Difference between revisions of "Serializing and deserializing root objects"
From GlueXWiki
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#include "TMessage.h" | #include "TMessage.h" | ||
− | // create TMessage object | + | // create TMessage object capable of holding serialized ROOT object |
TMessage *tm = new TMessage(kMESS_OBJECT); | TMessage *tm = new TMessage(kMESS_OBJECT); | ||
+ | |||
+ | // fill internal buffer with serialized version of some ROOT object | ||
tm->WriteObject(some_root_object); | tm->WriteObject(some_root_object); | ||
+ | |||
+ | // get pointer to internal buffer and length | ||
+ | char *buffer = tm->Buffer(); | ||
+ | int bufferLength = tm->Length()); // in bytes | ||
+ | |||
</pre> | </pre> |
Revision as of 14:22, 30 June 2009
Introduction
ROOT objects can be serialized to a byte array or reconstructed from the byte array quite easily. One reason to do this might be to store or transport ROOT objects in a way not supported by ROOT itself. An example is transport of a ROOT histogram from a producer to a consumer program via the cMsg package, a publish/subscribe messaging system that will be used extensively in the Hall D online monitoring system (see section on Example Programs below).
Serialize
ROOT TMessage objects can hold serialized ROOT objects. They are filled via the write() method:
#include "TH1F.h" #include "TMessage.h" // create TMessage object capable of holding serialized ROOT object TMessage *tm = new TMessage(kMESS_OBJECT); // fill internal buffer with serialized version of some ROOT object tm->WriteObject(some_root_object); // get pointer to internal buffer and length char *buffer = tm->Buffer(); int bufferLength = tm->Length()); // in bytes
Deserialize
Example Programs
cMsgRootProducer.cc,cMsgRootConsumer.cc,Makefile Examples demonstrate transport via cMsg package.