Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.mixmin.net!eweka.nl!hq-usenetpeers.eweka.nl!border3.nntp.ams.giganews.com!Xl.tags.giganews.com!border1.nntp.ams.giganews.com!nntp.giganews.com!local2.nntp.ams.giganews.com!nntp.bt.com!news.bt.com.POSTED!not-for-mail NNTP-Posting-Date: Sun, 30 Dec 2012 05:02:51 -0600 Date: Sun, 30 Dec 2012 11:02:49 +0000 From: lipska the kat User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120410 Thunderbird/11.0.1 MIME-Version: 1.0 Newsgroups: comp.lang.java.programmer Subject: Re: Java servlet on browsers: dying or kicking ? References: <50d892e5$0$282$14726298@news.sunsite.dk> <50dbf6d1$0$80176$742ec2ed@news.sonic.net> <50dcfecc$0$292$14726298@news.sunsite.dk> <50dd5b51$0$80184$742ec2ed@news.sonic.net> <50de2260$0$293$14726298@news.sunsite.dk> <50df9ef7$0$284$14726298@news.sunsite.dk> In-Reply-To: <50df9ef7$0$284$14726298@news.sunsite.dk> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 8bit Message-ID: Lines: 47 X-Usenet-Provider: http://www.giganews.com X-AuthenticatedUsername: NoAuthUser X-Trace: sv3-MOH+DXOUYpD3gc3s5Dp7e+Vf+SLsm6meNprAZuWIRQZJ3yX4hpi8+FSlrZPGw1KBW5h9RMCZmQEaTQM!wSNi8hZ4b1iJsPNWTutGwmstmPE1oyt6MWvWHH5RGpZ3P6ZLGKaqnrVDxaRyeBklc6Qk8nEky3E= X-Complaints-To: abuse@btinternet.com X-DMCA-Complaints-To: abuse@btinternet.com X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 X-Original-Bytes: 3594 Xref: csiph.com comp.lang.java.programmer:20814 On 30/12/12 01:54, Arne Vajhøj wrote: > On 12/29/2012 8:00 AM, lipska the kat wrote: >> I see the _service layer_ as aggregating fine grained business methods >> behind a facade. The facade then exposes what are in effect 'atomic' >> services that implement a particular subset of the business as seen by >> the outside world. As far as external clients are concerned the >> interface to the business is clearly defined. > > Facade pattern Your point being ? >> My question is how can the orchestration of service layer services >> outside the system boundary be controlled in a way that would be >> guaranteed not to potentially break the [business] rules ? > > You need to have context. Either have client send all > context or send a ref to context saved in service layer. Unconvinced I'm afraid There are two possible types of actor interaction with a business Stateless and statefull. A stateless interaction for example might be a request for currency conversion, or a free ESTIMATE for goods or services. You may offer these alongside other free services, Clients can mix and match your stateless services all they want and it has no impact on your business. The other type is statefull. These interactions do impact the state of your business, In 20 odd years of designing and implementing business systems I have never come across a situation where a business is happy to allow it's clients to dictate the terms of business in a random and uncontrollable way. Any control exercised over the combination of statefull services effectively extends the system boundary so the whole argument (allowing external orchestration of services) becomes moot. This is not some academic conjecture on my part but hard experience in the real world. I'd be interested to hear what the original responder has to say about this. lipska -- Lipska the Kat©: Troll hunter, sandbox destroyer and farscape dreamer of Aeryn Sun