diff --git a/Sources/OpenTelemetrySdk/Metrics/Stable/NoopAttributesProcessor.swift b/Sources/OpenTelemetrySdk/Metrics/Stable/NoopAttributesProcessor.swift
deleted file mode 100644
index 71fce2d9..00000000
--- a/Sources/OpenTelemetrySdk/Metrics/Stable/NoopAttributesProcessor.swift
+++ /dev/null
@@ -1,17 +0,0 @@
-//
-// Copyright The OpenTelemetry Authors
-// SPDX-License-Identifier: Apache-2.0
-// 
-
-import Foundation
-import OpenTelemetryApi
-
-
-class NoopAttributesProcessor : AttributeProcessorProtocol {
-
-  func process(incoming attributes: [String : OpenTelemetryApi.AttributeValue]) ->  [String: OpenTelemetryApi.AttributeValue] {
-        return attributes
-    }
-
-    public static let noop = NoopAttributesProcessor()
-}
diff --git a/Sources/OpenTelemetrySdk/Metrics/Stable/View/AttributeProcessor.swift b/Sources/OpenTelemetrySdk/Metrics/Stable/View/AttributeProcessor.swift
index f50166c5..9dfb9b13 100644
--- a/Sources/OpenTelemetrySdk/Metrics/Stable/View/AttributeProcessor.swift
+++ b/Sources/OpenTelemetrySdk/Metrics/Stable/View/AttributeProcessor.swift
@@ -6,12 +6,12 @@
 import Foundation
 import OpenTelemetryApi
 
-public protocol AttributeProcessorProtocol  {
+public protocol AttributeProcessor  {
     func process(incoming : [String: AttributeValue]) -> [String: AttributeValue]
 }
-public class AttributeProcessor : AttributeProcessorProtocol {
-    
-    public func then(other : AttributeProcessor) -> AttributeProcessor {
+
+public extension AttributeProcessor {
+    func then(other : AttributeProcessor) -> AttributeProcessor {
         if type(of: other) == NoopAttributeProcessor.self {
             return self
         }
@@ -19,18 +19,29 @@ public class AttributeProcessor : AttributeProcessorProtocol {
             return other
         }
         
-        if type(of: other) == JoinedAttributeProcessor.self {
-            return (other as! JoinedAttributeProcessor).prepend(processor:self)
+        if let joined = self as? JoinedAttributeProcessor {
+            return joined.append(processor:other)
         }
+        if let joined = other as? JoinedAttributeProcessor {
+            return joined.prepend(processor:self)
+        }
+
         return JoinedAttributeProcessor([self, other])
     }
+}
+
+public class SimpleAttributeProcessor : AttributeProcessor {
+    let attributeProcessor : ([String: AttributeValue]) -> [String:AttributeValue]
     
+    init(attributeProcessor : @escaping ([String: AttributeValue]) -> [String: AttributeValue]) {
+        self.attributeProcessor = attributeProcessor
+    }
     
     public func process(incoming: [String : AttributeValue]) -> [String : AttributeValue] {
-        return incoming
+        return attributeProcessor(incoming)
     }
     
-    public static func filterByKeyName( nameFilter : @escaping (String) -> Bool) -> AttributeProcessor {
+    static func filterByKeyName( nameFilter : @escaping (String) -> Bool) -> AttributeProcessor {
         return SimpleAttributeProcessor { attributes in
             attributes.filter { key, value in
                 nameFilter(key)
@@ -38,37 +49,19 @@ public class AttributeProcessor : AttributeProcessorProtocol {
         }
     }
     
-    public static func append(attributes: [String : AttributeValue]) -> AttributeProcessor {
+    static func append(attributes: [String : AttributeValue]) -> AttributeProcessor {
         SimpleAttributeProcessor { incoming in
             incoming.merging(attributes) { a, b in
                 b
             }
         }
     }
-    
-    
-}
-
-internal class SimpleAttributeProcessor : AttributeProcessor {
-    
-    let attributeProcessor : ([String: AttributeValue]) -> [String:AttributeValue]
-    
-    init(attributeProcessor : @escaping ([String: AttributeValue]) -> [String: AttributeValue]) {
-        self.attributeProcessor = attributeProcessor
-        
-    }
-    
-    override func process(incoming: [String : OpenTelemetryApi.AttributeValue]) -> [String : OpenTelemetryApi.AttributeValue] {
-        return attributeProcessor(incoming)
-    }
-    
-    
 }
 
 
 public class JoinedAttributeProcessor : AttributeProcessor {
     
-    override public func process(incoming: [String : OpenTelemetryApi.AttributeValue]) -> [String : OpenTelemetryApi.AttributeValue] {
+    public func process(incoming: [String : AttributeValue]) -> [String : AttributeValue] {
         var result = incoming
         for processor in processors {
             result = processor.process(incoming: result)
@@ -76,17 +69,17 @@ public class JoinedAttributeProcessor : AttributeProcessor {
         return result
     }
     
-    override public func then(other: AttributeProcessor) -> AttributeProcessor {
+    public func append(processor: AttributeProcessor) -> JoinedAttributeProcessor {
         var newList = processors
-        if let otherJoined = other as? JoinedAttributeProcessor {
-            newList.append(contentsOf: otherJoined.processors)
+        if let joinedProcessor = processor as? JoinedAttributeProcessor {
+            newList.append(contentsOf: joinedProcessor.processors)
         } else {
-            newList.append(other)
+            newList.append(processor)
         }
         return JoinedAttributeProcessor(newList)
     }
     
