le_messaging.h

    1 /**
    2  * @page c_messaging Low-level Messaging API
    3  *
    4  * @ref le_messaging.h "API Reference"
    5  *
    6  * <HR>
    7  *
    8  * Message-based interfaces in Legato are implemented in layers.
    9  * This low-level messaging API is at the bottom layer.
   10  * It's designed to support higher layers of the messaging system.  But it's also
   11  * intended to be easy to hand-code low-level messaging in C, when necessary.
   12  *
   13  * This low-level messaging API supports:
   14  *  - remote party identification (addressing)
   15  *  - very late (runtime) discovery and binding of parties
   16  *  - in-process and inter-process message delivery
   17  *  - location transparency
   18  *  - sessions
   19  *  - access control
   20  *  - request/reply transactions
   21  *  - message buffer memory management
   22  *  - support for single-threaded and multi-threaded programs
   23  *  - some level of protection from protocol mismatches between parties in a session.
   24  *
   25  * This API is integrated with the Legato Event Loop API so components can interact with each
   26  * other using messaging without having to create threads or file descriptor
   27  * sets that block other software from handling other events.  Support for
   28  * integration with legacy POSIX-based programs is also provided.
   29  *
   30  * @section c_messagingInteractionModel Interaction Model
   31  *
   32  * The Legato low-level messaging system follows a service-oriented pattern:
   33  *  - Service providers advertise their service.
   34  *  - Clients open sessions with those services
   35  *  - Both sides can send and receive messages through the session.
   36  *
   37  * Clients and servers can both send one-way messages within a session.
   38  * Clients can start a request-response transaction by sending a request to the server,
   39  * and the server can send a response. Request-response transactions can be blocking or
   40  * non-blocking (with a completion callback). If the server dies or terminates the session
   41  * before sending the response, Legato will automatically terminate the transaction.
   42  *
   43  * Servers are prevented from sending blocking requests to clients as a safety measure.
   44  * If a server were to block waiting for one of its clients, it would open up the server
   45  * to being blocked indefinitely by one of its clients, which would allow one client to cause
   46  * a server to deny service to other clients.  Also, if a client started a blocking request-response
   47  * transaction at the same time that the server started a blocking request-response transaction
   48  * in the other direction, a deadlock would occur.
   49  *
   50  * @section c_messagingAddressing Addressing
   51  *
   52  * Servers and clients have interfaces that can been connected to each other via bindings.  Both
   53  * client-side and server-side interfaces are identified by name, but the names don't have to match
   54  * for them to be bound to each other.  The binding determines which server-side interface will
   55  * be connected to when a client opens a session.
   56  *
   57  * Server-side interfaces are also known as "services".
   58  *
   59  * When a session is opened by a client, a session reference is provided to both the client
   60  * and the server.  Messages are then sent within the session using the session reference.
   61  * This session reference becomes invalid when the session is closed.
   62  *
   63  * @section c_messagingProtocols Protocols
   64  *
   65  * Communication between client and server is done using a message-based protocol. This protocol
   66  * is defined at a higher layer than this API, so this API doesn't know the structure of the
   67  * message payloads or the correct message sequences. That means this API can't check
   68  * for errors in the traffic it carries. However, it does provide a basic mechanism for detecting
   69  * protocol mismatches by forcing both client and server to provide the protocol identifier
   70  * of the protocol to be used.  The client and server must also provide
   71  * the maximum message size, as an extra sanity check.
   72  *
   73  * To make this possible, the client and server must independently call
   74  * @c le_msg_GetProtocolRef(), to get a reference to a "Protocol" object that encapsulates these
   75  * protocol details:
   76  *
   77  * @code
   78  * protocolRef = le_msg_GetProtocolRef(MY_PROTOCOL_ID, sizeof(myproto_Msg_t));
   79  * @endcode
   80  *
   81  * @note In this example, the protocol identifier (which is a string uniquely identifying a
   82  *       specific version of a specific protocol) and the message structure
   83  *       would be defined elsewhere, in a header file shared between the client and the
   84  *       server.  The structure @c myproto_Msg_t contains a
   85  *       @c union of all of the different messages included in the protocol, thereby
   86  *       making @c myproto_Msg_t as big as the biggest message in the protocol.
   87  *
   88  * When a server creates a service (by calling le_msg_CreateService()) and when a client creates
   89  * a session (by calling le_msg_CreateSession()), they are required to provide a reference to a
   90  * Protocol object that they obtained from le_msg_GetProtocolRef().
   91  *
   92  * @section c_messagingClientUsage Client Usage Model
   93  *
   94  * @ref c_messagingClientSending <br>
   95  * @ref c_messagingClientReceiving <br>
   96  * @ref c_messagingClientClosing <br>
   97  * @ref c_messagingClientMultithreading <br>
   98  * @ref c_messagingClientExample
   99  *
  100  * Clients that want to use a service do the following:
  101  *  -# Get a reference to the protocol they want to use by calling @c le_msg_GetProtocolRef().
  102  *  -# Create a session using @c le_msg_CreateSession(), passing in the protocol reference and
  103  *     the client's interface name.
  104  *  -# Optionally register a message receive callback using @c le_msg_SetSessionRecvHandler().
  105  *  -# Open the session using le_msg_OpenSession(), le_msg_OpenSessionSync(), or
  106  *     le_msg_TryOpenSessionSync().
  107  *
  108  * @code
  109  *     protocolRef = le_msg_GetProtocolRef(PROTOCOL_ID, sizeof(myproto_Msg_t));
  110  *     sessionRef = le_msg_CreateSession(protocolRef, MY_INTERFACE_NAME);
  111  *     le_msg_SetSessionRecvHandler(sessionRef, NotifyMsgHandlerFunc, NULL);
  112  *     le_msg_OpenSession(sessionRef, SessionOpenHandlerFunc, NULL);
  113  * @endcode
  114  *
  115  * The Legato framework takes care of setting up any IPC connections, as needed (or not, if the
  116  * client and server happen to be in the same process).
  117  *
  118  * When the session opens, the Event Loop will call the "session open handler" call-back function
  119  * that was passed into le_msg_OpenSession().
  120  *
  121  * le_msg_OpenSessionSync() is a synchronous alternative to le_msg_OpenSession(). The difference
  122  * is that le_msg_OpenSessionSync() will not return until the session has opened or failed to
  123  * open (most likely due to permissions settings).
  124  *
  125  * le_msg_TryOpenSessionSync() is like le_msg_OpenSessionSync() except that it will not wait
  126  * for a server session to become available if it's not already available at the time of the
  127  * call.  That is, if the client's interface is not bound to any service, or if the service that
  128  * it's bound to is not currently advertised by the server, then le_msg_TryOpenSessionSync()
  129  * will return an error code.
  130  *
  131  * @subsection c_messagingClientSending Sending a Message
  132  *
  133  * Before sending a message, the client must first allocate the message from the session's message
  134  * pool using le_msg_CreateMsg(). It can then get a pointer to the payload part of the
  135  * message using le_msg_GetPayloadPtr(). Once the message payload is populated, the client sends
  136  * the message.
  137  *
  138  * @code
  139  *     msgRef = le_msg_CreateMsg(sessionRef);
  140  *     msgPayloadPtr = le_msg_GetPayloadPtr(msgRef);
  141  *     msgPayloadPtr->... = ...; // <-- Populate message payload...
  142  * @endcode
  143  *
  144  * If no response is required from the server, the client sends the message using le_msg_Send().
  145  * At this point, the client has handed off the message to the messaging system, and the messaging
  146  * system will delete the message automatically once it has finished sending it.
  147  *
  148  * @code
  149  *     le_msg_Send(msgRef);
  150  * @endcode
  151  *
  152  * If the client expects a response from the server, the client can use
  153  * le_msg_RequestResponse() to send their message and specify a callback function to be called
  154  * when the response arrives.  This callback will be called by the event loop of the thread that
  155  * created the session (i.e., the thread that called le_msg_CreateSession()).
  156  *
  157  * @code
  158  *     le_msg_RequestResponse(msgRef, ResponseHandlerFunc, NULL);
  159  * @endcode
  160  *
  161  * If the client expects an immediate response from the server, and the client wants to block until
  162  * that response is received, it can use le_msg_RequestSyncResponse() instead of
  163  * le_msg_RequestResponse().  However, keep in mind that blocking the client thread will
  164  * block all event handlers that share that thread.  That's why le_msg_RequestSyncResponse() should
  165  * only be used when the server is expected to respond immediately, or when the client thread
  166  * is not shared by other event handlers.
  167  *
  168  * @code
  169  *     responseMsgRef = le_msg_RequestSyncResponse(msgRef);
  170  * @endcode
  171  *
  172  * @warning If the client and server are running in the same thread, and the
  173  * client calls le_msg_RequestSyncResponse(), it will return an error immediately, instead of
  174  * blocking the thread.  If the thread were blocked in this scenario, the server would also be
  175  * blocked and would therefore be unable to receive the request and respond to it, resulting in
  176  * a deadlock.
  177  *
  178  * When the client is finished with it, the <b> client must release its reference
  179  * to the response message </b> by calling le_msg_ReleaseMsg().
  180  *
  181  * @code
  182  *     le_msg_ReleaseMsg(responseMsgRef);
  183  * @endcode
  184  *
  185  * @subsection c_messagingClientReceiving Receiving a Non-Response Message
  186  *
  187  * When a server sends a message to the client that is not a response to a request from the client,
  188  * that non-response message will be passed to the receive handler that the client
  189  * registered using le_msg_SetSessionRecvHandler().  In fact, this is the only kind of message
  190  * that will result in that receive handler being called.
  191  *
  192  * @note Some protocols don't include any messages that are not responses to client requests,
  193  * which is why it's optional to register a receive handler on the client side.
  194  *
  195  * The payload of a received message can be accessed using le_msg_GetPayloadPtr(), and the client
  196  * can check what session the message arrived through by calling le_msg_GetSession().
  197  *
  198  * When the client is finished with the message, the <b> client must release its reference
  199  * to the message </b> by calling le_msg_ReleaseMsg().
  200  *
  201  * @code
  202  * // Function will be called whenever the server sends us a notification message.
  203  * static void NotifyHandlerFunc
  204  * (
  205  *     le_msg_MessageRef_t  msgRef,    // Reference to the received message.
