diff --git a/.github/scripts/graphql.sh b/.github/scripts/graphql.sh
new file mode 100755
index 000000000..f76ad3a8d
--- /dev/null
+++ b/.github/scripts/graphql.sh
@@ -0,0 +1,11 @@
+#!/bin/bash -e
+
+SCRIPT_DIR="$(dirname "$(readlink -f "$0")")"
+. "$SCRIPT_DIR/util.sh"
+
+BASE="http://localhost:8080/fhir"
+TYPE=$1
+EXPECTED_SIZE=$(curl -s "$BASE/${TYPE}?_summary=count" | jq -r .total)
+ACTUAL_SIZE=$(curl -s -H "Content-Type: application/graphql" -d "{ ${TYPE}List { id } }" "$BASE/\$graphql" | jq ".data.${TYPE}List | length")
+
+test "size" "$ACTUAL_SIZE" "$EXPECTED_SIZE"
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a6343f94f..c8a9a24c5 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -59,6 +59,7 @@ jobs:
         - luid
         - metrics
         - openid-auth
+        - operation-graphql
         - operation-measure-evaluate-measure
         - page-store
         - page-store-cassandra
@@ -531,6 +532,12 @@ jobs:
     - name: Conditional Update If-None-Match
       run: .github/scripts/conditional-update-if-none-match.sh
 
+    - name: GraphQL Patient
+      run: .github/scripts/graphql.sh Patient
+
+    - name: GraphQL Observation
+      run: .github/scripts/graphql.sh Observation
+
   not-enforcing-referential-integrity-test:
     needs: build
     runs-on: ubuntu-22.04
@@ -1238,6 +1245,12 @@ jobs:
     - name: Conditional Update If-None-Match
       run: .github/scripts/conditional-update-if-none-match.sh
 
+    - name: GraphQL Patient
+      run: .github/scripts/graphql.sh Patient
+
+    - name: GraphQL Observation
+      run: .github/scripts/graphql.sh Observation
+
     - name: Docker Stats
       run: docker stats --no-stream
 
diff --git a/deps.edn b/deps.edn
index 0952670f1..f84f104ec 100644
--- a/deps.edn
+++ b/deps.edn
@@ -10,6 +10,9 @@
   blaze/interaction
   {:local/root "modules/interaction"}
 
+  blaze.operation/graphql
+  {:local/root "modules/operation-graphql"}
+
   blaze.operation/measure-evaluate-measure
   {:local/root "modules/operation-measure-evaluate-measure"}
 
@@ -80,7 +83,7 @@
   :outdated
   {:replace-deps
    {com.github.liquidz/antq
-    {:mvn/version "2.2.992"}
+    {:mvn/version "2.2.999"}
 
     org.slf4j/slf4j-nop
     {:mvn/version "2.0.6"}}
@@ -114,6 +117,7 @@
     "-d" "modules/metrics"
     "-d" "modules/module-base"
     "-d" "modules/openid-auth"
+    "-d" "modules/operation-graphql"
     "-d" "modules/operation-measure-evaluate-measure"
     "-d" "modules/page-store"
     "-d" "modules/page-store-cassandra"
@@ -127,6 +131,8 @@
     "-d" "modules/test-util"
     "-d" "modules/thread-pool-executor-collector"
     "--exclude" "com.taoensso/timbre"
+    "--exclude" "org.antlr/antlr4"
     "--exclude" "org.eclipse.jetty/jetty-server"
     "--exclude" "org.clojure/alpha.spec"
+    "--exclude" "com.walmartlabs/lacinia"
     "--exclude" "lambdaisland/kaocha"]}}}
diff --git a/docs/performance.md b/docs/performance.md
index 82887f884..609eaf0cc 100644
--- a/docs/performance.md
+++ b/docs/performance.md
@@ -4,6 +4,10 @@
 
 A section about FHIR Search performance can be found [here](performance/fhir-search.md).
 
+## GraphQL
+
+A section about GraphQL performance can be found [here](performance/graphql.md).
+
 ## Transaction Bundle Upload - Summary
 
 | CPU         | # Cores | RAM (GB) | Xmx | MBJ³ | -c¹ | # Resources | Disk Util.² | Duration (s) | Resources/s |
diff --git a/docs/performance/graphql.md b/docs/performance/graphql.md
new file mode 100644
index 000000000..10430cd4b
--- /dev/null
+++ b/docs/performance/graphql.md
@@ -0,0 +1,32 @@
+# GraphQL
+
+## Simple Code Search
+
+In this section, GraphQL for selecting Observation resources with a certain code is used.
+
+### Download of Resources
+
+All measurements are done after Blaze is in a steady state with all resources to download in it's resource cache in order to cancel out resource load times from disk or file system cache.
+
+Download is done using the following `curl` command:
+
+```sh
+curl -s -H "Content-Type: application/graphql" -d "{ ObservationList { subject { reference } } }" "http://localhost:8080/\$graphql" > /dev/null"
+```
+
+| CPU        | Heap Mem | Block Cache | # Res. ¹ | # Obs. ² | Code    | # Hits | Time (s) | T / 1M ³ |
+|------------|---------:|------------:|---------:|---------:|---------|-------:|---------:|---------:|
+| EPYC 7543P |     8 GB |        1 GB |     29 M |     28 M | 17861-6 |  171 k |    1.045 |     6.11 |
+| EPYC 7543P |     8 GB |        1 GB |     29 M |     28 M | 39156-5 |  967 k |    5.740 |     5.94 |
+| EPYC 7543P |     8 GB |        1 GB |     29 M |     28 M | 29463-7 |  1.3 M |    8.057 |     6.20 |
+| EPYC 7543P |    30 GB |       10 GB |    292 M |    278 M | 17861-6 |  1.7 M |   10.744 |     6.32 |
+| EPYC 7543P |    30 GB |       10 GB |    292 M |    278 M | 39156-5 |  9.7 M |   70.122 |     7.23 |
+| EPYC 7543P |    30 GB |       10 GB |    292 M |    278 M | 29463-7 |   13 M |   96.735 |     7.44 |
+
+¹ Number of Resources, ² Number of Observations, ³ Time in seconds per 1 million resources, The amount of system memory was 128 GB in all cases.
+
+According to the measurements, the time needed by Blaze to deliver Observations containing only the subject reference is about **twice as fast** as returning the same information via [Subsetted FHIR Search](fhir-search.md#download-of-resources-with-subsetting) and **4 times as fast** as downloading the whole Observation Resources using [FHIR Search](fhir-search.md#download-of-resources).
+
+## Used Dataset
+
+The dataset was the same as in [FHIR Search](fhir-search.md) performance tests.
diff --git a/modules/interaction/.clj-kondo/config.edn b/modules/interaction/.clj-kondo/config.edn
index 78125243f..a5d4f5356 100644
--- a/modules/interaction/.clj-kondo/config.edn
+++ b/modules/interaction/.clj-kondo/config.edn
@@ -4,27 +4,16 @@
   blaze.async.comp/do-sync clojure.core/let
   blaze.db.api-stub/with-system-data clojure.core/with-open
   blaze.interaction.create-test/with-handler clojure.core/fn
-  blaze.interaction.create-test/with-handler-data clojure.core/fn
   blaze.interaction.delete-test/with-handler clojure.core/fn
-  blaze.interaction.delete-test/with-handler-data clojure.core/fn
   blaze.interaction.history.instance-test/with-handler clojure.core/fn
-  blaze.interaction.history.instance-test/with-handler-data clojure.core/fn
   blaze.interaction.history.system-test/with-handler clojure.core/fn
-  blaze.interaction.history.system-test/with-handler-data clojure.core/fn
   blaze.interaction.history.type-test/with-handler clojure.core/fn
-  blaze.interaction.history.type-test/with-handler-data clojure.core/fn
   blaze.interaction.read-test/with-handler clojure.core/fn
-  blaze.interaction.read-test/with-handler-data clojure.core/fn
   blaze.interaction.search-compartment-test/with-handler clojure.core/fn
-  blaze.interaction.search-compartment-test/with-handler-data clojure.core/fn
   blaze.interaction.search-system-test/with-handler clojure.core/fn
-  blaze.interaction.search-system-test/with-handler-data clojure.core/fn
   blaze.interaction.search-type-test/with-handler clojure.core/fn
-  blaze.interaction.search-type-test/with-handler-data clojure.core/fn
   blaze.interaction.transaction-test/with-handler clojure.core/fn
-  blaze.interaction.transaction-test/with-handler-data clojure.core/fn
   blaze.interaction.update-test/with-handler clojure.core/fn
-  blaze.interaction.update-test/with-handler-data clojure.core/fn
   blaze.test-util/with-system clojure.core/with-open}
 
