SystemWorker

System workers allow the 4D code to call any external process (a shell command, PHP, etc.) on the same machine. Os trabalhadores do sistema são chamados assíncronos. Ao utilizar os callbacks, 4D torna possível a comunicação de ambas as maneiras.

The SystemWorker class is available from the 4D class store.

Exemplo

    // Windows example to get access to the ipconfig information
var $myWinWorker : 4D.SystemWorker
var $ipConfig : Text
$myWinWorker:= 4D.SystemWorker.new("ipconfig")
$ipConfig:=$myWinWorker.wait(1).response //timeout 1 second

    // macOS example to change the permissions for a file on macOS
    // chmod is the macOS command used to modify file access
var $myMacWorker : 4D.SystemWorker
$myMacWorker:= 4D.SystemWorker.new("chmod +x /folder/myfile.sh")

Resumo

| 4D.SystemWorker.new ( commandLine : Text { ; options : Object } ) : 4D.SystemWorker
creates and returns a 4D.SystemWorker object that will execute the commandLine you passed as parameter to launch an external process | | .closeInput()
closes the input stream (stdin) of the external process | | .commandLine : Text
contains the command line passed as parameter to the new() function | | .currentDirectory : 4D.Folder
contains the working directory in which the external process is executed | | .dataType : Text
contains the type of the response body content | | .encoding : Text
contains the encoding of the response body content | | .errors : Collection
contains a collection of 4D errors in case of execution error(s) if any | | .exitCode : Integer
contains the exit code returned by the external process | | .hideWindow : Boolean
can be used to hide the window of the DOS console or the window of the launched executable (Windows only) | | .pid : Integer
contains the process unique identifier of the external process at the system level | | .postMessage( message : Text)
.postMessage( messageBLOB : Blob)
allows you to write on the input stream (stdin) of the external process | | .response : Text
.response : Blob
contains the concatenation of all data returned once the request is terminated | | .responseError : Text
contains the concatenation of all the errors returned, once the request is terminated | | .terminate()
forces the SystemWorker to terminate its execution | | .terminated : Boolean
contains true if the external process is terminated | | .timeout : Integer
contains the duration in seconds before the external process will be killed if it is still alive | | .wait( {timeout : Real} ) : 4D.SystemWorker
waits until the end of the SystemWorker execution or the specified timeout |

4D.SystemWorker.new()

História

Release	Mudanças
19 R4	Adicionado

4D.SystemWorker.new ( commandLine : Text { ; options : Object } ) : 4D.SystemWorker

Parâmetro	Tipo		Descrição
commandLine	Text	->	Linha de comando a executar
options	Object	->	Parâmetros worker
result	4D.SystemWorker	<-	Novo System worker assíncrono ou nulo se o processo não for iniciado

Descrição

The 4D.SystemWorker.new() function creates and returns a 4D.SystemWorker object that will execute the commandLine you passed as parameter to launch an external process.

O objecto worker do sistema devolvido pode ser utilizado para postar mensagens ao worker e obter a saída do worker.

If an error occurs during the creation of the proxy object, the function returns a null object and an error is thrown.

In the commandLine parameter, pass the full path of the application's file to be executed (posix syntax), as well as any required arguments, if necessary. If you pass only the application name, 4D will use the PATH environment variable to locate the executable.

Warning: This function can only launch executable applications; it cannot execute instructions that are part of the shell (command interpreter). For example, under Windows it is not possible to use this command to execute the dir instruction.

options Object

In the options parameter, pass an object that can contain the following properties:

Propriedade	Tipo	Por padrão	Descrição
onResponse	Formula	indefinido	Chamada de retorno para mensagens de worker do sistema. Esta chamada de retorno é chamada assim que a resposta completa é recebida. Recebe dois objectos como parâmetros (ver abaixo)
onData	Formula	indefinido	Chamada de retorno para os dados do worker do sistema. Esta chamada de retorno é chamada cada vez que o worker do sistema recebe dados. Recebe dois objectos como parâmetros (ver abaixo)
onDataError	Formula	indefinido	Callback for the external process errors (stderr of the external process). Recebe dois objectos como parâmetros (ver abaixo)
onError	Formula	indefinido	Chamada de retorno para erros de execução, devolvida pelo worker do sistema em caso de condições anormais de tempo de execução (erros de sistema). Recebe dois objectos como parâmetros (ver abaixo)
onTerminate	Formula	indefinido	Chamada de retorno quando o processo externo é terminado. Recebe dois objectos como parâmetros (ver abaixo)
timeout	Number	indefinido	Tempo em segundos antes de o processo ser terminado se ainda estiver vivo
dataType	Text	"text"	Tipo de conteúdo do corpo da resposta. Valores possíveis: "text" (predefinição), "blob".
encoding	Text	"UTF-8"	Only if dataType="text". Codificação do conteúdo do corpo da resposta. For the list of available values, see the CONVERT FROM TEXT command description
variables	Object		Define variáveis de ambiente personalizadas para o system worker. Syntax: variables.key=value, where key is the variable name and value its value. Os valores são convertidos em cordas quando possível. O valor não pode conter um '='. Se não estiver definido, o system worker herda do ambiente 4D.
currentDirectory	Folder		Directório de trabalho no qual o processo é executado
hideWindow	Parâmetros	true	(Windows) Esconder a janela de aplicação (se possível) ou a consola Windows

