMember(IsKey = true, Order = 0)]

public DateTime Time { get; set; }

public State State { get; set; }

public double Measurement { get; set; }

}

SdsType simpleType = SdsTypeBuilder.CreateSdsType<Simple>();

simpleType.Id = "Simple";

simpleType.Name = "Simple";

await config.GetOrCreateTypeAsync(simpleType);

SdsStream simpleStream = await config.GetOrCreateStreamAsync(new SdsStream()

{

Id = "Simple",

Name = "Simple",

TypeId = simpleType.Id

});

DateTime start = new DateTime(2017, 4, 1).ToUniversalTime();

for (int i = 0; i < 10; i++)

{

Simple value = new Simple()

{

Time = start + TimeSpan.FromMinutes(i),

State = State.Warning,

Measurement = i

};

await client.InsertValueAsync(simpleStream.Id, value);

}

IEnumerable<Simple> simpleValues = await client.GetWindowValuesAsync<Simple>(simpleStream.Id, start.ToString("o"),

start.Add(TimeSpan.FromMinutes(10)).ToString("o"));

foreach (Simple value in simpleValues)

Console.WriteLine($"{value.Time}: {value.State}, {value.Measurement}");

// The example displays the following output:

// 4 / 1 / 2017 7:00:00 AM: Warning, 0

// 4 / 1 / 2017 7:01:00 AM: Warning, 1

// 4 / 1 / 2017 7:02:00 AM: Warning, 2

// 4 / 1 / 2017 7:03:00 AM: Warning, 3

// 4 / 1 / 2017 7:04:00 AM: Warning, 4

// 4 / 1 / 2017 7:05:00 AM: Warning, 5

// 4 / 1 / 2017 7:06:00 AM: Warning, 6

// 4 / 1 / 2017 7:07:00 AM: Warning, 7

// 4 / 1 / 2017 7:08:00 AM: Warning, 8

// 4 / 1 / 2017 7:09:00 AM: Warning, 9

To map the Measurement property to a property in the same location of the same type, allow SDS to automatically determine mapping.

public class Simple1

{

[SdsMember(IsKey = true, Order = 0)]

public DateTime Time { get; set; }

public State State { get; set; }

public double Value { get; set; }

}

SdsType simple1Type = SdsTypeBuilder.CreateSdsType<Simple1>();

simple1Type.Id = "Simple1";

simple1Type.Name = "Simple1";

simple1Type = await config.GetOrCreateTypeAsync(simple1Type);

SdsStreamView view = new SdsStreamView()

{

Id = "StreamView",

Name = "StreamView",

SourceTypeId = simpleType.Id,

TargetTypeId = simple1Type.Id,

};

view = await config.GetOrCreateStreamViewAsync(view);

SdsStreamViewMap map = await config.GetStreamViewMapAsync(view.Id);

Console.WriteLine($"{map.SourceTypeId} to {map.TargetTypeId}");

for (int i = 0; i < map.Properties.Count; i++)

Console.WriteLine($"\t{i}) {map.Properties[i].SourceId} to {map.Properties[i].TargetId} - {map.Properties[i].Mode}");

Console.WriteLine();

IEnumerable<Simple1> simple1Values = await client.GetWindowValuesAsync<Simple1>(simpleStream.Id, start.ToString("o"),

start.Add(TimeSpan.FromMinutes(10)).ToString("o"), view.Id);

foreach (Simple1 value in simple1Values)

Console.WriteLine($"{value.Time}: {value.State}, {value.Value}");

// The example displays the following output:

// Simple to Simple1

// 0) Time to Time - None

// 1) State to State - None

// 2) Measurement to Value - FieldRename

//

// 4 / 1 / 2017 7:00:00 AM: Warning, 0

// 4 / 1 / 2017 7:01:00 AM: Warning, 1

// 4 / 1 / 2017 7:02:00 AM: Warning, 2

// 4 / 1 / 2017 7:03:00 AM: Warning, 3

// 4 / 1 / 2017 7:04:00 AM: Warning, 4

// 4 / 1 / 2017 7:05:00 AM: Warning, 5

// 4 / 1 / 2017 7:06:00 AM: Warning, 6

// 4 / 1 / 2017 7:07:00 AM: Warning, 7

// 4 / 1 / 2017 7:08:00 AM: Warning, 8

// 4 / 1 / 2017 7:09:00 AM: Warning, 9

The SdsStreamViewMap shows that SDS was able to determine that mapping from Measurement to Value resulted in renaming.

