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Quick start 2002-03-05 Quick start with UBF This will jump start you with UBF. All you need is an internet connection and Telnet to get started. First read the contract - in the next section. Then fire up Telnet and investigate the server (by hand) - then you can see what's really going on The Contract +NAME("file_server"). +VSN("ubf1.0"). +TYPES info() = info; description() = description; services() = services; contract() = contract; file() = string(); ls() = ls; files() = {files, [file()]}; getFile() = {get, file()}; noSuchFile() = noSuchFile. +STATE start ls() => files() & start; getFile() => binary() & start | noSuchFile() & stop. +ANYSTATE info() => string(); description() => string(); contract() => term(). A telnet session The following is a telnet session. User input is in red. Comments are in blue. Server output is in black, some lines have been omitted: Set up a connection telnet enfield.sics.se 2000 telnet localhost 2000 Trying 127.0.0.1... Connected to localhost.localdomain. Escape character is '^]'. {'ubf1.0',"meta_server"," see http://www.sics.se/~joe/ubf/ for details of this service type 'info'$ for information "}$ Ask for information 'info'$ {"I am a meta server - type 'help'$ to find out what I can do",'start'}$ Ask for a list of servers 'services'$ {#"test_server"&"irc_server"&"file_server"&,'start'}$ Activate a service {'startService',"file_server",#}$ {{'ok',"I am a mini file server"},'start'}$ Ask for information - note this has now changed since we are now talking to a different service 'info'$ {"I am a mini file server",'start'}$ Ask for the long description - note this has now changed since we are now talking to a different service 'description'$ {" Commands: 'ls'$ List files {'get' File} => Length ~ ... ~ | noSuchFile ",'start'}$ Do a list command 'ls'$ {{'files',#"ubf.erl"&"client.erl"&"Makefile"& ... Fetch a file {'get',"Makefile"}$ {1274~ ... ~'start'}$ Fetch the contract - this is the UBF(A) parse tree of the UBF(B) contract given above :-) {'contract'$ {'contract', {{'name',"file_server"}, {'info',"I am a mini file server"}, {'description'," Commands: 'ls'$ List files {'get' File} => Length ~ ... ~ | noSuchFile "}, {'services',#}, {'states', #{'start', #{'input',{'tuple',#{'prim','file'}&{'constant','get'}&}, #{'output',{'constant','noSuchFile'},'stop'}& {'output',{'prim','binary'},'start'}&}& {'input',{'constant','ls'}, #{'output', {'tuple', #{'list',{'prim','string'}}& {'constant','files'}&},'start'}&}&}&}, {'types', #{'file',{'prim','string'}}&}}}$ (  )