Recently I have been playing around with Canvas, a technology that seems quite promising for the integration of third party applications within salesforce.

The canvas JavaScript API provides ways of making cross domain http request at an asynchronous level. I am interested in having synchronous method calls, and I don´t know whether that can be achieved. 

The following is the JavaScript example (combining the two examples given in the manual)

        function displayChatterUsers() {
          var NumberUsers = 0;
          // Reference the Chatter user's URL from Context.Links object.
          var chatterUsersUrl = canvasContext.context.links.chatterUsersUrl;

          // Make an XHR call back to salesforce through the supplied browser proxy.
          Sfdc.canvas.client.ajax(chatterUsersUrl,
            {
              token: canvasContext.oauthToken,
              success: function (data) {
                // Make sure the status code is OK.
                if (data.status === 200) {
                  numberUsers = data.payload.users.length;
                  // Alert with how many Chatter users were returned.
                  alert( "Got back " + numberUsers +
                    " users"); // Returned 2 users
                }
              }
            });
          alert( "Test for the number of users is " + numberUsers );
            var url = canvasContext.context.links.chatterFeedsUrl + "/news/" + canvasContext.context.user.userId + "/feed-items";
            var body = { body: { messageSegments: [{ type: "Text", text: "The number of users is " + numberUsers}]} };
          Sfdc.canvas.client.ajax( url,
            {
              token: canvasContext.oauthToken,
              method: 'POST',
              contentType: "application/json",
              data: JSON.stringify( body ),
              success: function( data ) {
                if ( 201 === data.status ) {
                  alert( "Success" );
                }
              }
            } );
        }

 When running the above mentioned example, you could see that the Sfdc.canvas.client.ajax get delayed in its execution, disallowing me from use of the results of the method call in outer levels of nesting (for instance, in the top level alert()).

I tried adding async:true as part of the values for the method call (as one might infer from the canvas-all.js specification) with no luck.

Any hints are greatly appreciated.

Andy