SDS can also determine property mapping of the same name but different type. Note that the location of the Measurement property is different, yet it is still mapped.

public class Simple2

{

[SdsMember(IsKey = true, Order = 0)]

public DateTime Time { get; set; }

public int Measurement { get; set; }

public State State { get; set; }

}

SdsType simple2Type = SdsTypeBuilder.CreateSdsType<Simple2>();

simple2Type.Id = "Simple2";

simple2Type.Name = "Simple2";

simple2Type = await config.GetOrCreateTypeAsync(simple2Type);

SdsStreamView view = new SdsStreamView()

{

Id = "StreamView1",

Name = "StreamView1",

SourceTypeId = simpleType.Id,

TargetTypeId = simple2Type.Id,

};

view = await config.GetOrCreateStreamViewAsync(view);

SdsStreamViewMap map = await config.GetStreamViewMapAsync(view.Id);

Console.WriteLine($"{map.SourceTypeId} to {map.TargetTypeId}");

for (int i = 0; i < map.Properties.Count; i++)

Console.WriteLine($"\t{i}) {map.Properties[i].SourceId} to {map.Properties[i].TargetId} - {map.Properties[i].Mode}");

Console.WriteLine();

IEnumerable<Simple2> simple2Values = await client.GetWindowValuesAsync<Simple2>(simpleStream.Id, start.ToString("o"),

start.Add(TimeSpan.FromMinutes(10)).ToString("o"), view.Id);

foreach (Simple2 value in simple2Values)

Console.WriteLine($"{value.Time}: {value.State}, {value.Measurement}");

//The example displays the following output:

// Simple to Simple2

// 0) Time to Time - None

// 1) State to State - None

// 2) Measurement to Measurement - FieldConversion

//

// 4 / 1 / 2017 7:00:00 AM: Warning, 0

// 4 / 1 / 2017 7:01:00 AM: Warning, 1

// 4 / 1 / 2017 7:02:00 AM: Warning, 2

// 4 / 1 / 2017 7:03:00 AM: Warning, 3

// 4 / 1 / 2017 7:04:00 AM: Warning, 4

// 4 / 1 / 2017 7:05:00 AM: Warning, 5

// 4 / 1 / 2017 7:06:00 AM: Warning, 6

// 4 / 1 / 2017 7:07:00 AM: Warning, 7

// 4 / 1 / 2017 7:08:00 AM: Warning, 8

// 4 / 1 / 2017 7:09:00 AM: Warning, 9

The SdsStreamViewMap shows that the source Measurement floating point is converted to integer in the target.

When neither the field name, the field type, or location matches, SDS does not determine mapping. The source is eliminated and the target is added and assigned the default value.

public class Simple3

{

[SdsMember(IsKey = true, Order = 0)]

public DateTime Time { get; set; }

public State State { get; set; }

public int Value { get; set; }

}

SdsType simple3Type = SdsTypeBuilder.CreateSdsType<Simple3>();

simple3Type.Id = "Simple3";

simple3Type.Name = "Simple3";

simple3Type = await config.GetOrCreateTypeAsync(simple3Type);

SdsStreamView view = new SdsStreamView()

{

Id = "StreamView2",

Name = "StreamView2",

SourceTypeId = simpleType.Id,

TargetTypeId = simple3Type.Id,

};

view = await config.GetOrCreateStreamViewAsync(view);

SdsStreamViewMap map = await config.GetStreamViewMapAsync(view.Id);

