Simplified server configuration, HTTPD modules now use deployment composite to route service requests, minor fixes to store integration test.

git-svn-id: http://svn.us.apache.org/repos/asf/tuscany@893939 13f79535-47bb-0310-9956-ffa450edef68

10 files changed, 373 insertions, 324 deletions

diff --git a/sca-cpp/trunk/modules/server/domain-test.composite b/sca-cpp/trunk/modules/server/domain-test.composite
index 48570e64d3..b39f66c30a 100644
--- a/sca-cpp/trunk/modules/server/domain-test.composite
+++ b/sca-cpp/trunk/modules/server/domain-test.composite
@@ -41,7 +41,7 @@
         <service name="client">
             <t:binding.http uri="client"/>
         </service>
-        <reference name="ref" target="test">
+        <reference name="ref" target="server-test">
             <t:binding.http/>
         </reference>
     </component>
diff --git a/sca-cpp/trunk/modules/server/httpd-test b/sca-cpp/trunk/modules/server/httpd-test
index 2f50c9f3c3..7dccfbf112 100755
--- a/sca-cpp/trunk/modules/server/httpd-test
+++ b/sca-cpp/trunk/modules/server/httpd-test
@@ -24,16 +24,14 @@ echo "Testing..."
 ./server-conf tmp
 cat >>tmp/conf/httpd.conf <<EOF
 
-<Location /test>
-SetHandler mod_tuscany_eval
+<Location />
 SCAContribution `pwd`/
 SCAComposite domain-test.composite
-SCAComponent server-test
 </Location>
 EOF
 
 apachectl -k start -d `pwd`/tmp
-sleep 1
+sleep 2
 
 # Test HTTP GET
 curl http://localhost:8090/index.html 2>/dev/null >tmp/index.html
@@ -73,7 +71,7 @@ fi
 
 # Cleanup
 apachectl -k stop -d `pwd`/tmp
-sleep 1
+sleep 2
 if [ "$rc" = "0" ]; then
     echo "OK"
 fi
diff --git a/sca-cpp/trunk/modules/server/impl-test.cpp b/sca-cpp/trunk/modules/server/impl-test.cpp
index 217c6f5171..171a78f2d5 100644
--- a/sca-cpp/trunk/modules/server/impl-test.cpp
+++ b/sca-cpp/trunk/modules/server/impl-test.cpp
@@ -51,7 +51,7 @@ const failable<value, std::string> del(unused const list<value>& params) {
 }
 
 const failable<value, std::string> hello(const list<value>& params) {
-    return value("hello " + std::string(car(params)));
+    return value(std::string("hello ") + std::string(car(params)));
 }
 
 }
@@ -59,17 +59,18 @@ const failable<value, std::string> hello(const list<value>& params) {
 
 extern "C" {
 
-const tuscany::failable<tuscany::value, std::string> eval(const tuscany::value& func, const tuscany::list<tuscany::value>& params) {
+const tuscany::value eval(const tuscany::list<tuscany::value>& params) {
+    const tuscany::value func(car(params));
     if (func == "get")
-        return tuscany::server::get(params);
+        return tuscany::server::get(cdr(params));
     if (func == "post")
-        return tuscany::server::post(params);
+        return tuscany::server::post(cdr(params));
     if (func == "put")
-        return tuscany::server::put(params);
+        return tuscany::server::put(cdr(params));
     if (func == "del")
-        return tuscany::server::del(params);
+        return tuscany::server::del(cdr(params));
     if (func == "hello")
-        return tuscany::server::hello(params);
+        return tuscany::server::hello(cdr(params));
     return tuscany::mkfailure<tuscany::value, std::string>(std::string("Function not supported: ") + std::string(func));
 }
 
diff --git a/sca-cpp/trunk/modules/server/mod-cpp.hpp b/sca-cpp/trunk/modules/server/mod-cpp.hpp
index 99b69a0d9f..664e9d2e41 100644
--- a/sca-cpp/trunk/modules/server/mod-cpp.hpp
+++ b/sca-cpp/trunk/modules/server/mod-cpp.hpp
@@ -37,10 +37,8 @@
 #include "debug.hpp"
 #include "monad.hpp"
 #include "dynlib.hpp"
-#include "cache.hpp"
 #include "../eval/driver.hpp"
 #include "../http/httpd.hpp"
-#include "mod-eval.hpp"
 
 namespace tuscany {
 namespace server {
@@ -52,14 +50,14 @@ namespace cpp {
  */
 struct evalImplementation {
     const lib ilib;
-    const ilambda impl;
+    const lambda<value(const list<value>&)> impl;
     const list<value> px;
-    evalImplementation(const lib& ilib, const ilambda& impl, const list<value>& px) : ilib(ilib), impl(impl), px(px) {
+    evalImplementation(const lib& ilib, const lambda<value(const list<value>&)>& impl, const list<value>& px) : ilib(ilib), impl(impl), px(px) {
     }
-    const failable<value, std::string> operator()(const value& func, const list<value>& params) const {
-        debug(cons<value>(func, params), "modeval::cpp::evalImplementation::input");
-        const failable<value, std::string> val = impl(func, append(params, px));
-        debug(content(val), "modeval::cpp::evalImplementation::result");
+    const value operator()(const list<value>& params) const {
+        debug(params, "modeval::cpp::evalImplementation::input");
+        const value val = impl(append(params, px));
+        debug(val, "modeval::cpp::evalImplementation::result");
         return val;
     }
 };
@@ -67,22 +65,15 @@ struct evalImplementation {
 /**
  * Read a C++ component implementation.
  */
-const failable<ilambda, std::string> readLatestImplementation(const std::string path, const list<value>& px) {
-    const failable<lib, std::string> ilib(dynlib(path));
+const failable<lambda<value(const list<value>&)>, std::string> readImplementation(const std::string path, const list<value>& px) {
+    const failable<lib, std::string> ilib(dynlib(path + dynlibExt));
     if (!hasContent(ilib))
-        return mkfailure<ilambda, std::string>(reason(ilib));
+        return mkfailure<lambda<value(const list<value>&)>, std::string>(reason(ilib));
 