Todas as funções de chamada de retorno recebem dois parâmetros de objectos. O seu conteúdo depende do retorno da chamada:

Parâmetro	Tipo	onResponse	onData	onDataError	onError	onTerminate
$param1	Object	SystemWorker	SystemWorker	SystemWorker	SystemWorker	SystemWorker
$param2.type	Text	"response"	"data"	"error"	"error"	"termination"
$param2.data	Text ou Blob		dados recebidos	dados de erro

Aqui está a sequência de chamadas de retorno:

1. onData and onDataError are executed one or several times
2. if called, onError is executed once (stops the system worker processing)
3. if no error occured, onResponse is executed once
4. onTerminate is always executed

Valor retornado

A função devolve um objecto system worker sobre o qual se pode chamar funções e propriedades da classe SystemWorker.

Exemplos no Windows

1. Para abrir o Bloco de Notas e abrir um documento específico:

var $sw : 4D.SystemWorker
var $options : Object
$options:=New object
$options.hideWindow:= False

$sw:=4D.SystemWorker.new ("C:\\WINDOWS\\notepad.exe C:\\Docs\\new folder\\res.txt";$options)

2. Executar npm instalar na consola:

var $folder : 4D.Folder
var $options : Object
var $worker : 4D.SystemWorker

$folder:=Folder(fk database folder)
$options:=New object
$options.currentDirectory:=$folder
$options.hideWindow:=False

$worker:=4D.SystemWorker.new("cmd /c npm install";$options)

3. Para lançar a aplicação Microsoft® Word® e abrir um documento específico:

$mydoc:="C:\\Program Files\\Microsoft Office\\Office15\\WINWORD.EXE C:\\Tempo\\output.txt"
var $sw : 4D.SystemWorker
$sw:=4D.SystemWorker.new($mydoc)

4. Para lançar um comando com o diretório atual e publicar uma mensagem:

var $param : Object
var $sys : 4D.SystemWorker

$param:=New object
$param.currentDirectory:=Folder(fk database folder)
$sys:=4D.SystemWorker.new("git commit -F -";$param)
$sys.postMessage("This is a postMessage")
$sys.closeInput()

5. Para permitir que o utilizador abra um documento externo no Windows:

$docname:=Select document("";"*.*";"Choose the file to open";0)
If(OK=1)
 var $sw : 4D.SystemWorker
 $sw:=4D.SystemWorker.new("cmd.exe /C start \"\" \""+$docname+"\"")
End if

Exemplos em macOS

1. Edit a text file (cat is the macOS command used to edit files). Neste exemplo, o caminho de acesso completo do comando é passado:

var $sw : 4D.SystemWorker
$sw:=4D.SystemWorker.new("/bin/cat /folder/myfile.txt")
$sw.wait() //synchronous execution

2. To launch an independent "graphic" application, it is preferable to use the open system command (in this case, the code has the same effect as double-clicking the application):

var $sw : 4D.SystemWorker
$sw:=4D.SystemWorker.new ("open /Applications/Calculator.app")

3. Para obter o conteúdo da pasta "Users" (ls -l é o equivalente em macOS do comando dir em DOS).

var $systemworker : 4D.SystemWorker
var $output : Text
var $errors : Collection

$systemworker:=4D.SystemWorker.new("/bin/ls -l /Users ")
$systemworker.wait(5)
$output:=$systemworker.response
$error:=$systemworker.errors

4. O mesmo comando que acima, mas usando uma amostra de classe de utilizador "Params" para mostrar como lidar com as funções de callback:

var $systemworker : 4D.SystemWorker
$systemworker:=4D.SystemWorker.new("/bin/ls -l /Users ";cs.Params.new())


// "Params" class

Class constructor
 This.dataType:="text"
    This.data:=""
    This.dataError:=""

Function onResponse($systemWorker : Object)
     This._createFile("onResponse"; $systemWorker.response)

Function onData($systemWorker : Object; $info : Object)
     This.data+=$info.data
     This._createFile("onData";this.data)

Function onDataError($systemWorker : Object; $info : Object)
     This.dataError+=$info.data
     This._createFile("onDataError";this.dataError)

Function onTerminate($systemWorker : Object)
     var $textBody : Text
     $textBody:="Response: "+$systemWorker.response
     $textBody+="ResponseError: "+$systemWorker.responseError
     This._createFile("onTerminate"; $textBody)

Function _createFile($title : Text; $textBody : Text)
     TEXT TO DOCUMENT(Get 4D folder(Current resources folder)+$title+".txt"; $textBody)

.closeInput()

História

Release	Mudanças
19 R4	Adicionado

.closeInput()

Parâmetro	Tipo		Descrição
			Não exige nenhum parâmetro

Descrição

The .closeInput() function closes the input stream (stdin) of the external process.

