Hermes: A Tutorial and Reference Manual - Researcher - IBM
Hermes: A Tutorial and Reference Manual - Researcher - IBM
Hermes: A Tutorial and Reference Manual - Researcher - IBM
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username<strong>and</strong>theresourceoriginallyposted,<strong>and</strong>theneitherreturnsthe resourcebeinggrantedtotheuser,orreturnsaDeniedexception.1 gainaccess.Toprovideaccesscontrol,werequiretheownertoprovidea portintoanaccesscontrolfunction.Theaccesscontrolfunctionacceptsa postingtheresource.Therequestorofaresourcesuppliesaresourcename <strong>and</strong>receivesbackapolymorph,whichtherequestormustthenunwrap. Theownerofaresourcemaynotwishtoallowanyarbitraryuserto 4.Additional<strong>Hermes</strong>Constructs65<br />
Hereistheinterface: RepositoryExternal:using()definitions Resource:polymorph;<br />
PostOut:outportofPostIn; PostIn:inportofPostInterfaceffullg; PostInterface:callmessage( AccessFunction:AccessOut)--accesscontrolfunction constant(ResourceName,AccessFunction) exitffullg exceptionDuplicateNameffullg; PostedResource:Resource,--resourcebeingposted ResourceName:Charstring,--namebeinggiventoresource<br />
AccessInterface:callmessage( AccessIn:inportofAccessInterfacefinit(UserName),init(PostedResource)g; AccessOut:outportofAccessIn; constant(UserName,PostedResource) exitffullg exceptionAccessDeniedfinit(UserName),init(PostedResource)g; ReturnedResource:Resource)--theresourcegranted UserName:Charstring,--nameoftherequestor<br />
RequestInterface:callmessage( PostedResource:Resource,--resourceoriginallyposted<br />
RequestOut:outportofRequestIn; RequestIn:inportofRequestInterfacefinit(ResourceName)g; constant(ResourceName) Resource:Resource)--theresourcegranted exitffullg exceptionNotFoundfinit(ResourceName)g exceptionAccessDeniedfinit(ResourceName)g; ResourceName:Charstring,--nameofresourcebeingrequested<br />
ratherthantheportintotheresource. throughalter,forexample,inwhichcaseitwillreturnaportintothelter Theaccesscontrolfunctionmaydecidetograntlimitedaccesstotheresource 1Theresourcereturnedmayormaynotbethesameastheresourceposted.
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