-    const failable<ilambda, std::string> impl(dynlambda<failable<value, std::string>(value, list<value>)>("eval", content(ilib)));
+    const failable<lambda<value(const list<value>&)>, std::string> impl(dynlambda<value(const list<value>&)>("eval", content(ilib)));
     if (!hasContent(impl))
         return impl;
-    return ilambda(evalImplementation(content(ilib), content(impl), px));
-}
-
-const cached<failable<ilambda, std::string> > readImplementation(const std::string& path, const list<value>& px) {
-    const lambda<failable<ilambda, std::string>(std::string, list<value>)> ri(readLatestImplementation);
-    const lambda<unsigned long(std::string)> ft(latestFileTime);
-    const std::string p(path + dynlibExt);
-    return cached<failable<ilambda, std::string> >(curry(ri, p, px), curry(ft, p));
+    return lambda<value(const list<value>&)>(evalImplementation(content(ilib), content(impl), px));
 }
 
 }
diff --git a/sca-cpp/trunk/modules/server/mod-eval.cpp b/sca-cpp/trunk/modules/server/mod-eval.cpp
index aa0a6067a1..d8354c6a58 100644
--- a/sca-cpp/trunk/modules/server/mod-eval.cpp
+++ b/sca-cpp/trunk/modules/server/mod-eval.cpp
@@ -30,17 +30,16 @@
 
 #include "function.hpp"
 #include "list.hpp"
+#include "tree.hpp"
 #include "slist.hpp"
 #include "value.hpp"
 #include "element.hpp"
 #include "monad.hpp"
-#include "cache.hpp"
 #include "../atom/atom.hpp"
 #include "../json/json.hpp"
 #include "../scdl/scdl.hpp"
 #include "../http/curl.hpp"
 #include "../http/httpd.hpp"
-#include "mod-eval.hpp"
 #include "mod-scm.hpp"
 #include "mod-cpp.hpp"
 
@@ -57,41 +56,41 @@ namespace modeval {
  */
 class ServerConf {
 public:
-    ServerConf(server_rec* s) : s(s), home(""), wiringHost("") {
+    ServerConf(server_rec* s) : s(s), home(""), wiringServerName("") {
     }
     const server_rec* s;
     std::string home;
-    std::string wiringHost;
+    std::string wiringServerName;
 };
 
 /**
- * Port number used for wiring requests. Set it to zero to use the current
- * server port number, set it to a port number to direct wiring requests
- * to that port, for debugging or tracing for example.
- */
-int debugWiringPort = 0;
-
-/**
  * Directory configuration.
  */
 class DirConf {
 public:
-    DirConf(char* dirspec) : dirspec(dirspec), contributionPath(""), compositeName(""), componentName(""), implementationPath("") {
+    DirConf(char* dirspec) : dirspec(dirspec), contributionPath(""), compositeName("") {
     }
     const char* dirspec;
     std::string contributionPath;
     std::string compositeName;
-    std::string componentName;
-    std::string implementationPath;
-    cached<failable<value, std::string> > component;
-    cached<failable<ilambda, std::string> > implementation;
+    list<value> implementations;
 };
 
 /**
+ * Convert a result represented as a content + failure pair to a
+ * failable monad.
+ */
+const failable<value, std::string> failableResult(const list<value>& v) {
+    if (isNil(cdr(v)))
+        return car(v);
+    return mkfailure<value, std::string>(cadr(v));
+}
+
+/**
  * Handle an HTTP GET.
  */
-const failable<int, std::string> get(request_rec* r, const ilambda& impl) {
-    debug(r->uri, "modeval::get::url");
+const failable<int, std::string> get(request_rec* r, const lambda<value(const list<value>&)>& impl) {
+    debug(r->uri, "modeval::get::uri");
 
     // Inspect the query string
     const list<list<value> > args = httpd::queryArgs(r);
@@ -104,10 +103,9 @@ const failable<int, std::string> get(request_rec* r, const ilambda& impl) {
         // Extract the request id, method and params
         const value id = cadr(ia);
         const value func = std::string(cadr(ma)).c_str();
-        const list<value> params = httpd::queryParams(args);
 
         // Apply the requested function
-        const failable<value, std::string> val = impl(func, params);
+        const failable<value, std::string> val = failableResult(impl(cons(func, httpd::queryParams(args))));
         if (!hasContent(val))
             return mkfailure<int, std::string>(reason(val));
 
@@ -117,16 +115,16 @@ const failable<int, std::string> get(request_rec* r, const ilambda& impl) {
     }
 
     // Evaluate an ATOM GET request and return an ATOM feed
-    const list<value> id(httpd::path(r->path_info));
-    if (isNil(id)) {
-        const failable<value, std::string> val = impl("getall", list<value>());
+    const list<value> path(httpd::path(r->uri));
+    if (isNil(cddr(path))) {
+        const failable<value, std::string> val = failableResult(impl(cons<value>("getall", list<value>())));
         if (!hasContent(val))
             return mkfailure<int, std::string>(reason(val));
         return httpd::writeResult(atom::writeATOMFeed(atom::feedValuesToElements(content(val))), "application/atom+xml;type=feed", r);
     }
 
     // Evaluate an ATOM GET and return an ATOM entry
-    const failable<value, std::string> val = impl("get", mklist<value>(car(id)));
+    const failable<value, std::string> val = failableResult(impl(cons<value>("get", mklist<value>(caddr(path)))));
     if (!hasContent(val))
         return mkfailure<int, std::string>(reason(val));
     return httpd::writeResult(atom::writeATOMEntry(atom::entryValuesToElements(content(val))), "application/atom+xml;type=entry", r);
@@ -135,7 +133,7 @@ const failable<int, std::string> get(request_rec* r, const ilambda& impl) {
 /**
  * Handle an HTTP POST.
  */
-const failable<int, std::string> post(request_rec* r, const ilambda& impl) {
+const failable<int, std::string> post(request_rec* r, const lambda<value(const list<value>&)>& impl) {
     const list<std::string> ls = httpd::read(r);
     debug(r->uri, "modeval::post::url");
     debug(ls, "modeval::post::input");
@@ -153,7 +151,7 @@ const failable<int, std::string> post(request_rec* r, const ilambda& impl) {
         const list<value> params = (list<value>)cadr(assoc(value("params"), args));
 
         // Evaluate the request expression
-        const failable<value, std::string> val = impl(func, params);
+        const failable<value, std::string> val = failableResult(impl(cons<value>(func, params)));
         if (!hasContent(val))
             return mkfailure<int, std::string>(reason(val));
 
