diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
new file mode 100644
index 0000000000..a057c1b1fa
--- /dev/null
+++ b/.github/CODEOWNERS
@@ -0,0 +1,5 @@
+# Code owners file.
+# This file controls who is tagged for review for any given pull request.
+
+ # For anything not explicitly taken by someone else:
+*               @bogdandrutu @carlosalberto @SergeyKanzhelev @yurishkuro
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000000..3e0746f040
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,40 @@
+# Gradle
+build
+gradle.properties
+.gradle
+local.properties
+out/
+
+# Maven (proto)
+target
+
+# IntelliJ IDEA
+.idea
+*.iml
+.editorconfig
+
+# Eclipse
+.classpath
+.project
+.settings
+bin
+
+# NetBeans
+/.nb-gradle
+/.nb-gradle-properties
+
+# VS Code
+.vscode
+
+# OS X
+.DS_Store
+
+# Emacs
+*~
+\#*\#
+
+# Vim
+.swp
+
+# Other
+TAGS
\ No newline at end of file
diff --git a/api/README.md b/api/README.md
new file mode 100644
index 0000000000..cebac7e758
--- /dev/null
+++ b/api/README.md
@@ -0,0 +1,6 @@
+OpenConsensus API
+======================================================
+
+* Java 7 and Android 14 compatible.
+* The abstract classes in this directory can be subclassed to create alternative
+  implementations of the OpenCensus library.
diff --git a/api/build.gradle b/api/build.gradle
new file mode 100644
index 0000000000..1fe72ca08b
--- /dev/null
+++ b/api/build.gradle
@@ -0,0 +1,10 @@
+description = 'OpenConsensus API'
+
+dependencies {
+    compile project(':openconsensus-context')
+
+    compileOnly libraries.auto_value
+
+    signature "org.codehaus.mojo.signature:java17:1.0@signature"
+    signature "net.sf.androidscents.signature:android-api-level-14:4.0_r4@signature"
+}
diff --git a/build.gradle b/build.gradle
new file mode 100644
index 0000000000..eb8d7ec52c
--- /dev/null
+++ b/build.gradle
@@ -0,0 +1,259 @@
+buildscript {
+    repositories {
+        mavenCentral()
+        mavenLocal()
+        maven {
+            url "https://plugins.gradle.org/m2/"
+        }
+    }
+    dependencies {
+        classpath 'ru.vyarus:gradle-animalsniffer-plugin:1.4.6'
+        classpath 'net.ltgt.gradle:gradle-errorprone-plugin:0.0.16'
+        classpath "net.ltgt.gradle:gradle-apt-plugin:0.18"
+        classpath 'com.github.ben-manes:gradle-versions-plugin:0.20.0'
+        classpath "gradle.plugin.com.github.sherter.google-java-format:google-java-format-gradle-plugin:0.8"
+        classpath "me.champeau.gradle:jmh-gradle-plugin:0.4.8"
+        classpath "gradle.plugin.io.morethan.jmhreport:gradle-jmh-report:0.9.0"
+    }
+}
+
+// Display the version report using: ./gradlew dependencyUpdates
+// Also see https://github.com/ben-manes/gradle-versions-plugin.
+apply plugin: 'com.github.ben-manes.versions'
+
+subprojects {
+    apply plugin: "checkstyle"
+    apply plugin: 'maven'
+    apply plugin: 'idea'
+    apply plugin: 'eclipse'
+    apply plugin: 'java'
+    apply plugin: "signing"
+    apply plugin: "jacoco"
+    // The plugin only has an effect if a signature is specified
+    apply plugin: 'ru.vyarus.animalsniffer'
+    apply plugin: 'findbugs'
+    apply plugin: 'net.ltgt.apt'
+    apply plugin: 'net.ltgt.apt-idea'
+    apply plugin: "me.champeau.gradle.jmh"
+    apply plugin: "io.morethan.jmhreport"
+    apply plugin: 'com.github.sherter.google-java-format'
+    apply plugin: "net.ltgt.errorprone"
+
+    group = "io.openconsensus"
+    version = "0.1.0-SNAPSHOT" // CURRENT_VERSION
+
+    sourceCompatibility = 1.7
+    targetCompatibility = 1.7
+
+    repositories {
+        mavenCentral()
+        mavenLocal()
+    }
+
+    [compileJava, compileTestJava, compileJmhJava].each() {
+        // We suppress the "try" warning because it disallows managing an auto-closeable with
+        // try-with-resources without referencing the auto-closeable within the try block.
