diff --git a/xo-webutil/.github/workflows/main.yml b/xo-webutil/.github/workflows/main.yml
new file mode 100644
index 00000000..8b3795c9
--- /dev/null
+++ b/xo-webutil/.github/workflows/main.yml
@@ -0,0 +1,117 @@
+name: build xo-callback + xo dependencies
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+env:
+  # Customize the CMake build type here (Release, Debug, RelWithDebInfo, etc.)
+  BUILD_TYPE: Release
+
+jobs:
+  build:
+    # The CMake configure and build commands are platform agnostic and should work equally well on Windows or Mac.
+    # You can convert this to a matrix build if you need cross-platform coverage.
+    # See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: checkout source
+      uses: actions/checkout@v3
+
+    - name: Install catch2
+      # install catch2.  see [[https://stackoverflow.com/questions/57982945/how-to-apt-get-install-in-a-github-actions-workflow]]
+      run: sudo apt-get install -y catch2
+
+    # ----------------------------------------------------------------
+
+    - name: Clone xo-cmake
+      uses: actions/checkout@v3
+      with:
+        repository: Rconybea/xo-cmake
+        path: repo/xo-cmake
+
+    - name: Configure xo-cmake
+      run: cmake -B ${{github.workspace}}/build_xo-cmake -DCMAKE_INSTALL_PREFIX=${{github.workspace}}/local repo/xo-cmake
+
+    - name: Build xo-cmake (trivial)
+      run: cmake --build ${{github.workspace}}/build_xo-cmake --config ${{env.BUILD_TYPE}}
+
+    - name: Install xo-cmake
+      run: cmake --install ${{github.workspace}}/build_xo-cmake
+
+    # ----------------------------------------------------------------
+
+    - name: Clone indentlog
+      uses: actions/checkout@v3
+      with:
+        repository: Rconybea/indentlog
+        path: repo/indentlog
+
+    - name: Configure indentlog
+      # configure cmake for indentlog in dedicated build directory.
+      run: cmake -B ${{github.workspace}}/build_indentlog -DCMAKE_MODULE_PATH=${{github.workspace}}/local/share/cmake -DCMAKE_INSTALL_PREFIX=${{github.workspace}}/local repo/indentlog
+
+    - name: Build indentlog
+      run: cmake --build ${{github.workspace}}/build_indentlog --config ${{env.BUILD_TYPE}}
+
+    - name: Install indentlog
+      # install into ${{github.workspace}}/local
+      run: cmake --install ${{github.workspace}}/build_indentlog
+
+    # ----------------------------------------------------------------
+
+    - name: Clone refcnt
+      uses: actions/checkout@v3
+      with:
+        repository: Rconybea/refcnt
+        path: repo/refcnt
+
+    - name: Configure refcnt
+      # configure cmake for refcnt in dedicated build directory.
+      run: cmake -B ${{github.workspace}}/build_refcnt -DCMAKE_MODULE_PATH=${{github.workspace}}/local/share/cmake -DCMAKE_PREFIX_PATH=${{github.workspace}}/local -DCMAKE_INSTALL_PREFIX=${{github.workspace}}/local repo/refcnt
+
+    - name: Build refcnt
+      run: cmake --build ${{github.workspace}}/build_refcnt --config ${{env.BUILD_TYPE}}
+
+    - name: Install refcnt
+      # install into ${{github.workspace}}/local
+      run: cmake --install ${{github.workspace}}/build_refcnt
+
+    # ----------------------------------------------------------------
+
+    - name: Clone callback
+      uses: actions/checkout@v3
+      with:
+        repository: Rconybea/xo-callback
+        path: repo/callback
+
+    - name: Configure callback
+      # configure cmake for callback in dedicated build directory.
+      run: cmake -B ${{github.workspace}}/build_callback -DCMAKE_MODULE_PATH=${{github.workspace}}/local/share/cmake -DCMAKE_PREFIX_PATH=${{github.workspace}}/local -DCMAKE_INSTALL_PREFIX=${{github.workspace}}/local repo/callback
+
+    - name: Build callback
+      run: cmake --build ${{github.workspace}}/build_callback --config ${{env.BUILD_TYPE}}
+
+    - name: Install callback
+      # install into ${{github.workspace}}/local
+      run: cmake --install ${{github.workspace}}/build_callback
+
+    # ----------------------------------------------------------------
+
+    - name: Configure self (webutil)
+      # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
+      # See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
+      run: cmake -B ${{github.workspace}}/build_webutil -DCMAKE_MODULE_PATH=${{github.workspace}}/local/share/cmake -DCMAKE_PREFIX_PATH=${{github.workspace}}/local -DCMAKE_INSTALL_PREFIX=${{github.workspace}}/local -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}}
+
+    - name: Build self (webutil)
+      # Build your program with the given configuration
+      run: cmake --build ${{github.workspace}}/build_webutil --config ${{env.BUILD_TYPE}}
+
+    - name: Test self (webutil)
+      working-directory: ${{github.workspace}}/build_webutil
+      # Execute tests defined by the CMake configuration.
