5.1.2 实践：CoAP 服务器和 Copper

首先获取火狐插件Copper (Cu) CoAP user-agent
Copper是一个用于浏览物联网Coap的嵌入式网络设备管理工具。集成到Web浏览器，更直观的调试COAP设备。
更多信息参见 Copper page。

实验用到两个节点：边界路由器（Border Router）和Coap server 节点。

If you are using the Z1 motes, ensure that the motes you will be using to
test this (border router, server, client) have been flashed with a node ID
to generate the MAC/IPv6 addresses as done in previous sessions, be
sure to write down the addresses! Another thing, if you get an error like
the following, go to platform/z1/contiki-conf.h and change
UIP_CONF_BUFFER_SIZE to 240:

error “UIP_CONF_BUFFER_SIZE too small for REST_MAX_CHUNK_SIZE”

make: * [obj_z1/er-coap-07-engine.o] Error 1

在Makefile中我们可以看到：资源文件添加到工程路径，所有资源文件编译加入。

  1. REST_RESOURCES_DIR = ./resources
  2. REST_RESOURCES_FILES = $(notdir $(shell find $(REST_RESOURCES_DIR) -name '*.c' ! -
  3. name 'res-plugtest*'))
  4. PROJECTDIRS += $(REST_RESOURCES_DIR)
  5. PROJECT_SOURCEFILES += $(REST_RESOURCES_FILES)

包含er-coap和rest-engine应用程序。

REST Engine shall use Erbium CoAP implementation

APPS += er-coap
APPS += rest-engine

删除以下内容，以避免冲突：

undef NETSTACK_CONF_MAC

define NETSTACK_CONF_MAC nullmac_driver

接下来检查project-conf.h相关配置。由于 CoAP是基于UDP，首先确保禁用TCP。
/ Disabling TCP on CoAP nodes. /

undef UIP_CONF_TCP

define UIP_CONF_TCP 0

REST_MAX_CHUNK_SIZE定义供资源响应的最大缓冲区大小。更大的数据由资源来处理，并由COAP块发送。COAP_MAX_OPEN_TRANSACTIONS定义节点能够处理的公开事务的最大值。
/ Increase rpl-border-router IP-buffer when using more than 64. /

undef REST_MAX_CHUNK_SIZE

define REST_MAX_CHUNK_SIZE 48

/ Multiplies with chunk size, be aware of memory constraints. /

undef COAP_MAX_OPEN_TRANSACTIONS

define COAP_MAX_OPEN_TRANSACTIONS 4

/ Filtering .well-known/core per query can be disabled to save space. /

undef COAP_LINK_FORMAT_FILTERING

define COAP_LINK_FORMAT_FILTERING 0

undef COAP_PROXY_OPTION_PROCESSING

define COAP_PROXY_OPTION_PROCESSING 0

/ Enable client-side support for COAP observe /

define COAP_OBSERVE_CLIENT 1

CoAP Server

下面分析er-example-server.c，看看是如何实现Coap server。首先要注意资源文件夹。 为了方便调试和维护，在不同的文件中实现资源。
COAP服务器包含的资源可声明如下：
extern resource_t
res_hello,
res_mirror,
res_chunks,
res_separate,
res_push,
res_event,
res_sub,
res_b1_sep_b2;

if PLATFORM_HAS_LEDS

extern resource_t res_leds, res_toggle;

endif

if PLATFORM_HAS_BATTERY

include “dev/battery-sensor.h”

extern resource_t res_battery;

endif

if PLATFORM_HAS_RADIO

include “dev/radio-sensor.h”

extern resource_t res_radio;

endif

PLATFORM_HAS_X硬件资源依赖于目标平台，如果平台启用，就可以获取到相关资源。
调用rest_init_engine()初始化REST引擎，并激活资源：
/ Initialize the REST engine. /
rest_init_engine();
/*

  • Bind the resources to their Uri-Path.
  • WARNING: Activating twice only means alternate path, not two instances!
  • All static variables are the same for each URI path.
    /
    rest_activate_resource(&res_hello, “test/hello”);
    rest_activate_resource(&res_push, “test/push”);
    rest_activate_resource(&res_event, “sensors/button”);     /

    if PLATFORM_HAS_LEDS

    rest_activate_resource(&res_toggle, “actuators/toggle”);

    endif

    (…)
    现在我们分析RES-hello.c如何实现测试的资源“Hello World”。
    RESOURCE宏定义资源，这里指定资源名称res_hello，
    我们执行指定资源名称为res_hello，链接格式属性和GET回调函数。资源不支持POST，PUT和DELETE方法，所以参数作为空。
    RESOURCE(res_hello,
    “title=\”Hello world: ?len=0..\”;rt=\”Text\””,
    res_get_handler,
    NULL,
    NULL,
    NULL);
    GET请求事件回调res_get_handler：
    //