@@ -166,7 +164,7 @@ const failable<int, std::string> post(request_rec* r, const ilambda& impl) {
 
         // Evaluate the request expression
         const value entry = atom::entryValue(content(atom::readEntry(ls)));
-        const failable<value, std::string> val = impl("post", mklist<value>(entry));
+        const failable<value, std::string> val = failableResult(impl(cons<value>("post", mklist<value>(entry))));
         if (!hasContent(val))
             return mkfailure<int, std::string>(reason(val));
 
@@ -182,15 +180,15 @@ const failable<int, std::string> post(request_rec* r, const ilambda& impl) {
 /**
  * Handle an HTTP PUT.
  */
-const failable<int, std::string> put(request_rec* r, const ilambda& impl) {
+const failable<int, std::string> put(request_rec* r, const lambda<value(const list<value>&)>& impl) {
     const list<std::string> ls = httpd::read(r);
     debug(r->uri, "modeval::put::url");
     debug(ls, "modeval::put::input");
 
     // Evaluate an ATOM PUT request
-    const list<value> id(httpd::path(r->path_info));
+    const list<value> path(httpd::path(r->uri));
     const value entry = atom::entryValue(content(atom::readEntry(ls)));
-    const failable<value, std::string> val = impl("put", mklist<value>(car(id), entry));
+    const failable<value, std::string> val = failableResult(impl(cons<value>("put", mklist<value>(caddr(path), entry))));
     if (!hasContent(val))
         return mkfailure<int, std::string>(reason(val));
     if (val == value(false))
@@ -201,12 +199,12 @@ const failable<int, std::string> put(request_rec* r, const ilambda& impl) {
 /**
  * Handle an HTTP DELETE.
  */
-const failable<int, std::string> del(request_rec* r, const ilambda& impl) {
+const failable<int, std::string> del(request_rec* r, const lambda<value(const list<value>&)>& impl) {
     debug(r->uri, "modeval::delete::url");
 
     // Evaluate an ATOM delete request
-    const list<value> id(httpd::path(r->path_info));
-    const failable<value, std::string> val = impl("delete", mklist<value>(car(id)));
+    const list<value> path(httpd::path(r->uri));
+    const failable<value, std::string> val = failableResult(impl(cons<value>("delete", mklist<value>(caddr(path)))));
     if (!hasContent(val))
         return mkfailure<int, std::string>(reason(val));
     if (val == value(false))
@@ -215,53 +213,13 @@ const failable<int, std::string> del(request_rec* r, const ilambda& impl) {
 }
 
 /**
- * Read the SCDL configuration of a component.
- */
-const failable<value, std::string> readComponent(const std::string& path, const std::string& name) {
-
-    // Read composite
-    std::ifstream is(path);
-    if (is.fail() || is.bad())
-        return mkfailure<value, std::string>("Could not read composite: " + path);
-
-    // Return the component
-    const list<value> c = scdl::components(readXML(streamList(is)));
-    const value comp = scdl::named(name, c);
-    if (isNil(comp))
-        return mkfailure<value, std::string>("Could not find component: " + name);
-    return comp;
-}
-
-const cached<failable<value, std::string> > component(DirConf* conf) {
-    const std::string path(conf->contributionPath + conf->compositeName);
-    const lambda<failable<value, std::string>(std::string, std::string)> rc(readComponent);
-    const lambda<unsigned long(std::string)> ft(latestFileTime);
-    return cached<failable<value, std::string> >(curry(rc, path, conf->componentName), curry(ft, path));
-}
-
-/**
- * Convert a list of component references to a list of HTTP proxy lambdas.
- */
-const value mkproxy(const value& ref, const std::string& base, const http::CURLSession& ch) {
-    return lambda<value(list<value>&)>(http::proxy(base + std::string(scdl::name(ref)), ch));
-}
-
-const list<value> proxies(const list<value>& refs, const std::string& base, const http::CURLSession& ch) {
-    if (isNil(refs))
-        return refs;
-    return cons(mkproxy(car(refs), base, ch), proxies(cdr(refs), base, ch));
-}
-
-/**
- * Returns the component implementation with the given implementation type and path.
- * For now only Scheme and C++ implementations are supported.
+ * Translate a component request.
  */
-const cached<failable<ilambda, std::string> > implementation(const std::string& itype, const std::string& path, const list<value>& px) {
-    if (itype.find(".scheme") != std::string::npos)
-        return latest(scm::readImplementation(path, px));
-    if (itype.find(".cpp") != std::string::npos)
-        return latest(cpp::readImplementation(path, px));
-    return cached<failable<ilambda, std::string> >();
+int translate(request_rec *r) {
+    if (strncmp(r->uri, "/components/", 12) != 0)
+        return DECLINED;
+    r->handler = "mod_tuscany_eval";
+    return OK;
 }
 
 /**
@@ -277,80 +235,137 @@ int handler(request_rec *r) {
     if(rc != OK)
         return rc;
 
-    // Retrieve the latest component configuration
-    DirConf& conf = httpd::dirConf<DirConf>(r, &mod_tuscany_eval);
-    conf.component = latest(conf.component);
-    const failable<value, std::string> comp(content(conf.component));
-    if (!hasContent(comp))
-        return HTTP_NOT_FOUND;
-
-    // Retrieve the latest implementation
-    const value ielement= scdl::implementation(content(comp));
-    const std::string path = conf.contributionPath + std::string(scdl::uri(ielement));
-    if (path != conf.implementationPath) {
-
-        // Convert component references to configured proxy lambdas
-        const ServerConf& sconf = httpd::serverConf<ServerConf>(r, &mod_tuscany_eval);
-        std::ostringstream base;
-        if (sconf.wiringHost == "")
-            base << "http://localhost:" << ap_get_server_port(r) << "/references/" << std::string(scdl::name(content(comp))) << "/";
-        else
-            base << "http://" << sconf.wiringHost << "/references/" << std::string(scdl::name(content(comp))) << "/";
-        http::CURLSession ch;
-        const list<value> px(proxies(scdl::references(content(comp)), base.str(), ch));
-
-        conf.implementation = implementation(elementName(ielement), path, px);
-        conf.implementationPath = path;
-    }
-    else
-        conf.implementation = latest(conf.implementation);
-    const failable<ilambda, std::string> impl(content(conf.implementation));
-    if (!hasContent(impl))
+    // Get the component implementation lambda
+    DirConf& dc = httpd::dirConf<DirConf>(r, &mod_tuscany_eval);
+    const list<value> path(httpd::path(r->uri));
+    const list<value> impl(assoctree<value>(cadr(path), dc.implementations));
+    if (isNil(impl))
         return HTTP_NOT_FOUND;
 