+        // We suppress the "processing" warning as suggested in
+        // https://groups.google.com/forum/#!topic/bazel-discuss/_R3A9TJSoPM
+        it.options.compilerArgs += ["-Xlint:all", "-Xlint:-try", "-Xlint:-processing"]
+        it.options.compilerArgs += ["-XepAllDisabledChecksAsWarnings", "-XepDisableWarningsInGeneratedCode"]
+
+        // MutableMethodReturnType can suggest returning Guava types from
+        // API methods (https://github.com/google/error-prone/issues/982).
+        it.options.compilerArgs += ["-Xep:MutableMethodReturnType:OFF"]
+        
+	    // Doesn't currently use Var annotations.
+        it.options.compilerArgs += ["-Xep:Var:OFF"]
+
+        // ImmutableRefactoring suggests using com.google.errorprone.annotations.Immutable,
+        // but currently uses javax.annotation.concurrent.Immutable
+        it.options.compilerArgs += ["-Xep:ImmutableRefactoring:OFF"]
+
+        // This check causes a NullPointerException
+        // (https://github.com/google/error-prone/issues/1138).
+        it.options.compilerArgs += ["-Xep:NullableDereference:OFF"]
+
+        // ExpectedExceptionRefactoring and TestExceptionRefactoring suggest using
+        // assertThrows, but assertThrows only works well with lambdas.
+        it.options.compilerArgs += ["-Xep:ExpectedExceptionRefactoring:OFF"]
+        it.options.compilerArgs += ["-Xep:TestExceptionRefactoring:OFF"]
+        it.options.encoding = "UTF-8"
+    }
+
+    compileTestJava {
+        // serialVersionUID is basically guaranteed to be useless in tests
+        options.compilerArgs += ["-Xlint:-serial"]
+        // It undeprecates DoubleSubject.isEqualTo(Double).
+        options.compilerArgs += ["-Xlint:-deprecation"]
+    }
+
+    jar.manifest {
+        attributes('Implementation-Title': name,
+                'Implementation-Version': version,
+                'Built-By': System.getProperty('user.name'),
+                'Built-JDK': System.getProperty('java.version'),
+                'Source-Compatibility': sourceCompatibility,
+                'Target-Compatibility': targetCompatibility)
+    }
+
+    javadoc.options {
+        encoding = 'UTF-8'
+        links 'https://docs.oracle.com/javase/8/docs/api/'
+    }
+
+    ext {
+        autoValueVersion = '1.4'
+        findBugsAnnotationsVersion = '3.0.1'
+        findBugsJsr305Version = '3.0.2'
+        errorProneVersion = '2.3.2'
+        grpcVersion = '1.18.0'
+        guavaVersion = '26.0-android'
+
+        libraries = [
+                auto_value: "com.google.auto.value:auto-value:${autoValueVersion}",
+                auto_service: 'com.google.auto.service:auto-service:1.0-rc3',
+                config: 'com.typesafe:config:1.2.1',
+                errorprone: "com.google.errorprone:error_prone_annotations:${errorProneVersion}",
+                findbugs_annotations: "com.google.code.findbugs:annotations:${findBugsAnnotationsVersion}",
+                grpc_context: "io.grpc:grpc-context:${grpcVersion}",
+                guava: "com.google.guava:guava:${guavaVersion}",
+                jsr305: "com.google.code.findbugs:jsr305:${findBugsJsr305Version}",
+
+                // Test dependencies.
+                guava_testlib: "com.google.guava:guava-testlib:${guavaVersion}",
+                junit: 'junit:junit:4.12',
+                mockito: 'org.mockito:mockito-core:1.9.5',
+                truth: 'com.google.truth:truth:0.42',
+        ]
+    }
+
+    configurations {
+        compile {
+            // Detect Maven Enforcer's dependencyConvergence failures. We only
+            // care for artifacts used as libraries by others.
+            resolutionStrategy.failOnVersionConflict()
+        }
+    }
+
+    dependencies {
+        compileOnly libraries.errorprone,
+                libraries.jsr305
+
+        testCompile libraries.guava_testlib,
+                libraries.junit,
+                libraries.mockito,
+                libraries.truth
+
+        // The ErrorProne plugin defaults to the latest, which would break our
+        // build if error prone releases a new version with a new check
+        errorprone "com.google.errorprone:error_prone_core:${errorProneVersion}"
+    }
+
+    findbugs {
+        toolVersion = findBugsAnnotationsVersion
+        ignoreFailures = false   // bug free or it doesn't ship!
