Execution failed with :Communication failure with broker

Dear all,
Do anyone meet the following error:Communication failure with broker ?
If,which situation will arouses this? Thanks a lot.

[1950]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.threadmgmt.ThreadPool – execute thread release : 0 / 30
[1949]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.exec.NodeRunner – Removed node : R_receiveShowCatalogFromPush[1948]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.exec.NodeRunner – fire next rules[1947]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.exec.NodeRunner – Got state change from R_receiveShowCatalogFromPush : 4[1946]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.wm.plugin.WmTemplateServiceNode – Execution failed with :Communication failure with broker[1945]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.wm.plugin.WmDeliverDocNode – publishing request to lgcyIntAribaApp : null[1944]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.wm.plugin.WmTemplateServiceNode – Translated to lgcyIntAribaApp for instances :1[1943]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.wm.plugin.WmTemplateServiceNode – Converting logical routing code lgcyIntAribaApp[1942]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.wm.plugin.WmTemplateServiceNode – Populating request envelope for rule R_receiveShowCatalogFromPush[1941]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.exec.NodeRunner – fire next rules[1940]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.exec.NodeRunner – Got state change from R_receiveShowCatalogFromPush : 1[1939]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.threadmgmt.ThreadPool – execute thread consumed : 1 / 30[1938]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.exec.NodeRunner – Adding ‘R_receiveShowCatalogFromPush’ to pending list : 14098818[1937]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.exec.NodeRunner – Nodes to execute : 1[1936]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.ServiceBusMgr – Rule script found : alu.canonicals.Push:PushDoc[1935]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.store.InvokeContextStoreMap – Using context id : :1281332097471[1934]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.rulesengine.ruleflow.impl.BasicPayload – /PushDoc/PushDoc/header/group_no = 05[1933]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.rulesengine.ruleflow.impl.BasicPayload – /PushDoc/PushDoc/header/document_type = CatalogUploadRequest[1932]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.rulesengine.ruleflow.impl.BasicPayload – /PushDoc/PushDoc/header/group_no = 05[1931]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.rulesengine.ruleflow.impl.BasicPayload – /PushDoc/PushDoc/header/document_type = CatalogUploadRequest[1930]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.rulesengine.ruleflow.impl.BasicPayload – /PushDoc/PushDoc/header/group_no = 05[1929]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.rulesengine.ruleflow.impl.BasicPayload – /PushDoc/PushDoc/header/document_type = CatalogUploadRequest[1928]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.rulesengine.ruleflow.impl.BasicPayload – /PushDoc/PushDoc/header/document_type = CatalogUploadRequest[1927]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.store.RulesStoreMap – Found version : 0[1926]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.store.RulesStoreMap – Checking database to find latest version : null[1925]2010-08-09 13:34:57 CST [ISP.0090.0004C] com.alu.esb.mgr.store.RulesStoreMap – Using latest version : null for alu.canonicals.Push:PushDoc

Your broker may not be connected with IS.