     // Handle HTTP method
+    const lambda<value(const list<value>&)> l(cadr<value>(impl));
     if (r->header_only)
          return OK;
     if(r->method_number == M_GET)
-        return httpd::reportStatus(get(r, content(impl)));
+        return httpd::reportStatus(get(r, l));
     if(r->method_number == M_POST)
-        return httpd::reportStatus(post(r, content(impl)));
+        return httpd::reportStatus(post(r, l));
     if(r->method_number == M_PUT)
-        return httpd::reportStatus(put(r, content(impl)));
+        return httpd::reportStatus(put(r, l));
     if(r->method_number == M_DELETE)
-        return httpd::reportStatus(del(r, content(impl)));
+        return httpd::reportStatus(del(r, l));
     return HTTP_NOT_IMPLEMENTED;
 }
 
 /**
- * Configuration commands.
+ * Convert a list of component references to a list of HTTP proxy lambdas.
  */
-const char *confHome(cmd_parms *cmd, unused void *dummy, const char *arg) {
-    ServerConf *c = (ServerConf*)ap_get_module_config(cmd->server->module_config, &mod_tuscany_eval);
-    c->home = arg;
-    return NULL;
+const value mkproxy(const value& ref, const std::string& base) {
+    return lambda<value(const list<value>&)>(http::proxy(base + std::string(scdl::name(ref))));
+}
+
+const list<value> proxies(const list<value>& refs, const std::string& base) {
+    if (isNil(refs))
+        return refs;
+    return cons(mkproxy(car(refs), base), proxies(cdr(refs), base));
+}
+
+/**
+ * Return a configured component implementation.
+ * For now only Scheme and C++ implementations are supported.
+ */
+const failable<lambda<value(const list<value>&)>, std::string> readImplementation(const std::string& itype, const std::string& path, const list<value>& px) {
+    if (itype.find(".scheme") != std::string::npos)
+        return scm::readImplementation(path, px);
+    if (itype.find(".cpp") != std::string::npos)
+        return cpp::readImplementation(path, px);
+    return mkfailure<lambda<value(const list<value>&)>, std::string>("Unsupported implementation type: " + itype);
+}
+
+const value confImplementation(DirConf& dc, ServerConf& sc, server_rec& server, const value& comp) {
+    const value impl = scdl::implementation(comp);
+    const std::string path = dc.contributionPath + std::string(scdl::uri(impl));
+
+    // Convert component references to configured proxy lambdas
+    std::ostringstream base;
+    if (sc.wiringServerName == "")
+        base << (server.server_scheme == NULL? "http" : server.server_scheme)
+            << "://" << (server.server_hostname == NULL? "localhost" : server.server_hostname)
+            << ":" << (server.port == 0? 80 : server.port)
+            << "/references/" << std::string(scdl::name(comp)) << "/";
+    else
+        base << sc.wiringServerName << "/references/" << std::string(scdl::name(comp)) << "/";
+    const list<value> px(proxies(scdl::references(comp), base.str()));
+
+    // Read and configure the implementation
+    const failable<lambda<value(const list<value>&)>, std::string> cimpl(readImplementation(elementName(impl), path, px));
+    if (!hasContent(cimpl))
+        return reason(cimpl);
+    return content(cimpl);
+}
+
+/**
+ * Return a tree of component-name + configured-implementation pairs.
+ */
+const list<value> componentToImplementationAssoc(DirConf& dc, ServerConf& sc, server_rec& server, const list<value>& c) {
+    if (isNil(c))
+        return c;
+    return cons<value>(mklist<value>(scdl::name(car(c)), confImplementation(dc, sc, server, car(c))), componentToImplementationAssoc(dc, sc, server, cdr(c)));
+}
+
+const list<value> componentToImplementationTree(DirConf& dc, ServerConf& sc, server_rec& server, const list<value>& c) {
+    return mkbtree(sort(componentToImplementationAssoc(dc, sc, server, c)));
+}
+
+/**
+ * Read the components declared in a composite.
+ */
+const failable<list<value>, std::string> readComponents(const std::string& path) {
+    std::ifstream is(path);
+    if (is.fail() || is.bad())
+        return mkfailure<list<value>, std::string>("Could not read composite: " + path);
+    return scdl::components(readXML(streamList(is)));
 }
-const char *confWiringHost(cmd_parms *cmd, unused void *dummy, const char *arg) {
-    ServerConf *c = (ServerConf*)ap_get_module_config(cmd->server->module_config, &mod_tuscany_eval);
-    c->wiringHost = arg;
+
+/**
+ * Configure the components declared in the deployed composite.
+ */
+const bool confComponents(DirConf& dc, ServerConf& sc, server_rec& server) {
+    if (dc.contributionPath == "" || dc.compositeName == "")
+        return true;
+    const failable<list<value>, std::string> comps = readComponents(dc.contributionPath + dc.compositeName);
+    if (!hasContent(comps))
+        return true;
+    dc.implementations = componentToImplementationTree(dc, sc, server, content(comps));
+    debug(dc.implementations, "modeval::confComponents::implementations");
+    return true;
+}
+
+/**
+ * Configuration commands.
+ */
+const char *confHome(cmd_parms *cmd, unused void *c, const char *arg) {
+    ServerConf& sc = httpd::serverConf<ServerConf>(cmd, &mod_tuscany_eval);
+    sc.home = arg;
     return NULL;
 }
-const char *confContribution(unused cmd_parms *cmd, void *c, const char *arg) {
-    DirConf* conf = (DirConf*)c;
-    conf->contributionPath = arg;
-    conf->component = component(conf);
+const char *confWiringServerName(cmd_parms *cmd, unused void *c, const char *arg) {
+    ServerConf& sc = httpd::serverConf<ServerConf>(cmd, &mod_tuscany_eval);
+    sc.wiringServerName = arg;
     return NULL;
 }
-const char *confComposite(unused cmd_parms *cmd, void *c, const char *arg) {
-    DirConf* conf = (DirConf*)c;
-    conf->compositeName = arg;
-    conf->component = component(conf);
+const char *confContribution(cmd_parms *cmd, void *c, const char *arg) {
+    ServerConf& sc = httpd::serverConf<ServerConf>(cmd, &mod_tuscany_eval);
+    DirConf& dc = *(DirConf*)c;
+    dc.contributionPath = arg;
+    confComponents(dc, sc, *cmd->server);
     return NULL;
 }
-const char *confComponent(unused cmd_parms *cmd, void *c, const char *arg) {
-    DirConf* conf = (DirConf*)c;
-    conf->componentName = arg;
-    conf->component = component(conf);
+const char *confComposite(cmd_parms *cmd, void *c, const char *arg) {
+    ServerConf& sc = httpd::serverConf<ServerConf>(cmd, &mod_tuscany_eval);
+    DirConf& dc = *(DirConf*)c;
+    dc.compositeName = arg;
+    confComponents(dc, sc, *cmd->server);
     return NULL;
 }
 
