diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 0000000..097f9f9
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,9 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+
diff --git a/.github/workflows/ci-test.yml b/.github/workflows/ci-test.yml
new file mode 100644
index 0000000..828fb3c
--- /dev/null
+++ b/.github/workflows/ci-test.yml
@@ -0,0 +1,26 @@
+name: Test Build
+on:
+  pull_request:
+  push:
+    branches:
+      - 'main'
+
+jobs:
+  tests:
+    name: "Test build"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-java@v3
+        with:
+          distribution: zulu
+          java-version: 8
+      - uses: gradle/gradle-build-action@v2
+        with:
+          gradle-version: 8.3
+      - run: git submodule update --init --recursive && sleep 10 && gradle build
+      - name: Dump docker logs
+        if: always()
+        uses: jwalton/gh-docker-logs@v2
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v3
\ No newline at end of file
diff --git a/.gitignore b/.gitignore
index 524f096..ff00d6a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,11 @@
 # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
 hs_err_pid*
 replay_pid*
+
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build
+
+.idea
\ No newline at end of file
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..e4090fe
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "xdb-apis"]
+	path = xdb-apis
+	url = https://github.com/xdblab/xdb-apis
diff --git a/README.md b/README.md
index e955e2a..501d145 100644
--- a/README.md
+++ b/README.md
@@ -1 +1 @@
-# xdb-java-sdk
\ No newline at end of file
+# xdb-java-sdk
diff --git a/build.gradle b/build.gradle
new file mode 100644
index 0000000..61f614f
--- /dev/null
+++ b/build.gradle
@@ -0,0 +1,196 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * This is a general purpose Gradle build.
+ * To learn more about Gradle by exploring our Samples at https://docs.gradle.org/8.3/samples
+ * This project uses @Incubating APIs which are subject to change.
+ */
+
+plugins {
+	id 'java-library'
+	id "org.openapi.generator" version "6.6.0"
+	id 'io.github.gradle-nexus.publish-plugin' version '1.1.0'
+	id "maven-publish"
+	id 'signing'
+	id 'jacoco'
+	id 'com.diffplug.spotless' version "6.13.0"
+}
+
+java {
+	sourceCompatibility = JavaVersion.VERSION_1_8
+	targetCompatibility = JavaVersion.VERSION_1_8
+	withJavadocJar()
+	withSourcesJar()
+}
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	// for openapi generator
+	implementation 'com.google.guava:guava:32.1.2-jre'
+	implementation "com.fasterxml.jackson.datatype:jackson-datatype-jsr310"
+	implementation 'com.fasterxml.jackson.core:jackson-databind:2.15.2'
+	implementation 'io.github.openfeign:feign-okhttp:12.5'
+	implementation 'io.github.openfeign:feign-jackson:12.5'
+	implementation 'io.github.openfeign:feign-slf4j:12.5'
+	implementation 'io.github.openfeign.form:feign-form:3.8.0'
+	implementation 'org.openapitools:jackson-databind-nullable:0.2.6'
+	implementation 'javax.annotation:javax.annotation-api:1.3.2'
+
+	// lombok
+	compileOnly 'org.projectlombok:lombok:1.18.30'
+	annotationProcessor 'org.projectlombok:lombok:1.18.30'
+
+	testImplementation 'org.junit.jupiter:junit-jupiter:5.10.0'
+	testCompileOnly 'org.projectlombok:lombok:1.18.30'
+	testAnnotationProcessor 'org.projectlombok:lombok:1.18.30'
+}
+
+// open api
+
+openApiValidate {
+	inputSpec.set("$rootDir/xdb-apis/api-schema/xdb.yaml")
+}
+
+openApiGenerate {
+	generatorName = "java"
+	inputSpec = "$rootDir/xdb-apis/api-schema/xdb.yaml".toString()
+	outputDir = "$buildDir/generated".toString()
+	apiPackage = "io.xdb.gen.api"
+	modelPackage = "io.xdb.gen.models"
+	invokerPackage = "io.xdb.gen.api"
+	configOptions = [
+			configPackage: "io.xdb.gen.configuration",
+			basePackage  : "io.xdb.gen",
+			library      : "feign",
+			interfaceOnly: "true"
+	]
+}
+
+compileJava.dependsOn tasks.openApiGenerate
+sourceSets.main.java.srcDirs += "$buildDir/generated/src/main/java"
+
+tasks.named('sourcesJar').configure {
+	dependsOn tasks.openApiGenerate
+}
+
+// test
+
+tasks.named('test') {
+	// Use JUnit Platform for unit tests.
