How can C++ read the R object written into socket with saveRDS or save
On Jun 25, 2013, at 11:52 AM, Rong lI Li wrote:
Hi, all, Recently, I met one issue when using socket between R & C++ to transmit R object. Would you pls help give me some suggestions? Many thanks! [Background]: I create a socket connection between R & C++ binary first, and then, want to use saveRDS() or save() in R to save the object into connection directly. So that the C++ binary can read the object, and send it to another remote R. [What I did so far]: 1. I used socketConnection in R and listen/accept in C++, to establish one blocking socket. 2. I used saveRDS to save the R object into socket directly 3. I want to use "recv()" in C++ to receive the R object. [Issues I met]: I found actually, the saveRDS writes the R object with XDR format. I could not know how many bytes are sent into socket, when calling saveRDS to save R object. So in the C++ binary, I could not know exactly how many bytes I should receive from the socket. It is not safe for me, to always use a pre-defined buffer size to read from the socket. Any suggestions for this? Are there safe way for me to read the R object from the socket?
There is nothing preventing you from adding a frame with the size of the serialization - that is what Rserve does (mentioned earlier by Dirk - it even has a C++ client ...): it uses a fixed-size header that specifies the kind of payload and its length, then the serialization follows in the payload. That way you only need to read a fixed header. Cheers, Simon
I do not do any conversion with the received data, and only need to transfer them into a remote R to do the function execution. ===================== Rong "Jessica", Li (????) Platform Symphony TET, CSTL, IBM Systems &Technology Group, Development Tel:86-10-82451010 Email:ronglli at cn.ibm.com [[alternative HTML version deleted]]
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