java - Whats the point of transactional non xa JMS Sessions? -

-

is me or jms api inconsistent regards how models transacted , xa transacted equivalents ?

i dont appreciate why there xa forms connectionfactory, queueconnectionfactory, session , on , duplication:

for example

xaqueueconnection      xaqueuesession     createxaqueuesession() throws jmsexception;      queuesession     createqueuesession(boolean transacted,                        int acknowledgemode) throws jmsexception;

contains methods non transacted , transacted session ?

  • why both ?
  • if have xaqc why want non transacted qs ?
  • if wanted why create xaqueueconnection ?

these provide gradient of classes of service. jms allows for...

  • messages outside of unit of work
  • messages inside of single-phase commit (1pc)
  • messages inside of two-phase commit (2pc / xa)

the cost of each of these increases degree of reliability. generally, want use least-cost method application requires. if have non-persistent, expiring, fire-and-forget message (for example, stock ticker event) putting inside unit of work wasteful. similarly, if need transacted session jms resource manager, xa waste.

on other hand, if need xa operations, not mean should use xa operations. example, may have single connection within maintain 1 session xa transactions , session non-xa messaging. first of these receiving requests long-running processes , updating database process details. other session used send periodic status updates. connection must xaconnection performance purposes need both xa , non-xa session underneath it. maintain separate connections method allows perform both xa , non-xa messaging within single connection. brokers many connections, optimization can critical.

admittedly not common use case, it still valid case , useful enough have been included in specification.


Comments

Post a Comment

Popular posts from this blog

python - Scipy curvefit RuntimeError:Optimal parameters not found: Number of calls to function has reached maxfev = 1000 -

-
Image
i want make logharitmic fit. keep getting runtime error: optimal parameters not found: number of calls function has reached maxfev = 1000 i use following script. can tell me go wrong? use spyder still beginner. import math import matplotlib mpl scipy.optimize import curve_fit import numpy np #data f1=[735.0,696.0,690.0,683.0,680.0,678.0,679.0,675.0,671.0,669.0,668.0,664.0,664.0] t1=[1,90000.0,178200.0,421200.0,505800.0,592200.0,768600.0,1036800.0,1371600.0,1630800.0,1715400.0,2345400.0,2409012.0] f1n=np.array(f1) t1n=np.array(t1) plt.plot(t1,f1,'ro',label="original data") # curvefit def func(t,a,b): return a+b*np.log(t) t=np.linspace(0,3600*24*28,13) popt, pcov = curve_fit(func, t, f1n, maxfev=1000) plt.plot(t, func(t, *popt), label="fitted curve") plt.legend(loc='upper left') plt.show() your original data t1 , f1 . therefore curve_fit should given t1 second argument, not t . popt, pcov = curve_fit(func,...
Read more

binding - How can you make the color of elements of a WPF DrawingImage dynamic? -

-
we have need make vector graphic images change color of elements within graphic @ runtime. seem setting colors based on either static or dynamic resource values wouldn't work. want have multiple versions of same graphic, each abilty set graphic elements (path, line, etc) different colors don't think dynamic resource approach work. leaves data binding seems right approach. update graphic use data binding expr instead of hard-coded brush color so: <drawingimage x:key="graphic1"> <drawingimage.drawing> <drawinggroup> <drawinggroup.children> <geometrydrawing geometry="f1 m 8.4073,23.9233l"> <geometrydrawing.pen> <pen linejoin="round" brush="{binding line1brush, mode=oneway}"/> </geometrydrawing.pen> </geometrydrawing> <geometrydrawing geometry="f1 m 3.6875,2.56251l"> <geometrydrawing....
Read more

c# - How to add a new treeview at the selected node? -

-
i have treeview 4 levels; parent, child, grandchild, great-grandchild. selectednode @ grandchild level. what i'm trying create new "treeview" @ grandchild - no, dont wnat create new node "selectednode" (grandchild). should somelike this: parent child grandchild (new treeview) parent grandchild great-grandchild child great-grandchild child grandchild grandchild it similar parent table mother , father went off , had new childern different spouse other spouse of there existing children. private sub populaterootlevel() ' query find first round of parent populatenodes(dt, jcatreeview.nodes) end sub private sub populatenodes(byval dt datatable, byval nodes treenodecollection) each dr datarow in dt.rows dim tn new treenode() tn.text = dr("title").tostring()...
Read more