Differences

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--- integration_with_other_systems [2020/05/22 10:14] – [GET example] emozolyak
+++ integration_with_other_systems [2024/04/04 10:18] (current) – [Troubleshooting CURL requests from WebHMI] emozolyak
@@ Line 7: / Line 7: @@
 ===== POST example =====
-An example of a program executing an HTTPS request to send data as a file at URL https://demo.com/upload:
+An example of a program executing an HTTPS request to send data as a file at URL https://example.com/upload:
 <code lua>
@@ Line 15: / Line 15: @@
   c = cURL.easy_init()
-  c:setopt_url("https://demo.com/upload")
+  c:setopt_url("https://example.com/upload")
   c:setopt_timeout(5)
@@ Line 56: / Line 56: @@
 ===== Implementing other requests like PUT =====
-To implement other requests, you can indicate for cURL call that you need custom request
+To implement other requests, you can use special field in the cURL for the custom methods.
+Here is the example of PUT request to WebHMI itself from its Lua.
 <code lua>
 function main (userId)
+  local new_value = "new string"
-    INFO("Doing CURL");
+  write_reg_with_API(1, new_value)
+end
-  str = ''
+function write_reg_with_API(reg_id, val_)
   c = cURL.easy_init()
-  c:setopt_url("http://192.168.1.230:8000")
-  c:setopt_timeout(15)
-  c:setopt{[cURL.OPT_CUSTOMREQUEST] = "PUT"}  -- this is custom method
-  c:setopt{
+  c:setopt_url("http://127.0.1.1/api/register-values/" .. reg_id)    -- local host addr indicated
-        [cURL.OPT_POSTFIELDS] = 'Content-type: text/html'
+  c:setopt_timeout(2)
-  }
-  c:post({'THIS IS CONTENT OF THE PUT'})
+  c:setopt{[cURL.OPT_CUSTOMREQUEST] = "PUT"}
-  c:perform({writefunction = function(res) str = res end })
+  c:setopt{[cURL.OPT_POSTFIELDS]    = '{"value":"' .. val_ .. '"}'}   -- insert value here
+  c:setopt_httpheader({
+      'Content-type: application/json',
+      'Accept: application/json',
+      'X-WH-APIKEY: 976FA578CF3B11ADA06564464B1F01823AF81C3D'         -- check APIKEY
+  })
+  c:perform({writefunction = function(res) str = res end })           -- you can print str for debug purposes
   c:close()
+end
-  INFO("CURL done\n" .. str);
-end
 </code>
 ===== Example - connecting to a remote module via its web server =====
@@ Line 87: / Line 95: @@
 For a example we have the UC20-FBC-xxx (any bus Modubs, Ethernet/IP, DeviceNet etc) remote I/O module from Weidmuller. The module has web server for diagnostinc and setup:
-{{ ::uremote_config_page.gif?direct&600 |}}
+{{ network:uremote_config_page.gif?direct&600 |}}
 On this page you press **F12** to get necesssary information for the POST request:
-{{ ::post_info_out.png?direct&600 |}}
+{{ network:post_info_out.png?direct&600 |}}
 Then, use this information for POST request in Lua script on the WebHMI:
-{{ ::post_lua_example2.gif?direct&600 |}}
+{{ network:post_lua_example2.gif?direct&600 |}}
 The function returns json object which you can then analize and check necessary fileds to read:
-{{ ::json_viewer.png?direct&600 |}}
+{{ network:json_viewer.png?direct&600 |}}
+===== Notes on cURL usage =====
+<WRAP center round important 80%>
+In the fw of 4.0 version, the following issue was reported:
+When there are multiple cURL requests from the WebHMI to the unavailable resource, a system crash may happen. The timeout settings won't affect the sysem behaviour. Use this feature with care when you need cyclical calls of multiple cURLs in your scripts:
+  * use one script which detect availablity of the resource and locks following execution for a while
+  * use external watchdog circuit to reset WebHMI if you use it to control mission - critical system.
+If the curl stability is the issue in your project, you can implement HTTP requests using custom protocol. See the [[http_get_custom |example]]
+</WRAP>
+==== HTTP / HTTPS requests ====
+<WRAP center round info 80%>
+Please note that HTTPS requests are only possible in **WebHMI Pro** version and virtualization images.
+</WRAP>
+==== Troubleshooting CURL requests from WebHMI ====
+When troubleshooting your requests, you can turn on verbose information in your script. Please refer to the example below:
+<code lua>
+function main (userId)
+    local res = ""
+    local c = cURL.easy_init()
+    c : setopt{ url = 'http://danepubliczne.imgw.pl/api/data/hydro/id/153160210',
+              timeout = 30,
+              httpheader = {'Accept: application/json',
+                            'Content-Type: gzip, deflate, br',
+                            -- 'Host: <calculated when request is sent>',
+                        }
+             }
+     -- sw on verbose info
+     c : setopt{[cURL.OPT_VERBOSE] = 1}
+     c : setopt{[cURL.OPT_DEBUGFUNCTION] = function(...)
+                for i, v in pairs(arg) do DEBUG(i .. ' ' .. v) end
+                return 0
+         end }
+     c : perform{writefunction = function(str)
+                res = res .. str
+            end}
+        c : close()
+        INFO(res)
+        if (res == '') or (res == '%[%]')then
+            ERROR('No data in response!')
+        else
+            INFO('\n' .. res)
+        end
+end
+</code>