  206  *     void*                contextPtr // contextPtr passed into le_msg_SetSessionRecvHandler().
  207  * )
  208  * {
  209  *     // Process notification message from the server.
  210  *     myproto_Msg_t* msgPayloadPtr = le_msg_GetPayloadPtr(msgRef);
  211  *     ...
  212  *
  213  *     // Release the message, now that we are finished with it.
  214  *     le_msg_ReleaseMsg(msgRef);
  215  * }
  216  *
  217  * COMPONENT_INIT
  218  * {
  219  *     le_msg_ProtocolRef_t protocolRef;
  220  *     le_msg_SessionRef_t sessionRef;
  221  *
  222  *     protocolRef = le_msg_GetProtocolRef(PROTOCOL_ID, sizeof(myproto_Msg_t));
  223  *     sessionRef = le_msg_CreateSession(protocolRef, MY_INTERFACE_NAME);
  224  *     le_msg_SetSessionRecvHandler(sessionRef, NotifyHandlerFunc, NULL);
  225  *     le_msg_OpenSession(sessionRef, SessionOpenHandlerFunc, NULL);
  226  * }
  227  * @endcode
  228  *
  229  * @subsection c_messagingClientClosing Closing Sessions
  230  *
  231  * When the client is done using a service, it can close the session using le_msg_CloseSession().
  232  * This will leave the session object in existence, though, so that it can be opened again
  233  * using le_msg_OpenSession().
  234  *
  235  * @code
  236  *     le_msg_CloseSession(sessionRef);
  237  * @endcode
  238  *
  239  * To delete a session object, call le_msg_DeleteSession().  This will automatically close the
  240  * session, if it's still open (but won't automatically delete any messages).
  241  *
  242  * @code
  243  *     le_msg_DeleteSession(sessionRef);
  244  * @endcode
  245  *
  246  * @note If a client process dies while it has a session open, that session will be
  247  * automatically closed and deleted by the Legato framework, so there's no need to register process
  248  * clean-up handlers or anything like that for this purpose.
  249  *
  250  * Additionally, clients can choose to call le_msg_SetSessionCloseHandler() to register to be
  251  * notified when a session gets closed by the server.  Servers often keep state on behalf of their
  252  * clients, and if the server closes the session (or if the system closes the session because the
  253  * server died), the client most likely will still be operating under the assumption (now false)
  254  * that the server is maintaining state on its behalf.  If a client is designed to recover from
  255  * the server losing its state, the client can register a close handler and handle the close.
  256  *
  257  * @code
  258  *     le_msg_SetSessionCloseHandler(sessionRef, SessionCloseHandler, NULL);
  259  * @endcode
  260  *
  261  * However, most clients are not designed to recover from their session being closed by someone
  262  * else, so if a close handler is not registered by a client and the session closes for some
  263  * reason other than the client calling le_msg_CloseSession(), then the client process
  264  * will be terminated.
  265  *
  266  * @note If the client closes the session, the client-side session close handler will not be called,
  267  * even if one is registered.
  268  *
  269  * @subsection c_messagingClientMultithreading Multithreading
  270  *
  271  * The Low-Level Messaging API is thread safe, but not async safe.
  272  *
  273  * When a client creates a session, that session gets "attached" to the thread that created it
  274  * (i.e., the thread that called le_msg_CreateSession()).  That thread will then call any callbacks
  275  * registered for that session.
  276  *
  277  * Note that this implies that if the client thread that creates the session does not
  278  * run the Legato event loop then no callbacks will ever be called for that session.
  279  * To work around this, move the session creation to another thread that that uses the Legato event
  280  * loop.
  281  *
  282  * Furthermore, to prevent race conditions, only the thread that is attached to a given session
  283  * is allowed to call le_msg_RequestSyncResponse() for that session.
  284  *
  285  * @subsection c_messagingClientExample Sample Code
  286  *
  287  * @code
  288  * // Function will be called whenever the server sends us a notification message.
  289  * static void NotifyHandlerFunc
  290  * (
  291  *     le_msg_MessageRef_t  msgRef,    // Reference to the received message.
  292  *     void*                contextPtr // contextPtr passed into le_msg_SetSessionRecvHandler().
  293  * )
  294  * {
  295  *     // Process notification message from the server.
  296  *     myproto_Msg_t* msgPayloadPtr = le_msg_GetPayloadPtr(msgRef);
  297  *     ...
  298  *
  299  *     // Release the message, now that we are finished with it.
  300  *     le_msg_ReleaseMsg(msgRef);
  301  * }
  302  *
  303  * // Function will be called whenever the server sends us a response message or our
  304  * // request-response transaction fails.
  305  * static void ResponseHandlerFunc
  306  * (
  307  *     le_msg_MessageRef_t  msgRef,    // Reference to response message (NULL if transaction failed).
  308  *     void*                contextPtr // contextPtr passed into le_msg_RequestResponse().
  309  * )
  310  * {
  311  *     // Check if we got a response.
  312  *     if (msgRef == NULL)
  313  *     {
  314  *         // Transaction failed.  No response received.
  315  *         // This might happen if the server deleted the request without sending a response,
  316  *         // or if we had registered a "Session End Handler" and the session terminated before
  317  *         // the response was sent.
  318  *         LE_ERROR("Transaction failed!");
  319  *     }
  320  *     else
  321  *     {
  322  *         // Process response message from the server.
  323  *         myproto_Msg_t* msgPayloadPtr = le_msg_GetPayloadPtr(msgRef);
  324  *         ...
  325  *
  326  *         // Release the response message, now that we are finished with it.
  327  *         le_msg_ReleaseMsg(msgRef);
  328  *     }
  329  * }
  330  *
  331  * // Function will be called when the client-server session opens.
  332  * static void SessionOpenHandlerFunc
  333  * (
  334  *     le_msg_SessionRef_t  sessionRef, // Reference tp the session that opened.
  335  *     void*                contextPtr  // contextPtr passed into le_msg_OpenSession().
  336  * )
  337  * {
  338  *     le_msg_MessageRef_t msgRef;
  339  *     myproto_Msg_t* msgPayloadPtr;
  340  *
  341  *     // Send a request to the server.
  342  *     msgRef = le_msg_CreateMsg(sessionRef);
  343  *     msgPayloadPtr = le_msg_GetPayloadPtr(msgRef);
  344  *     msgPayloadPtr->... = ...; // <-- Populate message payload...
  345  *     le_msg_RequestResponse(msgRef, ResponseHandlerFunc, NULL);
  346  * }
  347  *
  348  * COMPONENT_INIT
  349  * {
  350  *     le_msg_ProtocolRef_t protocolRef;
  351  *     le_msg_SessionRef_t sessionRef;
  352  *
  353  *     // Open a session.
  354  *     protocolRef = le_msg_GetProtocolRef(PROTOCOL_ID, sizeof(myproto_Msg_t));
  355  *     sessionRef = le_msg_CreateSession(protocolRef, MY_INTERFACE_NAME);
  356  *     le_msg_SetSessionRecvHandler(sessionRef, NotifyHandlerFunc, NULL);
  357  *     le_msg_OpenSession(sessionRef, SessionOpenHandlerFunc, NULL);
  358  * }
  359  * @endcode
  360  *
  361  * @section c_messagingServerUsage Server Usage Model
  362  *
  363  * @ref c_messagingServerProcessingMessages <br>
  364  * @ref c_messagingServerSendingNonResponse <br>
  365  * @ref c_messagingServerCleanUp <br>
  366  * @ref c_messagingRemovingService <br>
  367  * @ref c_messagingServerMultithreading <br>
  368  * @ref c_messagingServerExample
  369  *
  370  * Servers that wish to offer a service do the following:
  371  *  -# Get a reference to the protocol they want to use by calling le_msg_GetProtocolRef().
  372  *  -# Create a Service object using le_msg_CreateService(), passing in the protocol reference and
  373  *     the service name.
  374  *  -# Call le_msg_SetServiceRecvHandler() to register a function to handle messages received from
  375  *     clients.
  376  *  -# Advertise the service using le_msg_AdvertiseService().
  377  *
  378  * @code
  379  *     protocolRef = le_msg_GetProtocolRef(PROTOCOL_ID, sizeof(myproto_Msg_t));
  380  *     serviceRef = le_msg_CreateService(protocolRef, SERVER_INTERFACE_NAME);
  381  *     le_msg_SetServiceRecvHandler(serviceRef, RequestMsgHandlerFunc, NULL);
  382  *     le_msg_AdvertiseService(serviceRef);
  383  * @endcode
  384  *
  385  * Once the service is advertised, clients can open it and start sending it messages.  The server
  386  * will receive messages via callbacks to the function it registered using
  387  * le_msg_SetServiceRecvHandler().
  388  *
  389  * Servers also have the option of being notified when sessions are opened by clients.  They
  390  * get this notification by registering a handler function using le_msg_AddServiceOpenHandler().
  391  *
  392  * @code
  393  * // Function will be called whenever a client opens a session with our service.
  394  * static void SessionOpenHandlerFunc
  395  * (
  396  *     le_msg_SessionRef_t  sessionRef, ///< [in] Reference to the session object.
  397  *     void*                contextPtr  ///< [in] contextPtr passed to le_msg_SetSessionOpenHandler().
  398  * )
  399  * {
  400  *     // Handle new session opening...
  401  *     ...
  402  * }
  403  *
  404  * COMPONENT_INIT
  405  * {
  406  *     le_msg_ProtocolRef_t protocolRef;
  407  *     le_msg_ServiceRef_t serviceRef;
  408  *
  409  *     // Create my service and advertise it.
  410  *     protocolRef = le_msg_GetProtocolRef(PROTOCOL_ID, sizeof(myproto_Msg_t));
  411  *     serviceRef = le_msg_CreateService(protocolRef, SERVER_INTERFACE_NAME);
  412  *     le_msg_AddServiceOpenHandler(serviceRef, SessionOpenHandlerFunc, NULL);
  413  *     le_msg_AdvertiseService(serviceRef);
  414  * }
  415  * @endcode
  416  *
  417  * Both the "Open Handler" and the "Receive Handler" will be called by the Legato event loop in
  418  * the thread that registered those handlers (which must also be the same thread that created the
  419  * service).