+        effort = 'max'
+        reportLevel = 'low'      // low = sensitive to even minor mistakes
+        omitVisitors = []        // bugs that we want to ignore
+        excludeFilter = file("$rootDir/findbugs-exclude.xml")
+    }
+    // Generate html report for findbugs.
+    findbugsMain {
+        reports {
+            xml.enabled = false
+            html.enabled = true
+        }
+    }
+    findbugsTest {
+        reports {
+            xml.enabled = false
+            html.enabled = true
+        }
+    }
+    findbugsJmh {
+        reports {
+            xml.enabled = false
+            html.enabled = true
+        }
+    }
+
+    checkstyle {
+        configFile = file("$rootDir/buildscripts/checkstyle.xml")
+        toolVersion = "8.12"
+        ignoreFailures = false
+        if (rootProject.hasProperty("checkstyle.ignoreFailures")) {
+            ignoreFailures = rootProject.properties["checkstyle.ignoreFailures"].toBoolean()
+        }
+        configProperties["rootDir"] = rootDir
+    }
+
+    googleJavaFormat {
+        toolVersion '1.7'
+    }
+
+    afterEvaluate {  // Allow subproject to add more source sets.
+        tasks.googleJavaFormat {
+            source = sourceSets*.allJava
+            include '**/*.java'
+        }
+
+        tasks.verifyGoogleJavaFormat {
+            source = sourceSets*.allJava
+            include '**/*.java'
+        }
+    }
+
+    signing {
+        required false
+        sign configurations.archives
+    }
+
+    task javadocJar(type: Jar) {
+        classifier = 'javadoc'
+        from javadoc
+    }
+
+    task sourcesJar(type: Jar) {
+        classifier = 'sources'
+        from sourceSets.main.allSource
+    }
+
+    artifacts {
+        archives javadocJar, sourcesJar
+    }
+
+    jmh {
+        jmhVersion = '1.20'
+        warmupIterations = 10
+        iterations = 10
+        fork = 1
+        failOnError = true
+        resultFormat = 'JSON'
+        // Allow to run single benchmark class like:
+        // ./gradlew -PjmhIncludeSingleClass=StatsTraceContextBenchmark clean :grpc-core:jmh
+        if (project.hasProperty('jmhIncludeSingleClass')) {
+            include = [
+                    project.property('jmhIncludeSingleClass')
+            ]
+        }
+    }
+
+    jmhReport {
+        jmhResultPath = project.file("${project.buildDir}/reports/jmh/results.json")
+        jmhReportOutput = project.file("${project.buildDir}/reports/jmh")
+    }
+
+    tasks.jmh.finalizedBy tasks.jmhReport
+
+    // At a test failure, log the stack trace to the console so that we don't
+    // have to open the HTML in a browser.
+    test {
+        testLogging {
+            exceptionFormat = 'full'
+            showExceptions true
+            showCauses true
+            showStackTraces true
+        }
+        maxHeapSize = '1500m'
+    }
+}
diff --git a/buildscripts/checkstyle.xml b/buildscripts/checkstyle.xml
new file mode 100644
index 0000000000..09fe7d24e9
--- /dev/null
+++ b/buildscripts/checkstyle.xml
@@ -0,0 +1,278 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+          "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
+          "https://checkstyle.org/dtds/configuration_1_3.dtd">
+
+<!--
+    Checkstyle configuration that checks the Google coding conventions from Google Java Style
+    that can be found at https://google.github.io/styleguide/javaguide.html.
+
+    Checkstyle is very configurable. Be sure to read the documentation at
+    http://checkstyle.sf.net (or in your downloaded distribution).
+
+    To completely disable a check, just comment it out or delete it from the file.
+
+    Authors: Max Vetrenko, Ruslan Diachenko, Roman Ivanov.
