HTTP Client in mruby | ArangoDB Blog 2012

As Dorthe pointed out, we are on the road for the next two weeks. So, I thought it might be a good idea to put everything together. In the last blog posts, I described

• how to wrap a C / C++ structure
• how to define Ruby classes and functions in C
• construct a interactive REPL

Now in order to construct an alternative to the JavaScript shell “arangosh” for ArangoDB, what is missing is a HTTP client. The JavaScript shell already has a builtin C++ class, so I decided to use the same class for the Ruby version. In principle it would be possible to use curl or other libraries.

The wrapper is straight forward.

static mrb_value ClientConnection_httpGet (mrb_state* mrb, mrb_value self) {
  char* url;
  /* int res; */
  size_t l;
  struct RData* rdata;
  MRubyClientConnection* connection;

 /* res = */ mrb_get_args(mrb, "s", &url, &l);

  if (url == 0) {
    return self;
  }

  // looking at "mruby.h" I assume that is the way to unwrap the pointer
  rdata = (struct RData*) mrb_object(self);
  connection = (MRubyClientConnection*) rdata->data;

  if (connection == NULL) {
    printf("unknown connection (TODO raise error)\n");
    return self;
  }

  // check header fields
  map headerFields;

  // and execute
  return ClientConnection->getData(url, headerFields);
}

static void MR_ArangoConnection_Free (mrb_state* mrb, void* p) {
  printf("free of ArangoCollection called\n");
}

static const struct mrb_data_type MR_ArangoConnection_Type = {
  "ArangoConnection", MR_ArangoConnection_Free
};

static void InitMRClientConnection (MR_state_t* mrs, MRubyClientConnection* connection) {
  struct RClass *rcl;
  mrb_state* mrb;

  mrb = &mrs->_mrb;

  rcl = mrb_define_class(&mrs->_mrb, "ArangoConnection", mrs->_mrb.object_class);

  mrb_define_method(&mrs->_mrb, rcl, "get", ClientConnection_httpGet, ARGS_REQ(1));

  // create the connection variable
  mrb_value arango = mrb_obj_value(Data_Wrap_Struct(&mrs->_mrb, rcl, &MR_ArangoConnection_Type, (void*) connection));
  mrb_gv_set(mrb, mrb_intern(mrb, "$arango"), arango);
}

The whole source code can be found on github in MRClient/arangoirb.cpp. You can either use

brew install --HEAD arangodb

or install everything from scratch.

This defines a class ArangoConnection with a method get and a global variable $arango. This now allows to connection to the ArangoDB server.

fceller@opensuse121:~/ArangoDB> ./arangoirb 
                                   _      _     
  __ _ _ __ __ _ _ __   __ _  ___ (_)_ __| |__  
 / _` | '__/ _` | '_ \ / _` |/ _ \| | '__| '_ \ 
| (_| | | | (_| | | | | (_| | (_) | | |  | |_) |
 \__,_|_|  \__,_|_| |_|\__, |\___/|_|_|  |_.__/ 
                       |___/                    

Welcome to arangoirb 0.5.2. Copyright (c) 2012 triAGENS GmbH.
Using MRUBY 2012-05-16 (a3a9d136aa4835eb50f4be92fbbce1ad503ec4c7) engine. Copyright (c) 2012 mruby developers.
Using READLINE 6.2.

Connected to Arango DB 127.0.0.1:8529 Version 0.5.2
arangoirb> $arango
#
arangoirb> $res = $arango.get "/_api/version"
{"server"=>"arango", "version"=>"0.5.2"}
arangoirb> $res["version"]
"0.5.2"
arangoirb> 
Bye Bye! Auf Wiedersehen! さようなら

The next steps are to add the other methods, make it a bit more like HTTParty, and write the server related functions. I’m not really sure, who a good Ruby interface should look like. So, if you happen to be at NoSQL Matters an Tuesday/Wednesday or at the EuRuKo on Friday/Saturday, please contact us. I would really like to discuss this matter with some Ruby experts.