  420  *
  421  * @subsection c_messagingServerProcessingMessages Processing Messages from Clients
  422  *
  423  * The payload of any received message can be accessed using le_msg_GetPayloadPtr().
  424  *
  425  * If a received message does not require a response (i.e., if the client sent it using
  426  * le_msg_Send()), then when the server is finished with the message, the server must release
  427  * the message by calling le_msg_ReleaseMsg().
  428  *
  429  * @code
  430  * void RequestMsgHandlerFunc
  431  * (
  432  *     le_msg_MessageRef_t msgRef  // Reference to the received message.
  433  * )
  434  * {
  435  *     myproto_Msg_t* msgPtr = le_msg_GetPayloadPtr(msgRef);
  436  *     LE_INFO("Received request '%s'", msgPtr->request.string);
  437  *
  438  *     // No response required and I'm done with this message, so release it.
  439  *     le_msg_ReleaseMsg(msgRef);
  440  * }
  441  * @endcode
  442  *
  443  * If a received message requires a response (i.e., if the client sent it using
  444  * le_msg_RequestResponse() or le_msg_RequestSyncResponse()), the server must eventually respond
  445  * to that message by calling le_msg_Respond() on that message.  le_msg_Respond() sends the message
  446  * back to the client that sent the request.  The response payload is stored inside the same
  447  * payload buffer that contained the request payload.
  448  *
  449  * To do this, the request payload pointer can be cast to a pointer to the response
  450  * payload structure, and then the response payload can be written into it.
  451  *
  452  * @code
  453  * void RequestMsgHandlerFunc
  454  * (
  455  *     le_msg_MessageRef_t msgRef  // Reference to the received message.
  456  * )
  457  * {
  458  *     myproto_RequestMsg_t* requestPtr = le_msg_GetPayloadPtr(msgRef);
  459  *     myproto_ResponseMsg_t* responsePtr;
  460  *
  461  *     LE_INFO("Received request '%s'", requestPtr->string);
  462  *
  463  *     responsePtr = (myproto_ResponseMsg_t*)requestPtr;
  464  *     responsePtr->value = Value;
  465  *     le_msg_Respond(msgRef);
  466  * }
  467  * @endcode
  468  *
  469  * Alternatively, the request payload structure and the response payload structure could be placed
  470  * into a union together.
  471  *
  472  * @code
  473  * typedef union
  474  * {
  475  *     myproto_Request_t request;
  476  *     myproto_Response_t response;
  477  * }
  478  * myproto_Msg_t;
  479  *
  480  *  ...
  481  *
  482  * void RequestMsgHandlerFunc
  483  * (
  484  *     le_msg_MessageRef_t msgRef  // Reference to the received message.
  485  * )
  486  * {
  487  *     myproto_Msg_t* msgPtr = le_msg_GetPayloadPtr(msgRef);
  488  *     LE_INFO("Received request '%s'", msgPtr->request.string);
  489  *     msgPtr->response.value = Value;
  490  *     le_msg_Respond(msgRef);
  491  * }
  492  * @endcode
  493  *
  494  * @warning Of course, once you've started writing the response payload into the buffer, the request payload
  495  * is no longer available, so if you still need it, copy it somewhere else first.
  496  *
  497  * @note The server doesn't have to send the response back to the client right away.  It could
  498  *       hold onto the request for an indefinite amount of time, for whatever reason.
  499  *
  500  * Whenever any message is received from a client, the message is associated with the session
  501  * through which the client sent it.  A reference to the session can be retrieved from the message,
  502  * if needed, by calling le_msg_GetSession().  This can be handy for tagging things in the
  503  * server's internal data structures that need to be cleaned up when the client closes the session
  504  * (see @ref c_messagingServerCleanUp for more on this).
  505  *
  506  * The function le_msg_NeedsResponse() can be used to check if a received message requires a
  507  * response or not.
  508  *
  509  * @subsection c_messagingServerSendingNonResponse Sending Non-Response Messages to Clients
  510  *
  511  * If a server wants to send a non-response message to a client, it first needs a reference
  512  * to the session that client opened.  It could have got the session reference from a previous
  513  * message received from the client (by calling le_msg_GetSession() on that message).
  514  * Or, it could have got the session reference from a Session Open Handler callback (see
  515  * le_msg_AddServiceOpenHandler()).  Either way, once it has the session reference, it can call
  516  * le_msg_CreateMsg() to create a message from that session's server-side message pool.  The
  517  * message can then be populated and sent in the same way that a client would send a message
  518  * to the server using le_msg_GetPayloadPtr() and le_msg_Send().
  519  *
  520  * @todo Explain how to configure the sizes of the server-side message pools.
  521  *
  522  * @code
  523  * // Function will be called whenever a client opens a session with our service.
  524  * static void SessionOpenHandlerFunc
  525  * (
  526  *     le_msg_SessionRef_t  sessionRef, ///< [in] Reference to the session object.
  527  *     void*                contextPtr  ///< [in] contextPtr passed to le_msg_SetSessionOpenHandler().
  528  * )
  529  * {
  530  *     le_msg_MessageRef_t msgRef;
  531  *     myproto_Msg_t* msgPayloadPtr;
  532  *
  533  *     // Send a "Welcome" message to the client.
  534  *     msgRef = le_msg_CreateMsg(sessionRef);
  535  *     msgPayloadPtr = le_msg_GetPayloadPtr(msgRef);
  536  *     msgPayloadPtr->... = ...; // <-- Populate message payload...
  537  *     le_msg_Send(msgRef);
  538  * }
  539  *
  540  * COMPONENT_INIT
  541  * {
  542  *     le_msg_ProtocolRef_t protocolRef;
  543  *     le_msg_ServiceRef_t serviceRef;
  544  *
  545  *     // Create my service and advertise it.
  546  *     protocolRef = le_msg_GetProtocolRef(PROTOCOL_ID, sizeof(myproto_Msg_t));
  547  *     serviceRef = le_msg_CreateService(protocolRef, SERVER_INTERFACE_NAME);
  548  *     le_msg_AddServiceOpenHandler(serviceRef, SessionOpenHandlerFunc, NULL);
  549  *     le_msg_AdvertiseService(serviceRef);
  550  * }
  551  * @endcode
  552  *
  553  * @subsection c_messagingServerCleanUp Cleaning up when Sessions Close
  554  *
  555  * If a server keeps state on behalf of its clients, it can call le_msg_AddServiceCloseHandler()
  556  * to ask to be notified when clients close sessions with a given service.  This allows the server
  557  * to clean up any state associated with a given session when the client closes that session
  558  * (or when the system closes the session because the client died).  The close handler is passed a
  559  * session reference, so the server can check its internal data structures and clean up anything
  560  * that it has previously tagged with that same session reference.
  561  *
  562  * @note    Servers don't delete sessions.  On the server side, sessions are automatically deleted
  563  *          when they close.
  564  *
  565  * @subsection c_messagingRemovingService Removing Service
  566  *
  567  * If a server wants to stop offering a service, it can hide the service by calling
  568  * le_msg_HideService().  This will not terminate any sessions that are already open, but it
  569  * will prevent clients from opening new sessions until it's advertised again.
  570  *
  571  * @warning Watch out for race conditions here. It's possible that a client is in the process
  572  * of opening a session when you decide to hide your service.  In this case, a new session may
  573  * open after you hid the service.  Be prepared to handle that gracefully.
  574  *
  575  * The server also has the option to delete the service. This hides the service and closes
  576  * all open sessions.
  577  *
  578  * If a server process dies, the Legato framework will automatically delete all of its services.
  579  *
  580  * @subsection c_messagingServerMultithreading Multithreading
  581  *
  582  * The Low-Level Messaging API is thread safe, but not async safe.
  583  *
  584  * When a server creates a service, that service gets attached to the thread that created it
  585  * (i.e., the thread that called le_msg_CreateService()).  That thread will call any handler
  586  * functions registered for that service.
  587  *
  588  * This implies that if the thread that creates the service doesn't
  589  * run the Legato event loop, then no callbacks will ever be called for that service.
  590  * To work around this, you could move the service to another thread that that runs the Legato event
  591  * loop.
  592  *
  593  * @subsection c_messagingServerExample Sample Code
  594  *
  595  * @code
  596  * void RequestMsgHandlerFunc
  597  * (
  598  *     le_msg_MessageRef_t msgRef,     // Reference to the received message.
  599  *     void*               contextPtr  ///< [in] contextPtr passed to le_msg_SetServiceRecvHandler().
  600  * )
  601  * {
  602  *     // Check the message type to decide what to do.
  603  *     myproto_Msg_t* msgPtr = le_msg_GetPayloadPtr(msgRef);
  604  *     switch (msgPtr->type)
  605  *     {
  606  *         case MYPROTO_MSG_TYPE_SET_VALUE:
  607  *              // Message doesn't require a response.
  608  *              Value = msgPtr->...;
  609  *              le_msg_ReleaseMsg(msgRef);
  610  *              break;
  611  *
  612  *         case MYPROTO_MSG_TYPE_GET_VALUE:
  613  *              // Message is a request that requires a response.
  614  *              // Notice that we just reuse the request message buffer for the response.
  615  *              msgPtr->... = Value;
  616  *              le_msg_Respond(msgRef);
  617  *              break;
  618  *
  619  *         default:
  620  *              // Unexpected message type!
  621  *              LE_ERROR("Received unexpected message type %d from session %s.",
  622  *                       msgPtr->type,
  623  *                       le_msg_GetInterfaceName(le_msg_GetSessionInterface(le_msg_GetSession(msgRef))));
  624  *              le_msg_ReleaseMsg(msgRef);
  625  *     }
  626  * }
  627  *
  628  * COMPONENT_INIT
  629  * {
  630  *     le_msg_ProtocolRef_t protocolRef;
  631  *     le_msg_ServiceRef_t serviceRef;
  632  *
  633  *     // Create my service and advertise it.