+ -->
+
+<module name = "Checker">
+    <property name="charset" value="UTF-8"/>
+
+    <property name="severity" value="error"/>
+
+
+    <module name="RegexpHeader">
+        <property name="headerFile" value="${rootDir}/buildscripts/checkstyle.license"/>
+        <property name="fileExtensions" value="java"/>
+    </module>
+
+    <property name="fileExtensions" value="java, properties, xml"/>
+    <!-- Checks for whitespace                               -->
+    <!-- See http://checkstyle.sf.net/config_whitespace.html -->
+    <module name="FileTabCharacter">
+        <property name="eachLine" value="true"/>
+    </module>
+
+    <module name="TreeWalker">
+        <module name="OuterTypeFilename"/>
+        <module name="IllegalTokenText">
+            <property name="tokens" value="STRING_LITERAL, CHAR_LITERAL"/>
+            <property name="format"
+             value="\\u00(09|0(a|A)|0(c|C)|0(d|D)|22|27|5(C|c))|\\(0(10|11|12|14|15|42|47)|134)"/>
+            <property name="message"
+             value="Consider using special escape sequence instead of octal value or Unicode escaped value."/>
+        </module>
+        <module name="AvoidEscapedUnicodeCharacters">
+            <property name="allowEscapesForControlCharacters" value="true"/>
+            <property name="allowByTailComment" value="true"/>
+            <property name="allowNonPrintableEscapes" value="true"/>
+        </module>
+        <module name="LineLength">
+            <property name="max" value="100"/>
+            <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
+        </module>
+        <module name="AvoidStarImport"/>
+        <module name="RedundantImport"/>
+        <module name="OneTopLevelClass"/>
+        <module name="NoLineWrap"/>
+        <module name="EmptyBlock">
+            <property name="option" value="TEXT"/>
+            <property name="tokens"
+             value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
+        </module>
+        <module name="NeedBraces"/>
+        <module name="LeftCurly"/>
+        <module name="RightCurly">
+            <property name="id" value="RightCurlySame"/>
+            <property name="tokens"
+             value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE,
+                    LITERAL_DO"/>
+        </module>
+        <module name="RightCurly">
+            <property name="id" value="RightCurlyAlone"/>
+            <property name="option" value="alone"/>
+            <property name="tokens"
+             value="CLASS_DEF, METHOD_DEF, CTOR_DEF, LITERAL_FOR, LITERAL_WHILE, STATIC_INIT,
+                    INSTANCE_INIT"/>
+        </module>
+        <module name="WhitespaceAround">
+            <property name="allowEmptyConstructors" value="true"/>
+            <property name="allowEmptyMethods" value="true"/>
+            <property name="allowEmptyTypes" value="true"/>
+            <property name="allowEmptyLoops" value="true"/>
+            <message key="ws.notFollowed"
+             value="WhitespaceAround: ''{0}'' is not followed by whitespace. Empty blocks may only be represented as '{}' when not part of a multi-block statement (4.1.3)"/>
+            <message key="ws.notPreceded"
+             value="WhitespaceAround: ''{0}'' is not preceded with whitespace."/>
+        </module>
+        <module name="OneStatementPerLine"/>
+        <module name="MultipleVariableDeclarations"/>
+        <module name="ArrayTypeStyle"/>
+        <!-- <!-\- This rule conflicts with Error Prone's exhaustiveness checking. -\-> -->
+        <!-- <module name="MissingSwitchDefault"/> -->
+        <module name="FallThrough"/>
+        <module name="UpperEll"/>
+        <module name="ModifierOrder"/>
+        <module name="EmptyLineSeparator">
+            <property name="allowNoEmptyLineBetweenFields" value="true"/>
+        </module>
+        <module name="SeparatorWrap">
+            <property name="id" value="SeparatorWrapDot"/>
+            <property name="tokens" value="DOT"/>
+            <property name="option" value="nl"/>
+        </module>
+        <module name="SeparatorWrap">
+            <property name="id" value="SeparatorWrapComma"/>
+            <property name="tokens" value="COMMA"/>
+            <property name="option" value="EOL"/>
+        </module>
+        <module name="SeparatorWrap">
+            <!-- ELLIPSIS is EOL until https://github.com/google/styleguide/issues/258 -->
+            <property name="id" value="SeparatorWrapEllipsis"/>
+            <property name="tokens" value="ELLIPSIS"/>
+            <property name="option" value="EOL"/>
+        </module>
+        <module name="SeparatorWrap">
+            <!-- ARRAY_DECLARATOR is EOL until https://github.com/google/styleguide/issues/259 -->
+            <property name="id" value="SeparatorWrapArrayDeclarator"/>
+            <property name="tokens" value="ARRAY_DECLARATOR"/>