When the executable waits for all data to be received through postMessage(), .closeInput() is useful to indicate to the executable that data sending is finished and that it can proceed.

Exemplo

// Create some data to gzip
var $input;$output : Blob
var $gzip : Text
TEXT TO BLOB("Hello, World!";$input)
$gzip:="\"C:\\Program Files (x86)\\GnuWin32\\bin\\gzip.exe\" "

// Create an asynchronous system worker
var $worker : 4D.SystemWorker
$worker:= 4D.SystemWorker.new($gzip;New object("dataType";"blob"))

// Send the compressed file on stdin.
$worker.postMessage($input)
// Note that we call closeInput() to indicate we're done.
// gzip (and most program waiting data from stdin) will wait for more data until the input is explicitely closed.
$worker.closeInput()
$worker.wait()

$output:=$worker.response

.commandLine

.commandLine : Text

Descrição

The .commandLine property contains the command line passed as parameter to the new() function.

This property is read-only.

.currentDirectory

.currentDirectory : 4D.Folder

Descrição

The .currentDirectory property contains the working directory in which the external process is executed.

.dataType

.dataType : Text

Descrição

The .dataType property contains the type of the response body content. Valores possíveis: "text" ou "blob".

This property is read-only.

.encoding

.encoding : Text

Descrição

The .encoding property contains the encoding of the response body content. This property is only available if the dataType is "text".

This property is read-only.

.errors

.errors : Collection

Descrição

The .errors property contains a collection of 4D errors in case of execution error(s) if any.

Cada elemento da coleção é um objeto com as seguintes propriedades:

Propriedade	Tipo	Descrição
[].errorCode	number	Código de erro 4D
[].message	text	Descrição do erro 4D
[ ].componentSignature	text	Assinatura da componente interna que devolveu o erro

If no error occured, .errors is undefined.

.exitCode

.exitCode : Integer

Descrição

The .exitCode property contains the exit code returned by the external process. If the process did not terminate normaly, exitCode is undefined.

This property is read-only.

.hideWindow

.hideWindow : Boolean

Descrição

The .hideWindow property can be used to hide the window of the DOS console or the window of the launched executable (Windows only).

This property is read-write.

.pid

.pid : Integer

Descrição

The .pid property contains the process unique identifier of the external process at the system level.

This property is read-only.

.postMessage()

.postMessage( message : Text)
.postMessage( messageBLOB : Blob)

Parâmetro	Tipo		Descrição
message	Text	->	Texto para escrever no fluxo de entrada (stdin) do processo externo
messageBLOB	Blob	->	Bytes escritos no fluxo de entrada

Descrição

The .postMessage() function allows you to write on the input stream (stdin) of the external process. In the message parameter, pass the text to write in stdin.

The .postMessage() function also accepts a Blob type value in messageBLOB to pass in stdin, so that you can post binary data.

You can use the .dataType property of the options object to make response body return Blob values.

.response

.response : Text
.response : Blob

Descrição

The .response property contains the concatenation of all data returned once the request is terminated, i.e. the full message received from the process output.

The type of the message is defined according to the dataType attribute.

This property is read-only.

.responseError

.responseError : Text

Descrição

The .responseError property contains the concatenation of all the errors returned, once the request is terminated.

.terminate()

.terminate()

Parâmetro	Tipo		Descrição
			Não exige nenhum parâmetro

Descrição

The .terminate() function forces the SystemWorker to terminate its execution.

Esta função envia a instrução para terminar e devolver o controlo ao guião de execução.

.terminated

.terminated : Boolean

Descrição

The .terminated property contains true if the external process is terminated.

This property is read-only.

.timeout

.timeout : Integer

Descrição

The .timeout property contains the duration in seconds before the external process will be killed if it is still alive.

This property is read-only.

.wait()

História

Release	Mudanças

|19 R4|Adicionado|

.wait( {timeout : Real} ) : 4D.SystemWorker

Parâmetro	Tipo		Descrição
timeout	Real	->	Tempo de espera (em segundos)
Resultados	4D.SystemWorker	<-	Objecto SystemWorker

Descrição

The .wait() function waits until the end of the SystemWorker execution or the specified timeout.

In timeout, pass a value in seconds. The SystemWorker script will wait for the external process for the amount of time defined in the timeout parameter. If you omit the timeout parameter, the script execution will wait indefinitely.

Actually, .wait() waits until the end of processing of the onTerminate formula, except if the timeout is reached. If timeout is reached, the SystemWorker is not killed.

During a .wait() execution, callback functions are executed, especially callbacks from other events or from other SystemWorker instances. You can exit from a .wait() by calling terminate() from a callback.

Esta função devolve o objecto SystemWorker.

This function is not necessary if you created the SystemWorker from a 4D worker process.