  634  *     protocolRef = le_msg_GetProtocolRef(PROTOCOL_ID, sizeof(myproto_Msg_t));
  635  *     serviceRef = le_msg_CreateService(protocolRef, SERVER_INTERFACE_NAME);
  636  *     le_msg_SetServiceRecvHandler(serviceRef, RequestMsgHandlerFunc, NULL);
  637  *     le_msg_AdvertiseService(serviceRef);
  638  * }
  639  * @endcode
  640  *
  641  * @section c_messagingStartUp Start Up Sequencing
  642  *
  643  * Worthy of special mention is the fact that the low-level messaging system can be used to
  644  * solve the age-old problem of coordinating the start-up sequence of processes that interact with
  645  * each other. Far too often, the start-up sequence of multiple interacting processes is addressed
  646  * using hacks like polling or sleeping for arbitrary lengths of time. These solutions can
  647  * waste a lot of CPU cycles and battery power, slow down start-up, and (in the case of arbitrary
  648  * sleeps) introduce race conditions that can cause failures in the field.
  649  *
  650  * In Legato, a messaging client can attempt to open a session before the server process has even
  651  * started.  The client will be notified asynchronously (via callback) when the server advertises
  652  * its service.
  653  *
  654  * In this way, clients are guaranteed to wait for the servers they use, without the inefficiency
  655  * of polling, and without having to add code elsewhere to coordinate the start-up sequence.
  656  * If there's work that needs to be done by the client at start-up before it opens
  657  * a session with the server, the client is allowed to do that work in parallel with the start-up
  658  * of the server, so the CPU can be more fully utilized to shorten the overall duration of the
  659  * start-up sequence.
  660  *
  661  * @section c_messagingMemoryManagement Memory Management
  662  *
  663  * Message buffer memory is allocated and controlled behind the scenes, inside the Messaging API.
  664  * This allows the Messaging API to
  665  *  - take some steps to remove programmer pitfalls,
  666  *  - provide some built-in remote troubleshooting features
  667  *  - encapsulate the IPC implementation, allowing for future optimization and porting.
  668  *
  669  * Each message object is allocated from a session. The sessions' message pool sizes can
  670  * be tuned through component and application configuration files and device configuration
  671  * settings.
  672  *
  673  * @todo    Explain how to configure message pools.
  674  *
  675  * Generally speaking, message payload sizes are determined by the protocol that is being used.
  676  * Application protocols and the packing of messages into message buffers are the domain of
  677  * higher-layers of the software stack. But, at this low layer, servers and clients just declare
  678  * the name and version of the protocol, and the size of the largest message in the protocol.
  679  * From this, they obtain a protocol reference that they provide to sessions when they create
  680  * them.
  681  *
  682  * @section c_messagingSecurity Security
  683  *
  684  * Security is provided in the form of authentication and access control.
  685  *
  686  * Clients cannot open sessions with servers until their client-side interface is "bound" to a
  687  * server-side interface (service).  The binding thereby provides configuration of both routing and
  688  * access control.
  689  *
  690  * Neither the client-side nor the server-side IPC sockets are named.  Therefore, no process other
  691  * than the Service Directory has access to these sockets.  The Service Directory passes client
  692  * connections to the appropriate server based on the binding configuration of the client's interface.
  693  *
  694  * The binding configuration is kept in the "system" configuration tree, so clients that do not
  695  * have write access to the "system" configuration tree have no control over their own binding
  696  * configuration.  By default, sandboxed apps do not have any access (read or write) to the
  697  * "system" configuration tree.
  698  *
  699  * @section c_messagingGetClientInfo Get Client Info
  700  *
  701  * In rare cases, a server may wish to check the user ID of the remote client.  Generally,
  702  * this is not necessary because the IPC system enforces user-based access control restrictions
  703  * automatically before allowing an IPC connection to be established.  However, sometimes it
  704  * may be useful when the service wishes to change the way it behaves, based on what user is
  705  * connected to it.
  706  *
  707  * le_msg_GetClientUserId() can be used to fetch the user ID of the client at the far end of a
  708  * given IPC session.
  709  *
  710  * @code
  711  * uid_t clientUserId;
  712  * if (le_msg_GetClientUserId(sessionRef, &clientUserId) != LE_OK)
  713  * {
  714  *     // The session must have closed.
  715  *     ...
  716  * }
  717  * else
  718  * {
  719  *     LE_INFO("My client has user ID %ud.", clientUserId);
  720  * }
  721  * @endcode
  722  *
  723  * le_msg_GetClientProcessId() can be used to fetch the process ID from the client.
  724  *
  725  * @code
  726  * pid_t clientProcessId;
  727  * if (le_msg_GetClientProcessId (sessionRef, &clientProcessId) != LE_OK)
  728  * {
  729  * {
  730  *     // The session must have closed.
  731  *     ...
  732  * }
  733  * else
  734  * {
  735  *    LE_INFO("My client has process ID %ud.", clientProcessId);
  736  * }
  737  * @endcode
  738  *
  739  * le_msg_GetClientUserCreds() can be used to fetch the user credentials from the client.
  740  *
  741  * @code
  742  *    le_msg_SessionRef_t sessionRef,
  743  *    uid_t*              userIdPtr,
  744  *    pid_t*              processIdPtr
  745  * @endcode
  746  *
  747  * @section c_messagingSendingFileDescriptors Sending File Descriptors
  748  *
  749  * It's possible to send an open file descriptor through an IPC session by adding an fd to a
  750  * message before sending it.  On the sender's side, le_msg_SetFd() is used to set the
  751  * file descriptor to be sent.  On the receiver's side, le_msg_GetFd() is used to get the fd
  752  * from the message.
  753  *
  754  * The IPC API will close the original fd in the sender's address space once it has
  755  * been sent, so if the sender still needs the fd open on its side, it should duplicate the fd
  756  * (e.g., using dup() ) before sending it.
  757  *
  758  * On the receiving side, if the fd is not extracted from the message, it will be closed when
  759  * the message is released.  The fd can only be extracted from the message once.  Subsequent
  760  * calls to le_msg_GetFd() will return -1.
  761  *
  762  * As a denial-of-service prevention measure, receiving of file descriptors is disabled by
  763  * default on servers.  To enable receiving of file descriptors, the server must call
  764  * le_msg_EnableFdReception() on their service.
  765  *
  766  * @warning DO NOT SEND DIRECTORY FILE DESCRIPTORS.  That can be exploited to break out of chroot()
  767  * jails.
  768  *
  769  * @section c_messagingFutureEnhancements Future Enhancements
  770  *
  771  * As an optimization to reduce the number of copies in cases where the sender of a message
  772  * already has the message payload of their message assembled somewhere (perhaps as static data
  773  * or in another message buffer received earlier from somewhere), a pointer to the payload could
  774  * be passed to the message, instead of having to copy the payload into the message.
  775  *
  776  * @code
  777  *     msgRef = le_msg_CreateMsg(sessionRef);
  778  *     le_msg_SetPayloadBuff(msgRef, &msgPayload, sizeof(msgPayload));
  779  *     msgRef = le_msg_RequestResponse(msgRef, ResponseHandlerFunc, contextPtr);
  780  * @endcode
  781  *
  782  * Perhaps an "iovec" version could be added to do scatter-gather too?
  783  *
  784  * @section c_messagingDesignNotes Design Notes
  785  *
  786  * We explored the option of having asynchronous messages automatically released when their
  787  * handler function returns, unless the handler calls an "AddRef" function before returning.
  788  * That would reduce the amount of code required in the common case.  However, we chose to require
  789  * that the client release the message explicitly in all cases, because the consequences of using
  790  * an invalid reference can be catastrophic and much more difficult to debug than forgetting to
  791  * release a message (which will generate pool growth warning messages in the log).
  792  *
  793  * @section c_messagingTroubleshooting Troubleshooting
  794  *
  795  * If you're running as the super-user (root), you can trace messaging traffic using @b TBD.
  796  * You can also inspect message queues and view lists of outstanding message objects within
  797  * processes using the Process Inspector tool.
  798  *
  799  * If you're leaking messages by forgetting to release them when you're finished with them,
  800  * you'll see warning messages in the log indicating your message pool is growing.
  801  * You should be able to tell the related messaging service by the name of the expanding pool.
  802  *
  803  * @todo Finish this section later, when the diagnostic tools become available.
  804  *
  805  * <HR>
  806  *
  807  * Copyright (C) Sierra Wireless Inc. Use of this work is subject to license.
  808  */
  809 
  810 
  811 /** @file le_messaging.h
  812  *
  813  * Legato @ref c_messaging include file.
  814  *
  815  * Copyright (C) Sierra Wireless Inc. Use of this work is subject to license.
  816  */
  817 
  818 #ifndef LE_MESSAGING_H_INCLUDE_GUARD
  819 #define LE_MESSAGING_H_INCLUDE_GUARD
  820 
  821 // =======================================
  822 //  DATA TYPES
  823 // =======================================
  824 
  825 //--------------------------------------------------------------------------------------------------
  826 /**
  827  * Reference to a protocol.
  828  */
  829 //--------------------------------------------------------------------------------------------------
  830 typedef struct le_msg_Protocol* le_msg_ProtocolRef_t;
  831 
  832 //--------------------------------------------------------------------------------------------------
  833 /**
  834  * Reference to an interface's service instance.
  835  */
  836 //--------------------------------------------------------------------------------------------------
  837 typedef struct le_msg_Interface* le_msg_InterfaceRef_t;
  838 
  839 //--------------------------------------------------------------------------------------------------
  840 /**
  841  * Reference to a server's service instance.
  842  */
  843 //--------------------------------------------------------------------------------------------------
  844 typedef struct le_msg_Service* le_msg_ServiceRef_t;
  845 
  846 //--------------------------------------------------------------------------------------------------
  847 /**
  848  * Reference to a client's service instance.
  849  */
  850 //--------------------------------------------------------------------------------------------------
  851 typedef struct le_msg_ClientInterface* le_msg_ClientInterfaceRef_t;
  852 
  853 //--------------------------------------------------------------------------------------------------
  854 /**
  855  * Reference to a client-server session.
  856  */
  857 //--------------------------------------------------------------------------------------------------
  858 typedef struct le_msg_Session* le_msg_SessionRef_t;
  859 
  860 //--------------------------------------------------------------------------------------------------
  861 /**
  862  * Reference to a message.
  863  */
  864 //--------------------------------------------------------------------------------------------------
  865 typedef struct le_msg_Message* le_msg_MessageRef_t;
  866 
  867 //--------------------------------------------------------------------------------------------------
  868 /**
  869  * Reference to a handler (call-back) function for events that can occur on a service (such as
  870  * opening and closing of sessions and receipt of messages).