@@ -359,19 +374,18 @@ const char *confComponent(unused cmd_parms *cmd, void *c, const char *arg) {
  */
 const command_rec commands[] = {
     AP_INIT_TAKE1("TuscanyHome", (const char*(*)())confHome, NULL, RSRC_CONF, "Tuscany home directory"),
-    AP_INIT_TAKE1("SCAWiringHost", (const char*(*)())confWiringHost, NULL, RSRC_CONF, "SCA wiring host"),
+    AP_INIT_TAKE1("SCAWiringServerName", (const char*(*)())confWiringServerName, NULL, RSRC_CONF, "SCA wiring server name"),
     AP_INIT_TAKE1("SCAContribution", (const char*(*)())confContribution, NULL, ACCESS_CONF, "SCA contribution location"),
     AP_INIT_TAKE1("SCAComposite", (const char*(*)())confComposite, NULL, ACCESS_CONF, "SCA composite location"),
-    AP_INIT_TAKE1("SCAComponent", (const char*(*)())confComponent, NULL, ACCESS_CONF, "SCA component name"),
     {NULL, NULL, NULL, 0, NO_ARGS, NULL}
 };
 
 int postConfig(unused apr_pool_t *p, unused apr_pool_t *plog, unused apr_pool_t *ptemp, unused server_rec *s) {
-   return OK;
+    return OK;
 }
 
 void childInit(unused apr_pool_t* p, server_rec* svr_rec) {
-    ServerConf *c = (ServerConf*)ap_get_module_config(svr_rec->module_config, &mod_tuscany_eval);
+    ServerConf* c = (ServerConf*)ap_get_module_config(svr_rec->module_config, &mod_tuscany_eval);
     if(c == NULL) {
         std::cerr << "[Tuscany] Due to one or more errors mod_tuscany_eval loading failed. Causing apache to stop loading." << std::endl;
         exit(APEXIT_CHILDFATAL);
@@ -382,6 +396,7 @@ void registerHooks(unused apr_pool_t *p) {
     ap_hook_post_config(postConfig, NULL, NULL, APR_HOOK_MIDDLE);
     ap_hook_child_init(childInit, NULL, NULL, APR_HOOK_MIDDLE);
     ap_hook_handler(handler, NULL, NULL, APR_HOOK_MIDDLE);
+    ap_hook_translate_name(translate, NULL, NULL, APR_HOOK_FIRST);
 }
 
 }
diff --git a/sca-cpp/trunk/modules/server/mod-eval.hpp b/sca-cpp/trunk/modules/server/mod-eval.hpp
deleted file mode 100644
index a350538956..0000000000
--- a/sca-cpp/trunk/modules/server/mod-eval.hpp
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-/* $Rev$ $Date$ */
-
-#ifndef tuscany_modeval_hpp
-#define tuscany_modeval_hpp
-
-/**
- * Defines the signature of component implementation lambdas
- * expected by mod-eval.
- */
-
-#include <string>
-
-#include "function.hpp"
-#include "list.hpp"
-#include "value.hpp"
-#include "monad.hpp"
-
-namespace tuscany {
-namespace server {
-namespace modeval {
-
-/**
- * Represents a component implementation lambda function.
- */
-typedef lambda<failable<value, std::string>(value, list<value>)> ilambda;
-
-}
-}
-}
-
-#endif /* tuscany_modeval_hpp */
diff --git a/sca-cpp/trunk/modules/server/mod-scm.hpp b/sca-cpp/trunk/modules/server/mod-scm.hpp
index 586b90190f..c454c6a216 100644
--- a/sca-cpp/trunk/modules/server/mod-scm.hpp
+++ b/sca-cpp/trunk/modules/server/mod-scm.hpp
@@ -36,11 +36,9 @@
 #include "value.hpp"
 #include "debug.hpp"
 #include "monad.hpp"
-#include "cache.hpp"
 #include "../eval/primitive.hpp"
 #include "../eval/driver.hpp"
 #include "../http/httpd.hpp"
-#include "mod-eval.hpp"
 
 namespace tuscany {
 namespace server {
@@ -64,36 +62,30 @@ struct evalImplementation {
     const list<value> px;
     evalImplementation(const value& impl, const list<value>& px) : impl(impl), px(eval::quotedParameters(primitiveProcedures(px))) {
     }
-    const failable<value, std::string> operator()(const value& func, const list<value>& params) const {
-        const value expr = cons<value>(func, append(eval::quotedParameters(params), px));
+    const value operator()(const list<value>& params) const {
+        const value expr = cons<value>(car(params), append(eval::quotedParameters(cdr(params)), px));
         debug(expr, "modeval::scm::evalImplementation::input");
         gc_pool pool;
         eval::Env globalEnv = eval::setupEnvironment(pool);
         const value val = eval::evalScript(expr, impl, globalEnv, pool);
         debug(val, "modeval::scm::evalImplementation::result");
         if (isNil(val))
-            return mkfailure<value, std::string>("Could not evaluate expression");
-        return val;
+            return mklist<value>(value(), std::string("Could not evaluate expression"));
+        return mklist<value>(val);
     }
 };
 