  :linters
diff --git a/modules/interaction/test/blaze/interaction/create_test.clj b/modules/interaction/test/blaze/interaction/create_test.clj
index 6da134eba..de1104d37 100644
--- a/modules/interaction/test/blaze/interaction/create_test.clj
+++ b/modules/interaction/test/blaze/interaction/create_test.clj
@@ -12,7 +12,7 @@
     [blaze.fhir.response.create-spec]
     [blaze.fhir.spec.type]
     [blaze.interaction.create]
-    [blaze.interaction.test-util :as itu :refer [wrap-error]]
+    [blaze.interaction.test-util :refer [wrap-error]]
     [blaze.interaction.util-spec]
     [blaze.test-util :as tu :refer [given-thrown with-system]]
     [clojure.spec.alpha :as s]
@@ -95,7 +95,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{handler# :blaze.interaction/create} system]
        ~txs
        (let [~handler-binding (-> handler# wrap-defaults wrap-error)]
diff --git a/modules/interaction/test/blaze/interaction/delete_test.clj b/modules/interaction/test/blaze/interaction/delete_test.clj
index 198612d6b..762e65435 100644
--- a/modules/interaction/test/blaze/interaction/delete_test.clj
+++ b/modules/interaction/test/blaze/interaction/delete_test.clj
@@ -6,7 +6,6 @@
     [blaze.db.api-stub :refer [mem-node-system with-system-data]]
     [blaze.executors :as ex]
     [blaze.interaction.delete]
-    [blaze.interaction.test-util :as itu]
     [blaze.test-util :as tu :refer [given-thrown]]
     [clojure.spec.alpha :as s]
     [clojure.spec.test.alpha :as st]
@@ -55,7 +54,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{handler# :blaze.interaction/delete} system]
        ~txs
        (let [~handler-binding handler#]
diff --git a/modules/interaction/test/blaze/interaction/history/instance_test.clj b/modules/interaction/test/blaze/interaction/history/instance_test.clj
index caf2fd3ba..a611ee2ba 100644
--- a/modules/interaction/test/blaze/interaction/history/instance_test.clj
+++ b/modules/interaction/test/blaze/interaction/history/instance_test.clj
@@ -9,7 +9,7 @@
     [blaze.db.api-stub :refer [mem-node-system with-system-data]]
     [blaze.interaction.history.instance]
     [blaze.interaction.history.util-spec]
-    [blaze.interaction.test-util :as itu :refer [wrap-error]]
+    [blaze.interaction.test-util :refer [wrap-error]]
     [blaze.middleware.fhir.db :refer [wrap-db]]
     [blaze.middleware.fhir.db-spec]
     [blaze.test-util :as tu :refer [given-thrown]]
@@ -91,7 +91,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{node# :blaze.db/node
                          handler# :blaze.interaction.history/instance} system]
        ~txs
diff --git a/modules/interaction/test/blaze/interaction/history/system_test.clj b/modules/interaction/test/blaze/interaction/history/system_test.clj
index 896f8620f..9730fdb78 100644
--- a/modules/interaction/test/blaze/interaction/history/system_test.clj
+++ b/modules/interaction/test/blaze/interaction/history/system_test.clj
@@ -8,7 +8,6 @@
     [blaze.db.api-stub :refer [mem-node-system with-system-data]]
     [blaze.interaction.history.system]
     [blaze.interaction.history.util-spec]
-    [blaze.interaction.test-util :as itu]
     [blaze.middleware.fhir.db :refer [wrap-db]]
     [blaze.middleware.fhir.db-spec]
     [blaze.test-util :as tu :refer [given-thrown]]
@@ -93,7 +92,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{node# :blaze.db/node
                          handler# :blaze.interaction.history/system} system]
        ~txs
diff --git a/modules/interaction/test/blaze/interaction/history/type_test.clj b/modules/interaction/test/blaze/interaction/history/type_test.clj
index 719510464..14172afc7 100644
--- a/modules/interaction/test/blaze/interaction/history/type_test.clj
+++ b/modules/interaction/test/blaze/interaction/history/type_test.clj
@@ -8,7 +8,6 @@
     [blaze.db.api-stub :refer [mem-node-system with-system-data]]
     [blaze.interaction.history.type]
     [blaze.interaction.history.util-spec]
-    [blaze.interaction.test-util :as itu]
     [blaze.middleware.fhir.db :refer [wrap-db]]
     [blaze.middleware.fhir.db-spec]
     [blaze.test-util :as tu :refer [given-thrown]]
@@ -94,7 +93,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{node# :blaze.db/node
                          handler# :blaze.interaction.history/type} system]
        ~txs
diff --git a/modules/interaction/test/blaze/interaction/read_test.clj b/modules/interaction/test/blaze/interaction/read_test.clj
index 4f82d2982..83576f32c 100644
--- a/modules/interaction/test/blaze/interaction/read_test.clj
+++ b/modules/interaction/test/blaze/interaction/read_test.clj
@@ -9,7 +9,7 @@
     [blaze.db.api-stub :refer [mem-node-system with-system-data]]
     [blaze.db.spec]
     [blaze.interaction.read]
-    [blaze.interaction.test-util :as itu :refer [wrap-error]]
+    [blaze.interaction.test-util :refer [wrap-error]]
     [blaze.middleware.fhir.db :refer [wrap-db]]
     [blaze.middleware.fhir.db-spec]
     [blaze.test-util :as tu]
@@ -43,7 +43,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{node# :blaze.db/node
                          handler# :blaze.interaction/read} system]
        ~txs
diff --git a/modules/interaction/test/blaze/interaction/search_compartment_test.clj b/modules/interaction/test/blaze/interaction/search_compartment_test.clj
index 58975055b..fe431c64c 100644
--- a/modules/interaction/test/blaze/interaction/search_compartment_test.clj
+++ b/modules/interaction/test/blaze/interaction/search_compartment_test.clj
@@ -9,7 +9,7 @@
     [blaze.interaction.search.nav-spec]
     [blaze.interaction.search.params-spec]
     [blaze.interaction.search.util-spec]
-    [blaze.interaction.test-util :as itu :refer [wrap-error]]
+    [blaze.interaction.test-util :refer [wrap-error]]
     [blaze.middleware.fhir.db :refer [wrap-db]]
     [blaze.middleware.fhir.db-spec]
     [blaze.page-store-spec]
@@ -99,7 +99,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{node# :blaze.db/node
                          handler# :blaze.interaction/search-compartment} system]
        ~txs
diff --git a/modules/interaction/test/blaze/interaction/search_system_test.clj b/modules/interaction/test/blaze/interaction/search_system_test.clj
index 3e73bd47b..03fc3e7bf 100644
