Slashdot Mirror
Java RMI
The Scoop
Remote Method Invocation (RMI) is the object-oriented remote procedure call (ORPC) facility for distributed programming in Java, since the 1.1 days. RMI also served as motivation and a proof-of-concept for jini, javaspaces, and numerous other solid distributed networking technologies. Of course, anyone from the academic distributed programming world knows Wollrath, Waldo, and Riggs.
Yet, despite a myriad of books over the past five years on network programming, RMI always seemed to be the stepchild: relegated to a single chapter (buried on page 496, of course) that always said that RMI was "better" than sockets and "worse" than CORBA. Now, granted that RMI is operationally rather trivial compared with CORBA and was (prior to RMI/IIOP) a unilanguage distributed ORPC technology -- but still. For those of us who have to interoperate with RMI (whether welcome from the Java world or not), the lack of in-depth technical analysis (beyond the spec) has been a hindrance.
Fortunately, this trend is finally starting to buckle with the release of several in-depth RMI books including: Java RMI, Java.rmi, and Mastering RMI: Developing Enterprise Applications in Java and EJB. As evidence of this problem, Grosso states the same in his introduction – and actually pulls it off without sounding self-serving.
I chose Grosso's text because of the cute squirrel (aka the O'Reilly brand), Grosso's recent series of articles on the hashbelt algorithm, and his unadulterated academic knowledge management and mathematics bent. Fortunately, I was rewarded: this animal returns to O'Reilly's pre-bubble quality. Koodoos to both Grosso and his editors (Knudsen, Loukides, and Eckstein) for getting the train back on the track.
What's to Like
Bottom line is that Grosso simply covers the topics and does so with solid conceptual and code coherence – even by O'Reilly standards (over 40 animals grace my shelves). His prose and explanatory patterns make it clear that he has actually gotten into the real-world of RMI, and doesn't hesitate to highlight both good and bad parts. You cannot be dozing off when you read this (at least not if you expect to understand it) -- this is written by someone with solid analytic thinking skills and it shows. After too many years of "there are no caveats" journalism and publishing, this is a nice reversion. Further, I can only imagine that his current employment is a testament to his real-world knowledge of RMI.
Grosso hits on a vein which is not well-appreciated: when not smoothed over by marketing people, RMI is actually a mostly-capable ORPC technology. Certainly activation and RMI/IIOP really began to make things interesting, from Java2 and EJB respectively. Discussion of reference-counted distributed garbage collection, a feature missing from CORBA and other popular ORPC standards, also contributes a nice bonus (although Grosso's ardent attempt to debunk the "RMI doesn't scale" argument is rather weak, even going so far as to rehash the definition of Threads and threadpools – this complexity mismatch is an ugly giveaway that a well-intentioned editor went astray).
What sets this text apart is the tight focus on nitty-gritty implementation details of RMI itself. After all, these RMI texts are way too late to the game to reteach how to write "baby RMI" code: 5 years after the original spec, you either know how to write RMI or you don't. Grosso simply gives you a solid in-depth analysis of all the obscurities of the RMI runtime, custom sockets, dynamic classloading, activation, MarshalledObjects, and HTTP tunneling. In other words, all the interesting real-world topics whose official documentation is poor and which the various RMI tutorials (written many years ago) ignored.
While canonical, the single banking example followed through the text was well-executed, although authors continue to underestimate the prevalence of readers who consume textbooks non-linearly.
What's Not to Like
RMI/IIOP is shaping up to be a fascinating contributor to the "cleanup the EJB mess" discussion. Dedicating a measly 13 pages (beginning on page 503, no less) to this critical topic seems a bit of an oversight – but maybe that is just my CORBA sentiments speaking. Either way, the mechanics of CORBA are sufficiently intricate in real-world deployments that saying "if you can build an RMI system, you can build a CORBA system" (p. 511) is a bit brazen (or naïve) for my tastebuds. I can only chalk up this oversight to deadline pressure, which is probably a Good Thing, since the book was supposedly in production over almost 2 years.
A minor point: the top-level organization of the book (Part I, II, III) is arbitrary, ignore it -- use the chapter organization instead.
The Summary
Quality: solid practical insight into the nitty-gritty operational implementation details of RMI in the real-world. You simply are not going to find solid O'Reilly-quality coverage of the topics elsewhere.
Relevance: If you are responsible for making RMI actually work in production systems, this might well be the next animal on your shelf – either now or later. If you want a breezy afternoon saunter around RMI, skip this. Instead, google one (of the many) free tutorials online."
You can purchase Java RMI from Fatbrain. Want to see your own review here? Just read the book review guidelines, then use Slashdot's handy submission form.
The Scoop
Remote Method Invocation (RMI) is the object-oriented remote procedure call (ORPC) facility for distributed programming in Java, since the 1.1 days. RMI also served as motivation and a proof-of-concept for jini, javaspaces , and numerous other solid distributed networking technologies. Of course, anyone from the academic distributed programming world knows Wollrath, Waldo, and Riggs.
Yet, despite a myriad of books over the past five years on network programming, RMI always seemed to be the stepchild: relegated to a single chapter (buried on page 496, of course) that always said that RMI was "better" than sockets and "worse" than CORBA. Now, granted that RMI is operationally rather trivial compared with CORBA and was (prior to RMI/IIOP ) a unilanguage distributed ORPC technology -- but still. For those of us who have to interoperate with RMI (whether welcome from the Java world or not), the lack of in-depth technical analysis (beyond the spec) has been a hindrance.
