From 9d346aa8894e567d2871125826488c2ca181d0f5 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 9 Apr 2015 15:44:57 +0200
Subject: Further interface prototyping

---
 brep/module        | 43 +++++++++++++++++++++++++++++++++++++++++++
 brep/module.cxx    | 39 +++++++++++++++++++++++++++++++++++++++
 services.cxx       | 17 +++++++++++++++++
 web/apache/service | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 web/module         | 13 +++++++++++++
 5 files changed, 158 insertions(+)
 create mode 100644 brep/module
 create mode 100644 brep/module.cxx
 create mode 100644 services.cxx
 create mode 100644 web/apache/service

diff --git a/brep/module b/brep/module
new file mode 100644
index 0000000..6687a31
--- /dev/null
+++ b/brep/module
@@ -0,0 +1,43 @@
+// file      : brep/module -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef BREP_MODULE
+#define BREP_MODULE
+
+namespace brep
+{
+  // This exception is used to signal that the request is invalid
+  // (4XX codes) rather than that it could not be processed (5XX).
+  // By default 422 is returned, which means the request was
+  // semantically invalid.
+  //
+  struct invalid_request
+  {
+    web::status_code status {422};
+    std::string description;
+
+    //@@ Maybe optional "try again" link?
+    //
+  };
+
+  // Adaptation of the web::module to our needs.
+  //
+  class module: public web::module
+  {
+  public:
+    virtual void
+    handle (request&, response&) = 0;
+
+    // Implementation details.
+    //
+  protected:
+    virtual void
+    handle (request&, response&, log&);
+
+  protected:
+    log* log_;
+  };
+}
+
+#endif // BREP_MODULE
diff --git a/brep/module.cxx b/brep/module.cxx
new file mode 100644
index 0000000..1837ccd
--- /dev/null
+++ b/brep/module.cxx
@@ -0,0 +1,39 @@
+// file      : brep/module.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#include <brep/module>
+
+using namespace std;
+
+namespace brep
+{
+  void module::
+  handle (request& rq, response& rs, log& l)
+  {
+    log_ = &l;
+
+    try
+    {
+      handle (rq, rs);
+    }
+    catch (const invalid_request& e)
+    {
+      // @@ Format as HTML in proper style.
+      //
+      rs.content (e.status, "text/html;charset=utf-8") << e.description;
+    }
+    catch (const exception& e)
+    {
+      // @@ Exception: log e.what () & 505.
+      //
+      rs.status (505);
+    }
+    catch (...)
+    {
+      // @@ Unknown exception: log & 505.
+      //
+      rs.status (505);
+    }
+  }
+}
diff --git a/services.cxx b/services.cxx
new file mode 100644
index 0000000..746aefa
--- /dev/null
+++ b/services.cxx
@@ -0,0 +1,17 @@
+// file      : services.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#include <web/apache/service>
+
+#include <brep/search>
+#include <brep/view>
+
+using namespace brep;
+using web::apache::service;
+
+static const search search_mod;
+service<search> AP_MODULE_DECLARE_DATA search_srv ("search", search_mod);
+
+static const view view_mod;
+service<view> AP_MODULE_DECLARE_DATA view_srv ("view", view_mod);
diff --git a/web/apache/service b/web/apache/service
new file mode 100644
index 0000000..3c7a398
--- /dev/null
+++ b/web/apache/service
@@ -0,0 +1,46 @@
+// file      : web/apache/service -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef WEB_APACHE_SERVICE
+#define WEB_APACHE_SERVICE
+
+#include <string>
+
+#include <web/module>
+
+namespace web
+{
+  namespace apache
+  {
+    class service_common
+    {
+      //@@ Implementation that calls handle() below goes here.
+      //
+
+      virtual void
+      handle (request&, response&, log&) = 0;
+    };
+
+    template <typename M>
+    class service: public service_common
+    {
+    public:
+      // Note that the module exemplar is stored by-reference.
+      //
+      service (const std::string& name, const M& exemplar);
+
+      virtual void
+      handle (request& rq, response& rs, log& l)
+      {
+        M m (exemplar_);
+        m.handle (rq, rs, l);
+      }
+
+    private:
+      const M& exemplar_;
+    };
+  }
+}
+
+#endif // WEB_APACHE_SERVICE
diff --git a/web/module b/web/module
index d36bb26..e9787a4 100644
--- a/web/module
+++ b/web/module
@@ -22,6 +22,8 @@ namespace web
 
   // HTTP status code.
   //
+  // @@ Define some commonly used constants?
+  //
   using status_code = uint16_t;
 
   struct name_value
@@ -92,6 +94,17 @@ namespace web
     write (const char* msg);
   };
 
+  // The web server creates a new module instance for each request
+  // by copy-initializing it with the module exemplar. This way we
+  // achieve two things: we can freely use module data members
+  // without worrying about multi-threading issues and we
+  // automatically get started with the initial state for each
+  // request. If you really need to share some rw-data between
+  // all the modules, use static data members with appropriate
+  // locking. See the <service> header in one of the web server
+  // directories (e.g., apache/) if you need to see the code that
+  // does this.
+  //
   class module
   {
   public:
-- 
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