+	useJUnitPlatform()
+}
+
+jacocoTestReport {
+	reports {
+		html.outputLocation = layout.buildDirectory.dir('jacocoHtml')
+	}
+}
+
+check.dependsOn tasks.jacocoTestReport
+
+// spotless
+
+spotless {
+	def prettierPlugins = [
+			"prettier": "2.5.1",
+			"prettier-plugin-java": "1.6.1",
+	]
+
+	def ignoredDirs = [
+			'.gradle/**',
+			'.idea/**',
+			'build/**'
+	]
+
+	format 'misc', {
+		// define the files to apply `misc` to
+		target '*.gradle', '.gitignore'
+		targetExclude(ignoredDirs)
+
+		// define the steps to apply to those files
+		trimTrailingWhitespace()
+		indentWithTabs() // or spaces. Takes an integer argument if you don't like 4
+		endWithNewline()
+	}
+	format 'markdown', {
+		target '*.md'
+		targetExclude(ignoredDirs)
+
+		prettier(prettierPlugins).config([
+				'parser': 'markdown'
+		])
+	}
+	java {
+		targetExclude(ignoredDirs)
+
+		importOrder()
+
+		removeUnusedImports()
+
+		prettier(prettierPlugins).config([
+				'parser': 'java',
+				'tabWidth': 4,
+				'printWidth': 120
+		])
+	}
+}
+
+test.dependsOn tasks.spotlessApply
+
+// publish
+
+publishing {
+	publications {
+		mavenJava(MavenPublication) {
+			from(components.java)
+
+			pom {
+				name = "xdb-java-sdk"
+				description = "xdb java sdk core"
+				url = 'https://github.com/xdblab/xdb-java-sdk'
+
+				scm {
+					connection = 'scm:git@github.com:xdblab/xdb-java-sdk.git'
+					developerConnection = 'scm:git@github.com:xdblab/xdb-java-sdk.git'
+					url = 'https://github.com/xdblab/xdb-java-sdk'
+				}
+
+				licenses {
+					license {
+						name = 'The Apache License, Version 2.0'
+						url = 'http://www.apache.org/licenses/LICENSE-2.0.txt'
+					}
+				}
+
+				developers {
+					developer {
+						id = 'zhukaili'
+						name = 'Kaili Zhu'
+						email = 'kailizhu211@gmail.com'
+					}
+				}
+			}
+		}
+	}
+}
+
+signing {
+	sign publishing.publications.mavenJava
+}
+
+group = "io.xdb"
+version = "0.0.1"
+
+nexusPublishing {
+	repositories {
+		sonatype {
+			nexusUrl.set(uri("https://s01.oss.sonatype.org/service/local/"))
+			snapshotRepositoryUrl.set(uri("https://s01.oss.sonatype.org/content/repositories/snapshots/"))
+			// username = project.property('myNexusUsername')
+			// password = project.property('myNexusPassword')
+		}
+	}
+}
diff --git a/gradle.properties b/gradle.properties
new file mode 100644
index 0000000..18f452c
--- /dev/null
+++ b/gradle.properties
@@ -0,0 +1,6 @@
+# This file was generated by the Gradle 'init' task.
+# https://docs.gradle.org/current/userguide/build_environment.html#sec:gradle_configuration_properties
+
+org.gradle.parallel=true
+org.gradle.caching=true
+
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..ac72c34
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.3-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
diff --git a/gradlew b/gradlew
new file mode 100755
index 0000000..0adc8e1
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | 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: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    if ! command -v java >/dev/null 2>&1
+    then
+        die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+        # shellcheck disable=SC3045
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+
+# 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" "-Xms64m"'
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+    die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..93e3f59
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@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=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@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" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+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 execute
+
+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
+
+: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 %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 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!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle b/settings.gradle
new file mode 100644
index 0000000..a2ac823
--- /dev/null
+++ b/settings.gradle
@@ -0,0 +1,9 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * The settings file is used to specify which projects to include in your build.
+ * For more detailed information on multi-project builds, please refer to https://docs.gradle.org/8.3/userguide/building_swift_projects.html in the Gradle documentation.
+ * This project uses @Incubating APIs which are subject to change.