--- a/modules/interaction/test/blaze/interaction/search_system_test.clj
+++ b/modules/interaction/test/blaze/interaction/search_system_test.clj
@@ -8,7 +8,7 @@
     [blaze.interaction.search.nav-spec]
     [blaze.interaction.search.params-spec]
     [blaze.interaction.search.util-spec]
-    [blaze.interaction.test-util :as itu :refer [wrap-error]]
+    [blaze.interaction.test-util :refer [wrap-error]]
     [blaze.middleware.fhir.db :refer [wrap-db]]
     [blaze.middleware.fhir.db-spec]
     [blaze.page-store-spec]
@@ -101,7 +101,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{node# :blaze.db/node
                          handler# :blaze.interaction/search-system} system]
        ~txs
diff --git a/modules/interaction/test/blaze/interaction/search_type_test.clj b/modules/interaction/test/blaze/interaction/search_type_test.clj
index 9682a8e04..20dfa2bfc 100644
--- a/modules/interaction/test/blaze/interaction/search_type_test.clj
+++ b/modules/interaction/test/blaze/interaction/search_type_test.clj
@@ -10,7 +10,7 @@
     [blaze.interaction.search.nav-spec]
     [blaze.interaction.search.params-spec]
     [blaze.interaction.search.util-spec]
-    [blaze.interaction.test-util :as itu :refer [wrap-error]]
+    [blaze.interaction.test-util :refer [wrap-error]]
     [blaze.middleware.fhir.db :refer [wrap-db]]
     [blaze.middleware.fhir.db-spec]
     [blaze.page-store-spec]
@@ -171,7 +171,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{node# :blaze.db/node
                          handler# :blaze.interaction/search-type} system]
        ~txs
diff --git a/modules/interaction/test/blaze/interaction/test_util.clj b/modules/interaction/test/blaze/interaction/test_util.clj
index a85e2062e..562381cf3 100644
--- a/modules/interaction/test/blaze/interaction/test_util.clj
+++ b/modules/interaction/test/blaze/interaction/test_util.clj
@@ -8,9 +8,3 @@
   (fn [request]
     (-> (handler request)
         (ac/exceptionally handler-util/error-response))))
-
-
-(defn extract-txs-body [more]
-  (if (vector? (first more))
-    [(first more) (next more)]
-    [[] more]))
diff --git a/modules/interaction/test/blaze/interaction/transaction_test.clj b/modules/interaction/test/blaze/interaction/transaction_test.clj
index 0f2d7fba9..e2ff17cf4 100644
--- a/modules/interaction/test/blaze/interaction/transaction_test.clj
+++ b/modules/interaction/test/blaze/interaction/transaction_test.clj
@@ -14,7 +14,7 @@
     [blaze.interaction.delete]
     [blaze.interaction.read]
     [blaze.interaction.search-type]
-    [blaze.interaction.test-util :as itu :refer [wrap-error]]
+    [blaze.interaction.test-util :refer [wrap-error]]
     [blaze.interaction.transaction]
     [blaze.interaction.update]
     [blaze.interaction.util-spec]
@@ -177,7 +177,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{handler# :blaze.interaction/transaction
                          router# ::router} system]
        ~txs
diff --git a/modules/interaction/test/blaze/interaction/update_test.clj b/modules/interaction/test/blaze/interaction/update_test.clj
index b9b985b38..533bff091 100644
--- a/modules/interaction/test/blaze/interaction/update_test.clj
+++ b/modules/interaction/test/blaze/interaction/update_test.clj
@@ -11,7 +11,7 @@
     [blaze.executors :as ex]
     [blaze.fhir.response.create-spec]
     [blaze.fhir.spec.type]
-    [blaze.interaction.test-util :as itu :refer [wrap-error]]
+    [blaze.interaction.test-util :refer [wrap-error]]
     [blaze.interaction.update]
     [blaze.test-util :as tu :refer [given-thrown with-system]]
     [clojure.spec.alpha :as s]
@@ -98,7 +98,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (itu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{handler# :blaze.interaction/update} system]
        ~txs
        (let [~handler-binding (-> handler# wrap-defaults wrap-error)]
diff --git a/modules/operation-graphql/.clj-kondo/config.edn b/modules/operation-graphql/.clj-kondo/config.edn
new file mode 100644
index 000000000..2660210af
--- /dev/null
+++ b/modules/operation-graphql/.clj-kondo/config.edn
@@ -0,0 +1,22 @@
+{:lint-as
+ {blaze.anomaly/when-ok clojure.core/let
+  blaze.fhir.operation.graphql-test/with-handler clojure.core/fn
+  blaze.test-util/with-system clojure.core/with-open}
+
+ :linters
+ {:unsorted-required-namespaces
+  {:level :error}
+
+  :single-key-in
+  {:level :warning}
+
+  :keyword-binding
+  {:level :error}
+
+  :reduce-without-init
+  {:level :warning}
+
+  :warn-on-reflection
+  {:level :warning :warn-only-on-interop true}}
+
+ :skip-comments true}
diff --git a/modules/operation-graphql/Makefile b/modules/operation-graphql/Makefile
new file mode 100644
index 000000000..e4ae9e7ce
--- /dev/null
+++ b/modules/operation-graphql/Makefile
@@ -0,0 +1,19 @@
+lint:
+	clj-kondo --lint src test deps.edn
+
+prep:
+	clojure -X:deps prep
+
+test: prep
+	clojure -M:test:kaocha --profile :ci
+
+test-coverage: prep
+	clojure -M:test:coverage
+
+clean:
+	rm -rf .clj-kondo/.cache .cpcache target
+
+deps-tree:
+	clojure -X:deps tree
+
+.PHONY: lint prep test test-coverage clean deps-tree
diff --git a/modules/operation-graphql/deps.edn b/modules/operation-graphql/deps.edn
new file mode 100644
index 000000000..123fc0ad6
--- /dev/null
+++ b/modules/operation-graphql/deps.edn
@@ -0,0 +1,42 @@
+{:deps
+ {blaze/module-base
+  {:local/root "../module-base"}
+
+  blaze/rest-util
+  {:local/root "../rest-util"}
+
+  blaze/spec
+  {:local/root "../spec"}
+
+  com.walmartlabs/lacinia
+  {:git/url "https://github.com/alexanderkiel/lacinia.git"
+   :git/sha "d3aa6a7a4b452521f5f311683cc996e782f1f59d"}
+
+  org.antlr/antlr4
+  {:mvn/version "4.10.1"
+   :exclusions
+   [com.ibm.icu/icu4j
+    org.abego.treelayout/org.abego.treelayout.core
+    org.glassfish/javax.json]}}
+
+ :aliases
+ {:test
+  {:extra-paths ["test"]
+
+   :extra-deps
+   {blaze/db-stub
+    {:local/root "../db-stub"}}}
+
+  :kaocha
+  {:extra-deps
+   {lambdaisland/kaocha
+    {:mvn/version "1.71.1119"}}
+
+   :main-opts ["-m" "kaocha.runner"]}
+
+  :coverage
+  {:extra-deps
+   {cloverage/cloverage
+    {:mvn/version "1.2.4"}}
+
+   :main-opts ["-m" "cloverage.coverage" "--codecov" "-p" "src" "-s" "test"]}}}