-    public func prepend(processor: AttributeProcessor) -> AttributeProcessor {
+    public func prepend(processor: AttributeProcessor) -> JoinedAttributeProcessor {
         var newProcessors = [processor]
         newProcessors.append(contentsOf: processors)
         return JoinedAttributeProcessor(newProcessors)
@@ -101,8 +94,8 @@ public class JoinedAttributeProcessor : AttributeProcessor {
 
 public class NoopAttributeProcessor : AttributeProcessor {
     static let noop = NoopAttributeProcessor()
-    private override init() {}
-    override public func process(incoming: [String : AttributeValue]) -> [String : AttributeValue] {
+    private init() {}
+    public func process(incoming: [String : AttributeValue]) -> [String : AttributeValue] {
         return incoming
     }
 }
diff --git a/Sources/OpenTelemetrySdk/Metrics/Stable/View/ViewBuilder.swift b/Sources/OpenTelemetrySdk/Metrics/Stable/View/ViewBuilder.swift
index 14098d3f..46dc459c 100644
--- a/Sources/OpenTelemetrySdk/Metrics/Stable/View/ViewBuilder.swift
+++ b/Sources/OpenTelemetrySdk/Metrics/Stable/View/ViewBuilder.swift
@@ -30,8 +30,13 @@ public class ViewBuilder {
         return self
     }
     
+    public func withAttributeProcessor(processor: AttributeProcessor) -> Self {
+        self.processor = processor
+        return self
+    }
+
     public func addAttributeFilter(keyFilter: @escaping (String) -> Bool) -> Self {
-        addAttributeProcessor(processor: AttributeProcessor.filterByKeyName(nameFilter: keyFilter))
+        addAttributeProcessor(processor: SimpleAttributeProcessor.filterByKeyName(nameFilter: keyFilter))
     }
     
     public func addAttributeProcessor(processor: AttributeProcessor) -> Self {
diff --git a/Tests/OpenTelemetrySdkTests/Metrics/StableMetrics/AttributeProcessorTests.swift b/Tests/OpenTelemetrySdkTests/Metrics/StableMetrics/AttributeProcessorTests.swift
new file mode 100644
index 00000000..a1fbaa4e
--- /dev/null
+++ b/Tests/OpenTelemetrySdkTests/Metrics/StableMetrics/AttributeProcessorTests.swift
@@ -0,0 +1,44 @@
+//
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+// 
+
+import Foundation
+
+import OpenTelemetryApi
+@testable import OpenTelemetrySdk
+import XCTest
+
+class AttributeProcessorTests : XCTestCase {
+    func testStaticNoop() {
+        XCTAssertNotNil(NoopAttributeProcessor.noop)
+        XCTAssertEqual(NoopAttributeProcessor.noop.process(incoming: ["hello": AttributeValue.string("world")]), ["hello" : AttributeValue.string("world")])
+    }
+
+    func testSimpleProcessor() {
+        let incoming = ["hello": AttributeValue("world")]
+
+        var processor: AttributeProcessor = SimpleAttributeProcessor.append(attributes: ["foo" : .string("bar")])
+        XCTAssertEqual(processor.process(incoming: incoming), ["hello" : .string("world"), "foo": .string("bar")])
+
+        processor = processor.then(other: SimpleAttributeProcessor.filterByKeyName(nameFilter: { $0 == "foo" }))
+        XCTAssertEqual(processor.process(incoming: incoming), ["foo": .string("bar")])
+    }
+
+    func testJoinedProcessor() {
+        let incoming = ["hello": AttributeValue("world")]
+
+        let processor0 = SimpleAttributeProcessor.append(attributes: ["foo" : .string("bar0")])
+        let processor1 = SimpleAttributeProcessor.append(attributes: ["foo" : .string("bar1")])
+        let processor2 = SimpleAttributeProcessor.append(attributes: ["foo" : .string("bar2")])
+
+        var processor = JoinedAttributeProcessor([processor0])
+        XCTAssertEqual(processor.process(incoming: incoming), ["hello" : .string("world"), "foo": .string("bar0")])
+
+        processor = processor.prepend(processor: processor1)
+        XCTAssertEqual(processor.process(incoming: incoming), ["hello" : .string("world"), "foo": .string("bar0")])
+
+        processor = processor.append(processor: processor2)
+        XCTAssertEqual(processor.process(incoming: incoming), ["hello" : .string("world"), "foo": .string("bar2")])
+    }
+}
diff --git a/Tests/OpenTelemetrySdkTests/Metrics/StableMetrics/NoopAttributesProcessorTests.swift b/Tests/OpenTelemetrySdkTests/Metrics/StableMetrics/NoopAttributesProcessorTests.swift
deleted file mode 100644
index 433ae3c4..00000000
--- a/Tests/OpenTelemetrySdkTests/Metrics/StableMetrics/NoopAttributesProcessorTests.swift
+++ /dev/null
@@ -1,17 +0,0 @@
-//
-// Copyright The OpenTelemetry Authors
-// SPDX-License-Identifier: Apache-2.0
-// 
-
-import Foundation
-
-import OpenTelemetryApi
-@testable import OpenTelemetrySdk
-import XCTest
-
-class NoopAttributesProcessorTests : XCTestCase {
-  func testStaticNoop() {
-    XCTAssertNotNil(NoopAttributeProcessor.noop)
-    XCTAssertEqual(NoopAttributeProcessor.noop.process(incoming: ["hello": AttributeValue.string("world")]), ["hello" : AttributeValue.string("world")])
-  }
-}