+            <property name="option" value="EOL"/>
+        </module>
+        <module name="SeparatorWrap">
+            <property name="id" value="SeparatorWrapMethodRef"/>
+            <property name="tokens" value="METHOD_REF"/>
+            <property name="option" value="nl"/>
+        </module>
+        <module name="PackageName">
+            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]*)*$"/>
+            <message key="name.invalidPattern"
+             value="Package name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="TypeName">
+            <message key="name.invalidPattern"
+             value="Type name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="MemberName">
+            <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9]*$"/>
+            <message key="name.invalidPattern"
+             value="Member name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="ParameterName">
+            <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
+            <message key="name.invalidPattern"
+             value="Parameter name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="LambdaParameterName">
+            <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
+            <message key="name.invalidPattern"
+                     value="Lambda parameter name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="CatchParameterName">
+            <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
+            <message key="name.invalidPattern"
+             value="Catch parameter name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="LocalVariableName">
+            <property name="tokens" value="VARIABLE_DEF"/>
+            <property name="format" value="^[a-z]([a-z0-9][a-zA-Z0-9]*)?$"/>
+            <message key="name.invalidPattern"
+             value="Local variable name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="ClassTypeParameterName">
+            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
+            <message key="name.invalidPattern"
+             value="Class type name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="MethodTypeParameterName">
+            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
+            <message key="name.invalidPattern"
+             value="Method type name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="InterfaceTypeParameterName">
+            <property name="format" value="(^[A-Z][0-9]?)$|([A-Z][a-zA-Z0-9]*[T]$)"/>
+            <message key="name.invalidPattern"
+             value="Interface type name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="NoFinalizer"/>
+        <module name="GenericWhitespace">
+            <message key="ws.followed"
+             value="GenericWhitespace ''{0}'' is followed by whitespace."/>
+            <message key="ws.preceded"
+             value="GenericWhitespace ''{0}'' is preceded with whitespace."/>
+            <message key="ws.illegalFollow"
+             value="GenericWhitespace ''{0}'' should followed by whitespace."/>
+            <message key="ws.notPreceded"
+             value="GenericWhitespace ''{0}'' is not preceded with whitespace."/>
+        </module>
+        <!-- <!-\- Checkstyle indentation rules conflict with google-java-format: -\-> -->
+        <!-- <module name="Indentation"> -->
+        <!--     <property name="basicOffset" value="2"/> -->
+        <!--     <property name="braceAdjustment" value="0"/> -->
+        <!--     <property name="caseIndent" value="2"/> -->
+        <!--     <property name="throwsIndent" value="4"/> -->
+        <!--     <property name="lineWrappingIndentation" value="4"/> -->
+        <!--     <property name="arrayInitIndent" value="2"/> -->
+        <!-- </module> -->
+        <module name="AbbreviationAsWordInName">
+            <property name="ignoreFinal" value="false"/>
+            <property name="allowedAbbreviationLength" value="1"/>
+        </module>
+        <module name="OverloadMethodsDeclarationOrder"/>
+        <!-- <!-\- Many unit tests define all variables at the start of the method. -\-> -->
+        <!-- <module name="VariableDeclarationUsageDistance"/> -->
+        <module name="CustomImportOrder">
+            <property name="sortImportsInGroupAlphabetically" value="true"/>
+            <property name="separateLineBetweenGroups" value="true"/>
+            <property name="customImportOrderRules" value="STATIC###THIRD_PARTY_PACKAGE"/>
+        </module>
+        <module name="MethodParamPad"/>
+        <module name="NoWhitespaceBefore">
+            <property name="tokens"
+             value="COMMA, SEMI, POST_INC, POST_DEC, DOT, ELLIPSIS, METHOD_REF"/>
+            <property name="allowLineBreaks" value="true"/>
+        </module>
+        <module name="ParenPad"/>
+        <module name="OperatorWrap">
+            <property name="option" value="NL"/>
