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Re: [paho-dev] Lua client: Changing connect method 
Hi Dwayne,
My main reason about staying different from Java client is staying close to specs.
The connect method I advocating for is closer to connect description given by MQTT itself. 
I also believe it will be easier to use this way.
When you know about MQTT specs you will know where to search in lib API.

I want it to be as bare simple as possible.
I do appreciate you being interested and wondering about what going on with Lua client. 

Kevin

On 06/10/2014 23:43, Bradley, Dwayne wrote:

I'm like Ian  when it comes to not knowing much about Lua but I have a couple of quick observations after previously coding with the Java client and having just recently played with the Lua client.

Is there a reason to not follow the Java model a little closer with the Lua client?  For example, when we create new MqttClient object using the class' contructor in Java, we pass:

- The URI to the server and,
- The client identifier.

These are the required parts of a MqttConnection.  Any reason to not make the Lua client similar in this regard?  Currently the create() method of the Lua client passes:

- The IP address,
- Port and
- A callback method/pointer/or whatever it is called in Lua.

Why not put the identifier in the create() method as well since it is a required piece of information for the connection?  Any reason to not change the IP address/Port parameters over to a single URI field?  I do realize that we would have to handle setting the callback method differently than in Java though.

After the client object is created, we then call the connect() method on that client instance.  When we do this in Java, we have 2 options because of overloading:

1) Calling connect() with no parameters (i.e. no optional parameters required) or
2) Calling connect() with an MqttClientOptions object that contains all of the non-required part of a connection.  I think that this is partially what you are looking at by using a Lua table for the parameter but I personally would like to see what could be passed in this table being more defined (but then again, I'm not very familiar with Lua and how things are normally structured).

These non-required options are:

- Clean session flag
- Connection timeout
- Keep-alive interval
- Username
- Password
- SSL info
- Will topic info

I kind of like having the required portions of a connection being separated from the non-required portions and I feel like the current Java implementation does that nicely.

Just food for thought.

Dwayne Bradley
Technology Development Manager
Emerging Technology Office
Duke Energy


-----Original Message-----
From: paho-dev-bounces@xxxxxxxxxxx [mailto:paho-dev-bounces@xxxxxxxxxxx] On Behalf Of Ian Craggs
Sent: Monday, October 06, 2014 5:09 PM
To: paho-dev@xxxxxxxxxxx
Subject: Re: [paho-dev] Lua client: Changing connect method



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All sounds good to me (not knowing much about Lua).

Oh - the client identifier no longer has the 23 character limit in MQTT 3.1.1.

Ian

On 10/06/2014 04:53 PM, Kevin KIN-FOO wrote:

Hi,

I think we should change connect method to stick better whith MQTT 3.1
[1].

As I am writing this method method looks like:

   function MQTT.client:connect(                                     --
Public API
     identifier,    -- string: MQTT client identifier (maximum 23
characters)
     will_topic,    -- string: Last will and testament topic
     will_qos,      -- byte:   Last will and testament Quality Of Service
     will_retain,   -- byte:   Last will and testament retention status
     will_message)  -- string: Last will and testament message

I think it should follow specs and include authentication parameters.
Result is:

   function MQTT.client:connect(                                     --
Public API
     identifier,    -- string: MQTT client identifier (maximum 23
characters)
     will_topic,    -- string: Last will and testament topic
     will_message,  -- string: Last will and testament message
     user_name,     -- string: User who is connecting
     password,      -- string: Password corresponding to the user who
is connecting
     will_qos,      -- byte:   Last will and testament Quality Of Service
     will_retain)   -- byte:   Last will and testament retention status

Even better allowing to provide parameter within a table.
It avoid passing silly "nil" while connecting.
So users could type:

   client:connect({
     identifier = id,
     will_topic = will,
     will_retain = 'So long',
   })

Looking forward for comments.

Kevin

[1]
http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/mqtt-v3r1.ht
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--
Ian Craggs
icraggs@xxxxxxxxxx                 IBM United Kingdom
Paho Project Lead; Committer on Mosquitto

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