+      # See https://cmake.org/cmake/help/latest/manual/ctest.1.html for more detail
+      run: ctest -C ${{env.BUILD_TYPE}}
diff --git a/xo-webutil/.gitignore b/xo-webutil/.gitignore
new file mode 100644
index 00000000..b1adb07b
--- /dev/null
+++ b/xo-webutil/.gitignore
@@ -0,0 +1,6 @@
+# lsp keeps state here
+.cache
+# symlink -> build/compile_commands.json should be created manually
+compile_commands.json
+# typical build directories
+.build*
diff --git a/xo-webutil/CMakeLists.txt b/xo-webutil/CMakeLists.txt
new file mode 100644
index 00000000..76c8795a
--- /dev/null
+++ b/xo-webutil/CMakeLists.txt
@@ -0,0 +1,28 @@
+# xo-webutil/CMakeLists.txt
+
+cmake_minimum_required(VERSION 3.10)
+
+project(webutil VERSION 1.0)
+
+include(GNUInstallDirs)
+include(cmake/xo-bootstrap-macros.cmake)
+
+xo_cxx_toplevel_options3()
+
+# ----------------------------------------------------------------
+# common c++ settings
+
+# PROJECT_CXX_FLAGS: bespoke for this project - usually empty
+set(PROJECT_CXX_FLAGS "")
+#set(PROJECT_CXX_FLAGS "-fconcepts-diagnostics-depth=2")
+add_definitions(${PROJECT_CXX_FLAGS})
+
+# ----------------------------------------------------------------
+# sources
+
+add_subdirectory(src/webutil)
+
+# ----------------------------------------------------------------
+# provide find_package() support
+
+xo_export_cmake_config(${PROJECT_NAME} ${PROJECT_VERSION} ${PROJECT_NAME}Targets)
diff --git a/xo-webutil/README.md b/xo-webutil/README.md
new file mode 100644
index 00000000..0d906d20
--- /dev/null
+++ b/xo-webutil/README.md
@@ -0,0 +1,33 @@
+# webutil library
+
+## Getting Started
+
+### build + install dependencies
+
+- xo-callback [github/Rconybea/xo-callback](https://github.com/Rconybea/xo-callback)
+
+### clone repo
+
+```
+$ git clone git@github.com:Rconybea/xo-webutil.git
+```
+
+### build and install
+
+```
+$ cd xo-webutil
+$ BUILDDIR=build     # for example
+$ mkdir $BUILDDIR
+$ cd $BUILDDIR
+$ PREFIX=/usr/local  # for example
+$ cmake -DCMAKE_MODULE_PATH=${PREFIX}/share/cmake -DCMAKE_INSTALL_PREFIX=${PREFIX} ..
