Monday, July 20, 2009

Collaborative AT Instances: Pros & Cons

This post examines the pros and cons of consortial or collaborative AT instances. My comments are based on my experience administering the Yale University Library Collections Collaborative AT project and MSSA's AT development.

  1. The central benefit of a consortial/collaborative AT instance is the consolidation of systems, procedures, practices, and resources. Having one system, one set of procedures, one course of training across multiple repositories not only conserves resources, but also greatly facilitates consistency and efficiency across the institution. Such a configuration inherently allows for enhanced understanding of each other’s collections, and provides faster and more consistent access to collection information, as well as the possibility of—from one location—getting an overview of the special collections holdings across diverse repositories. In Manuscripts and Archives alone, implementation of the AT will result in the consolidation of numerous databases, centralizing collection information and reducing ongoing systems maintenance for these un-integrated databases.

  2. Centralizing collection and other archival information leads to increased security, as potentially sensitive information will no longer be scattered across databases, electronic office files, and often, paper logs.


  1. The primary challenge facing collaborative/consortial instances is that the AT does not scale well for large, complex data sets and hence causes noticeable performance issues. Based on an acknowledged design flaw, the AT will impede performance/functionality at a certain point (see my previous post on Resource loading). As a result, especially for large institutions with multiple repositories or, more importantly, with extensive legacy data, consolidating multiple systems in a single AT instance will result in a slow performing system. Unfortunately, there is currently no plan to alter the design of the AT to address this issue in the 2.0 release, but the potential exists for a third round of grant support (to merge the AT with Archon) that would allow for such. The only alternatives at this point are for one of us institutions to pay a consultant to do the redesign work, which might be costly, or to develop lookup tools/plug-ins that query the database without having to say build an entire Resource.

  2. Sustainability is another major issue. With two major releases left, development of the AT is coming to a close. Unfortunately this is happening just as many of us are finally getting around to evaluating and adopting the AT. Thankfully though with version 1.5.9 the AT team introduced plug-in functionality as a viable means for the community to customize and develop the AT. In addition, it's exciting to hear that the opportunity exists for a third round of grant support to merge the AT with Archon. Beyond greatly expanding the functionality and usability of AT/Archon, this would allow for finishing any existing development commitments still on the table when the AT development ends.

  3. A third issue for consortial/collaborative instances is that any modifications/customization done with the AT by the superuser, e.g. modifying default values, lookup lists, user-defined fields, etc., apply to the instance as a whole and cannot be applied to just a single repository. Extensive modification of lookup lists, user-defined fields, and default values may thus result in a cluttered, hard to use interface or may even impede efficiency and performance. Plug-ins may be a solution to this problem though as they can be used to alter appearance and workflow.

  4. A fourth issue is that the only way to restore an instance (e.g. after a crash or failure) is to import an entire MySQL dump. Hence if one repository or individual screws something up, you'll have to go back to the last backup of the entire database, which may cause lots of data to be re-entered.

  5. A fifth challenge is the difficulty of migrating legacy data, especially instance or box information (e.g. location, box type, barcode, etc.) into the AT. Migration can also be difficult for those institutions that do not have EAD 2002 or who lack the expertise to export, format and import their legacy data. For those institutions like us with an significant amount of complex legacy data the only real option is to hire a consultant and develop a custom import process/plug-in.

  6. A sixth shortcoming of the AT is it's inability to support the full EAD tag set, meaning that addition tools (e.g. stylesheets) or systems may be necessary to fully manage an institution's finding aids. On the bright side, especially for smaller institutions or those who lack a finding aid display/delivery system, the proposed AT-Archon merger might address the issue of full EAD support.

  7. A seventh issue is the inability to batch edit data in the AT. For those with a little know-how though a MySQL database administration tool such as Navicat can be used to query and update data in the AT's MySQL tables. This is definitely beyond the capability of the typical user so you may want to address this inability via a plug-in.

All told, it might seem that AT has more than its fair share of cons. This is not what I want to get across. True, there are some issues to take into consideration especially when creating a collaborative instance, but as MSSA is easily the largest user of the AT, none of what we've encountered thus far is a real deal-breaker. True, we'd like it to perform better, but there are options at this point to at least sidestep this issue until the AT/Archon redesign. And with plug-in functionality now available and soon to be expanded, the means for addressing the AT's shortcomings is now in the hands of the community. We just need to step up.

Monday, July 6, 2009

AT Issues: Resource Handling

We have run into a significant performance issue at the half-way juncture in our legacy data migration efforts. We have found that Resources are taking much too long to load--small ones are taking at least 15 seconds; medium resources are taking up to 3 minutes; our largest ones are taking upwards of 5 minutes. Again, since we're only half-finished migrating our legacy data, the problem is likely to get much worse, especially as we begin to create/describe the thousands of digital objects we've been waiting to use the AT for.

We think the reason for the problem is how the AT loads Resources, i.e. recursively issuing SQL commands for each component, rather than issuing a single command for all resource components at once. Hence, given a large, complex finding aid (e.g. one with several levels of nested components and associated instance and location information), the AT grinds to a stand-still as it tries to systematically open all of the hierarchy. The main issue here appears to be the number and depth of nested components. Resources with only one or two levels of nested components do seem to open right up, the exception being two-level resources that have larger numbers of sub-components. However, resources that have three or more levels of nested hierarchy always open slowly, even if they don't have many actual associated instances.

We have tried to address the problem by maximizing the memory assigned to the client (see AT Wiki), boosting the database server's use of system memory, increasing the key buffer size, and engaging Memory Lock to discourage swapping--all to no avail. These steps however did boost performance of the MySQL database administration tool Navicat, which we use to access the MySQL database. This therefore points to the problem as lying in the AT and its Java encoding. This hypothesis was further supported when we set up a slow query log (i.e. anything over 2 seconds) on the database and tested resource loading, finding that no such queries were logged. As a result, all of our efforts seem to suggest that while we can indeed speed up operation of the MySQL database, we cannot speed up the performance of the Java that hits or interacts with the database. Since this however lies in the core of the AT code, it would have to be addressed either by the AT development team and put into the next/final release, or developed externally and then somehow offered back to the AT community. We are not sure yet how to proceed. An alternative that we and perhaps others might be happy with would be for only the top-level components (i.e. c01s) be built and displayed within the main Resources window, with further sub-components built when clicked. After all, you don't need to see/retrieve the whole Resource to make an edit to a specific part.

One of the questions this problem has raised for us is why hasn't anyone noticed/reported this performance issue? Was this borne out in scale testing? Surely there are other repositories who have loaded large finding aids, or who are working with complex resources or digital objects. Are they not using/editing these Resources and therefore not noticing the lag in performance? Perhaps they haven't ingested the amount of instance and location information that we have? Or, is there an upper data limit to the AT's functionality? That seems short-sighted. Regardless, others are bound to run into the problem sooner or later as they begin to ingest more and more data into the AT. As a result, we hope that progress can be made to address this critical problem.