Optimizing Performance

• Export smaller sized web pages - Generating a map server image of 400 x 300 requires less computation than an image of 800 x 600. Larger views will usually include more objects and so require greater display computation. In addition, serving larger images means moving larger amounts of pixels into the created image and then transmitting those larger numbers of pixels down the Internet pipes connecting the server to the user's browser.

• Avoid use of very large .map files - The larger and more complex the component the slower will be the response of the map server. Just as with interactive use of Manifold, performance of the map server will improve as the user zooms in so that fewer objects participate in the display.

• Avoid unnecessary use of images and surfaces - Images and surfaces are much slower than drawings for the information they provide. The Manifold map server will happily serve images and surfaces but these should not be used as casual substitutions for drawings when a drawing will do as well and will provide higher performance.

• Install adequate RAM - As components in the .map file are used, they are read off disk and brought into RAM. Once a component is in RAM, it stays there unless the RAM must be freed for some other purpose. The map server can work faster if the components it needs are already in RAM. As the parts of the .map that are served are brought into RAM and stay there (as a result of normal Windows RAM caching) access speed will increase. This only works, of course, if there is enough RAM so that the cached .map data is not flushed from RAM because some other Windows application needs the RAM.

• Eliminate initial load lag - The first time a very large map is served the map server will be slow to respond while the .map is opened and loaded for the first time. After creating a site the webmaster should browse the site and choose Zoom to Fit with all layers turned on. This will load the entire .map file into RAM. Thereafter, server response will be faster.

• Match component projections to maps - If a map is served, all layers in that map should have exactly the same native projection as used by the map. This will eliminate any need to re-project on the fly. This is especially important for images and surfaces.

• Delete unused components from the .map file - If the .map file contains many components other than those published in the web page the map server will respond slightly more slowly than if the .map file contained only those components being published. Delete any unused components from the .map file. This is normally a very minor impediment to maximum performance. However, if the .map file contains very large components that are not used the performance difference may be noticeable.

• Delete unused data from components - If the web site does not enable the Find tool or use queries there is no point in publishing a drawing that contains data attributes. Delete the columns in the drawing's table. When publishing maps that contain more than one drawing the Find tool will list all fields in all drawings in the map. Delete all fields that you do not want users to be able to employ in Find. This will reduce the size of the .map file.

• Avoid use of unnecessarily detailed data - A web site that provides overall, national data should not use extremely detailed high-resolution drawings. Use Normalize Topology with appropriate Location Precision settings to simplify drawings. This is often a key step to increasing the speed of redisplay, pan, zoom, etc.

• Use Zoom Ranges to present the level of detail required - Suppose we would like to show a national map for user orientation when zoomed out but we would also like to show very detailed shorelines when users zoom in. Create a map using two drawings: a highly detailed drawing plus a second, low resolution drawing created from the first by generalizing with Normalize Topology to a lower Location Precision value. Assign zoom ranges to the drawings so that the low-resolution drawing is the only drawing displayed when zoomed out and the high-resolution drawing is the only drawing displayed when zoomed in. When users browse the map in a zoomed out view the display will be fast because a fewer number of coordinates need be used to display the low-resolution drawing. When users are zoomed in the high-resolution drawing will become visible; however, only a portion of the high-resolution drawing will be seen in a zoomed in view so the display will still be fast.

• Store the .map file used on a fast, local hard disk - When the Manifold map server operates it accesses the .map file that was used with File - Export - Web Page to create the web page. If the .map file is located on a slow hard disk or on a different machine that must be accessed via a local area network then performance will not be as fast as if the .map file was immediately available on a local, fast hard disk.

• Avoid using intrinsic fields in queries. For example, if the length of a road line must be used, do not compute the length on the fly via the Length (I) intrinsic field. Instead, create a new column called Length and copy the contents of the Length (I) intrinsic field into this new column using the transform toolbar Copy command. When an intrinsic field is used in a query a small computation must be performed for every record for every query. If the intrinsic field is copied to a regular column the computation is done only once. The query can then use the regular column for faster operation.

• Very Important: If you create a default_admin.asp page for your IMS site, make sure to change access permissions on it so that ordinary Internet browsers cannot use it. To do this, in Windows Explorer right click on the default_admin.asp file, choose Properties and choose the Security tab. Remove all entries for allowed user names except Administrator or whatever other login name you wish to allow access to the administration page. Apply the settings and press OK. Neglecting this important step will not create a security breach in that hackers will be able to steal your data, but it will allow a malevolent user to effectively shut down your map server by repeatedly causing it to Reload .map files.

• Create an application and consider using High (isolated). - Create an application on the directory in which the web page is located and run it with high isolation. This runs the map server process as an isolated process outside of the IIS process and separate from any other applications running on IIS. This helps performance slightly (albeit at the cost of creating temporary files for every user), and also isolates the application so any errors in the scripts or map server application won't bring down IIS or any other application. For performance reasons, don't run more than ten IIS applications as High (Isolated). To run additional map server applications beyond ten, if the map server application is well debugged (that is, the scripts used in default.asp and other files are well debugged), use Medium (pooled) for the additional applications. Medium pooling might also be a good idea to reduce the creation of per-user temp files (see comments below).