+$ make
+$ make install
+```
+
+### LSP support
+
+```
+$ cd xo-webutil
+$ ln -s $BUILDDIR/compile_commands.json
+```
diff --git a/xo-webutil/cmake/webutilConfig.cmake.in b/xo-webutil/cmake/webutilConfig.cmake.in
new file mode 100644
index 00000000..79a9df3d
--- /dev/null
+++ b/xo-webutil/cmake/webutilConfig.cmake.in
@@ -0,0 +1,6 @@
+@PACKAGE_INIT@
+
+include(CMakeFindDependencyMacro)
+find_dependency(callback)
+include("${CMAKE_CURRENT_LIST_DIR}/webutilTargets.cmake")
+check_required_components("@PROJECT_NAME@")
diff --git a/xo-webutil/cmake/xo-bootstrap-macros.cmake b/xo-webutil/cmake/xo-bootstrap-macros.cmake
new file mode 100644
index 00000000..aba31169
--- /dev/null
+++ b/xo-webutil/cmake/xo-bootstrap-macros.cmake
@@ -0,0 +1,35 @@
+# ----------------------------------------------------------------
+# for example:
+#   $ PREFIX=/usr/local   # for example
+#   $ cmake -DCMAKE_MODULE_PATH=prefix -DCMAKE_INSTALL_PREFIX=$PREFIX -B .build
+#
+# will get
+#   CMAKE_MODULE_PATH
+# from xo-cmake-config --cmake-module-path
+#
+# and expect .cmake macros in
+#   CMAKE_MODULE_PATH/xo_macros/xo_cxx.cmake
+# ----------------------------------------------------------------
+
+find_program(XO_CMAKE_CONFIG_EXECUTABLE NAMES xo-cmake-config REQUIRED)
+
+if ("${XO_CMAKE_CONFIG_EXECUTABLE}" STREQUAL "XO_CMAKE_CONFIG_EXECUTABLE-NOT_FOUND")
+    message(FATAL "could not find xo-cmake-config executable")
+endif()
+
+message(STATUS "XO_CMAKE_CONFIG_EXECUTABLE=${XO_CMAKE_CONFIG_EXECUTABLE}")
+
+if (NOT XO_SUBMODULE_BUILD)
+    if (("${CMAKE_MODULE_PATH}" STREQUAL "") OR ("${CMAKE_MODULE_PATH}" STREQUAL prefix))
+        # default to typical install location for xo-project-macros
+        execute_process(COMMAND ${XO_CMAKE_CONFIG_EXECUTABLE} --cmake-module-path OUTPUT_VARIABLE CMAKE_MODULE_PATH)
+        message(STATUS "CMAKE_MODULE_PATH=${CMAKE_MODULE_PATH}")
+    endif()
+endif()
+
+# needs to have been installed somewhere on CMAKE_MODULE_PATH,
+# (e.g. from xo-cmake with the same value for CMAKE_INSTALL_PREFIX)
+#
+include(xo_macros/xo_cxx)
+
+xo_cxx_bootstrap_message()
diff --git a/xo-webutil/include/xo/webutil/Alist.hpp b/xo-webutil/include/xo/webutil/Alist.hpp
new file mode 100644
index 00000000..4bc5a305
--- /dev/null
+++ b/xo-webutil/include/xo/webutil/Alist.hpp
@@ -0,0 +1,33 @@
+/* file Alist.hpp
+ *
+ * author: Roland Conybeare, Sep 2022
+ */
+
+#pragma once
+
+#include <vector>
+#include <string>
+#include <string_view>
+
+namespace xo {
+    namespace web {
+        /* assocation list, maps strings to strings
+         * use this for arguments to dynamic-endpoint-callbacks
+         */
+        class Alist {
+        public:
+            Alist() = default;
+
+            /* lookup association by name */
+            std::string_view lookup(std::string n) const;
+
+            void push_back(std::string n, std::string v);
+
+        private:
+            std::vector<std::pair<std::string, std::string>> assoc_v_;
+        }; /*Alist*/
+
+    } /*namespace web*/
+} /*namespace xo*/
+
+/* end Alist.hpp */
diff --git a/xo-webutil/include/xo/webutil/HttpEndpointDescr.hpp b/xo-webutil/include/xo/webutil/HttpEndpointDescr.hpp
new file mode 100644
index 00000000..f3598cbb
--- /dev/null
+++ b/xo-webutil/include/xo/webutil/HttpEndpointDescr.hpp
@@ -0,0 +1,68 @@
+/* file EndpointDescr.hpp
+ *
+ * author: Roland Conybeare, Sep 2022
+ */
+
+#pragma once
+
+#include "Alist.hpp"
+#include "xo/refcnt/Refcounted.hpp"
+#include <functional>
+#include <string>
+
+namespace xo {
+    namespace web {
+        /* a function that can deliver http content on demand. */
+        using HttpEndpointFn = std::function<void (std::string const &,
+                                                   Alist const &,
+                                                   std::ostream *)>;
+
+        /* describes an http endpoint --
+         * this comprises:
+         * - a uri pattern.
+         * - a function that can deliver http content on demand
+         */
+        class HttpEndpointDescr {
+        public:
+            HttpEndpointDescr(std::string uri_pattern,
+                              HttpEndpointFn endpoint_fn);
+
+            std::string const & uri_pattern() const { return uri_pattern_; }
+            HttpEndpointFn const & endpoint_fn() const { return endpoint_fn_; }
+
+            void display(std::ostream & os) const;
+
+            std::string display_string() const;
+
+        private:
+            /* unique pattern in URI-space for this endpoint.