diff --git a/modules/operation-graphql/src/blaze/fhir/operation/graphql.clj b/modules/operation-graphql/src/blaze/fhir/operation/graphql.clj
new file mode 100644
index 000000000..487e7f37c
--- /dev/null
+++ b/modules/operation-graphql/src/blaze/fhir/operation/graphql.clj
@@ -0,0 +1,123 @@
+(ns blaze.fhir.operation.graphql
+  "Main entry point into the $graphql operation."
+  (:require
+    [blaze.async.comp :as ac]
+    [blaze.db.api :as d]
+    [blaze.executors :as ex]
+    [blaze.fhir.operation.graphql.spec]
+    [blaze.middleware.fhir.metrics :refer [wrap-observe-request-duration]]
+    [clojure.spec.alpha :as s]
+    [com.walmartlabs.lacinia :as lacinia]
+    [com.walmartlabs.lacinia.resolve :as resolve]
+    [com.walmartlabs.lacinia.schema :as ls]
+    [com.walmartlabs.lacinia.util :as lu]
+    [integrant.core :as ig]
+    [ring.util.response :as ring]
+    [taoensso.timbre :as log])
+  (:import
+    [java.util.concurrent TimeUnit]))
+
+
+(def schema
+  {:objects
+   {:Patient
+    {:fields
+     {:id {:type 'String}
+      :gender {:type 'String}}}
+
+    :Observation
+    {:fields
+     {:id {:type 'String}
+      :subject {:type :Reference}}}
+
+    :Reference
+    {:fields
+     {:reference {:type 'String}}}
+
+    :Query
+    {:fields
+     {:PatientList
+      {:type '(list :Patient)
+       :args {:gender {:type 'String}}}
+
+      :ObservationList
+      {:type '(list :Observation)
+       :args {:code {:type 'String}}}}}}})
+
+
+(defn- clauses [args]
+  (mapv (fn [[key value]] [(name key) value]) args))
+
+
+(defn- type-query [db type args]
+  (if (seq args)
+    (d/type-query db type (clauses args))
+    (d/type-list db type)))
+
+
+(defn- resolve-type-list [type {:blaze/keys [db]} args _]
+  (log/trace (format "execute %sList query" type))
+  (let [result (resolve/resolve-promise)]
+    (-> (d/pull-many db (type-query db type args))
+        (ac/when-complete (partial resolve/deliver! result)))
+    result))
+
+
+(defn- compile-schema [options]
+  (-> schema
+      (lu/inject-resolvers
+        {:Query/PatientList (partial resolve-type-list "Patient")
+         :Query/ObservationList (partial resolve-type-list "Observation")})
+      (ls/compile options)))
+
+
+(defn- execute-query [schema db {:keys [request-method] :as request}]
+  (if (= :post request-method)
+    (let [{{:keys [query variables]} :body} request]
+      (lacinia/execute schema query variables {:blaze/db db}))
+    (lacinia/execute schema (get (:params request) "query") nil {:blaze/db db})))
+
+
+(defn- handler [{:keys [executor] :as context}]
+  (let [schema (compile-schema context)]
+    (fn [{:blaze/keys [db] :as request}]
+      (ac/supply-async
+        #(ring/response (execute-query schema db request))
+        executor))))
+
+
+(defmethod ig/pre-init-spec ::handler [_]
+  (s/keys :req-un [:blaze.db/node ::executor]))
+
+
+(defmethod ig/init-key ::handler [_ context]
+  (log/info "Init FHIR $graphql operation handler")
+  (-> (handler context)
+      (wrap-observe-request-duration "operation-graphql")))
+
+
+
+(defmethod ig/pre-init-spec ::executor [_]
+  (s/keys :opt-un [::num-threads]))
+
+
+(defn- executor-init-msg [num-threads]
+  (format "Init $graphql operation executor with %d threads" num-threads))
+
+
+(defmethod ig/init-key ::executor
+  [_ {:keys [num-threads] :or {num-threads 4}}]
+  (log/info (executor-init-msg num-threads))
+  (ex/io-pool num-threads "operation-graphql-%d"))
+
+
+(defmethod ig/halt-key! ::executor
+  [_ executor]
+  (log/info "Stopping $graphql operation executor...")
+  (ex/shutdown! executor)
+  (if (ex/await-termination executor 10 TimeUnit/SECONDS)
+    (log/info "$graphql operation executor was stopped successfully")
+    (log/warn "Got timeout while stopping the $graphql operation executor")))
+
+
+(derive ::executor :blaze.metrics/thread-pool-executor)
diff --git a/modules/operation-graphql/src/blaze/fhir/operation/graphql/middleware.clj b/modules/operation-graphql/src/blaze/fhir/operation/graphql/middleware.clj
new file mode 100644
index 000000000..9e8229e92
--- /dev/null
+++ b/modules/operation-graphql/src/blaze/fhir/operation/graphql/middleware.clj
@@ -0,0 +1,9 @@
+(ns blaze.fhir.operation.graphql.middleware
+  (:require
+    [blaze.fhir.operation.graphql.middleware.query :refer [wrap-query]]
+    [integrant.core :as ig]))
+
+
+(defmethod ig/init-key ::query [_ _]
+  {:name ::query
+   :wrap wrap-query})
diff --git a/modules/operation-graphql/src/blaze/fhir/operation/graphql/middleware/query.clj b/modules/operation-graphql/src/blaze/fhir/operation/graphql/middleware/query.clj
new file mode 100644
index 000000000..30ba516f3
--- /dev/null
+++ b/modules/operation-graphql/src/blaze/fhir/operation/graphql/middleware/query.clj
@@ -0,0 +1,81 @@
+(ns blaze.fhir.operation.graphql.middleware.query
+  (:require
+    [blaze.anomaly :as ba :refer [if-ok when-ok]]
+    [blaze.async.comp :as ac]
+    [clojure.string :as str]
+    [cognitect.anomalies :as anom]
+    [jsonista.core :as j]
+    [ring.util.request :as request]))
+
+
+(defn- query-request-graphql [{:keys [body] :as request}]
+  (if body
+    (assoc request :body {:query (slurp body)})
+    (ba/incorrect "Missing HTTP body.")))
+
+
+(def ^:private object-mapper
+  (j/object-mapper
+    {:decode-key-fn true}))
+
+
+(defn- parse-json [body]
+  (ba/try-all ::anom/incorrect (j/read-value body object-mapper)))
+
+
+(defn- conform-json [json]
+  (if (map? json)
+    (select-keys json [:query])
+    (ba/incorrect
+      "Expect a JSON object."
+      :fhir/issue "structure"
+      :fhir/operation-outcome "MSG_JSON_OBJECT")))
+
+
+(defn- query-request-json [{:keys [body] :as request}]
+  (if body
+    (when-ok [x (parse-json body)
+              query (conform-json x)]
+      (assoc request :body query))
+    (ba/incorrect "Missing HTTP body.")))
+
+
+(defn- unsupported-media-type-msg [media-type]
+  (format "Unsupported media type `%s` expect one of `application/graphql` or `application/json`."
+          media-type))
+
+
+(defn- query-request [request]
+  (if-let [content-type (request/content-type request)]
+    (cond
+      (str/starts-with? content-type "application/graphql")
+      (query-request-graphql request)
+
+      (str/starts-with? content-type "application/json")