• Don't enable session state - Within the IIS manager, in Properties - Configuration - App Options uncheck Enable session state. The Manifold map server does not use sessions so this can be unchecked if desired to eliminate the overhead of maintaining session state. In the same dialog it is a good idea to also uncheck Enable parent paths if desired. This has no impact on performance but it does improve security. Unchecking this box means the application can not refer to anything in higher directories. The map server application itself only refers to files within its own directory or subdirectories such as the images folder.

• Enable object pooling - If there are more than about 10 simultaneous users, enable object pooling. This is done in the Control Panel - Administrative Tools - Component Services manager. Drill down into COM+ Applications and find your map server application. Drill down into Components for that application and right click on the component there and choose Properties. Object pooling settings are on the Activation tab. Check the Enable object pooling box. The pooling parameters may be left on default settings.

• Store the .map file used on a fast, local hard disk - When the Manifold map server operates it accesses the .map file that was used with File - Export - Web Page to create the web page. If the .map file is located on a slow hard disk or on a different machine that must be accessed via a local area network then performance will not be as fast as if the .map file was immediately available on a local, fast hard disk.

• Install lots of RAM - Installing plenty of dynamic RAM is often the most efficient way to enable a server to serve more users faster. RAM is now so inexpensive (under $40 for a gigabyte) that it makes sense even for a hobbyist to install two or three gigabytes of RAM. If you are running an older motherboard that can hold only one and a half gigabytes, fill it up with the maximum amount of RAM right away it even if you don't feel you need it because eventually memory for older motherboards will be difficult to get.

• Use a fast processor - A faster processor will be able to serve more users. Upgrade to a gigahertz class processor.

• Use Windows Server 2003 or XP - Windows Server 2003 provides the best performance. Windows XP provides slightly better performance than Windows 2000. Do not use Windows NT or 16 bit Windows releases such as Windows Me or 98.

• Very Important: If you create a default_admin.asp page for your IMS site, make sure to change access permissions on it so that ordinary Internet browsers cannot use it. To do this, in Windows Explorer right click on the default_admin.asp file, choose Properties and choose the Security tab. Remove all entries for allowed user names except Administrator or whatever other login name you wish to allow access to the administration page. Apply the settings and press OK. Neglecting this important step will not create a security breach in that hackers will be able to steal your data, but it will allow a malevolent user to effectively shut down your map server by repeatedly causing it to Reload .map files.

• Use Windows Server 2003, XP or 2000.

• Do not allow anyone to work interactively, to read mail or to browse web sites on the machine that hosts your web site. If you must use the same machine interactively, make sure that users do not have Administrator privileges. If a user with Administrator privileges just once opens a malevolent email attachment the web server itself could be infected with a wide variety of "backdoor" viruses or Trojan Horse attacks. Never read email or browse the web when logged in as Administrator.

• Install the latest Service Pack for Windows. Service packs include many security patches.

• Install any supplemental security patches published by Microsoft after the last Windows Service Pack. Microsoft now has tools that can scan your system to determine if there are security patches published that have not yet been installed. Visit Microsoft TechNet at http://www.microsoft.com/technet/default.asp and drill down to their Security pages for information on the latest security tools and patches.

• Install anti-virus software. Keep your anti-virus software updated with regular downloads from your vendor.

• Install Microsoft URLScan (a free download from Microsoft TechNet) or similar tool. URLScan is a ISAPI filtering tool for IIS that rejects a wide variety of malformed URL requests before they can hit IIS. It is very easy to use. It was published by Microsoft in 2001 and is an absolutely essential tool to prevent many different types of Denial of Service attacks. No doubt the functions provided by URLScan will continue to be offered by Microsoft either as independent tools or built into IIS. Manifold IMS works perfectly with URLScan.

• Apply Microsoft's IIS Lockdown Tool (a free download from Microsoft TechNet) using Advanced Lockdown. Uncheck the box that disables support for Active Server Pages (.asp) and otherwise accept all of the defaults suggested by Advanced Lockdown. Manifold IMS works perfectly with Advanced Lockdown settings so long as Active Server Pages are still enabled. This tool is also very easy to use.

• Do not run unnecessary services. If your server runs a web site only, do not install or enable additional services such as FTP, NNTP or others. If such services are already installed, use Internet Services Manager to stop them. Do not install any accessory software or Windows components that are not required.

• Learn to use Advanced TCP/IP settings for the Internet Protocol in your Network properties for your network card. If your web site is intended only for specific machines (such as those on an Intranet), use IP security to deny access to any unauthorized machines (IP addresses). If you are connected to Internet, use TCP/IP filtering to permit only those TCP ports absolutely required to service your web site (typically, port 80 for HTTP and port 443 for HTTPS).

• If you can afford it, install a firewall and learn to use it. Use a hardware firewall and/or software solution such as Microsoft's Internet Security and Acceleration Server. Hardware firewalls now cost well under $200.

• Install the latest updates for Manifold System from manifold.net.

• Get a good book on Windows and IIS security. Read it carefully and apply the recommendations.

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