open62541
=========
open62541 (http://open62541.org) is an open source and free implementation of OPC UA (OPC Unified Architecture). open62541 is a C-based library that contains all the necessary tools to set up a dedicated OPC UA server, to integrate OPC UA-based communication into existing applications (linking with C++ projects [is possible](examples/server.cpp)), or to create an OPC UA client. The library is distributed as a single pair of [header](https://github.com/open62541/open62541/releases/download/v0.1.1/open62541.h) and [source](https://github.com/open62541/open62541/releases/download/v0.1.1/open62541.c) files, that can be easily dropped into your project. An example server and client implementation can be found in the [/examples](examples/) directory or further down on this page.
open62541 is licensed under the LGPL + static linking exception. That means **open62541 can be freely used also in commercial projects**, although changes to the open62541 library itself need to be released under the same license. The server and client implementations in the [/examples](examples/) directory are in the public domain (CC0 license). They can be used under any license and changes don't have to be published.
[](https://www.ohloh.net/p/open62541)
[](https://travis-ci.org/open62541/open62541)
[](https://ci.appveyor.com/project/Stasik0/open62541/branch/master)
[](https://coveralls.io/r/open62541/open62541?branch=master)
[](https://scan.coverity.com/projects/1864)
### Documentation
A general introduction to OPC UA and the open62541 documentation can be found at http://open62541.org/doc/current.
Build instruction are here: https://github.com/open62541/open62541/wiki/Building-open62541.
For discussion and help, you can use
- the [mailing list](https://groups.google.com/d/forum/open62541)
- our [IRC channel](http://webchat.freenode.net/?channels=%23open62541)
- the [bugtracker](https://github.com/open62541/open62541/issues)
Automated builds of 50 last single-file distributions are available [here](http://open62541.org/releases).
Automatically compiled MSVC binaries are available [here](https://ci.appveyor.com/project/Stasik0/open62541/build/artifacts).
### Contribute to open62541
As an open source project, we invite new contributors to help improving open62541. If you are a developer, your bugfixes and new features are very welcome. Note that there are ways to contribute even without deep knowledge of the project or the UA standard:
- [Report bugs](https://github.com/open62541/open62541/issues)
- Improve the [documentation for 0.1](http://open62541.org/doc/0.1) and [documentation for 0.2](http://open62541.org/doc/current)
- Work on issues marked as "[easy hacks](https://github.com/open62541/open62541/labels/easy%20hack)"
### Example Server Implementation
Compile the examples with the single file distribution `open62541.h` and `open62541.c` from the latest [release](https://github.com/open62541/open62541/releases).
With the GCC compiler, just run ```gcc -std=c99 <server.c> open62541.c -o server```.
```c
#include <signal.h>
#include "open62541.h"
#define PORT 16664
UA_Logger logger = Logger_Stdout;
UA_Boolean running = UA_TRUE;
void signalHandler(int sign) {
running = UA_FALSE;
}
int main(int argc, char** argv)
{
/* catch ctrl-c */
signal(SIGINT, signalHandler);
/* init the server */
UA_ServerConfig config = UA_ServerConfig_standard;
UA_ServerNetworkLayer nl = UA_ServerNetworkLayerTCP(UA_ConnectionConfig_standard, 16664, logger);
config.logger = logger;
config.networkLayers = &nl;
config.networkLayersSize = 1;
UA_Server *server = UA_Server_new(config);
/* add a variable node */
/* 1) set the variable attributes (no memory allocations here) */
UA_Int32 myInteger = 42;
UA_VariableAttributes attr;
UA_VariableAttributes_init(&attr);
UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
attr.displayName = UA_LOCALIZEDTEXT("en_US","the answer");
/* 2) define where the variable shall be added with which browsename */
UA_NodeId newNodeId = UA_NODEID_STRING(1, "the.answer");
UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);
UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES);
UA_NodeId variableType = UA_NODEID_NULL; /* no variable type defined */
UA_QualifiedName browseName = UA_QUALIFIEDNAME(1, "the answer");
/* 3) add the variable */
UA_Server_addVariableNode(server, newNodeId, parentNodeId,
parentReferenceNodeId, browseName,
variableType, attr, NULL);
/* run the server loop */
UA_StatusCode retval = UA_Server_run(server, &running);
UA_Server_delete(server);
nl.deleteMembers(&nl);
return retval;
}
```
### Example Client Implementation
```c
#include <stdio.h>
#include "open62541.h"
int main(int argc, char *argv[])
{
/* create a client and connect */
UA_Client *client = UA_Client_new(UA_ClientConfig_standard, Logger_Stdout);
UA_StatusCode retval = UA_Client_connect(client, UA_ClientConnectionTCP,
"opc.tcp://localhost:16664");
if(retval != UA_STATUSCODE_GOOD) {
UA_Client_delete(client);
return retval;
}
/* create a readrequest with one entry */
UA_ReadRequest req;
UA_ReadRequest_init(&req);
req.nodesToRead = UA_Array_new(1, &UA_TYPES[UA_TYPES_READVALUEID]);
req.nodesToReadSize = 1;
/* define the node and attribute to be read */
req.nodesToRead[0].nodeId = UA_NODEID_STRING_ALLOC(1, "the.answer");
req.nodesToRead[0].attributeId = UA_ATTRIBUTEID_VALUE;
/* call the service and print the result */
UA_ReadResponse resp = UA_Client_Service_read(client, req);
if(resp.responseHeader.serviceResult == UA_STATUSCODE_GOOD &&
resp.resultsSize > 0 && resp.results[0].hasValue &&
UA_Variant_isScalar(&resp.results[0].value) &&
resp.results[0].value.type == &UA_TYPES[UA_TYPES_INT32]) {
UA_Int32 *value = (UA_Int32*)resp.results[0].value.data;
printf("the value is: %i\n", *value);
}
UA_ReadRequest_deleteMembers(&req);
UA_ReadResponse_deleteMembers(&resp);
UA_Client_disconnect(client);
UA_Client_delete(client);
return UA_STATUSCODE_GOOD;
}
```