  871  */
  872 //--------------------------------------------------------------------------------------------------
  873 typedef struct le_msg_SessionEventHandler* le_msg_SessionEventHandlerRef_t;
  874 
  875 //--------------------------------------------------------------------------------------------------
  876 /**
  877  * Handler function prototype for handlers that take session references as their arguments.
  878  *
  879  * See le_msg_SetSessionCloseHandler(), le_msg_AddServiceOpenHandler(), and
  880  * le_msg_AddServiceCloseHandler().
  881  *
  882  * @param sessionRef [in] Reference to the session that experienced the event.
  883  *
  884  * @param contextPtr [in] Opaque contextPtr value provided when the handler was registered.
  885  */
  886 //--------------------------------------------------------------------------------------------------
  887 typedef void (* le_msg_SessionEventHandler_t)
  888 (
  889     le_msg_SessionRef_t sessionRef,
  890     void*               contextPtr
  891 );
  892 
  893 
  894 //--------------------------------------------------------------------------------------------------
  895 /**
  896  * Receive handler function prototype.
  897  *
  898  * See le_msg_SetSessionRecvHandler() and le_msg_SetServiceRecvHandler().
  899  *
  900  * @param msgRef       [in] Reference to the received message.  Don't forget to release this using
  901  *                          le_msg_ReleaseMsg() when you're finished with it.
  902  *
  903  * @param contextPtr   [in] Opaque contextPtr value provided when the handler was registered.
  904  */
  905 //--------------------------------------------------------------------------------------------------
  906 typedef void (* le_msg_ReceiveHandler_t)
  907 (
  908     le_msg_MessageRef_t msgRef,
  909     void*               contextPtr
  910 );
  911 
  912 
  913 //--------------------------------------------------------------------------------------------------
  914 /**
  915  * Asynchronous response callback function prototype.
  916  *
  917  * See le_msg_RequestResponse().
  918  *
  919  * @param msgRef       [in] Reference to the received response message, or NULL if the transaction
  920  *                          failed and no response was received.  If not NULL, don't forget to
  921  *                          release it by calling le_msg_ReleaseMsg() when you're finished with it.
  922  *
  923  * @param contextPtr   [in] Opaque contextPtr value passed to le_msg_RequestResponse().
  924  */
  925 //--------------------------------------------------------------------------------------------------
  926 typedef void (* le_msg_ResponseCallback_t)
  927 (
  928     le_msg_MessageRef_t msgRef,
  929     void*               contextPtr
  930 );
  931 
  932 
  933 // =======================================
  934 //  PROTOCOL FUNCTIONS
  935 // =======================================
  936 
  937 //--------------------------------------------------------------------------------------------------
  938 /**
  939  * Gets a reference to refer to a particular version of a particular protocol.
  940  *
  941  * @return  Protocol reference.
  942  */
  943 //--------------------------------------------------------------------------------------------------
  944 le_msg_ProtocolRef_t le_msg_GetProtocolRef
  945 (
  946     const char* protocolId,     ///< [in] String uniquely identifying the the protocol and version.
  947     size_t largestMsgSize       ///< [in] Size (in bytes) of the largest message in the protocol.
  948 );
  949 
  950 
  951 //--------------------------------------------------------------------------------------------------
  952 /**
  953  * Gets the unique identifier string of the protocol.
  954  *
  955  * @return  Pointer to the protocol identifier (null-terminated, UTF-8 string).
  956  */
  957 //--------------------------------------------------------------------------------------------------
  958 const char* le_msg_GetProtocolIdStr
  959 (
  960     le_msg_ProtocolRef_t protocolRef    ///< [in] Reference to the protocol.
  961 );
  962 
  963 
  964 //--------------------------------------------------------------------------------------------------
  965 /**
  966  * Gets the protocol's maximum message size.
  967  *
  968  * @return  The size, in bytes.
  969  */
  970 //--------------------------------------------------------------------------------------------------
  971 size_t le_msg_GetProtocolMaxMsgSize
  972 (
  973     le_msg_ProtocolRef_t protocolRef    ///< [in] Reference to the protocol.
  974 );
  975 
  976 
  977 // =======================================
  978 //  SESSION FUNCTIONS
  979 // =======================================
  980 
  981 //--------------------------------------------------------------------------------------------------
  982 /**
  983  * Creates a session that will make use of a protocol to talk to a service on a given client
  984  * interface.
  985  *
  986  * @note    This doesn't actually attempt to open the session.  It just creates the session
  987  *          object, allowing the client the opportunity to register handlers for the session
  988  *          before attempting to open it using le_msg_OpenSession().
  989  *
  990  * @return  Session reference.
  991  */
  992 //--------------------------------------------------------------------------------------------------
  993 le_msg_SessionRef_t le_msg_CreateSession
  994 (
  995     le_msg_ProtocolRef_t    protocolRef,    ///< [in] Reference to the protocol to be used.
  996     const char*             interfaceName   ///< [in] Name of the client-side interface.
  997 );
  998 
  999 
 1000 //--------------------------------------------------------------------------------------------------
 1001 /**
 1002  * Sets an opaque context value (void pointer) that can be retrieved from that session later using
 1003  * le_msg_GetSessionContextPtr().
 1004  */
 1005 //--------------------------------------------------------------------------------------------------
 1006 void le_msg_SetSessionContextPtr
 1007 (
 1008     le_msg_SessionRef_t sessionRef, ///< [in] Reference to the session.
 1009 
 1010     void*               contextPtr  ///< [in] Opaque value to be returned by
 1011                                     ///         le_msg_GetSessionContextPtr().
 1012 );
 1013 
 1014 //--------------------------------------------------------------------------------------------------
 1015 /**
 1016  * Fetches the opaque context value (void pointer) that was set earlier using
 1017  * le_msg_SetSessionContextPtr().
 1018  *
 1019  * @return  Context Ptr value passed into le_msg_SetSessionContextPtr(), or NULL if
 1020  *          le_msg_SetSessionContextPtr() has not been called for this session yet.
 1021  */
 1022 //--------------------------------------------------------------------------------------------------
 1023 void* le_msg_GetSessionContextPtr
 1024 (
 1025     le_msg_SessionRef_t sessionRef  ///< [in] Reference to the session.
 1026 );
 1027 
 1028 
 1029 //--------------------------------------------------------------------------------------------------
 1030 /**
 1031  * Deletes a session.  This will end the session and free up any resources associated
 1032  * with it.  Any pending request-response transactions in this session will be terminated.
 1033  * If the far end has registered a session close handler callback, it will be called.
 1034  *
 1035  * @note    Function is only used by clients.  On the server side, sessions are automatically
 1036  *          deleted when they close.
 1037  */
 1038 //--------------------------------------------------------------------------------------------------
 1039 void le_msg_DeleteSession
 1040 (
 1041     le_msg_SessionRef_t sessionRef  ///< [in] Reference to the session.
 1042 );
 1043 
 1044 
 1045 //--------------------------------------------------------------------------------------------------
 1046 /**
 1047  * Sets the receive handler callback function to be called when a non-response message arrives
 1048  * on this session.
 1049  *
 1050  * The handler function will be called by the Legato event loop of the thread that created
 1051  * the session.
 1052  *
 1053  * @note    This is a client-only function.  Servers are expected to use
 1054  *          le_msg_SetServiceRecvHandler() instead.
 1055  */
 1056 //--------------------------------------------------------------------------------------------------
 1057 void le_msg_SetSessionRecvHandler
 1058 (
 1059     le_msg_SessionRef_t     sessionRef, ///< [in] Reference to the session.
 1060     le_msg_ReceiveHandler_t handlerFunc,///< [in] Handler function.
 1061     void*                   contextPtr  ///< [in] Opaque pointer value to pass to the handler.
 1062 );
 1063 
 1064 
 1065 //--------------------------------------------------------------------------------------------------
 1066 /**
 1067  * Sets the handler callback function to be called when the session is closed from the other
 1068  * end.  A local termination of the session will not trigger this callback.
 1069  *
 1070  * The handler function will be called by the Legato event loop of the thread that created
 1071  * the session.
 1072  *
 1073  * @note
 1074  * - If this isn't set on the client side, the framework assumes the client is not designed
 1075  *   to recover from the server terminating the session, and the client process will terminate
 1076  *   if the session is terminated by the server.
 1077  * - This is a client-only function.  Servers are expected to use le_msg_AddServiceCloseHandler()
 1078  *   instead.
 1079  */
 1080 //--------------------------------------------------------------------------------------------------
 1081 void le_msg_SetSessionCloseHandler
 1082 (
 1083     le_msg_SessionRef_t             sessionRef, ///< [in] Reference to the session.
 1084     le_msg_SessionEventHandler_t    handlerFunc,///< [in] Handler function.
 1085     void*                           contextPtr  ///< [in] Opaque pointer value to pass to handler.
 1086 );
 1087 
 1088 
 1089 //--------------------------------------------------------------------------------------------------
 1090 /**
 1091  * Opens a session with a service, providing a function to be called-back when the session is
 1092  * open.
 1093  *
 1094  * @note    Only clients open sessions.  Servers must patiently wait for clients to open sessions
 1095  *          with them.
 1096  *
 1097  * @warning If the client and server don't agree on the maximum message size for the protocol,
 1098  *          a fatal error will be logged and the client process will be killed.
 1099  */
 1100 //--------------------------------------------------------------------------------------------------
 1101 void le_msg_OpenSession
 1102 (
 1103     le_msg_SessionRef_t             sessionRef,     ///< [in] Reference to the session.
 1104     le_msg_SessionEventHandler_t    callbackFunc,   ///< [in] Function to be called when open.
 1105                                                     ///       NULL if no notification is needed.
 1106     void*                           contextPtr      ///< [in] Opaque value to pass to the callback.
 1107 );
 1108 
 1109 
 1110 //--------------------------------------------------------------------------------------------------
 1111 /**
 1112  * Synchronously open a session with a service.  Blocks until the session is open.
 1113  *
 1114  * This function logs a fatal error and terminates the calling process if unsuccessful.
 1115  *
 1116  * @note    Only clients open sessions.  Servers must patiently wait for clients to open sessions
 1117  *          with them.