1.应答帧默认长度，这里只发送Hello World!字符串
2.如果指定了len选项，则发送消息字符串长度字节数
3.如果该值为负，送一个空字符串
4.如果len大于允许的最大值，那么我们只能发送最大默认lenght值。
5.复制默认长度。
6.设置响应消息内容类型为Content-Type：text / plain
7.附加帧头到响应消息，设置有效载荷长度域。
8.附加有效载荷到响应消息

在project-conf.h文件中添加以下内容：

undef NETSTACK_CONF_RDC

define NETSTACK_CONF_RDC nullrdc_driver

编译下载
cd examples/er-rest-example/
make TARGET=zoul savetarget
make er-example-server.upload && make login
记下Coap服务器IPv6地址。
下面将另一个节点配置成边界路由器：
Border-Router
cd ../ipv6/rpl-border-router/
make TARGET=z1 savetarget
make border-router.upload && make connect-router
或者
make TARGET=zoul savetarget && make border-router.upload && make connect-router
不要关闭此窗口！等节点连接后，现在你会看到如下输出：
SLIP started on /dev/ttyUSB0'' opened tun device/dev/tun0’’
ifconfig tun0 inet hostname up
ifconfig tun0 add aaaa::1/64
ifconfig tun0 add fe80::0:0:0:1/64
ifconfig tun0
tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet addr:127.0.1.1 P-t-P:127.0.1.1 Mask:255.255.255.255
inet6 addr: fe80::1/64 Scope:Link
inet6 addr: aaaa::1/64 Scope:Global
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:500
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
Rime started with address 193.12.0.0.0.0.3.229
MAC c1:0c:00:00:00:00:03:e5 Contiki-2.5-release-681-gc5e9d68 started. Node id
is set to 997.
CSMA nullrdc, channel check rate 128 Hz, radio channel 26
Tentative link-local IPv6 address fe80:0000:0000:0000:c30c:0000:0000:03e5
Starting ‘Border router process’ ‘Web server’
Address:aaaa::1 => aaaa:0000:0000:0000
Got configuration message of type P
Setting prefix aaaa::
Server IPv6 addresses:
aaaa::c30c:0:0:3e5
fe80::c30c:0:0:3e5
ping测试边界路由器的连接
ping6 aaaa:0000:0000:0000:c30c:0000:0000:03e5
PING aaaa:0000:0000:0000:c30c:0000:0000:03e5(aaaa::c30c:0:0:3e5) 56 data bytes
64 bytes from aaaa::c30c:0:0:3e5: icmp_seq=1 ttl=64 time=21.0 ms
64 bytes from aaaa::c30c:0:0:3e5: icmp_seq=2 ttl=64 time=19.8 ms
64 bytes from aaaa::c30c:0:0:3e5: icmp_seq=3 ttl=64 time=22.2 ms
64 bytes from aaaa::c30c:0:0:3e5: icmp_seq=4 ttl=64 time=20.7 ms
等Coap server节点连接到边界路由器后，ping Coap server节点
ping6 aaaa:0000:0000:0000:c30c:0000:0000:0001
PING aaaa:0000:0000:0000:c30c:0000:0000:0001(aaaa::c30c:0:0:1) 56 data bytes
64 bytes from aaaa::c30c:0:0:1: icmp_seq=1 ttl=63 time=40.3 ms
64 bytes from aaaa::c30c:0:0:1: icmp_seq=2 ttl=63 time=34.2 ms
64 bytes from aaaa::c30c:0:0:1: icmp_seq=3 ttl=63 time=35.7 ms
下面我们可以开始发现服务器资源，打开Firefox和键入服务器地址
coap://[aaaa::c30c:0000:0000:0001]:5683/
点击DISCOVER按钮，左侧页面将显示有效的资源。
选中toggle资源并点击POST，你可以看到服务器节点的红色LED状态翻转。
如果你选择Sensors → Button事件，然后单击OBSERVE，每次触发用户按钮事件都会产生报告。
最后，如果在er-example-server.c使能以下定义，可以获得更多的可用资源：

  1. #define REST_RES_HELLO 1
  2. #define REST_RES_SEPARATE 1
  3. #define REST_RES_PUSHING 1
  4. #define REST_RES_EVENT 1
  5. #define REST_RES_SUB 1
  6. #define REST_RES_LEDS 1
  7. #define REST_RES_TOGGLE 1
  8. #define REST_RES_BATTERY 1
  9. #define REST_RES_RADIO 1

而现在获得收发器的当前RSSI强度。
coap://[aaaa::c30c:0000:0000:0001]:5683/sensor/radio?p=rssi
读取电池电压值
coap://[aaaa::c30c:0000:0000:0001]:5683/sensors/battery
最后返回节点连接到USB时ADC值，实际值毫伏为
V [mV] = (units * 5000)/4096
如果想打开绿色LED灯，浏览器输入，并点击POST 或PUT：
coap://[aaaa::c30c:0000:0000:0001]:5683/actuators/leds?color=g
成功后在运行栏显示负载
mode=”on”