 /**
  * Read a script component implementation.
  */
-const failable<ilambda, std::string> readLatestImplementation(const std::string path, const list<value>& px) {
+const failable<lambda<value(const list<value>&)>, std::string> readImplementation(const std::string path, const list<value>& px) {
     std::ifstream is(path.c_str(), std::ios_base::in);
     if (is.fail() || is.bad())
-        return mkfailure<ilambda, std::string>("Could not read implementation: " + path);
+        return mkfailure<lambda<value(const list<value>&)>, std::string>("Could not read implementation: " + path);
     const value impl = eval::readScript(is);
     if (isNil(impl))
-        return mkfailure<ilambda, std::string>("Could not read implementation: " + path);
-    return ilambda(evalImplementation(impl, px));
-}
-
-const cached<failable<ilambda, std::string> > readImplementation(const std::string& path, const list<value>& px) {
-    const lambda<failable<ilambda, std::string>(std::string, list<value>)> ri(readLatestImplementation);
-    const lambda<unsigned long(std::string)> ft(latestFileTime);
-    return cached<failable<ilambda, std::string> >(curry(ri, path, px), curry(ft, path));
+        return mkfailure<lambda<value(const list<value>&)>, std::string>("Could not read implementation: " + path);
+    return lambda<value(const list<value>&)>(evalImplementation(impl, px));
 }
 
 }
diff --git a/sca-cpp/trunk/modules/server/mod-wiring.cpp b/sca-cpp/trunk/modules/server/mod-wiring.cpp
index 0d5262d730..1bb5d1a687 100644
--- a/sca-cpp/trunk/modules/server/mod-wiring.cpp
+++ b/sca-cpp/trunk/modules/server/mod-wiring.cpp
@@ -20,7 +20,8 @@
 /* $Rev$ $Date$ */
 
 /**
- * HTTPD module used to wire component references.
+ * HTTPD module used to wire component references and route requests to
+ * target service components.
  */
 
 #include <sys/stat.h>
@@ -32,10 +33,10 @@
 
 #include "list.hpp"
 #include "slist.hpp"
+#include "tree.hpp"
 #include "value.hpp"
 #include "debug.hpp"
 #include "monad.hpp"
-#include "cache.hpp"
 #include "../scdl/scdl.hpp"
 #include "../http/httpd.hpp"
 
@@ -52,11 +53,11 @@ namespace modwiring {
  */
 class ServerConf {
 public:
-    ServerConf(server_rec* s) : s(s), home(""), wiringHost("") {
+    ServerConf(server_rec* s) : s(s), home(""), wiringServerName("") {
     }
     const server_rec* s;
     std::string home;
-    std::string wiringHost;
+    std::string wiringServerName;
 };
 
 /**
@@ -74,27 +75,11 @@ public:
     const char* dirspec;
     std::string contributionPath;
     std::string compositeName;
-    cached<failable<list<value>, std::string> > components;
+    list<value> references;
+    list<value> services;
 };
 
 /**
- * Read the SCDL configuration of the deployed components.
- */
-const failable<list<value>, std::string> readComponents(const std::string& path) {
-    std::ifstream is(path);
-    if (is.fail() || is.bad())
-        return mkfailure<list<value>, std::string>("Could not read composite: " + path);
-    return scdl::components(readXML(streamList(is)));
-}
-
-const cached<failable<list<value>, std::string> > components(DirConf* conf) {
-    const std::string path(conf->contributionPath + conf->compositeName);
-    const lambda<failable<list<value>, std::string>(std::string)> rc(readComponents);
-    const lambda<unsigned long(std::string)> ft(latestFileTime);
-    return cached<failable<list<value>, std::string> >(curry(rc, path), curry(ft, path));
-}
-
-/**
  * Returns true if a URI is absolute.
  */
 const bool isAbsolute(const std::string& uri) {
@@ -102,34 +87,29 @@ const bool isAbsolute(const std::string& uri) {
 }
 
 /**
- * Translate an HTTP request URI. Wire a URI in the form /references/component-name/reference-name
- * to the target of the reference.
+ * Route a /references/component-name/reference-name request,
+ * to the target of the component reference.
  */
-int translate(request_rec *r) {
-    if (strncmp(r->uri, "/references/", 12) != 0)
-        return DECLINED;
-    httpdDebugRequest(r, "modwiring::translate::input");
-    debug(r->uri, "modwiring::translate::uri");
+int translateReference(request_rec *r) {
+    httpdDebugRequest(r, "modwiring::translateReference::input");
+    debug(r->uri, "modwiring::translateReference::uri");
 
-    // Find the requested component, reference and its target configuration
-    DirConf& conf = httpd::dirConf<DirConf>(r, &mod_tuscany_wiring);
-    conf.components = latest(conf.components);
-    const failable<list<value>, std::string> comps(content(conf.components));
-    if (!hasContent(comps))
-        return HTTP_INTERNAL_SERVER_ERROR;
+    // Find the requested component
+    DirConf& dc = httpd::dirConf<DirConf>(r, &mod_tuscany_wiring);
     const list<value> rpath(httpd::path(r->uri));
-    const value comp(scdl::named(cadr(rpath), list<value>(content(comps))));
+    const list<value> comp(assoctree(cadr(rpath), dc.references));
     if (isNil(comp))
         return HTTP_NOT_FOUND;
-    const value ref(scdl::named(caddr(rpath), scdl::references(comp)));
+
+    // Find the requested reference and target configuration
+    const list<value> ref(assoctree<value>(caddr(rpath), cadr(comp)));
     if (isNil(ref))
         return HTTP_NOT_FOUND;
-    const std::string target(scdl::target(ref));
+    const std::string target(cadr(ref));
+    debug(target, "modwiring::translateReference::target");
 
-    // Absolute target URI
+    // Route to an absolute target URI using mod_proxy or an HTTP client redirect
     if (isAbsolute(target)) {
-
-        // Wire using mod_proxy
         if (useModProxy) {
             r->filename = apr_pstrdup(r->pool, std::string("proxy:" + target).c_str());
             r->proxyreq = PROXYREQ_REVERSE;
@@ -137,21 +117,85 @@ int translate(request_rec *r) {
             return OK;
         }
 
-        // Wire using an HTTP client redirect
         r->status = HTTP_MOVED_TEMPORARILY;
         apr_table_setn(r->headers_out, "Location", apr_pstrdup(r->pool, target.c_str()));
         r->handler = "mod_tuscany_wiring";
         return OK;
-
     }
 
