# Spark Core and MDNS

**URL:** <https://community.particle.io/t/spark-core-and-mdns/4945>\
**Category:** Libraries\
**Created:** [June 8, 2014, 6:51pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945 "2014-06-08T18:51:17Z")\
**Posts on this page:** 13\
**Page:** 1

<div class="post-metadata">

**Author:** ![krvarma](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/krvarma/32/3089_2.png) [@krvarma](https://community.particle.io/u/krvarma)\
**Post date:** [June 8, 2014, 6:51pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/1 "2014-06-08T18:51:17Z")

</div>

## Spark Core and MDNS

Here is the Spark Core port of Adafruit MDNS library. The library provides the ability to setup a name for the Spark Core and resolve it. We can name the Core anything we want, the library will append “ **.local** ” to the name and we can access the Core using the URL “_name_.local”.

The sample application names the Core as “ **_myspark_** ”. If the MDNS is setup correctly then it creates a TCPServer on port 80. The Core can be accessed using the URL “**[http://myspark.local](http://myspark.local)**”. The server simply prints a test message.

> **[krvarma/MDNS\_SparkCore](https://github.com/krvarma/MDNS_SparkCore)**
>
> MDNS\_SparkCore - Adafruit MDNS port for Spark Core

**Requirement**

1. For Mac OSX support is built in through Bonjour already.
2. For Linux, install Avahi.
3. For Windows, install Bonjour.

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<div class="post-metadata">

**Author:** ![kennethlimcp](https://avatars.discourse-cdn.com/v4/letter/k/c0e974/32.png) [@kennethlimcp](https://community.particle.io/u/kennethlimcp)\
**Post date:** [June 8, 2014, 10:29pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/2 "2014-06-08T22:29:42Z")

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I think your library url was eaten up… 👻

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<div class="post-metadata">

**Author:** ![krvarma](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/krvarma/32/3089_2.png) [@krvarma](https://community.particle.io/u/krvarma)\
**Post date:** [June 9, 2014, 4:52am UTC](https://community.particle.io/t/spark-core-and-mdns/4945/3 "2014-06-09T04:52:31Z")

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Oh… my mistake, its corrected. Thanks @kennethlimcp for pointing out.

Sorry about that ☹

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<div class="post-metadata">

**Author:** ![bko](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/bko/32/20704_2.png) [@bko](https://community.particle.io/u/bko)\
**Post date:** [June 11, 2014, 11:24am UTC](https://community.particle.io/t/spark-core-and-mdns/4945/4 "2014-06-11T11:24:19Z")

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Hi @kvarma

I have tried this out with both an iOS device and a Mac and it is not working for me. I have a couple Bonjour explorer type programs and none can see the core. I see the request packets on wireshark but I don’t see responses. The core eventually goes into flashing cyan and reboots–I am not sure why.

Is there something else you did to get this to work?

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<div class="post-metadata">

**Author:** ![krvarma](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/krvarma/32/3089_2.png) [@krvarma](https://community.particle.io/u/krvarma)\
**Post date:** [June 11, 2014, 12:51pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/5 "2014-06-11T12:51:32Z")

</div>

@bko, the following code works for me when I am connected to same network.

```
// This #include statement was automatically added by the Spark IDE.
#include "mdns/mdns.h"

#define LISTEN_PORT 7

TCPServer echoServer(LISTEN_PORT);
MDNSResponder mdns;

char szIP[64];
bool isStarted;
char szHTML[] = "<html><body><p>Spark Core and MDNS Working :)</p></body></html>";

TCPServer server = TCPServer(80);

void setup() {
    // Retrieve and convert to integer format
    IPAddress addr = Network.localIP();
    uint32_t ip = (addr[0] * 16777216) + (addr[1] * 65536) + (addr[2] * 256) + (addr[3]);
    
    // Begin MDNS
    isStarted = mdns.begin("myspark", ip);
    
    // If started, set the variable to IP address of the Spark Core
    // else set error message
    if(isStarted){
        sprintf(szIP, "%d.%d.%d.%d (%u)", addr[0], addr[1], addr[2], addr[3], ip);
         server.begin();
    }
    else{
        sprintf(szIP, "Error starting MDNS.");
    }
    
    Spark.variable("mdnsstatus", szIP, STRING);
}

void loop() {
    // If we started successfully, then wait for the client to connect
    // else do nothing
    if(isStarted){
        mdns.update();
        
        TCPClient client = server.available();
        if (client){
            client.write(szHTML);
            client.flush();
            client.stop();
        }
    }
    
    delay(2000);
}

```

I experienced this issue while developing and when I forgot to add the `mdns.update();` in `loop`. Once it is added it is working on Mac, I didn’t test on Windows. Will that be the issue in your case?. Also could you please check the `mdnsstatus` variable?

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<div class="post-metadata">

**Author:** ![bko](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/bko/32/20704_2.png) [@bko](https://community.particle.io/u/bko)\
**Post date:** [June 11, 2014, 12:53pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/6 "2014-06-11T12:53:45Z")

</div>

OK, that must be it. I had pulled your example out from your github. If you haven’t already updated it, that might be good to do. I will try it again tonight.

Thanks!

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<div class="post-metadata">

**Author:** ![krvarma](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/krvarma/32/3089_2.png) [@krvarma](https://community.particle.io/u/krvarma)\
**Post date:** [June 11, 2014, 1:10pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/7 "2014-06-11T13:10:51Z")

</div>

Yes, I updated example the code already, by mistake I pushed the example code with out the `mdns.update()` first, then I corrected it later. I should be more careful next time 😄

Thanks @bko and please update the result.

