binary wire format with flatbuffers (#509)

* first flatbuffer schema

* do not lint auto-generated files

* add flatbuffers package

* add flatbuffer module

* wire up /data/X/T route

* use flatbuffers for matrix data fetc

* clarity and comments

* add flatbuffer layout route

* clean up obsolete code

* fix tests

* move flake8 config to setup.cfg

* add comments

* lint

* rework layout routes for fbs

* add more type support to fbs

* lint

* add flatbuffer support for annotations

* function name improvements

* fix botched merge with master

* remove unused import

* route cleanup for flatbuffers

* rename function for clarity

* add missing globals to Jest tests

* fix client JS tests

* fix routes for Python tests

* comments for clarity

* non-finite floating point hardening

* more non-finite number handling

* lint

* fix tests for summarizeAnnotations

* harden diffexp calculation against FP errors

* cleanup unused code

* lint

* add encoding tests for flatbuffers

* application type specified as strings

* fix spelling error

* improve variable names

* add note about documentation gap

* rename FBS DataFrame to Matrix

client/src/util/actionHelpers.js

@@ -25,17 +25,18 @@ export function catchErrorsWrap(fn, dispatchToUser = false) {
 }
 
 /*
-Wrapper to perform an async fetch and JSON decode response.
+Wrapper to perform async fetch with some modest error handling
+and decoding.
 */
-export const doJsonRequest = async url => {
+const doFetch = async (url, acceptType) => {
   const res = await fetch(url, {
     method: "get",
     headers: new Headers({
-      "Content-Type": "application/json"
+      Accept: acceptType
     })
   });
-  if (res.ok && res.headers.get("Content-Type") === "application/json") {
-    return res.json();
+  if (res.ok && res.headers.get("Content-Type") === acceptType) {
+    return res;
   }
   // else an error
   let msg = `Unexpected HTTP response ${res.status}, ${res.statusText}`;
@@ -47,6 +48,22 @@ export const doJsonRequest = async url => {
   throw new Error(msg);
 };
 
+/*
+Wrapper to perform an async fetch and JSON decode response.
+*/
+export const doJsonRequest = async url => {
+  const res = await doFetch(url, "application/json");
+  return res.json();
+};
+
+/*
+Wrapper to perform an async fetch for binary data.
+*/
+export const doBinaryRequest = async url => {
+  const res = await doFetch(url, "application/octet-stream");
+  return res.arrayBuffer();
+};
+
 /*
 This function "packs" filter index lists into the more efficient
 "range" form specified in the REST 0.2 spec.