+      (query-request-json request)
+
+      :else
+      (ba/incorrect (unsupported-media-type-msg content-type)
+                    :http/status 415))
+    (ba/incorrect "Content-Type header expected, but is missing.")))
+
+
+(defn wrap-query
+  "Middleware to slurp a GraphQL query from the body according the content-type
+  header.
+
+  Updates the :body key in the request map with a map consisting of at least a
+  :query key. If the content-type is `application/graphql` the body string is
+  the value of the query key. If the content-type is `application/json` the map
+  is the parsed JSON body.
+
+  Returns an OperationOutcome in the internal format, skipping the handler, with
+  an appropriate error when a content-type other than `application/graphql` or
+  `application/json` was specified.
+
+  See also: https://graphql.org/learn/serving-over-http/"
+  [handler]
+  (fn [request]
+    (if-ok [request (query-request request)]
+      (handler request)
+      ac/completed-future)))
diff --git a/modules/operation-graphql/src/blaze/fhir/operation/graphql/spec.clj b/modules/operation-graphql/src/blaze/fhir/operation/graphql/spec.clj
new file mode 100644
index 000000000..3ee178622
--- /dev/null
+++ b/modules/operation-graphql/src/blaze/fhir/operation/graphql/spec.clj
@@ -0,0 +1,13 @@
+(ns blaze.fhir.operation.graphql.spec
+  (:require
+    [blaze.executors :as ex]
+    [blaze.fhir.operation.graphql :as-alias graphql]
+    [clojure.spec.alpha :as s]))
+
+
+(s/def ::graphql/executor
+  ex/executor?)
+
+
+(s/def ::graphql/num-threads
+  pos-int?)
diff --git a/modules/operation-graphql/test/blaze/fhir/operation/graphql/middleware/query_test.clj b/modules/operation-graphql/test/blaze/fhir/operation/graphql/middleware/query_test.clj
new file mode 100644
index 000000000..c2d01588a
--- /dev/null
+++ b/modules/operation-graphql/test/blaze/fhir/operation/graphql/middleware/query_test.clj
@@ -0,0 +1,117 @@
+(ns blaze.fhir.operation.graphql.middleware.query-test
+  (:require
+    [blaze.async.comp :as ac]
+    [blaze.fhir.operation.graphql.middleware.query :refer [wrap-query]]
+    [blaze.fhir.spec :as fhir-spec]
+    [blaze.handler.util :as handler-util]
+    [blaze.test-util :as tu]
+    [clojure.spec.test.alpha :as st]
+    [clojure.test :as test :refer [deftest is testing]]
+    [juxt.iota :refer [given]]
+    [taoensso.timbre :as log])
+  (:import
+    [java.io ByteArrayInputStream]
+    [java.nio.charset StandardCharsets]))
+
+
+(set! *warn-on-reflection* true)
+(st/instrument)
+(log/set-level! :trace)
+
+
+(test/use-fixtures :each tu/fixture)
+
+
+(defn wrap-error [handler]
+  (fn [request]
+    (-> (handler request)
+        (ac/exceptionally handler-util/error-response))))
+
+
+(def handler
+  "A handler which just returns the :body from the request."
+  (-> (comp ac/completed-future :body)
+      wrap-query
+      wrap-error))
+
+
+(defn input-stream
+  ([^String s]
+   (ByteArrayInputStream. (.getBytes s StandardCharsets/UTF_8)))
+  ([^String s closed?]
+   (proxy [ByteArrayInputStream] [(.getBytes s StandardCharsets/UTF_8)]
+     (close []
+       (reset! closed? true)))))
+
+
+(deftest wrap-query-test
+  (testing "application/graphql"
+    (let [closed? (atom false)]
+      (given @(handler
+                {:headers {"content-type" "application/graphql"}
+                 :body (input-stream "query-160125" closed?)})
+        :query := "query-160125")
+      (is (true? @closed?))))
+
+  (testing "application/json"
+    (let [closed? (atom false)]
+      (given @(handler
+                {:headers {"content-type" "application/json"}
+                 :body (input-stream "{\"query\": \"query-155956\"}" closed?)})
+        :query := "query-155956")
+      (is (true? @closed?)))
+
+    (testing "unknown keys are ignored"
+      (given @(handler
+                {:headers {"content-type" "application/json"}
+                 :body (input-stream "{\"query\": \"query-155956\", \"foo\": \"bar\"}")})
+        :query := "query-155956"
+        :foo :? nil?)))
+
+  (testing "body with invalid JSON"
+    (given @(handler
+              {:headers {"content-type" "application/json"}
+               :body (input-stream "x")})
+      :status := 400
+      [:body fhir-spec/fhir-type] := :fhir/OperationOutcome
+      [:body :issue 0 :severity] := #fhir/code"error"
+      [:body :issue 0 :code] := #fhir/code"invalid"
+      [:body :issue 0 :diagnostics] := "Unrecognized token 'x': was expecting (JSON String, Number, Array, Object or token 'null', 'true' or 'false')\n at [Source: (ByteArrayInputStream); line: 1, column: 2]"))
+
+  (testing "body with no JSON object"
+    (given @(handler
+              {:headers {"content-type" "application/json"}
+               :body (input-stream "1")})
+      :status := 400
+      [:body fhir-spec/fhir-type] := :fhir/OperationOutcome
+      [:body :issue 0 :severity] := #fhir/code"error"
+      [:body :issue 0 :code] := #fhir/code"structure"
+      [:body :issue 0 :details :coding 0 :system] := #fhir/uri"http://terminology.hl7.org/CodeSystem/operation-outcome"
+      [:body :issue 0 :details :coding 0 :code] := #fhir/code"MSG_JSON_OBJECT"
+      [:body :issue 0 :diagnostics] := "Expect a JSON object."))
+
+  (testing "other content is invalid"
+    (testing "without content-type header"
+      (given @(handler {})
+        :status := 400
+        [:body fhir-spec/fhir-type] := :fhir/OperationOutcome
+        [:body :issue 0 :severity] := #fhir/code"error"
+        [:body :issue 0 :code] := #fhir/code"invalid"
+        [:body :issue 0 :diagnostics] := "Content-Type header expected, but is missing."))
+
+    (testing "with unknown content-type header"
+      (given @(handler {:headers {"content-type" "text/plain"} :body (input-stream "")})
+        :status := 415
+        [:body fhir-spec/fhir-type] := :fhir/OperationOutcome
+        [:body :issue 0 :severity] := #fhir/code"error"
+        [:body :issue 0 :code] := #fhir/code"invalid"
+        [:body :issue 0 :diagnostics] := "Unsupported media type `text/plain` expect one of `application/graphql` or `application/json`."))
+
+    (testing "missing body"
+      (doseq [content-type ["application/graphql" "application/json"]]
+        (given @(handler