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<div class="post-metadata">

**Author:** ![mars](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/mars/32/3588_2.png) [@mars](https://community.particle.io/u/mars)\
**Post date:** [October 14, 2015, 5:39pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/8 "2015-10-14T17:39:46Z")

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Cool stuff. Does the mDNS library work on the Photon?  
Or is there some other way of doing service discovery on the Photon that people have used?

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<div class="post-metadata">

**Author:** ![krvarma](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/krvarma/32/3089_2.png) [@krvarma](https://community.particle.io/u/krvarma)\
**Post date:** [October 14, 2015, 5:56pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/9 "2015-10-14T17:56:29Z")

</div>

@mars, it didn’t check it but it should work.

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<div class="post-metadata">

**Author:** ![Jackson\_lv](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/jackson_lv/32/8180_2.png) [@Jackson\_lv](https://community.particle.io/u/Jackson_lv)\
**Post date:** [December 25, 2015, 8:36am UTC](https://community.particle.io/t/spark-core-and-mdns/4945/10 "2015-12-25T08:36:35Z")

</div>

Hello krvarma,it is this example is suitable for Spark Photon either? I vertifyed your example in the particle build and it showed some errors.Can you help me ?thanks!

```nohighlight
mdns.cpp:136:54: error: 'socket' was not declared in this scope
     int soc = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
mdns.cpp:141:5: error: 'sockaddr_in' was not declared in this scope
     sockaddr_in address;
mdns.cpp:141:17: error: expected ';' before 'address'
     sockaddr_in address;
mdns.cpp:142:13: error: 'address' was not declared in this scope
     memset(&address, 0, sizeof(address));
mdns.cpp:144:34: error: 'htons' was not declared in this scope
     address.sin_port = htons(5353);
mdns.cpp:145:59: error: 'htonl' was not declared in this scope
     address.sin_addr.s_addr = htonl(ip2int(224, 0, 0, 251)); ^
mdns.cpp:147:20: error: 'sockaddr' was not declared in this scope
     if (bind(soc, (sockaddr*) &address, sizeof(address)) < 0) {
mdns.cpp:147:29: error: expected primary-expression before ')' token
     if (bind(soc, (sockaddr*) &address, sizeof(address)) < 0) {                         
mdns.cpp:147:56: error: 'bind' was not declared in this scope
     if (bind(soc, (sockaddr*) &address, sizeof(address)) < 0) {
mdns.cpp:146:15: warning: unused variable 'len' [-Wunused-variable]
     socklen_t len = sizeof(address);
mdns.cpp: In member function 'void MDNSResponder::update()':
mdns.cpp:167:3: error: 'timeval' was not declared in this scope
   timeval timeout;
mdns.cpp:167:11: error: expected ';' before 'timeout'
   timeval timeout;
mdns.cpp:168:3: error: 'timeout' was not declared in this scope
   timeout.tv_sec = 0;
mdns.cpp:170:3: error: '_types_fd_set_cc3000' was not declared in this scope
   _types_fd_set_cc3000 reads
mdns.cpp:170:24: error: expected ';' before 'reads'
   _types_fd_set_cc3000 reads;
mdns.cpp:171:12: error: 'reads' was not declared in this scope
   FD_ZERO(&reads); ^
mdns.cpp:172:24: error: 'reads' was not declared in this scope
   FD_SET(_mdnsSocket, &reads);
mdns.cpp:173:55: error: 'select' was not declared in this scope
   select(_mdnsSocket + 1, &reads, NULL, NULL, &timeout);
mdns.cpp:180:55: error: 'recv' was not declared in this scope
   int n = recv(_mdnsSocket, &buffer, sizeof(buffer), 0);
mdns.cpp: In member function 'void MDNSResponder::sendResponse()':
mdns.cpp:241:47: error: 'send' was not declared in this scope
   send(_mdnsSocket, _response, _responseLen, 0);

```

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<div class="post-metadata">

**Author:** ![krvarma](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/krvarma/32/3089_2.png) [@krvarma](https://community.particle.io/u/krvarma)\
**Post date:** [December 25, 2015, 7:47pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/11 "2015-12-25T19:47:20Z")

</div>

@Jackson_lv, I think we need to chage the socket functions, let me take a look at it and get back to you.

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<div class="post-metadata">

**Author:** ![sravanjosh](https://avatars.discourse-cdn.com/v4/letter/s/41988e/32.png) [@sravanjosh](https://community.particle.io/u/sravanjosh)\
**Post date:** [March 20, 2016, 6:02pm UTC](https://community.particle.io/t/spark-core-and-mdns/4945/12 "2016-03-20T18:02:17Z")

</div>

Hi krvarma, Me too getting same errors as Jackson\_Iv. Can you please help us with this.

I am trying it for photon.

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<div class="post-metadata">

**Author:** ![krvarma](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/krvarma/32/3089_2.png) [@krvarma](https://community.particle.io/u/krvarma)\
**Post date:** [March 21, 2016, 6:14am UTC](https://community.particle.io/t/spark-core-and-mdns/4945/13 "2016-03-21T06:14:02Z")

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@sravanjosh, I too facing this problem but because of some time restriction I didn’t work on that. There are some changes for Photons we need to make, like passing network interface to the socket functions. I am not sure about what all the changes we need to make. Hopefully I can work on it this weekend. Will let you know the progress.