-    // Local internal redirect
-    r->filename = apr_pstrdup(r->pool, std::string("/redirect:/" + target).c_str());
+    // Route to a relative target URI using a local internal redirect
+    r->filename = apr_pstrdup(r->pool, std::string("/redirect:/components/" + target).c_str());
     r->handler = "mod_tuscany_wiring";
     return OK;
 }
 
 /**
+ * Find a leaf matching a request path in a tree of URI paths.
+ */
+const int matchPath(const list<value>& k, const list<value>& p) {
+    if (isNil(p))
+        return true;
+    if (isNil(k))
+        return false;
+    if (car(k) != car(p))
+        return false;
+    return matchPath(cdr(k), cdr(p));
+}
+
+const list<value> assocPath(const value& k, const list<value>& tree) {
+    if (isNil(tree))
+        return tree;
+    if (matchPath(k, car<value>(car(tree))))
+        return car(tree);
+    if (k < car<value>(car(tree)))
+        return assocPath(k, cadr(tree));
+    return assocPath(k, caddr(tree));
+}
+
+/**
+ * Route a service request to the component providing the requested service.
+ */
+int translateService(request_rec *r) {
+    httpdDebugRequest(r, "modwiring::translateService::input");
+    debug(r->uri, "modwiring::translateService::uri");
+
+    // Find the requested component
+    DirConf& dc = httpd::dirConf<DirConf>(r, &mod_tuscany_wiring);
+    const list<value> path(httpd::path(r->uri));
+    const list<value> svc(assocPath(path, dc.services));
+    if (isNil(svc))
+        return DECLINED;
+    debug(svc, "modwiring::translateService::service");
+
+    // Build a component-name + path-info URI
+    const list<value> target(cons<value>(cadr(svc), httpd::pathInfo(path, car(svc))));
+    debug(target, "modwiring::translateService::target");
+
+    // Dispatch to the target component using a local internal redirect
+    const std::string redir(std::string("/redirect:/components") + httpd::path(target));
+    debug(redir, "modwiring::translateService::redirect");
+    r->filename = apr_pstrdup(r->pool, redir.c_str());
+    r->handler = "mod_tuscany_wiring";
+    return OK;
+}
+
+/**
+ * Translate an HTTP service or reference request and route it
+ * to the target component.
+ */
+int translate(request_rec *r) {
+    if (!strncmp(r->uri, "/components/", 12) != 0)
+        return DECLINED;
+
+    // Translate a component reference request
+    if (!strncmp(r->uri, "/references/", 12) != 0)
+        return translateReference(r);
+
+    // Translate a service request
+    return translateService(r);
+}
+
+/**
  * Construct a redirect URI.
  */
 const std::string redirect(const std::string& file, const std::string& pi) {
@@ -163,7 +207,7 @@ const std::string redirect(const std::string& file, const std::string& pi, const
 }
 
 /**
- * HTTP request internal redirect handler.
+ * HTTP request handler, redirect to a target component.
  */
 int handler(request_rec *r) {
     if(strcmp(r->handler, "mod_tuscany_wiring"))
@@ -175,6 +219,7 @@ int handler(request_rec *r) {
         return DECLINED;
     debug(r->uri, "modwiring::handler::uri");
     debug(r->filename, "modwiring::handler::filename");
+    debug(r->path_info, "modwiring::handler::path info");
 
     if (r->args == NULL) {
         ap_internal_redirect(apr_pstrdup(r->pool, redirect(r->filename + 10, r->path_info).c_str()), r);
@@ -185,28 +230,109 @@ int handler(request_rec *r) {
 }
 