+            <property name="tokens"
+             value="BAND, BOR, BSR, BXOR, DIV, EQUAL, GE, GT, LAND, LE, LITERAL_INSTANCEOF, LOR,
+                    LT, MINUS, MOD, NOT_EQUAL, PLUS, QUESTION, SL, SR, STAR, METHOD_REF "/>
+        </module>
+        <module name="AnnotationLocation">
+            <property name="id" value="AnnotationLocationMostCases"/>
+            <property name="tokens"
+             value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF"/>
+        </module>
+        <module name="AnnotationLocation">
+            <property name="id" value="AnnotationLocationVariables"/>
+            <property name="tokens" value="VARIABLE_DEF"/>
+            <property name="allowSamelineMultipleAnnotations" value="true"/>
+        </module>
+        <module name="NonEmptyAtclauseDescription"/>
+        <module name="JavadocTagContinuationIndentation"/>
+        <module name="SummaryJavadoc">
+            <property name="forbiddenSummaryFragments"
+             value="^@return the *|^This method returns |^A [{]@code [a-zA-Z0-9]+[}]( is a )"/>
+        </module>
+        <module name="JavadocParagraph"/>
+        <module name="AtclauseOrder">
+            <property name="tagOrder" value="@param, @return, @throws, @deprecated"/>
+            <property name="target"
+             value="CLASS_DEF, INTERFACE_DEF, ENUM_DEF, METHOD_DEF, CTOR_DEF, VARIABLE_DEF"/>
+        </module>
+        <module name="JavadocMethod">
+            <property name="scope" value="public"/>
+            <property name="allowMissingParamTags" value="true"/>
+            <property name="allowMissingThrowsTags" value="true"/>
+            <property name="allowMissingReturnTag" value="true"/>
+            <property name="minLineCount" value="2"/>
+            <!-- <!-\- Too restrictive for tests -\-> -->
+            <!-- <property name="allowedAnnotations" value="Override, Test"/ -->
+            <property name="allowedAnnotations"
+                      value="Override, Test, Before, After, BeforeClass, AfterClass, Setup,
+                             TearDown"/>
+            <property name="allowThrowsTagsForSubclasses" value="true"/>
+        </module>
+        <module name="MethodName">
+            <property name="format" value="^[a-z][a-z0-9][a-zA-Z0-9_]*$"/>
+            <message key="name.invalidPattern"
+             value="Method name ''{0}'' must match pattern ''{1}''."/>
+        </module>
+        <module name="SingleLineJavadoc">
+            <!-- <!-\- Wrong interpretation of the style guide; -\-> -->
+            <!-- <property name="ignoreInlineTags" value="false"/ -->
+        </module>
+        <module name="EmptyCatchBlock">
+            <property name="exceptionVariableName" value="expected"/>
+        </module>
+        <module name="CommentsIndentation"/>
+        <module name="SuppressWarningsHolder"/>
+        <!-- <!-\- Enable ImportControl later. -\-> -->
+        <!-- module name="ImportControl" -->
+            <!-- property name="file" value="${rootDir}/buildscripts/import-control.xml"/ -->
+            <!-- property name="path" value="^.*[\\/]src[\\/]main[\\/]java[\\/].*$"/ -->
+        <!-- /module -->
+        <module name="SuppressionCommentFilter"/>
+    </module>
+    <module name="SuppressWarningsFilter"/>
+</module>
diff --git a/context/README.md b/context/README.md
new file mode 100644
index 0000000000..5065ebd9df
--- /dev/null
+++ b/context/README.md
@@ -0,0 +1,5 @@
+OpenConsensus Context
+======================================================
+
+* Java 7 and Android 14 compatible.
+* Generic Context implementation.
diff --git a/context/build.gradle b/context/build.gradle
new file mode 100644
index 0000000000..486c1795f0
--- /dev/null
+++ b/context/build.gradle
@@ -0,0 +1,10 @@
+description = 'OpenConsensus Context'
+
+dependencies {
+    compile libraries.grpc_context
+
+    compileOnly libraries.auto_value
+
+    signature "org.codehaus.mojo.signature:java17:1.0@signature"
+    signature "net.sf.androidscents.signature:android-api-level-14:4.0_r4@signature"
+}
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000000..87b738cbd0
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000000..a95009c3b9
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.9-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
new file mode 100755
index 0000000000..af6708ff22
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000000..0f8d5937c4
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle b/settings.gradle
new file mode 100644
index 0000000000..868d5b5da5
--- /dev/null
+++ b/settings.gradle
@@ -0,0 +1,7 @@
+rootProject.name = "openconsensus"
+
+include ":openconsensus-api"
+include ":openconsensus-context"
+
+project(':openconsensus-api').projectDir = "$rootDir/api" as File
+project(':openconsensus-context').projectDir = "$rootDir/context" as File