+             * for example
+             *    .uri_pattern = /stem/${foo}/${bar}
+             * means this endpoint generates contents for uri's
+             *    /stem/apple/banana
+             *    /stem/aphid/green
+             * but not for
+             *    /stem/apple/banana/carrot
+             */
+            std::string uri_pattern_;
+            /* a function that can construct http output on demand
+             *   .endpoint_fn(uri, alist, &os)
+             * writes http output to os.   output is parameterized
+             * by name-value pairs in alist,  and is prepared on behalf
+             * of .uri_pattern
+             * alist will report name-value pairs for each variable that
+             * appears in .uri_pattern (surrounded by ${..})
+             */
+            HttpEndpointFn endpoint_fn_;
+        }; /*HttpEndpointDescr*/
+
+        inline std::ostream &
+        operator<<(std::ostream & os, HttpEndpointDescr const & x) {
+            x.display(os);
+            return os;
+        } /*operator<<*/
+
+    } /*namespace web*/
+} /*namespace xo*/
+
+/* end EndpointDescr.hpp */
diff --git a/xo-webutil/include/xo/webutil/StreamEndpointDescr.hpp b/xo-webutil/include/xo/webutil/StreamEndpointDescr.hpp
new file mode 100644
index 00000000..93a2e77b
--- /dev/null
+++ b/xo-webutil/include/xo/webutil/StreamEndpointDescr.hpp
@@ -0,0 +1,69 @@
+/* file StreamEndpointDescr.hpp
+ *
+ * author: Roland Conybeare, Sep 2022
+ */
+
+#pragma once
+
+#include "Alist.hpp"
+#include "xo/refcnt/Refcounted.hpp"
+#include "xo/callback/CallbackSet.hpp"
+#include <functional>
+
+namespace xo {
+    namespace reactor { class AbstractSink; }
+
+    namespace web {
+        /* a function that creates an event subscription */
+        using StreamSubscribeFn = std::function<fn::CallbackId (rp<reactor::AbstractSink> const & ws_sink)>;
+        using StreamUnsubscribeFn = std::function<void (fn::CallbackId id)>;
+
+        /* describes a stream endpoint
+         * this comprises
+         * - a uri pattern (matches stream name)
+         * - a function that establishes subscription
+         *   (by attaching supplied WebsocketSink to an event source)
+         */
+        class StreamEndpointDescr {
+        public:
+            StreamEndpointDescr(std::string uri_pattern,
+                                StreamSubscribeFn subscribe_fn,
+                                StreamUnsubscribeFn unsubscribe_fn);
+
+            std::string const & uri_pattern() const { return uri_pattern_; }
+            StreamSubscribeFn const & subscribe_fn() const { return subscribe_fn_; }
+            StreamUnsubscribeFn const & unsubscribe_fn() const { return unsubscribe_fn_; }
+
+            void display(std::ostream & os) const;
+
+            std::string display_string() const;
+
+        private:
+            /* unique pattern in URI-space for this endpoint
+             * for example
+             *    .uri_pattern = /stem/${foo}/${bar}
+             * means this endpoint generates contents for uri's
+             *    /stem/apple/banana
+             *    /stem/aphid/green
+             * but not for
+             *    /stem/apple/banana/carrot
+             */
+            std::string uri_pattern_;
+            /* a function that subscribes to an event stream
+             * (by attaching a websocket sink)
+             */
+            StreamSubscribeFn subscribe_fn_;
+            /* reverses effect of a particular call to .subscribe_fn */
+            StreamUnsubscribeFn unsubscribe_fn_;
+        }; /*StreamEndpointDescr*/
+
+        inline std::ostream &
+        operator<<(std::ostream & os, StreamEndpointDescr const & x) {
+            x.display(os);
+            return os;
+        } /*operator<<*/
+
+    } /*namespace web*/
+} /*namespace xo*/
+
+/* end StreamEndpointDescr.hpp */
