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I/O and DB Maker Operation
Offline computing tutorial Maintained by Victor Perevoztchikov

New features preliminary description

      Some remarks about IO in makers.

   Maker StTreeMaker provides I/O in postMDC2 format.

   It is based on StTree class.

1.  All the data is split into different branches.

2.  Branches can be grouped several to a file, but by default
    one branch - one file.

3.  Each branch has its own I/O mode:

     "0"=Do nothing

    Let us  write the data

StTreeMaker *treeMk = new

//  "tree"      here is arbitrary name assigned to maker instance
//  "psc0049_08_40evts.fzd" is the name of input file for run.
//              Only the part "psc0049_08_40evts" is used by the maker
//              to construct default output file names.
//              The directory path and extension is ignored

//  "bfcTree"   is the name of tree. By default it is bfcTree which is used
//              for main STAR output stream. But user can define his own
//              with different name

    treeMk->SetIOMode("w");     //define write mode

    treeMk->SetDebug();         //debug is ON

//      Now define different branches.

//      define branch with name "dstBranch" which will be filled
//      by dataset with name "dst"



//      trgBranch will be filled by ctf mwc trg structures

    treeMk->IntoBranch("trgBranch","ctf mwc trg");

//      Default output files for these branches will be:
//  dstBranch:  psc0049_08_40evts.dst.root
//  ftpc_rawBranch:  psc0049_08_40evts.ftpc_raw.root
//  trgBranch:  psc0049_08_40evts.trg.root
//  So you see, the word "Branch" is removed from file name

//      NOW, redefine output file for trgBranch


//      NOW, redefine output file for "trgBranch" & "ftpc_rawBranch"
//      and send them in one file

    treeMk->SetBranch("dstBranch",     "myFile.root")

//      OK, let us put all the branches in ONE file

    treeMk->SetBranch("*",     "All.root")

//  SPECIAL hist(ogram) or hist(ory) branch

//If name of branch is started from "hist" it is a special branch.
//It is filled only at the end of run, and apart of user defined information
//it is filled by all histograms from all makers

    treeMk->IntoBranch("histBranch","someParams someConst geant/.data/geom

                HOW TO READ BRANCHES

StTreeMaker *treeReadMk  = new StTreeMaker("treeRead",

StTreeMaker *treeWriteMk = new

treeWriteMk->IntoBranch("newBranch","name1 name2 ");

// treeRead  maker will read existing tree
// treeWrite maker will add new branches and will write them

                HOW to READ OLD FORMATS

New maker StIOMaker was developed.

1. This maker does not read anything itself. It supervises other I/O makers.

2. It loads needed makers itself, depending on input file

3. It can read XDF,MDC2 and current StTree formats

4. All I/O makers now inherit from one abstract StIOInterFace I/O maker class
   which allows StIOMaker to treat other makers in a similar way

5. All the I/O makers including StIOMaker support all methods of StTreeMaker

6. All formats will be accessible via this maker. All detailis
   are hidden from the user.

7. StIOMaker can handle multiple input files via very simple StFile class

  StFile *setFile = new StFile();

//              Input Tree
  StIOMaker *IOMk = new StIOMaker("IO","r",setFile);
//StIOMaker *IOMk = new StIOMaker("IO","r",MainFile);
  IOMk->SetBranch("*",0,"0");  //deactivate all branches
  IOMk->SetBranch("dstBranch",0,"r");  // activate only dstBranch

                NEW FEATURES of DB maker

As before DB supports period of validity. The time stamp of start validity
is presented in the file name of ROOT macros


    or in symbolic form


If there is no time-stamp  19950101.000000 is assumed

In addition some aliases for validities are allowed

sd97       19970101.000000
sd98       19980101.000000
year_1a    19990101.000000
year_1b    19990501.000000
year_1c    19991001.000000
year_1d    19991101.000000
year_1e    19991210.000000
year_2a    20000101.000000

So file name tcc_params.year_1a.C == tcc_params.19990101.000000.C

Now we do not have real time-stamp on simulation data you can
define special DB time at the beginning

  St_db_Maker *dbMk = new St_db_Maker("db",mainDB);

  OR equivalent

After this only macros with appropriate validity will be loaded.

        OUR database, based on UNIX directories and CINT macros
        is rather primitive. It can handle only one key == time-stamp
        Sometimes it is not enough. If 2 CINT macros create the same
        type of structure, a clash is inevitable.

  Let us say we have


With the same structure, but only one must be used.

We can now select which we want

   dbMk->SetOff("params/tpc/trspars/Trs*")      Off all Trs
   dbMk->SetOn ("params/tpc/trspars/TrsTest")   On  TrsTest

Now only  TrsTest.C will be loaded.