+                  {:headers {"content-type" content-type}})
+          [:body fhir-spec/fhir-type] := :fhir/OperationOutcome
+          [:body :issue 0 :severity] := #fhir/code"error"
+          [:body :issue 0 :code] := #fhir/code"invalid"
+          [:body :issue 0 :diagnostics] := "Missing HTTP body.")))))
diff --git a/modules/operation-graphql/test/blaze/fhir/operation/graphql/middleware_test.clj b/modules/operation-graphql/test/blaze/fhir/operation/graphql/middleware_test.clj
new file mode 100644
index 000000000..7be908d06
--- /dev/null
+++ b/modules/operation-graphql/test/blaze/fhir/operation/graphql/middleware_test.clj
@@ -0,0 +1,24 @@
+(ns blaze.fhir.operation.graphql.middleware-test
+  (:require
+    [blaze.fhir.operation.graphql.middleware :as middleware]
+    [blaze.log]
+    [blaze.middleware.fhir.db-spec]
+    [blaze.test-util :as tu]
+    [clojure.spec.test.alpha :as st]
+    [clojure.test :as test :refer [deftest]]
+    [integrant.core :as ig]
+    [juxt.iota :refer [given]]
+    [taoensso.timbre :as log]))
+
+
+(st/instrument)
+(log/set-level! :trace)
+
+
+(test/use-fixtures :each tu/fixture)
+
+
+(deftest init-test
+  (given (ig/init {::middleware/query {}})
+    [::middleware/query :name] := ::middleware/query
+    [::middleware/query :wrap] :? fn?))
diff --git a/modules/operation-graphql/test/blaze/fhir/operation/graphql/test_util.clj b/modules/operation-graphql/test/blaze/fhir/operation/graphql/test_util.clj
new file mode 100644
index 000000000..a75ca2548
--- /dev/null
+++ b/modules/operation-graphql/test/blaze/fhir/operation/graphql/test_util.clj
@@ -0,0 +1,10 @@
+(ns blaze.fhir.operation.graphql.test-util
+  (:require
+    [blaze.async.comp :as ac]
+    [blaze.handler.util :as handler-util]))
+
+
+(defn wrap-error [handler]
+  (fn [request]
+    (-> (handler request)
+        (ac/exceptionally handler-util/error-response))))
diff --git a/modules/operation-graphql/test/blaze/fhir/operation/graphql_test.clj b/modules/operation-graphql/test/blaze/fhir/operation/graphql_test.clj
new file mode 100644
index 000000000..615d7cb39
--- /dev/null
+++ b/modules/operation-graphql/test/blaze/fhir/operation/graphql_test.clj
@@ -0,0 +1,220 @@
+(ns blaze.fhir.operation.graphql-test
+  (:require
+    [blaze.db.api-stub :refer [mem-node-system with-system-data]]
+    [blaze.executors :as ex]
+    [blaze.fhir.operation.graphql :as graphql]
+    [blaze.fhir.operation.graphql.test-util :refer [wrap-error]]
+    [blaze.log]
+    [blaze.middleware.fhir.db :refer [wrap-db]]
+    [blaze.middleware.fhir.db-spec]
+    [blaze.test-util :as tu :refer [given-thrown with-system]]
+    [clojure.spec.alpha :as s]
+    [clojure.spec.test.alpha :as st]
+    [clojure.test :as test :refer [deftest is testing]]
+    [integrant.core :as ig]
+    [juxt.iota :refer [given]]
+    [taoensso.timbre :as log]))
+
+
+(st/instrument)
+(log/set-level! :trace)
+
+
+(test/use-fixtures :each tu/fixture)
+
+
+(deftest init-test
+  (testing "nil config"
+    (given-thrown (ig/init {::graphql/handler nil})
+      :key := ::graphql/handler
+      :reason := ::ig/build-failed-spec
+      [:explain ::s/problems 0 :pred] := `map?))
+
+  (testing "missing config"
+    (given-thrown (ig/init {::graphql/handler {}})
+      :key := ::graphql/handler
+      :reason := ::ig/build-failed-spec
+      [:explain ::s/problems 0 :pred] := `(fn ~'[%] (contains? ~'% :node))
+      [:explain ::s/problems 1 :pred] := `(fn ~'[%] (contains? ~'% :executor))))
+
+  (testing "invalid executor"
+    (given-thrown (ig/init {::graphql/handler {:executor ::invalid}})
+      :key := ::graphql/handler
+      :reason := ::ig/build-failed-spec
+      [:explain ::s/problems 0 :pred] := `(fn ~'[%] (contains? ~'% :node))
+      [:explain ::s/problems 1 :pred] := `ex/executor?
+      [:explain ::s/problems 1 :val] := ::invalid)))
+
+
+(deftest executor-init-test
+  (testing "nil config"
+    (given-thrown (ig/init {::graphql/executor nil})
+      :key := ::graphql/executor
+      :reason := ::ig/build-failed-spec
+      [:explain ::s/problems 0 :pred] := `map?))
+
+  (testing "invalid num-threads"
+    (given-thrown (ig/init {::graphql/executor {:num-threads ::invalid}})
+      :key := ::graphql/executor
+      :reason := ::ig/build-failed-spec
+      [:explain ::s/problems 0 :pred] := `pos-int?
+      [:explain ::s/problems 0 :val] := ::invalid))
+
+  (testing "with default num-threads"
+    (with-system [{::graphql/keys [executor]}
+                  {::graphql/executor {}}]
+      (is (ex/executor? executor)))))
+
+
+(def system
+  (assoc mem-node-system
+    ::graphql/handler
+    {:node (ig/ref :blaze.db/node)
+     :executor (ig/ref :blaze.test/executor)}
+    :blaze.test/executor {}))
+
+
+(defmacro with-handler [[handler-binding] & more]
+  (let [[txs body] (tu/extract-txs-body more)]
+    `(with-system-data [{node# :blaze.db/node
+                         handler# ::graphql/handler} system]
+       ~txs
+       (let [~handler-binding (-> handler# (wrap-db node#) wrap-error)]
+         ~@body))))
+
+
+(deftest execute-query-test
+  (testing "query param"
+    (testing "invalid query"
+      (testing "via query param"
+        (with-handler [handler]
+          (let [{:keys [status body]}
+                @(handler
+                   {:request-method :get
+                    :params {"query" "{"}})]
+
+            (is (= 200 status))
+
+            (given body
+              [:errors 0 :message] := "Failed to parse GraphQL query."))))
+
+      (testing "via body"
+        (with-handler [handler]
+          (let [{:keys [status body]}
+                @(handler
+                   {:request-method :post
+                    :body {:query "{"}})]
+
+            (is (= 200 status))
+
+            (given body
+              [:errors 0 :message] := "Failed to parse GraphQL query.")))))
+
+    (testing "success"
+      (testing "Patient"
+        (testing "empty result"
+          (testing "via query param"
+            (with-handler [handler]
+              (let [{:keys [status body]}
+                    @(handler
+                       {:request-method :get
+                        :params {"query" "{ PatientList { gender } }"}})]
+
+                (is (= 200 status))