Console.WriteLine($"{map.SourceTypeId} to {map.TargetTypeId}");

for (int i = 0; i < map.Properties.Count; i++)

Console.WriteLine($"\t{i}) {map.Properties[i].SourceId} to {map.Properties[i].TargetId} - {map.Properties[i].Mode}");

Console.WriteLine();

IEnumerable<Simple3> simple3Values = await client.GetWindowValuesAsync<Simple3>(simpleStream.Id, start.ToString("o"),

start.Add(TimeSpan.FromMinutes(10)).ToString("o"), view.Id);

foreach (Simple3 value in simple3Values)

Console.WriteLine($"{value.Time}: {value.State}, {value.Value}");

//The example displays the following output:

// Simple to Simple3

// 0) Time to Time - None

// 1) State to State - None

// 2) Measurement to -FieldRemove

// 3) to Value -FieldAdd

//

// 4 / 1 / 2017 7:00:00 AM: Warning, 0

// 4 / 1 / 2017 7:01:00 AM: Warning, 0

// 4 / 1 / 2017 7:02:00 AM: Warning, 0

// 4 / 1 / 2017 7:03:00 AM: Warning, 0

// 4 / 1 / 2017 7:04:00 AM: Warning, 0

// 4 / 1 / 2017 7:05:00 AM: Warning, 0

// 4 / 1 / 2017 7:06:00 AM: Warning, 0

// 4 / 1 / 2017 7:07:00 AM: Warning, 0

// 4 / 1 / 2017 7:08:00 AM: Warning, 0

// 4 / 1 / 2017 7:09:00 AM: Warning, 0

To map when SDS cannot determine mapping, use SdsStreamView Properties.

SdsStreamView view = new SdsStreamView()

{

Id = "SteamView3",

Name = "StreamView3",

SourceTypeId = simpleType.Id,

TargetTypeId = simple3Type.Id,

Properties = new List<SdsStreamViewProperty>()

{

new SdsStreamViewProperty()

{

SourceId = "Time",

TargetId = "Time"

},

new SdsStreamViewProperty()

{

SourceId = "State",

TargetId = "State"

},

new SdsStreamViewProperty()

{

SourceId = "Measurement",

TargetId = "Value"

}

}

};

view = await config.GetOrCreateStreamViewAsync(view);

SdsStreamViewMap map = await config.GetStreamViewMapAsync(view.Id);

Console.WriteLine($"{map.SourceTypeId} to {map.TargetTypeId}");

for (int i = 0; i < map.Properties.Count; i++)

Console.WriteLine($"\t{i}) {map.Properties[i].SourceId} to {map.Properties[i].TargetId} - {map.Properties[i].Mode}");

Console.WriteLine();

IEnumerable<Simple3> simple3Values = await client.GetWindowValuesAsync<Simple3>(simpleStream.Id, start.ToString("o"),

start.Add(TimeSpan.FromMinutes(10)).ToString("o"), view.Id);

foreach (Simple3 value in simple3Values)

Console.WriteLine($"{value.Time}: {value.State}, {value.Value}");

//The example displays the following output:

// Simple to Simple3

// 0) Time to Time - None

// 1) State to State - None

// 2) Measurement to Value - FieldRename, FieldConversion

//

// 4 / 1 / 2017 7:00:00 AM: Warning, 0

// 4 / 1 / 2017 7:01:00 AM: Warning, 1

// 4 / 1 / 2017 7:02:00 AM: Warning, 2

// 4 / 1 / 2017 7:03:00 AM: Warning, 3

// 4 / 1 / 2017 7:04:00 AM: Warning, 4

// 4 / 1 / 2017 7:05:00 AM: Warning, 5

// 4 / 1 / 2017 7:06:00 AM: Warning, 6

// 4 / 1 / 2017 7:07:00 AM: Warning, 7

// 4 / 1 / 2017 7:08:00 AM: Warning, 8

// 4 / 1 / 2017 7:09:00 AM: Warning, 9