 /**
+ * Read the components declared in a composite.
+ */
+const failable<list<value>, std::string> readComponents(const std::string& path) {
+    std::ifstream is(path);
+    if (is.fail() || is.bad())
+        return mkfailure<list<value>, std::string>("Could not read composite: " + path);
+    return scdl::components(readXML(streamList(is)));
+}
+
+/**
+ * Return a tree of component-name + references pairs. The references are
+ * arranged in trees of reference-name + reference-target pairs.
+ */
+const list<value> componentReferenceToTargetTree(const value& c) {
+    return mklist<value>(scdl::name(c), mkbtree(sort(scdl::referenceToTargetAssoc(scdl::references(c)))));
+}
+
+const list<value> componentReferenceToTargetAssoc(const list<value>& c) {
+    if (isNil(c))
+        return c;
+    return cons<value>(componentReferenceToTargetTree(car(c)), componentReferenceToTargetAssoc(cdr(c)));
+}
+
+const list<value> componentReferenceToTargetTree(const list<value>& c) {
+    return mkbtree(sort(componentReferenceToTargetAssoc(c)));
+}
+
+/**
+ * Return a tree of service-URI-path + component-name pairs. Service-URI-paths are
+ * represented as lists of URI path fragments.
+ */
+const list<value> defaultBindingURI(const std::string& cn, const std::string& sn) {
+    return mklist<value>(cn, sn);
+}
+
+const list<value> bindingToComponentAssoc(const std::string& cn, const std::string& sn, const list<value>& b) {
+    if (isNil(b))
+        return b;
+    const value uri(scdl::uri(car(b)));
+    if (isNil(uri))
+        return cons<value>(mklist<value>(defaultBindingURI(cn, sn), cn), bindingToComponentAssoc(cn, sn, cdr(b)));
+    return cons<value>(mklist<value>(httpd::path(std::string(uri).c_str()), cn), bindingToComponentAssoc(cn, sn, cdr(b)));
+}
+
+const list<value> serviceToComponentAssoc(const std::string& cn, const list<value>& s) {
+    if (isNil(s))
+        return s;
+    const std::string sn(scdl::name(car(s)));
+    const list<value> btoc(bindingToComponentAssoc(cn, sn, scdl::bindings(car(s))));
+    if (isNil(btoc))
+        return cons<value>(mklist<value>(defaultBindingURI(cn, sn), cn), serviceToComponentAssoc(cn, cdr(s)));
+    return append<value>(btoc, serviceToComponentAssoc(cn, cdr(s)));
+}
+
+const list<value> uriToComponentAssoc(const list<value>& c) {
+    if (isNil(c))
+        return c;
+    return append<value>(serviceToComponentAssoc(scdl::name(car(c)), scdl::services(car(c))), uriToComponentAssoc(cdr(c)));
+}
+
+const list<value> uriToComponentTree(const list<value>& c) {
+    return mkbtree(sort(uriToComponentAssoc(c)));
+}
+
+/**
+ * Configure the components declared in the server's deployment composite.
+ */
+const bool confComponents(DirConf& dc) {
+    if (dc.contributionPath == "" || dc.compositeName == "")
+        return true;
+    const failable<list<value>, std::string> comps = readComponents(dc.contributionPath + dc.compositeName);
+    if (!hasContent(comps))
+        return true;
+    dc.references = componentReferenceToTargetTree(content(comps));
+    debug(dc.references, "modwiring::confComponents::references");
+    dc.services = uriToComponentTree(content(comps));
+    debug(dc.services, "modwiring::confComponents::services");
+    return true;
+}
+
+/**
  * Configuration commands.
  */
-const char *confHome(cmd_parms *cmd, unused void *dummy, const char *arg) {
-    ServerConf *c = (ServerConf*)ap_get_module_config(cmd->server->module_config, &mod_tuscany_wiring);
-    c->home = arg;
+const char *confHome(cmd_parms *cmd, unused void *c, const char *arg) {
+    ServerConf& sc = httpd::serverConf<ServerConf>(cmd, &mod_tuscany_wiring);
+    sc.home = arg;
     return NULL;
 }
-const char *confWiringHost(cmd_parms *cmd, unused void *dummy, const char *arg) {
-    ServerConf *c = (ServerConf*)ap_get_module_config(cmd->server->module_config, &mod_tuscany_wiring);
-    c->wiringHost = arg;
+const char *confWiringServerName(cmd_parms *cmd, unused void *c, const char *arg) {
+    ServerConf& sc = httpd::serverConf<ServerConf>(cmd, &mod_tuscany_wiring);
+    sc.wiringServerName = arg;
     return NULL;
 }
 const char *confContribution(unused cmd_parms *cmd, void *c, const char *arg) {
-    DirConf* conf = (DirConf*)c;
-    conf->contributionPath = arg;
-    conf->components = components(conf);
+    DirConf& dc = *(DirConf*)c;
+    dc.contributionPath = arg;
+    confComponents(dc);
     return NULL;
 }
 const char *confComposite(unused cmd_parms *cmd, void *c, const char *arg) {
-    DirConf* conf = (DirConf*)c;
-    conf->compositeName = arg;
-    conf->components = components(conf);
+    DirConf& dc = *(DirConf*)c;
+    dc.compositeName = arg;
+    confComponents(dc);
     return NULL;
 }
 
@@ -215,7 +341,7 @@ const char *confComposite(unused cmd_parms *cmd, void *c, const char *arg) {
  */
 const command_rec commands[] = {
     AP_INIT_TAKE1("TuscanyHome", (const char*(*)())confHome, NULL, RSRC_CONF, "Tuscany home directory"),
-    AP_INIT_TAKE1("SCAWiringHost", (const char*(*)())confWiringHost, NULL, RSRC_CONF, "SCA wiring host"),
+    AP_INIT_TAKE1("SCAWiringServerName", (const char*(*)())confWiringServerName, NULL, ACCESS_CONF, "SCA wiring server name"),
     AP_INIT_TAKE1("SCAContribution", (const char*(*)())confContribution, NULL, ACCESS_CONF, "SCA contribution location"),
     AP_INIT_TAKE1("SCAComposite", (const char*(*)())confComposite, NULL, ACCESS_CONF, "SCA composite location"),
     {NULL, NULL, NULL, 0, NO_ARGS, NULL}
diff --git a/sca-cpp/trunk/modules/server/server-test b/sca-cpp/trunk/modules/server/server-test
index 9c517f38b6..4c90711a30 100755
--- a/sca-cpp/trunk/modules/server/server-test
+++ b/sca-cpp/trunk/modules/server/server-test
@@ -22,23 +22,14 @@
 ./server-conf tmp
 cat >>tmp/conf/httpd.conf <<EOF
 
-<Location /test>
-SetHandler mod_tuscany_eval
+<Location />
 SCAContribution `pwd`/
 SCAComposite domain-test.composite
-SCAComponent server-test
-</Location>
-
-<Location /cpp>
-SetHandler mod_tuscany_eval
-SCAContribution `pwd`/
-SCAComposite domain-test.composite
-SCAComponent cpp-test
 </Location>
 EOF
 
 apachectl -k start -d `pwd`/tmp
-sleep 1
+sleep 2
 
 # Test
 ./client-test 2>/dev/null
@@ -46,5 +37,5 @@ rc=$?
 
 # Cleanup
 apachectl -k stop -d `pwd`/tmp
-sleep 1
+sleep 2
 return $rc
diff --git a/sca-cpp/trunk/modules/server/wiring-test b/sca-cpp/trunk/modules/server/wiring-test
index 5f77d4c6f8..5b3a678f7f 100755
--- a/sca-cpp/trunk/modules/server/wiring-test
+++ b/sca-cpp/trunk/modules/server/wiring-test
@@ -24,29 +24,14 @@ echo "Testing..."
 ./server-conf tmp
 cat >>tmp/conf/httpd.conf <<EOF
 
-<Location /test>
-SetHandler mod_tuscany_eval
-SCAContribution `pwd`/
-SCAComposite domain-test.composite
-SCAComponent server-test
-</Location>
-
-<Location /client>
-SetHandler mod_tuscany_eval
-SCAContribution `pwd`/
-SCAComposite domain-test.composite
-SCAComponent client-test
-</Location>
-
-<Location /references>
-SetHandler mod_tuscany_wiring
+<Location />
 SCAContribution `pwd`/
 SCAComposite domain-test.composite
 </Location>
 EOF
 
 apachectl -k start -d `pwd`/tmp
-sleep 1
+sleep 2
 
 # Test HTTP GET
 curl http://localhost:8090/index.html 2>/dev/null >tmp/index.html
@@ -86,7 +71,7 @@ fi
 
 # Cleanup
 apachectl -k stop -d `pwd`/tmp
-sleep 1
+sleep 2
 if [ "$rc" = "0" ]; then
     echo "OK"
 fi