 1118  *
 1119  * @warning If the client and server do not agree on the maximum message size for the protocol,
 1120  *          a fatal error will be logged and the client process will be killed.
 1121  */
 1122 //--------------------------------------------------------------------------------------------------
 1123 void le_msg_OpenSessionSync
 1124 (
 1125     le_msg_SessionRef_t             sessionRef      ///< [in] Reference to the session.
 1126 );
 1127 
 1128 
 1129 //--------------------------------------------------------------------------------------------------
 1130 /**
 1131  * Synchronously open a session with a service.  Does not wait for the session to become available
 1132  * if not available..
 1133  *
 1134  * le_msg_TryOpenSessionSync() differs from le_msg_OpenSessionSync() in that
 1135  * le_msg_TryOpenSessionSync() will not wait for a server session to become available if it's
 1136  * not already available at the time of the call.  That is, if the client's interface is not
 1137  * bound to any service, or if the service that it's bound to is not currently advertised
 1138  * by the server, then le_msg_TryOpenSessionSync() will return an error code, while
 1139  * le_msg_OpenSessionSync() will wait until the binding is created or the server advertises
 1140  * the service (or both).
 1141  *
 1142  * @return
 1143  *  - LE_OK if the session was successfully opened.
 1144  *  - LE_NOT_FOUND if the server is not currently offering the service to which the client is bound.
 1145  *  - LE_NOT_PERMITTED if the client interface is not bound to any service (doesn't have a binding).
 1146  *  - LE_COMM_ERROR if the Service Directory cannot be reached.
 1147  *
 1148  * @note    Only clients open sessions.  Servers' must patiently wait for clients to open sessions
 1149  *          with them.
 1150  *
 1151  * @warning If the client and server do not agree on the maximum message size for the protocol,
 1152  *          a fatal error will be logged and the client process will be killed.
 1153  */
 1154 //--------------------------------------------------------------------------------------------------
 1155 le_result_t le_msg_TryOpenSessionSync
 1156 (
 1157     le_msg_SessionRef_t             sessionRef      ///< [in] Reference to the session.
 1158 );
 1159 
 1160 
 1161 //--------------------------------------------------------------------------------------------------
 1162 /**
 1163  * Terminates a session.
 1164  */
 1165 //--------------------------------------------------------------------------------------------------
 1166 void le_msg_CloseSession
 1167 (
 1168     le_msg_SessionRef_t sessionRef  ///< [in] Reference to the session.
 1169 );
 1170 
 1171 
 1172 //--------------------------------------------------------------------------------------------------
 1173 /**
 1174  * Fetches a reference to the protocol that is being used for a given session.
 1175  *
 1176  * @return Reference to the protocol.
 1177  */
 1178 //--------------------------------------------------------------------------------------------------
 1179 le_msg_ProtocolRef_t le_msg_GetSessionProtocol
 1180 (
 1181     le_msg_SessionRef_t sessionRef  ///< [in] Reference to the session.
 1182 );
 1183 
 1184 
 1185 //--------------------------------------------------------------------------------------------------
 1186 /**
 1187  * Fetches a reference to the interface that is associated with a given session.
 1188  *
 1189  * @return Reference to the interface.
 1190  */
 1191 //--------------------------------------------------------------------------------------------------
 1192 le_msg_InterfaceRef_t le_msg_GetSessionInterface
 1193 (
 1194     le_msg_SessionRef_t sessionRef  ///< [in] Reference to the session.
 1195 );
 1196 
 1197 //--------------------------------------------------------------------------------------------------
 1198 /**
 1199  * Fetches the user ID of the client at the far end of a given IPC session.
 1200  *
 1201  * @warning This function can only be called for the server-side of a session.
 1202  *
 1203  * @return LE_OK if successful.
 1204  *         LE_CLOSED if the session has closed.
 1205  **/
 1206 //--------------------------------------------------------------------------------------------------
 1207 le_result_t le_msg_GetClientUserId
 1208 (
 1209     le_msg_SessionRef_t sessionRef, ///< [in] Reference to the session.
 1210     uid_t*              userIdPtr   ///< [out] Ptr to where the result is to be stored on success.
 1211 );
 1212 
 1213 //--------------------------------------------------------------------------------------------------
 1214 /**
 1215  * Fetches the user PID of the client at the far end of a given IPC session.
 1216  *
 1217  * @warning This function can only be called for the server-side of a session.
 1218  *
 1219  * @return LE_OK if successful.
 1220  *         LE_CLOSED if the session has closed.
 1221  **/
 1222 //--------------------------------------------------------------------------------------------------
 1223 le_result_t le_msg_GetClientProcessId
 1224 (
 1225     le_msg_SessionRef_t sessionRef,   ///< [in] Reference to the session.
 1226     pid_t*              processIdPtr  ///< [out] Ptr to where the result is to be stored on success.
 1227 );
 1228 
 1229 //--------------------------------------------------------------------------------------------------
 1230 /**
 1231  * Fetches the user credentials of the client at the far end of a given IPC session.
 1232  *
 1233  * @warning This function can only be called for the server-side of a session.
 1234  *
 1235  * @return LE_OK if successful.
 1236  *         LE_CLOSED if the session has closed.
 1237  **/
 1238 //--------------------------------------------------------------------------------------------------
 1239 le_result_t le_msg_GetClientUserCreds
 1240 (
 1241     le_msg_SessionRef_t sessionRef,   ///< [in] Reference to the session.
 1242     uid_t*              userIdPtr,    ///< [out] Ptr to where the uid is to be stored on success.
 1243     pid_t*              processIdPtr  ///< [out] Ptr to where the pid is to be stored on success.
 1244 );
 1245 
 1246 
 1247 
 1248 // =======================================
 1249 //  MESSAGE FUNCTIONS
 1250 // =======================================
 1251 
 1252 //--------------------------------------------------------------------------------------------------
 1253 /**
 1254  * Creates a message to be sent over a given session.
 1255  *
 1256  * @return  Message reference.
 1257  *
 1258  * @note
 1259  * - Function never returns on failure, there's no need to check the return code.
 1260  * - If you see warnings on message pools expanding, then you may be forgetting to
 1261  *   release the messages you have received.
 1262  */
 1263 //--------------------------------------------------------------------------------------------------
 1264 le_msg_MessageRef_t le_msg_CreateMsg
 1265 (
 1266     le_msg_SessionRef_t sessionRef  ///< [in] Reference to the session.
 1267 );
 1268 
 1269 
 1270 //--------------------------------------------------------------------------------------------------
 1271 /**
 1272  * Adds to the reference count on a message object.
 1273  */
 1274 //--------------------------------------------------------------------------------------------------
 1275 void le_msg_AddRef
 1276 (
 1277     le_msg_MessageRef_t msgRef      ///< [in] Reference to the message.
 1278 );
 1279 
 1280 
 1281 //--------------------------------------------------------------------------------------------------
 1282 /**
 1283  * Releases a message object, decrementing its reference count.  If the reference count has reached
 1284  * zero, the message object is deleted.
 1285  */
 1286 //--------------------------------------------------------------------------------------------------
 1287 void le_msg_ReleaseMsg
 1288 (
 1289     le_msg_MessageRef_t msgRef      ///< [in] Reference to the message.
 1290 );
 1291 
 1292 
 1293 //--------------------------------------------------------------------------------------------------
 1294 /**
 1295  * Checks whether a message requires a response or not.
 1296  *
 1297  * @note    This is intended for use on the server side only.
 1298  *
 1299  * @return
 1300  *  - TRUE if the message needs to be responded to using le_msg_Respond().
 1301  *  - FALSE if the message doesn't need to be responded to, and should be disposed of using
 1302  *    le_msg_ReleaseMsg() when it's no longer needed.
 1303  */
 1304 //--------------------------------------------------------------------------------------------------
 1305 bool le_msg_NeedsResponse
 1306 (
 1307     le_msg_MessageRef_t msgRef      ///< [in] Reference to the message.
 1308 );
 1309 
 1310 
 1311 //--------------------------------------------------------------------------------------------------
 1312 /**
 1313  * Gets a pointer to the message payload memory buffer.
 1314  *
 1315  * @return Pointer to the payload buffer.
 1316  *
 1317  * @warning Be careful not to overflow this buffer.
 1318  */
 1319 //--------------------------------------------------------------------------------------------------
 1320 void* le_msg_GetPayloadPtr
 1321 (
 1322     le_msg_MessageRef_t msgRef      ///< [in] Reference to the message.
 1323 );
 1324 
 1325 
 1326 //--------------------------------------------------------------------------------------------------
 1327 /**
 1328  * Gets the size, in bytes, of the message payload memory buffer.
 1329  *
 1330  * @return The size, in bytes.
 1331  */
 1332 //--------------------------------------------------------------------------------------------------
 1333 size_t le_msg_GetMaxPayloadSize
 1334 (
 1335     le_msg_MessageRef_t msgRef      ///< [in] Reference to the message.
 1336 );
 1337 
 1338 
 1339 //--------------------------------------------------------------------------------------------------
 1340 /**
 1341  * Sets the file descriptor to be sent with this message.
 1342  *
 1343  * This file descriptor will be closed when the message is sent (or when it's deleted without
 1344  * being sent).
 1345  *
 1346  * At most one file descriptor is allowed to be sent per message.
 1347  **/
 1348 //--------------------------------------------------------------------------------------------------
 1349 void le_msg_SetFd
 1350 (
 1351     le_msg_MessageRef_t msgRef,     ///< [in] Reference to the message.
 1352     int                 fd          ///< [in] File descriptor.
 1353 );
 1354 
 1355 
 1356 //--------------------------------------------------------------------------------------------------
 1357 /**
 1358  * Fetches a received file descriptor from the message.
 1359  *
 1360  * @return The file descriptor, or -1 if no file descriptor was sent with this message or if the
 1361  *         fd was already fetched from the message.
 1362  **/
 1363 //--------------------------------------------------------------------------------------------------
 1364 int le_msg_GetFd
 1365 (
 1366     le_msg_MessageRef_t msgRef      ///< [in] Reference to the message.
 1367 );
 1368 
 1369 
 1370 //--------------------------------------------------------------------------------------------------
 1371 /**
 1372  * Sends a message.  No response expected.