+
+                (given body
+                  [:data :PatientList] :? empty?
+                  [:errors] :? empty?))))
+
+          (testing "via body"
+            (with-handler [handler]
+              (let [{:keys [status body]}
+                    @(handler
+                       {:request-method :post
+                        :body {:query "{ PatientList { gender } }"}})]
+
+                (is (= 200 status))
+
+                (given body
+                  [:data :PatientList] :? empty?
+                  [:errors] :? empty?)))))
+
+        (testing "one Patient"
+          (with-handler [handler]
+            [[[:put {:fhir/type :fhir/Patient :id "0"
+                     :gender #fhir/code"male"}]]]
+
+            (let [{:keys [status body]}
+                  @(handler
+                     {:request-method :get
+                      :params {"query" "{ PatientList { id gender } }"}})]
+
+              (is (= 200 status))
+
+              (given body
+                [:data :PatientList 0 :id] := "0"
+                [:data :PatientList 0 :gender] := "male"
+                [:errors] :? empty?)))))
+
+      (testing "Observation"
+        (testing "empty result"
+          (with-handler [handler]
+            (let [{:keys [status body]}
+                  @(handler
+                     {:request-method :get
+                      :params {"query" "{ ObservationList { subject { reference } } }"}})]
+
+              (is (= 200 status))
+
+              (given body
+                [:data :ObservationList] :? empty?
+                [:errors] :? empty?))))
+
+        (testing "one Observation"
+          (with-handler [handler]
+            [[[:put {:fhir/type :fhir/Patient :id "0"}]
+              [:put {:fhir/type :fhir/Observation :id "0"
+                     :subject #fhir/Reference{:reference "Patient/0"}}]]]
+
+            (let [{:keys [status body]}
+                  @(handler
+                     {:request-method :get
+                      :params {"query" "{ ObservationList { subject { reference } } }"}})]
+
+              (is (= 200 status))
+
+              (given body
+                [:data :ObservationList 0 :subject :reference] := "Patient/0"
+                [:errors] :? empty?))))
+
+        (testing "one Observation with code"
+          (with-handler [handler]
+            [[[:put {:fhir/type :fhir/Patient :id "0"}]
+              [:put {:fhir/type :fhir/Observation :id "0"
+                     :code
+                     #fhir/CodeableConcept
+                             {:coding
+                              [#fhir/Coding
+                                      {:system #fhir/uri"http://loinc.org"
+                                       :code #fhir/code"39156-5"}]}
+                     :subject #fhir/Reference{:reference "Patient/0"}}]
+              [:put {:fhir/type :fhir/Observation :id "1"
+                     :code
+                     #fhir/CodeableConcept
+                             {:coding
+                              [#fhir/Coding
+                                      {:system #fhir/uri"http://loinc.org"
+                                       :code #fhir/code"29463-7"}]}
+                     :subject #fhir/Reference{:reference "Patient/0"}}]]]
+
+            (let [{:keys [status body]}
+                  @(handler
+                     {:request-method :get
+                      :params {"query" "{ ObservationList(code: \"39156-5\") { subject { reference } } }"}})]
+
+              (is (= 200 status))
+
+              (given body
+                [:data :ObservationList count] := 1
+                [:data :ObservationList 0 :subject :reference] := "Patient/0"
+                [:errors] :? empty?))))))))
diff --git a/modules/operation-graphql/tests.edn b/modules/operation-graphql/tests.edn
new file mode 100644
index 000000000..94fe5636c
--- /dev/null
+++ b/modules/operation-graphql/tests.edn
@@ -0,0 +1,5 @@
+#kaocha/v1
+    #merge
+        [{}
+         #profile {:ci {:reporter kaocha.report/documentation
+                        :color? false}}]
diff --git a/modules/operation-measure-evaluate-measure/.clj-kondo/config.edn b/modules/operation-measure-evaluate-measure/.clj-kondo/config.edn
index 809ba05c7..0b290a0ed 100644
--- a/modules/operation-measure-evaluate-measure/.clj-kondo/config.edn
+++ b/modules/operation-measure-evaluate-measure/.clj-kondo/config.edn
@@ -3,7 +3,6 @@
   blaze.anomaly/when-ok clojure.core/let
   blaze.db.api-stub/with-system-data clojure.core/with-open
   blaze.fhir.operation.evaluate-measure-test/with-handler clojure.core/fn
-  blaze.fhir.operation.evaluate-measure-test/with-handler-data clojure.core/fn
   blaze.test-util/with-system clojure.core/with-open
   prometheus.alpha/defcounter clojure.core/def
   prometheus.alpha/defhistogram clojure.core/def}
diff --git a/modules/operation-measure-evaluate-measure/test/blaze/fhir/operation/evaluate_measure/test_util.clj b/modules/operation-measure-evaluate-measure/test/blaze/fhir/operation/evaluate_measure/test_util.clj
index 6644eaf96..e5dd5ed68 100644
--- a/modules/operation-measure-evaluate-measure/test/blaze/fhir/operation/evaluate_measure/test_util.clj
+++ b/modules/operation-measure-evaluate-measure/test/blaze/fhir/operation/evaluate_measure/test_util.clj
@@ -8,9 +8,3 @@
   (fn [request]
     (-> (handler request)
         (ac/exceptionally handler-util/error-response))))
-
-
-(defn extract-txs-body [more]
-  (if (vector? (first more))
-    [(first more) (next more)]
-    [[] more]))
diff --git a/modules/operation-measure-evaluate-measure/test/blaze/fhir/operation/evaluate_measure_test.clj b/modules/operation-measure-evaluate-measure/test/blaze/fhir/operation/evaluate_measure_test.clj
index 33e8d87f6..4367b0c4e 100644
--- a/modules/operation-measure-evaluate-measure/test/blaze/fhir/operation/evaluate_measure_test.clj
+++ b/modules/operation-measure-evaluate-measure/test/blaze/fhir/operation/evaluate_measure_test.clj
@@ -17,9 +17,7 @@
     [java-time.api :as time]
     [juxt.iota :refer [given]]
     [reitit.core :as reitit]
-    [taoensso.timbre :as log])
-  (:import
-    [java.util.concurrent ExecutorService]))
+    [taoensso.timbre :as log]))
 