+ */
+
+rootProject.name = 'xdb-java-sdk'
diff --git a/src/main/java/io/xdb/core/Client.java b/src/main/java/io/xdb/core/Client.java
new file mode 100644
index 0000000..9d4a819
--- /dev/null
+++ b/src/main/java/io/xdb/core/Client.java
@@ -0,0 +1,46 @@
+package io.xdb.core;
+
+import feign.Feign;
+import feign.Retryer;
+import io.xdb.gen.api.ApiClient;
+import io.xdb.gen.api.DefaultApi;
+import io.xdb.gen.models.ProcessExecutionStartRequest;
+import io.xdb.gen.models.ProcessExecutionStartResponse;
+
+public class Client {
+
+    private final DefaultApi defaultApi;
+    private final ClientOptions clientOptions;
+
+    public Client(final ClientOptions clientOptions) {
+        this.clientOptions = clientOptions;
+        this.defaultApi = buildDefaultApi();
+    }
+
+    private DefaultApi buildDefaultApi() {
+        final ApiClient apiClient = new ApiClient().setBasePath(clientOptions.getServerUrl());
+        apiClient.setObjectMapper(clientOptions.getObjectEncoder().getObjectMapper());
+
+        final Feign.Builder feignBuilder = apiClient
+            .getFeignBuilder()
+            .retryer(
+                new Retryer.Default(
+                    clientOptions.getInitialIntervalMills(),
+                    clientOptions.getMaximumIntervalMills(),
+                    clientOptions.getMaximumAttempts()
+                )
+            )
+            .errorDecoder(new ServerErrorDecoder());
+        apiClient.setFeignBuilder(feignBuilder);
+        return apiClient.buildClient(DefaultApi.class);
+    }
+
+    public String startProcess() {
+        final ProcessExecutionStartRequest request = new ProcessExecutionStartRequest()
+            .processId("")
+            .processType("")
+            .workerUrl("");
+        final ProcessExecutionStartResponse response = defaultApi.apiV1XdbServiceProcessExecutionStartPost(request);
+        return response.getProcessExecutionId();
+    }
+}
diff --git a/src/main/java/io/xdb/core/ClientOptions.java b/src/main/java/io/xdb/core/ClientOptions.java
new file mode 100644
index 0000000..59dbed0
--- /dev/null
+++ b/src/main/java/io/xdb/core/ClientOptions.java
@@ -0,0 +1,14 @@
+package io.xdb.core;
+
+import lombok.Data;
+
+@Data
+public class ClientOptions {
+
+    private final String serverUrl;
+    private final ObjectEncoder objectEncoder;
+
+    private long initialIntervalMills = 100;
+    private long maximumIntervalMills = 1000;
+    private int maximumAttempts = 10;
+}
diff --git a/src/main/java/io/xdb/core/ObjectEncoder.java b/src/main/java/io/xdb/core/ObjectEncoder.java
new file mode 100644
index 0000000..8d0dc41
--- /dev/null
+++ b/src/main/java/io/xdb/core/ObjectEncoder.java
@@ -0,0 +1,32 @@
+package io.xdb.core;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.xdb.gen.models.EncodedObject;
+
+public interface ObjectEncoder {
+    /**
+     * Each {@link ObjectEncoder} has an Encoding Type that it handles.
+     *
+     * @return encoding type that this converter handles.
+     */
+    String getEncodingType();
+
+    /**
+     * Encode a Java object to an EncodedObject
+     *
+     * @param object Java object to convert
+     * @return encoded object with the encoding type of the encoder
+     */
+    EncodedObject encode(final Object object);
+
+    /**
+     * Decode an encoded object into a Java object with input type
+     * @param encodedObject encoded object to decode
+     * @param type Java class to decode into
+     * @param <T> Java class to decode into
+     * @return decoded Java object
+     */
+    <T> T decode(final EncodedObject encodedObject, final Class<T> type);
+
+    ObjectMapper getObjectMapper();
+}
diff --git a/src/main/java/io/xdb/core/ServerErrorDecoder.java b/src/main/java/io/xdb/core/ServerErrorDecoder.java
new file mode 100644
index 0000000..3bd7004
--- /dev/null
+++ b/src/main/java/io/xdb/core/ServerErrorDecoder.java
@@ -0,0 +1,28 @@
+package io.xdb.core;
+
+import static feign.FeignException.errorStatus;
+
+import feign.FeignException;
+import feign.Response;
+import feign.RetryableException;
+import feign.codec.ErrorDecoder;
+
+public class ServerErrorDecoder implements ErrorDecoder {
+
+    @Override
+    public Exception decode(final String methodKey, final Response response) {
+        if (response.status() >= 500 && response.status() < 600) {
+            final FeignException exception = errorStatus(methodKey, response);
+            return new RetryableException(
+                response.status(),
+                exception.getMessage(),
+                response.request().httpMethod(),
+                exception,
+                null,
+                response.request()
+            );
+        }
+
+        return new ErrorDecoder.Default().decode(methodKey, response);
+    }
+}
diff --git a/xdb-apis b/xdb-apis
new file mode 160000
index 0000000..c17db3f
--- /dev/null
+++ b/xdb-apis
@@ -0,0 +1 @@
+Subproject commit c17db3fb56c7ff750ae269e986d0d14124bbf23b