 1373  */
 1374 //--------------------------------------------------------------------------------------------------
 1375 void le_msg_Send
 1376 (
 1377     le_msg_MessageRef_t msgRef      ///< [in] Reference to the message.
 1378 );
 1379 
 1380 
 1381 //--------------------------------------------------------------------------------------------------
 1382 /**
 1383  * Gets a reference to the session to which a given message belongs.
 1384  *
 1385  * @return Session reference.
 1386  */
 1387 //--------------------------------------------------------------------------------------------------
 1388 le_msg_SessionRef_t le_msg_GetSession
 1389 (
 1390     le_msg_MessageRef_t msgRef      ///< [in] Reference to the message.
 1391 );
 1392 
 1393 
 1394 //--------------------------------------------------------------------------------------------------
 1395 /**
 1396  * Requests a response from a server by sending it a request.  Doesn't block.  Instead,
 1397  * provides a callback function to be called when the response arrives or the transaction
 1398  * terminates without a response (due to the session terminating or the server deleting the
 1399  * request without responding).
 1400  *
 1401  * @note
 1402  *     - The thread attached to the session (i.e., thread created by the session)
 1403  *       will trigger the callback from its main event loop.  This means if
 1404  *       that thread doesn't run its main event loop, it won't trigger the callback.
 1405  *     - Function can only be used on the client side of a session.
 1406  */
 1407 //--------------------------------------------------------------------------------------------------
 1408 void le_msg_RequestResponse
 1409 (
 1410     le_msg_MessageRef_t         msgRef,     ///< [in] Reference to the request message.
 1411     le_msg_ResponseCallback_t   handlerFunc,///< [in] Function to be called when transaction done.
 1412     void*                       contextPtr  ///< [in] Opaque value to be passed to handler function.
 1413 );
 1414 
 1415 
 1416 //--------------------------------------------------------------------------------------------------
 1417 /**
 1418  * Requests a response from a server by sending it a request.  Blocks until the response arrives
 1419  * or until the transaction terminates without a response (i.e., if the session terminates or
 1420  * the server deletes the request without responding).
 1421  *
 1422  * @return  Reference to the response message, or NULL if the transaction terminated without a
 1423  *          response.
 1424  *
 1425  * @note
 1426  *        - To prevent deadlocks, this function can only be used on the client side of a session.
 1427  *          Servers can't use this function.
 1428  *        - To prevent race conditions, only the client thread attached to the session
 1429  *          (the thread that created the session) is allowed to perform a synchronous
 1430  *          request-response transaction.
 1431  *
 1432  * @warning
 1433  *        - The calling (client) thread will be blocked until the server responds, so no other
 1434  *          event handling will happen in that client thread until the response is received (or the
 1435  *          server dies).  This function should only be used when the server is certain
 1436  *          to respond quickly enough to ensure that it will not cause any event response time
 1437  *          deadlines to be missed by the client.  Consider using le_msg_RequestResponse()
 1438  *          instead.
 1439  *        - If this function is used when the client and server are in the same thread, then the
 1440  *          message will be discarded and NULL will be returned.  This is a deadlock prevention
 1441  *          measure.
 1442  */
 1443 //--------------------------------------------------------------------------------------------------
 1444 le_msg_MessageRef_t le_msg_RequestSyncResponse
 1445 (
 1446     le_msg_MessageRef_t msgRef      ///< [in] Reference to the request message.
 1447 );
 1448 
 1449 
 1450 //--------------------------------------------------------------------------------------------------
 1451 /**
 1452  * Sends a response back to the client that send the request message.
 1453  *
 1454  * Takes a reference to the request message.  Copy the response payload (if any) into the
 1455  * same payload buffer that held the request payload, then call le_msg_Respond().
 1456  *
 1457  * The messaging system will delete the message automatically when it's finished sending
 1458  * the response.
 1459  *
 1460  * @note    Function can only be used on the server side of a session.
 1461  */
 1462 //--------------------------------------------------------------------------------------------------
 1463 void le_msg_Respond
 1464 (
 1465     le_msg_MessageRef_t msgRef      ///< [in] Reference to the request message.
 1466 );
 1467 
 1468 
 1469 // =======================================
 1470 //  INTERFACE FUNCTIONS
 1471 // =======================================
 1472 
 1473 //--------------------------------------------------------------------------------------------------
 1474 /**
 1475  * Creates a service that is accessible using a protocol.
 1476  *
 1477  * @return  Service reference.
 1478  */
 1479 //--------------------------------------------------------------------------------------------------
 1480 le_msg_ServiceRef_t le_msg_CreateService
 1481 (
 1482     le_msg_ProtocolRef_t    protocolRef,    ///< [in] Reference to the protocol to be used.
 1483     const char*             interfaceName   ///< [in] Server-side interface name.
 1484 );
 1485 
 1486 
 1487 //--------------------------------------------------------------------------------------------------
 1488 /**
 1489  * Deletes a service. Any open sessions will be terminated.
 1490  *
 1491  * @note    Server-only function.
 1492  */
 1493 //--------------------------------------------------------------------------------------------------
 1494 void le_msg_DeleteService
 1495 (
 1496     le_msg_ServiceRef_t             serviceRef  ///< [in] Reference to the service.
 1497 );
 1498 
 1499 //--------------------------------------------------------------------------------------------------
 1500 /**
 1501  * Registers a function to be called when clients open sessions with this service.
 1502  *
 1503  * @note    Server-only function.
 1504  */
 1505 //--------------------------------------------------------------------------------------------------
 1506 le_msg_SessionEventHandlerRef_t le_msg_AddServiceOpenHandler
 1507 (
 1508     le_msg_ServiceRef_t             serviceRef, ///< [in] Reference to the service.
 1509     le_msg_SessionEventHandler_t    handlerFunc,///< [in] Handler function.
 1510     void*                           contextPtr  ///< [in] Opaque pointer value to pass to handler.
 1511 );
 1512 
 1513 //--------------------------------------------------------------------------------------------------
 1514 /**
 1515  * Registers a function to be called whenever one of this service's sessions is closed by
 1516  * the client.
 1517  *
 1518  * @note    Server-only function.
 1519  */
 1520 //--------------------------------------------------------------------------------------------------
 1521 le_msg_SessionEventHandlerRef_t le_msg_AddServiceCloseHandler
 1522 (
 1523     le_msg_ServiceRef_t             serviceRef, ///< [in] Reference to the service.
 1524     le_msg_SessionEventHandler_t    handlerFunc,///< [in] Handler function.
 1525     void*                           contextPtr  ///< [in] Opaque pointer value to pass to handler.
 1526 );
 1527 
 1528 //--------------------------------------------------------------------------------------------------
 1529 /**
 1530  * Remove a function previously registered by le_msg_AddServiceOpenHandler or
 1531  * le_msg_AddServiceCloseHandler.
 1532  *
 1533  * @note    This is a server-only function.
 1534  */
 1535 //--------------------------------------------------------------------------------------------------
 1536 void le_msg_RemoveServiceHandler
 1537 (
 1538     le_msg_SessionEventHandlerRef_t handlerRef   ///< [in] Reference to a previously call of
 1539                                                  ///       le_msg_AddServiceCloseHandler()
 1540 );
 1541 
 1542 //--------------------------------------------------------------------------------------------------
 1543 /**
 1544  * Registers a function to be called when messages are received from clients via sessions
 1545  * that they have open with this service.
 1546  *
 1547  * @note    Server-only function.
 1548  */
 1549 //--------------------------------------------------------------------------------------------------
 1550 void le_msg_SetServiceRecvHandler
 1551 (
 1552     le_msg_ServiceRef_t     serviceRef, ///< [in] Reference to the service.
 1553     le_msg_ReceiveHandler_t handlerFunc,///< [in] Handler function.
 1554     void*                   contextPtr  ///< [in] Opaque pointer value to pass to the handler.
 1555 );
 1556 
 1557 
 1558 //--------------------------------------------------------------------------------------------------
 1559 /**
 1560  * Associates an opaque context value (void pointer) with a given service that can be retrieved
 1561  * later using le_msg_GetServiceContextPtr().
 1562  *
 1563  * @note    Server-only function.
 1564  */
 1565 //--------------------------------------------------------------------------------------------------
 1566 void le_msg_SetServiceContextPtr
 1567 (
 1568     le_msg_ServiceRef_t serviceRef, ///< [in] Reference to the service.
 1569 
 1570     void*               contextPtr  ///< [in] Opaque value to be returned by
 1571                                     ///         le_msg_GetServiceContextPtr().
 1572 );
 1573 
 1574 
 1575 //--------------------------------------------------------------------------------------------------
 1576 /**
 1577  * Fetches the opaque context value (void pointer) associated with a specified service using
 1578  * le_msg_SetServiceContextPtr().
 1579  *
 1580  * @return  Context pointer value, or NULL if le_msg_SetServiceContextPtr() was never called
 1581  *          for this service.
 1582  *
 1583  * @note    Server-only function.
 1584  */
 1585 //--------------------------------------------------------------------------------------------------
 1586 void* le_msg_GetServiceContextPtr
 1587 (
 1588     le_msg_ServiceRef_t serviceRef  ///< [in] Reference to the service.
 1589 );
 1590 
 1591 
 1592 //--------------------------------------------------------------------------------------------------
 1593 /**
 1594  * Makes a given service available for clients to find.
 1595  *
 1596  * @note    Server-only function.
 1597  */
 1598 //--------------------------------------------------------------------------------------------------
 1599 void le_msg_AdvertiseService
 1600 (
 1601     le_msg_ServiceRef_t serviceRef  ///< [in] Reference to the service.
 1602 );
 1603 
 1604 
 1605 //--------------------------------------------------------------------------------------------------
 1606 /**
 1607  * Makes a specified service unavailable for clients to find without terminating any ongoing
 1608  * sessions.
 1609  *
 1610  * @note    Server-only function.
 1611  */
 1612 //--------------------------------------------------------------------------------------------------
 1613 void le_msg_HideService
 1614 (
 1615     le_msg_ServiceRef_t serviceRef  ///< [in] Reference to the service.
 1616 );
 1617 
 1618 
 1619 //--------------------------------------------------------------------------------------------------
 1620 /**
 1621  * Fetches a pointer to the name of an interface.
 1622  *
 1623  * @return Pointer to a null-terminated string.
 1624  *
 1625  * @warning Pointer returned will remain valid only until the interface is deleted.