Fortunately, this trend is finally starting to buckle with the release of several in-depth RMI books including: Java RMI, Java.rmi, and Mastering RMI: Developing Enterprise Applications in Java and EJB . As evidence of this problem, Grosso states the same in his introduction ? and actually pulls it off without sounding self-serving.
I chose Grosso's text because of the cute squirrel (aka the O'Reilly brand), Grosso's recent series of articles on the hashbelt algorithm, and his unadulterated academic knowledge management and mathematics bent. Fortunately, I was rewarded: this animal returns to O'Reilly's pre-bubble quality. Koodoos to both Grosso and his editors (Knudsen, Loukides, and Eckstein) for getting the train back on the track.
What's to Like
Bottom line is that Grosso simply covers the topics and does so with solid conceptual and code coherence ? even by O'Reilly standards (over 40 animals grace my shelves). His prose and explanatory patterns make it clear that he has actually gotten into the real-world of RMI, and doesn't hesitate to highlight both good and bad parts. You cannot be dozing off when you read this (at least not if you expect to understand it) -- this is written by someone with solid analytic thinking skills and it shows. After too many years of "there are no caveats" journalism and publishing, this is a nice reversion. Further, I can only imagine that his current employment is a testament to his real-world knowledge of RMI.
Grosso hits on a vein which is not well-appreciated: when not smoothed over by marketing people, RMI is actually a mostly-capable ORPC technology. Certainly activation and RMI/IIOP really began to make things interesting, from Java2 and EJB respectively. Discussion of reference-counted distributed garbage collection, a feature missing from CORBA and other popular ORPC standards, also contributes a nice bonus (although Grosso's ardent attempt to debunk the "RMI doesn't scale" argument is rather weak, even going so far as to rehash the definition of Threads and threadpools ? this complexity mismatch is an ugly giveaway that a well-intentioned editor went astray).
What sets this text apart is the tight focus on nitty-gritty implementation details of RMI itself. After all, these RMI texts are way too late to the game to reteach how to write "baby RMI" code: 5 years after the original spec, you either know how to write RMI or you don't. Grosso simply gives you a solid in-depth analysis of all the obscurities of the RMI runtime, custom sockets, dynamic classloading, activation, MarshalledObjects, and HTTP tunneling. In other words, all the interesting real-world topics whose official documentation is poor and which the various RMI tutorials (written many years ago) ignored.
While canonical, the single banking example followed through the text was well-executed, although authors continue to underestimate the prevalence of readers who consume textbooks non-linearly.
What's Not to Like
RMI/IIOP is shaping up to be a fascinating contributor to the "cleanup the EJB mess" discussion. Dedicating a measly 13 pages (beginning on page 503, no less) to this critical topic seems a bit of an oversight ? but maybe that is just my CORBA sentiments speaking. Either way, the mechanics of CORBA are sufficiently intricate in real-world deployments that saying "if you can build an RMI system, you can build a CORBA system" (p. 511) is a bit brazen (or naïve) for my tastebuds. I can only chalk up this oversight to deadline pressure, which is probably a Good Thing?, since the book was supposedly in production over almost 2 years.
A minor point: the top-level organization of the book (Part I, II, III) is arbitrary, ignore it -- use the chapter organization instead.
The Summary
Quality: solid practical insight into the nitty-gritty operational implementation details of RMI in the real-world. You simply are not going to find solid O'Reilly-quality coverage of the topics elsewhere.
Relevance: If you are responsible for making RMI actually work in production systems, this might well be the next animal on your shelf ? either now or later. If you want a breezy afternoon saunter around RMI, skip this. Instead, google one (of the many) free tutorials online."
I think that most of corba/dcom/rni etc. are particularly over complicated. They place a burden on the programmer in the wrong place. It's worth checking out plan9's approach to distributed computing. Authentication is taken care of by an authentication server. Once you've got an authentication ticket then you can access networked resources by binding remote services into your local namespace. Rights are granted by the usual mechanisms of usernames & groups.
The familair paradigm of users and groups has been deliberately leveraged because that's what is familiar, after all it's stood the 30 years test of time. This extends to which processors on the network you an run processes on etc. etc.
It's worth studying if nothing else.
There are places where the networks are not touching,and there are places where they are-Boeing's Lori Gunter
yes, I too found little in the review preview about XML.
I have used both CORBA and RMI. I don't know why they are shown as competitive products.
CORBA is used when you wan't cross language compatibility. (c / Java / C++, etc.)
RMI is used when you want Cross platform compatibility give by JAVA.(windows, Linux, Mac)
DCOM is used when you are working on M$ Windows.(windows, C++)
To me these 3 are complimentary, with CORBA being one of the hardest but most dynamic. So naturally I expected to see in the review a statement about where the XML thingy fit into this puzzle. Why would you mention these 3 technologies without mentioning that?
Er, given that DCOM is/was DCE RPC, and even Microsoft themselves are sending DCOM the way of the dinosaur, I think you're remembering the past through rose-tinted glasses...
They are messaging specs (at different layers). You can do RPC over them (SOAP includes a way to encode RPC requests, but you can send any sort of asynchronous message you want).
Come on people, stop talking about things you don't know anything about! The specs are public, READ THEM!
One other thing to consider is messaging, like that provided by JMS (now part of J2EE). It's a good alternative to the purely synchronous world of RPC (embodied by XML-RPC, SOAP, and the like) because it gets around some of the vagaries of making calls over an unpredictable environment (the Internet). Things like publish-and-subscribe, guaranteed delivery, and asynchronous processing are pretty cool, since synchronous RPCs can get waylaid by part of the network going down, etc.
I've only fooled around with it, never used it in a real project, since message-driven beans are pretty new. Does anyone know of a project that makes extensive use of Java messaging, particularly using message-driven beans?