diff --git a/xo-webutil/src/webutil/Alist.cpp b/xo-webutil/src/webutil/Alist.cpp
new file mode 100644
index 00000000..73905106
--- /dev/null
+++ b/xo-webutil/src/webutil/Alist.cpp
@@ -0,0 +1,28 @@
+/* @file Alist.cpp */
+
+#include "Alist.hpp"
+
+namespace xo {
+    namespace web {
+        /* lookup association by name */
+        std::string_view
+        Alist::lookup(std::string n) const {
+            for (auto const & ix : this->assoc_v_) {
+                if (ix.first == n) {
+                    return ix.second;
+                }
+            }
+
+            return "";
+        } /*lookup*/
+
+        void
+        Alist::push_back(std::string n, std::string v) {
+            this->assoc_v_.push_back(std::make_pair(std::move(n), std::move(v)));
+        }
+    } /*namespace web*/
+} /*namespace xo*/
+
+
+
+/* end Alist.cpp */
diff --git a/xo-webutil/src/webutil/CMakeLists.txt b/xo-webutil/src/webutil/CMakeLists.txt
new file mode 100644
index 00000000..54fe2a88
--- /dev/null
+++ b/xo-webutil/src/webutil/CMakeLists.txt
@@ -0,0 +1,15 @@
+# webutil/CMakeLists.txt
+
+set(SELF_LIB webutil)
+set(SELF_SRCS StreamEndpointDescr.cpp HttpEndpointDescr.cpp Alist.cpp)
+
+# reminder: can't be header-only library,  because depends on non-header-only callback (bc of non-header-only refcnt)
+xo_add_shared_library4(${SELF_LIB} ${PROJECT_NAME}Targets ${PROJECT_VERSION} 1 ${SELF_SRCS})
+
+# ----------------------------------------------------------------
+# external dependencies
+
+xo_dependency(${SELF_LIB} refcnt)
+xo_dependency(${SELF_LIB} callback)
+
+# end CMakeLists.txt
diff --git a/xo-webutil/src/webutil/HttpEndpointDescr.cpp b/xo-webutil/src/webutil/HttpEndpointDescr.cpp
new file mode 100644
index 00000000..fb9ab261
--- /dev/null
+++ b/xo-webutil/src/webutil/HttpEndpointDescr.cpp
@@ -0,0 +1,27 @@
+/* @file HttpEndpointDescr.cpp */
+
+#include "HttpEndpointDescr.hpp"
+#include "xo/indentlog/print/tag.hpp"
+#include "xo/indentlog/print/tostr.hpp"
+
+namespace xo {
+    namespace web {
+        HttpEndpointDescr::HttpEndpointDescr(std::string uri_pattern,
+                                             HttpEndpointFn endpoint_fn)
+            : uri_pattern_{std::move(uri_pattern)},
+              endpoint_fn_{std::move(endpoint_fn)}
+        {}
+
+        void
+        HttpEndpointDescr::display(std::ostream & os) const {
+            os << "<HttpEndpointDescr" << xtag("uri_pattern", uri_pattern_) << ">";
+        } /*display*/
+
+        std::string
+        HttpEndpointDescr::display_string() const { return tostr(*this); }
+    } /*namespace web*/
+
+} /*namespace xo*/
+
+
+/* end HttpEndpointDescr.cpp */
diff --git a/xo-webutil/src/webutil/StreamEndpointDescr.cpp b/xo-webutil/src/webutil/StreamEndpointDescr.cpp
new file mode 100644
index 00000000..03c2e961
--- /dev/null
+++ b/xo-webutil/src/webutil/StreamEndpointDescr.cpp
@@ -0,0 +1,28 @@
+/* @file StreamEndpointDescr.cpp */
+
+#include "StreamEndpointDescr.hpp"
+#include "xo/indentlog/print/tag.hpp"
+#include "xo/indentlog/print/tostr.hpp"
+
+namespace xo {
+    namespace web {
+        StreamEndpointDescr::StreamEndpointDescr(std::string uri_pattern,
+                                                 StreamSubscribeFn subscribe_fn,
+                                                 StreamUnsubscribeFn unsubscribe_fn)
+            : uri_pattern_{std::move(uri_pattern)},
+              subscribe_fn_{std::move(subscribe_fn)},
+              unsubscribe_fn_{std::move(unsubscribe_fn)}
+        {}
+
+        void
+        StreamEndpointDescr::display(std::ostream & os) const {
+            os << "<StreamEndpointDescr" << xtag("uri_pattern", uri_pattern_) << ">";
+        } /*display*/
+
+        std::string
+        StreamEndpointDescr::display_string() const { return tostr(*this); }
+    } /*namespace web*/
+} /*namespace xo*/
+
+
+/* end StreamEndpointDescr.cpp */