 
 (set! *warn-on-reflection* true)
@@ -141,7 +139,7 @@
   (testing "with default num-threads"
     (with-system [{::evaluate-measure/keys [executor]}
                   {::evaluate-measure/executor {}}]
-      (is (instance? ExecutorService executor)))))
+      (is (ex/executor? executor)))))
 
 
 (deftest compile-duration-seconds-collector-init-test
@@ -176,7 +174,7 @@
 
 
 (defmacro with-handler [[handler-binding] & more]
-  (let [[txs body] (etu/extract-txs-body more)]
+  (let [[txs body] (tu/extract-txs-body more)]
     `(with-system-data [{node# :blaze.db/node
                          handler# ::evaluate-measure/handler} system]
        ~txs
diff --git a/modules/rest-api/src/blaze/rest_api/middleware/output.clj b/modules/rest-api/src/blaze/rest_api/middleware/output.clj
index be9e1c1cf..691ddab12 100644
--- a/modules/rest-api/src/blaze/rest_api/middleware/output.clj
+++ b/modules/rest-api/src/blaze/rest_api/middleware/output.clj
@@ -4,6 +4,7 @@
     [blaze.fhir.spec :as fhir-spec]
     [clojure.data.xml :as xml]
     [clojure.java.io :as io]
+    [jsonista.core :as j]
     [muuntaja.parse :as parse]
     [prometheus.alpha :as prom]
     [ring.util.response :as ring]
@@ -100,3 +101,15 @@
   ([handler opts]
    (fn [request respond raise]
      (handler request #(respond (handle-response opts request %)) raise))))
+
+
+(defn- handle-json-response [response]
+  (-> (update response :body j/write-value-as-bytes)
+      (ring/content-type "application/json;charset=utf-8")))
+
+
+(defn wrap-json-output
+  "Middleware to output data (not resources) in JSON"
+  [handler]
+  (fn [request respond raise]
+    (handler request #(respond (handle-json-response %)) raise)))
diff --git a/modules/rest-api/src/blaze/rest_api/middleware/resource.clj b/modules/rest-api/src/blaze/rest_api/middleware/resource.clj
index 1ccb3ccd2..903c55a3e 100644
--- a/modules/rest-api/src/blaze/rest_api/middleware/resource.clj
+++ b/modules/rest-api/src/blaze/rest_api/middleware/resource.clj
@@ -105,7 +105,7 @@
 
 
 (defn- unsupported-media-type-msg [media-type]
-  (format "Unsupported Media Type `%s` expect one of `application/fhir+json` or `application/fhir+xml`."
+  (format "Unsupported media type `%s` expect one of `application/fhir+json` or `application/fhir+xml`."
           media-type))
 
 
diff --git a/modules/rest-api/src/blaze/rest_api/routes.clj b/modules/rest-api/src/blaze/rest_api/routes.clj
index 8780df22c..d4742d1f0 100644
--- a/modules/rest-api/src/blaze/rest_api/routes.clj
+++ b/modules/rest-api/src/blaze/rest_api/routes.clj
@@ -68,7 +68,10 @@
 
 (def ^:private wrap-output
   {:name :output
-   :wrap output/wrap-output})
+   :compile (fn [{:keys [response-type]} _]
+              (if (= :json response-type)
+                   output/wrap-json-output
+                   output/wrap-output))})
 
 
 (def ^:private wrap-error
@@ -169,13 +172,18 @@
 
 (defn- operation-system-handler-route
   [{:keys [node db-sync-timeout]}
-   {:blaze.rest-api.operation/keys [code system-handler]}]
+   {:blaze.rest-api.operation/keys
+    [code response-type post-middleware system-handler]}]
   (when system-handler
     [[(str "/$" code)
-      {:middleware [[wrap-db node db-sync-timeout]]
-       :get system-handler
-       :post {:middleware [wrap-resource]
-              :handler system-handler}}]]))
+      (cond-> {:middleware [[wrap-db node db-sync-timeout]]
+               :get system-handler
+               :post {:middleware [(if post-middleware
+                                     post-middleware
+                                     wrap-resource)]
+                      :handler system-handler}}
+        response-type
+        (assoc :response-type response-type))]]))
 
 
 (defn operation-type-handler-route
diff --git a/modules/rest-api/test/blaze/rest_api/middleware/resource_test.clj b/modules/rest-api/test/blaze/rest_api/middleware/resource_test.clj
index 2eeee418f..a7d951502 100644
--- a/modules/rest-api/test/blaze/rest_api/middleware/resource_test.clj
+++ b/modules/rest-api/test/blaze/rest_api/middleware/resource_test.clj
@@ -163,7 +163,7 @@
         [:body fhir-spec/fhir-type] := :fhir/OperationOutcome
         [:body :issue 0 :severity] := #fhir/code"error"
         [:body :issue 0 :code] := #fhir/code"invalid"
-        [:body :issue 0 :diagnostics] := "Unsupported Media Type `text/plain` expect one of `application/fhir+json` or `application/fhir+xml`."))
+        [:body :issue 0 :diagnostics] := "Unsupported media type `text/plain` expect one of `application/fhir+json` or `application/fhir+xml`."))
 
     (testing "missing body"
       (doseq [content-type ["application/fhir+json" "application/fhir+xml"]]
diff --git a/modules/test-util/src/blaze/test_util.clj b/modules/test-util/src/blaze/test_util.clj
index 99223740f..53f6d5225 100644
--- a/modules/test-util/src/blaze/test_util.clj
+++ b/modules/test-util/src/blaze/test_util.clj
@@ -104,3 +104,9 @@
   (st/instrument)
   (f)
   (st/unstrument))
+
+
+(defn extract-txs-body [more]
+  (if (vector? (first more))
+    [(first more) (next more)]
+    [[] more]))
diff --git a/resources/blaze.edn b/resources/blaze.edn
index cefedce07..63d98339b 100644
--- a/resources/blaze.edn
+++ b/resources/blaze.edn
@@ -69,7 +69,14 @@
         :def-uri "http://hl7.org/fhir/OperationDefinition/Measure-evaluate-measure"
         :resource-types ["Measure"]
         :type-handler #blaze/ref :blaze.fhir.operation.evaluate-measure/handler
-        :instance-handler #blaze/ref :blaze.fhir.operation.evaluate-measure/handler}]
+        :instance-handler #blaze/ref :blaze.fhir.operation.evaluate-measure/handler}
+    #:blaze.rest-api.operation
+       {:code "graphql"
+        :def-uri "http://hl7.org/fhir/OperationDefinition/Resource-graphql"
+        :resource-types ["Resource"]
+        :post-middleware #blaze/ref :blaze.fhir.operation.graphql.middleware/query
+        :response-type :json
+        :system-handler #blaze/ref :blaze.fhir.operation.graphql/handler}]
    :enforce-referential-integrity #blaze/cfg ["ENFORCE_REFERENTIAL_INTEGRITY" boolean? true]}
 
   ;;
@@ -156,6 +163,18 @@
   :blaze.fhir.operation.evaluate-measure/compile-duration-seconds {}
   :blaze.fhir.operation.evaluate-measure/evaluate-duration-seconds {}
 
+  ;;
+  ;; FHIR Operation GraphQL
+  ;;
+  :blaze.fhir.operation.graphql/handler
+  {:node #blaze/ref :blaze.db/node
+   :executor #blaze/ref :blaze.fhir.operation.graphql/executor}
+
+  :blaze.fhir.operation.graphql/executor
+  {:num-threads #blaze/cfg ["FHIR_OPERATION_GRAPHQL_THREADS" pos-int? 4]}
+
+  :blaze.fhir.operation.graphql.middleware/query {}
+
   ;;
   ;; Database Node
   ;;