diff --git a/src/io/InvalidHandleException.php b/src/io/InvalidHandleException.php
new file mode 100644
index 00000000..7ed6b25a
--- /dev/null
+++ b/src/io/InvalidHandleException.php
@@ -0,0 +1,20 @@
+<?hh // strict
+/*
+ *  Copyright (c) 2004-present, Facebook, Inc.
+ *  All rights reserved.
+ *
+ *  This source code is licensed under the MIT license found in the
+ *  LICENSE file in the root directory of this source tree.
+ *
+ */
+
+
+namespace HH\Lib\Experimental\IO;
+
+/** Indicates that an invalid handle was used or requested.
+ *
+ * For example, calling `IO\requestError()` throws this exception in an
+ * HTTP request, as the model only defines input and output streams, not an
+ * error stream.
+ */
+final class InvalidHandleException extends \Exception {}
diff --git a/src/io/_Private/StdioHandle.php b/src/io/_Private/StdioHandle.php
index 20f700ef..489dc58e 100644
--- a/src/io/_Private/StdioHandle.php
+++ b/src/io/_Private/StdioHandle.php
@@ -14,17 +14,41 @@
 
 final class StdioHandle extends NativeHandle {
   <<__Memoize>>
-  public static function stderr(): IO\WriteHandle {
-    return new self(\STDERR);
+  public static function serverError(): IO\WriteHandle {
+    // while the documentation says to use the STDERR constant, that is
+    // conditionally defined
+    return new self(\fopen('php://stderr', 'w'));
   }
 
   <<__Memoize>>
-  public static function stdout(): IO\WriteHandle {
-    return new self(\STDOUT);
+  public static function serverOutput(): IO\WriteHandle {
+    return new self(\fopen('php://stdout', 'w'));
   }
 
   <<__Memoize>>
-  public static function stdin(): IO\ReadHandle {
-    return new self(\STDIN);
+  public static function serverInput(): IO\ReadHandle {
+    return new self(\fopen('php://stdin', 'r'));
+  }
+
+  <<__Memoize>>
+  public static function requestInput(): IO\ReadHandle {
+    return new self(\fopen('php://input', 'r'));
+  }
+
+  <<__Memoize>>
+  public static function requestOutput(): IO\WriteHandle{
+    return new self(\fopen('php://output', 'w'));
+  }
+
+  <<__Memoize>>
+  public static function requestError(): IO\WriteHandle {
+    /* HH_FIXME[2049] deregistered PHP stdlib */
+    /* HH_FIXME[4107] deregistered PHP stdlib */
+    if (\php_sapi_name() !== "cli") {
+      throw new IO\InvalidHandleException(
+        "requestError is not supported in the current execution mode"
+      );
+    }
+    return self::serverError();
   }
 }
diff --git a/src/io/stdio.php b/src/io/stdio.php
index f31a1384..45faeee8 100644
--- a/src/io/stdio.php
+++ b/src/io/stdio.php
@@ -12,14 +12,60 @@
 
 use namespace HH\Lib\_Private;
 
-function stdout(): WriteHandle {
-  return _Private\StdioHandle::stdout();
+/** Return STDOUT for the server process.
+ *
+ * This is usually not the same thing as request output.
+ *
+ * @see request_output
+ */
+function server_output(): WriteHandle {
+  return _Private\StdioHandle::serverOutput();
 }
 
-function stderr(): WriteHandle {
-  return _Private\StdioHandle::stderr();
+/** Return STDERR for the server process.
+ *
+ * @see request_error
+ */
+function server_error(): WriteHandle {
+  return _Private\StdioHandle::serverError();
 }
 
-function stdin(): ReadHandle {
-  return _Private\StdioHandle::stdin();
+/** Return STDIN for the server process.
+ *
+ * @see request_input
+ */
+function server_input(): ReadHandle {
+  return _Private\StdioHandle::serverInput();
+}
+
+/** Return the output handle for the current request.
+ *
+ * This should generally be used for sending data to clients. In CLI mode, this
+ * is usually the process STDOUT.
+ *
+ * @see requestOutput
+ */
+function request_output(): WriteHandle {
+  return _Private\StdioHandle::requestOutput();
+}
+
+/** Return the error output handle for the current request.
+ *
+ * This is usually only available for CLI scripts; it will throw an
+ * `UnsupportedHandleException` in most other contexts, including HTTP
+ * requests.
+ *
+ * In CLI mode, this is usually the process STDERR.
+ */
+function request_error(): WriteHandle {
+  return _Private\StdioHandle::requestError();
+}
+
+/** Return the input handle for the current request.
+ *
+ * In CLI mode, this is likely STDIN; for HTTP requests, it may contain the
+ * POST data, if any.
+ */
+function request_input(): ReadHandle {
+  return _Private\StdioHandle::requestInput();
 }