MasteringVFP/14/2

=== 從COM到MTS ===
====介紹====
VFP 也能撰寫支援 MTS 伺服器的元件，最主要你得先生成 MTXAS.APPSERVER 物件，然後調用此物件來進行交易(Transaction)。
<pre>
#DEFINE MTX_CLASS   "MTXAS.APPSERVER.1"
LOCAL oMTX,oContext
oMtx = CREATEOBJECT(MTX_CLASS)
oContext = oMtx.GetObjectContext()
</pre>

在交易的最後記得呼叫 SetComplete() 表明交易完成，若失敗，則調用 SetAbort() 表明交易中止。另外還可以使用 IsInTransaction() 來測試目前是否在交易中。

====範例====
<pre>
DEFINE CLASS mts2 AS Custom OLEPUBLIC
   MyColor = "Green"
   PROCEDURE InUsa (tcCustID)
      LOCAL llInUSA,oMTX,oContext
      oMtx = CreateObject("MTXAS.APPSERVER.1")
      oContext = oMtx.GetObjectContext()
      llInUSA = .F.
      USE CUSTOMER AGAIN SHARED
      LOCATE FOR UPPER(cust_id) == UPPER(tcCustID)
      IF FOUND()
         llInUSA = (ATC("USA",country)#0)
      ENDIF
      oContext.SetComplete()
      RETURN llInUSA
   ENDPROC
ENDDEFINE
</pre>

====怎麼用程式來安裝呢??====
<pre>
#DEFINE   MTS_CATALOG      "MTSAdmin.Catalog.1"
#DEFINE   ERR_NOACTION_LOC   "No action taken."
LOCAL oCatalog,oPackages,oUtil,i,j,oComps,nPoslcPackage
LOCAL lPackageExists,oCompRef
LOCAL oProject,lnServers,laProgIds,lcSaveExact,oPackageRef,lctrans
lcPackage = ALLTRIM(THIS.cboPackages.DisplayValue)
lPackageExists = .f.
SELECT mtssvrs
LOCATE FOR include
IF !FOUND() OR EMPTY(lcPackage)
   MESSAGEBOX(ERR_NOACTION_LOC)
   RETURN
ENDIF
THIS.Hide
oCatalog = CreateObject(MTS_CATALOG)
oPackages = oCatalog.GetCollection("Packages")
oPackages.Populate()
FOR i = 0 TO oPackages.Count-1
   IF UPPER(oPackages.Item(m.i).Name) == UPPER(lcPackage)
      oPackageRef = oPackages.Item(m.i)
      lPackageExists=.T.
      EXIT
   ENDIF
ENDFOR
IF !lPackageExists   &&creating new package
   oPackageRef = oPackages.Add
   oPackageRef.Value("Name") = lcPackage
   oPackages.SaveChanges
ENDIF
oComps = oPackages.GetCollection("ComponentsInPackage",;
oPackageRef.Key)
oUtil = oComps.GetUtilInterface
SCAN FOR include
   oUtil.ImportComponentByName(ALLTRIM(progid))
ENDSCAN
oPackages.SaveChanges()
oComps.Populate()
SCAN FOR include
   DO CASE
   CASE trans = 1
      lctrans = "Supported"
   CASE trans = 2
      lctrans = "Required"
   CASE trans = 3
      lctrans = "Requires New"
   OTHERWISE
      lctrans = "Not Supported"         
   ENDCASE
   FOR j = 0 TO oComps.Count-1
      IF oComps.Item(m.j).Value("ProgID")=ALLTRIM(progid)
         oCompRef = oComps.Item(m.j)
         oCompRef.Value("Transaction") = lctrans
         oCompRef.Value("SecurityEnabled") = ;
IIF(THIS.chkSecurity.Value,"Y","N")
      ENDIF
   ENDFOR
ENDSCAN
oComps.SaveChanges()
oPackages.SaveChanges()
</pre>