 1626  */
 1627 //--------------------------------------------------------------------------------------------------
 1628 const char* le_msg_GetInterfaceName
 1629 (
 1630     le_msg_InterfaceRef_t interfaceRef  ///< [in] Reference to the interface.
 1631 );
 1632 
 1633 
 1634 //--------------------------------------------------------------------------------------------------
 1635 /**
 1636  * Fetches a reference to the protocol supported by a specified interface.
 1637  *
 1638  * @return  Protocol reference.
 1639  */
 1640 //--------------------------------------------------------------------------------------------------
 1641 le_msg_ProtocolRef_t le_msg_GetInterfaceProtocol
 1642 (
 1643     le_msg_InterfaceRef_t interfaceRef  ///< [in] Reference to the interface.
 1644 );
 1645 
 1646 
 1647 //--------------------------------------------------------------------------------------------------
 1648 /**
 1649  * Check if the calling thread is currently running a Service's message receive handler;
 1650  *  if so, return a reference to the message object being handled.
 1651  *
 1652  * @return  Reference to the message being handled, or NULL if no Service message receive handler
 1653  *          is currently running.
 1654  **/
 1655 //--------------------------------------------------------------------------------------------------
 1656 le_msg_MessageRef_t le_msg_GetServiceRxMsg
 1657 (
 1658     void
 1659 );
 1660 
 1661 
 1662 //--------------------------------------------------------------------------------------------------
 1663 /**
 1664  * Logs an error message (at EMERGENCY level) and:
 1665  *  - if the caller is running a server-side IPC function, kills the connection to the client
 1666  *    and returns.
 1667  *  - if the caller is not running a server-side IPC function, kills the caller (doesn't return).
 1668  **/
 1669 //--------------------------------------------------------------------------------------------------
 1670 #define LE_KILL_CLIENT(formatString, ...)  \
 1671 { \
 1672     le_msg_MessageRef_t msgRef = le_msg_GetServiceRxMsg(); \
 1673     LE_FATAL_IF(msgRef == NULL, formatString, ##__VA_ARGS__); \
 1674     LE_EMERG(formatString, ##__VA_ARGS__); \
 1675     le_msg_CloseSession(le_msg_GetSession(msgRef)); \
 1676 }
 1677 
 1678 #endif // LEGATO_MESSAGING_INCLUDE_GUARD
le_msg_GetServiceRxMsg
le_msg_MessageRef_t le_msg_GetServiceRxMsg(void)
le_msg_AddRef
void le_msg_AddRef(le_msg_MessageRef_t msgRef)
le_msg_GetProtocolRef
le_msg_ProtocolRef_t le_msg_GetProtocolRef(const char *protocolId, size_t largestMsgSize)
le_msg_NeedsResponse
bool le_msg_NeedsResponse(le_msg_MessageRef_t msgRef)
le_msg_GetProtocolMaxMsgSize
size_t le_msg_GetProtocolMaxMsgSize(le_msg_ProtocolRef_t protocolRef)
le_msg_ReleaseMsg
void le_msg_ReleaseMsg(le_msg_MessageRef_t msgRef)
le_msg_GetClientUserCreds
le_result_t le_msg_GetClientUserCreds(le_msg_SessionRef_t sessionRef, uid_t *userIdPtr, pid_t *processIdPtr)
le_result_t
le_result_t
Definition: le_basics.h:35
le_msg_GetServiceContextPtr
void * le_msg_GetServiceContextPtr(le_msg_ServiceRef_t serviceRef)
le_msg_SetServiceRecvHandler
void le_msg_SetServiceRecvHandler(le_msg_ServiceRef_t serviceRef, le_msg_ReceiveHandler_t handlerFunc, void *contextPtr)
le_msg_GetSessionContextPtr
void * le_msg_GetSessionContextPtr(le_msg_SessionRef_t sessionRef)
le_msg_SessionEventHandler_t
void(* le_msg_SessionEventHandler_t)(le_msg_SessionRef_t sessionRef, void *contextPtr)
Definition: le_messaging.h:888
le_msg_TryOpenSessionSync
le_result_t le_msg_TryOpenSessionSync(le_msg_SessionRef_t sessionRef)
le_msg_AdvertiseService
void le_msg_AdvertiseService(le_msg_ServiceRef_t serviceRef)
le_msg_DeleteSession
void le_msg_DeleteSession(le_msg_SessionRef_t sessionRef)
le_msg_GetProtocolIdStr
const char * le_msg_GetProtocolIdStr(le_msg_ProtocolRef_t protocolRef)
le_msg_SetSessionRecvHandler
void le_msg_SetSessionRecvHandler(le_msg_SessionRef_t sessionRef, le_msg_ReceiveHandler_t handlerFunc, void *contextPtr)
le_msg_GetPayloadPtr
void * le_msg_GetPayloadPtr(le_msg_MessageRef_t msgRef)
le_msg_GetInterfaceName
const char * le_msg_GetInterfaceName(le_msg_InterfaceRef_t interfaceRef)
le_msg_ClientInterfaceRef_t
struct le_msg_ClientInterface * le_msg_ClientInterfaceRef_t
Definition: le_messaging.h:851
le_msg_GetMaxPayloadSize
size_t le_msg_GetMaxPayloadSize(le_msg_MessageRef_t msgRef)
le_msg_GetSession
le_msg_SessionRef_t le_msg_GetSession(le_msg_MessageRef_t msgRef)
le_msg_SetFd
void le_msg_SetFd(le_msg_MessageRef_t msgRef, int fd)
le_msg_ReceiveHandler_t
void(* le_msg_ReceiveHandler_t)(le_msg_MessageRef_t msgRef, void *contextPtr)
Definition: le_messaging.h:907
le_msg_Send
void le_msg_Send(le_msg_MessageRef_t msgRef)
le_msg_GetInterfaceProtocol
le_msg_ProtocolRef_t le_msg_GetInterfaceProtocol(le_msg_InterfaceRef_t interfaceRef)
le_msg_SessionEventHandlerRef_t
struct le_msg_SessionEventHandler * le_msg_SessionEventHandlerRef_t
Definition: le_messaging.h:873
le_msg_CreateSession
le_msg_SessionRef_t le_msg_CreateSession(le_msg_ProtocolRef_t protocolRef, const char *interfaceName)
le_msg_CloseSession
void le_msg_CloseSession(le_msg_SessionRef_t sessionRef)
le_msg_DeleteService
void le_msg_DeleteService(le_msg_ServiceRef_t serviceRef)
le_msg_CreateService
le_msg_ServiceRef_t le_msg_CreateService(le_msg_ProtocolRef_t protocolRef, const char *interfaceName)
le_msg_GetSessionInterface
le_msg_InterfaceRef_t le_msg_GetSessionInterface(le_msg_SessionRef_t sessionRef)
le_msg_CreateMsg
le_msg_MessageRef_t le_msg_CreateMsg(le_msg_SessionRef_t sessionRef)
le_msg_AddServiceOpenHandler
le_msg_SessionEventHandlerRef_t le_msg_AddServiceOpenHandler(le_msg_ServiceRef_t serviceRef, le_msg_SessionEventHandler_t handlerFunc, void *contextPtr)
le_msg_GetFd
int le_msg_GetFd(le_msg_MessageRef_t msgRef)
le_msg_SessionRef_t
struct le_msg_Session * le_msg_SessionRef_t
Definition: le_messaging.h:858
le_msg_RequestResponse
void le_msg_RequestResponse(le_msg_MessageRef_t msgRef, le_msg_ResponseCallback_t handlerFunc, void *contextPtr)
le_msg_RemoveServiceHandler
void le_msg_RemoveServiceHandler(le_msg_SessionEventHandlerRef_t handlerRef)
le_msg_HideService
void le_msg_HideService(le_msg_ServiceRef_t serviceRef)
le_msg_SetSessionContextPtr
void le_msg_SetSessionContextPtr(le_msg_SessionRef_t sessionRef, void *contextPtr)
le_msg_GetClientProcessId
le_result_t le_msg_GetClientProcessId(le_msg_SessionRef_t sessionRef, pid_t *processIdPtr)
le_msg_OpenSession
void le_msg_OpenSession(le_msg_SessionRef_t sessionRef, le_msg_SessionEventHandler_t callbackFunc, void *contextPtr)
le_msg_SetServiceContextPtr
void le_msg_SetServiceContextPtr(le_msg_ServiceRef_t serviceRef, void *contextPtr)
le_msg_GetSessionProtocol
le_msg_ProtocolRef_t le_msg_GetSessionProtocol(le_msg_SessionRef_t sessionRef)
le_msg_Respond
void le_msg_Respond(le_msg_MessageRef_t msgRef)
le_msg_ProtocolRef_t
struct le_msg_Protocol * le_msg_ProtocolRef_t
Definition: le_messaging.h:830
le_msg_ResponseCallback_t
void(* le_msg_ResponseCallback_t)(le_msg_MessageRef_t msgRef, void *contextPtr)
Definition: le_messaging.h:927
le_msg_GetClientUserId
le_result_t le_msg_GetClientUserId(le_msg_SessionRef_t sessionRef, uid_t *userIdPtr)
le_msg_RequestSyncResponse
le_msg_MessageRef_t le_msg_RequestSyncResponse(le_msg_MessageRef_t msgRef)
le_msg_InterfaceRef_t
struct le_msg_Interface * le_msg_InterfaceRef_t
Definition: le_messaging.h:837
le_msg_OpenSessionSync
void le_msg_OpenSessionSync(le_msg_SessionRef_t sessionRef)
le_msg_MessageRef_t
struct le_msg_Message * le_msg_MessageRef_t
Definition: le_messaging.h:865
le_msg_ServiceRef_t
struct le_msg_Service * le_msg_ServiceRef_t
Definition: le_messaging.h:844
le_msg_AddServiceCloseHandler
le_msg_SessionEventHandlerRef_t le_msg_AddServiceCloseHandler(le_msg_ServiceRef_t serviceRef, le_msg_SessionEventHandler_t handlerFunc, void *contextPtr)
le_msg_SetSessionCloseHandler
void le_msg_SetSessionCloseHandler(le_msg_SessionRef_t sessionRef, le_msg_SessionEventHandler_t handlerFunc, void *contextPtr)