Recent blog entries for SeaDragons

12 Mar 2001 (updated 12 Mar 2001 at 17:44 UTC) »
apm (Andrew McKinlay) posted an article about Suneido recently, and, well, I can't reply to it. So I'm replying here with my comments.

I had recently decided to undertake an Obj-C project which would require a database backend. While I was thinking about file formats (before deciding not to reinvent the wheel, and while I thought I might implement the database part myself), I thought I'd dispense with file and record locking by having a single data manager which was messaged by (and messaged) an arbitrary number of client-interface-managers. Since only one object did read/write, file locking was unnecessary. I was excited to see Suneido use the same idea (no file/record locking, because a single database manager had exclusive read/write to files); not having studied databases, I thought it was interesting I'd come up with the same solution to simplify the ssytem. (ie, I was proud of myself for guessing a solution that turned out to be in existence)

BUT: what happens when the single database manager gets so many requests for data and instructions to write data that one manager running on one machine can't possibly withstand the load? If you scale this to enough clients, it will eventually happen regardless how small and quick the manager is. And if the manager is doing complicated search logic, these requests could potentially be so burdensome that even a relatively small number would kill it. Some possibilities that come to mind are:
(a) have several managers acting as peers to service requests filtered through a load-balancer; each manager has equal access to a shared drivespace ... but now they need to either
    (i) use file locking not to overwrite one another with simultaneous write requests,
    (ii) message one another to be sure nobody else is working on a simultaneous request that interferes, which could be a problem by causing delays while the managers message one another about individual files and waiting for the results instead of just getting the results, or
    (iii) the load balancer keeps all requests for any particular record going to the same database manager ... but if the clients don't know which records they're looking for until the search logic is processed, which is likely in lots of database uses, this can't be done without additional access by the load-balancer to the data, which makes the "database managers" irrelevant since the work is being done by the load-balancer .... or (hopefully not)
(b) it doesn't scale beyond the capabilities of the box containing the database manager, so either use a big, butch box or a non-intense request load.

Have I missed something? Please write. I'm trying to deal with the same problem myself, and am interested in either (a) using your solution as a backend for handling my problem, or (b) using your solution to enlighten my search for my solution.

I'm interested in creating a piece of open-source-ware which is capable of handling enterprise-level demands, so these concerns are fairly serious to me. Personally I will not soon need anything requiring load balancing of requests, but I think this is better built in than bolted on (like security). Also: Suneido's site offers binaries built for operating systems which offer apps the Win32 API ... does Suneido require this API? (I haven't looked at the code.) Assuming the guts of Suneido are mostly code for handling Suneido's OO language and its search info, there's little obvious reason the Win32 API need be invoked ... although the code for controlling MS "Windows" UI elements certainly would have to be.

Will Suneido be portable to non Win32 environments? Will it turn up on *nix boxes where I will want to use it? And mostly: How do you answer extreme request loads? (ie, assuming you put the database manager module on a dedicated box and this is not enough to satisfy the requests?) Is this a concern for Suneido?

Best wishes!

Edited Later: Andrew McKinlay posted this in Suneido's forums for discussion, and answered there that scalability was (at least temporarily) a sacrifice made for performance and for expediance (to get a product working, so people don't get tired cosing forever without the payoff of seeing the code doing work)

Frustrating not to be able to reply to articles. "Whatever" posted about a "lawyer-free" zone, and wondered about how to prevent lawsuits over things done in that space. "Whatever" apeared to want to bind everyone in the space to a covenant not to sue, but to be enforceable such agreements require formalities which no-one is likely to wish to ensure occur, if they are trying to permit membership in the "lawyer-free zone." What "Whatever" wants is perhaps an arbitration clause in the membership agreement, which appoints (for example) a panel of members to arbitrate disputes. Good language for arbitration clauses depends on what one hopes to do with them. A federal law declaring arbitration agreements enforceable under the conditions that contracts generally are enforceable would help Whatever's cause if it were dragged into court: whatever could refuse to defend on the merits of the complaint, and require remand to arbitration. The arbitors can be given authority to do quite a bit, including sanctioning persons who improperly take arbitration matters to court for harrassment purposes. I assume from Whatever's post that he doesn't want a zone of lawlessness, but of common courtesy and reasonableness within the framework of the values of the member community. A panel of members should be able to do this admirably. Of course, the presence of legal counsel to be sure the panel doesn't botch it in ways that would make the arbitor's decision unenforceable is a good idea. I think a short agreement which references membership materials but contains mostly just the terms of the arbitration agreement would be best for this sort of thing: people don't read click-wrap agreements, so it's got to be short and clear so people get it. It's got to be conspicuous, obvious ... and not hidden with unintelligible mumbo-jumbo.

A self-policing community could be achieved in this way, though the possibility exists that a litigious person could try to take a complaint to court. The positive side is that they're going to have to pay their attorney up-front, because an attorney looking at an apparently valid arbitration clause will not risk his own money walking into court when mandatory arbitration has been ignored .... And attorneys' fees are an effective bar to litigation for most complaintants. It's only certain types of well-heeled people that remain a problem.

An access problem exists, though: if the community's recources are available on the internet, people will be tempted to link to them in ways that ignore the sign-in sheet; so every page will have to look for a "I accepted the arbitration clause" cookie, and give non-cookie users the agreement first. Also, people tend to copy and paste text -- sometimes with attribution -- into emails, online bulletin boards, etc. People who do this will expose content which members think is not going to the courts to the world at large, which is not party to the membership agreement. One needs to think about what to do with reposts, and whether arbitration panels need some guidelines, such as a Membership Credo, to inform their judgment as to what to make of complaints.

Lawyer-free zone is "interesting" in concept, but what does one want to do that one is afraid of being sanctioned for in court? Or is not the sanction, but the fear of the expense of court? A more complete idea of what you want out of the "lawyer-free zone" is needed before it can be designed. Keep thinking on it.

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