IMS Queries

Web pages created with the Manifold map server can utilize queries that operate on the component being published. If any queries exist in the project they will be made available in the Queries pane of the Export Web Page dialog.

 

images\sc_ims_queries_02.gif

 

For example, if our project contains three queries as seen above, launching File - Export - Web Page will show them in the Queries pane as seen below:

 

images\sc_ims_queries_03.gif

 

Checking a query's checkbox will cause it to appear in the Queries pane of the generated web page. If we check all boxes in the Export Web Page dialog all three queries will appear in the web page:

 

images\sc_ims_queries_01.gif

 

Two of the queries are parameter queries - they allow user entry of a parameter and so are equipped with an edit box allowing user entry. The third query takes no parameter and so has no edit box.

 

images\sc_ims_queries_04.gif

 

Entering a value into a query edit box and pressing Query will launch the query.

 

images\sc_ims_queries_05.gif

 

The result is a table that lists the output of the query. Tables will appear either in a new browser window or in a frame in the same browser window depending on which template was used to create the web page. Any URL columns will have hyperlinks created for their entries in the table.

 

Optional templates used within the Export Web Page dialog will create different pages. The configuration seen in the browser window depends on choices made in the dialog. The illustrations shown in this topic use the Standard template, which is designed for use with newer browsers. The Compatible with 4.x browsers template uses a simpler style.

 

Tables in sites created with the Compatible template will be displayed in the same browser window, thus requiring a back command in the browser to go back to the map page.

 

Captions

 

The names of the queries are used for the text strings that appear in the Queries pane in the web page. The captions for the edit boxes are simply the name of the parameter variable used in the parameter query.

 

For example, the States with population query shown above contains the following SQL:

 

PARAMETERS exceeding LONG;

SELECT NAME, POP1990 FROM [States Drawing] WHERE

POP1990 > exceeding;

 

The parameter variable exceeding is accepts user entry and is used within the query to process the SQL statements.

 

images\sc_ims_queries_06.gif

 

Manifold will use the name of the query, States with population, together with the name of the parameter variable, exceeding, to construct the captions for the query. When creating a Manifold project for publication to the web it therefore is important to think ahead when naming queries and parameter variables so that the resulting captions are reasonably well self-documenting.

 

Rules

 

When using queries in web pages the following rules must be observed:

 

§      All queries in the project will be listed in the Queries pane in the Export Web Page dialog, even those that cannot legally be used within a map server site. It is the Manifold operator's responsibility to know the contents of the queries and to choose acceptable queries.

§      Only SELECT queries may be chosen for use in the generated site.

§      The Manifold operator is responsible for selecting queries that operate within the component being published. For example, if a project contains a query that reference a drawing that is not part of a map that was published, the query should not be chosen for use in the site.

§      Queries output a maximum of 200 records to a table on the web page.

§      Launching a new query will eliminate the results of the previous query.

 

To avoid errors, it is strongly recommended that projects used with the map server contain no unnecessary or unusable components.

 

Examples

 

The States matching query seen in the illustration at the beginning of this topic contains:

 

PARAMETERS pattern TEXT;

SELECT NAME FROM [States Drawing] WHERE NAME LIKEX pattern;

 

It uses the LIKEX operator to find the names of states matching the pattern provided by the user.

 

The 10 longest roads query contains:

 

SELECT TOP 10 LENGTH, TYPE, ROUTE FROM [Roads Drawing]

ORDER BY LENGTH;

 

There is no parameter used in this query. It simply always selects the ten longest roads based on the contents of the Length field.

 

Panning to Selected Objects / Suppression of ID Field

 

Objects are not selected by queries in Manifold unless the ID system field is selected by the query. For example, if we have a drawing of provinces that each has a name, the SQL fragment …

 

SELECT Name from [Provinces Table] WHERE…

 

… will create a table, but it will not select the objects associated with the records that appear in that table. In contrast, the fragment…

 

SELECT ID, Name from [Provinces Table] WHERE…

 

… will select the objects as well as creating the table.

 

If the first SQL fragment is part of a query that is used in a Manifold IMS web site the output of the query will be a table, but the IMS map window will not be panned or zoomed. If the second IMS fragment is used, a table will be created, the objects will be selected, and the IMS map window will pan to the center of the selected set of objects and will zoom to fit the selection.

 

Since we normally do not want to show internal system fields such as the ID field to people browsing our web site, the ID field will not be displayed as part of a table created by an IMS query.

 

Geocoding and Queries

 

The Manifold geocoder is accessed in IMS applications by using queries utilizing the geocoding SQL extensions. Manifold SQL includes geocoding SQL extensions that operate with Manifold's geocoding engine to perform spatial operations based upon an address string or zip code. Geocoding queries will not function unless either Manifold's US streets geocoding database is installed or Microsoft's MapPoint program is installed. If MapPoint is used, performance will be lower but coverage will extend to all countries covered by the MapPoint editions (North America and/or Europe) installed. See the Geocoding with MapPoint topic if MapPoint is to be used. Note that Internet access permissions must be adjusted (see below) if MapPoint is called from IMS.

 

Geocoding extensions will not work with Manifold IMS using the Manifold US streets geocoding database unless the geocoding database is installed within the Manifold application installation folder (normally, C:\Program Files\Manifold System). Therefore, the US streets geocoding database should be installed in the Manifold application installation folder on machines on which Manifold IMS operates. Geocoding queries using MapPoint will work so long as MapPoint is correctly installed on the server system regardless of the installation directory used.

 

Drawings must be projected for geocoding extensions to function correctly.

 

Boolean CloseToAddress(Number ID, String Address, Number Distance, [String Unit])

 

Given an object ID, an address string, a distance and an optional distance unit determine if the object lies within the specified distance of the address.

 

Boolean CloseToZip(Number ID, String Zip, Number Distance, [String Unit])

 

Given an object ID, a ZIP code string, a distance and an optional distance unit determine if the object lies within the specified distance of the zip code centroid.

 

Number DistanceToAddress(Number ID, String Address, [String Unit])

 

Given an object ID, an address string, and an optional distance unit computes the distance between the object and the address.

 

Number DistanceToZip(Number ID, String Zip, [String Unit])

 

Given an object ID, a ZIP code string, and an optional distance unit computes the distance between the object and the zip code centroid.

 

Notes on usage:

 

§      If an object is a line or an area the object's centroid is used for distance calculations.

§      If an address string produces more than one match, the system automatically selects the closest of the building-level matches (possibly with an "unknown street name, possible misspelling" error).

§      If an address string produces no building-level matches, CloseToAddress returns False and DistanceToAddress returns -1.

§      If a zip code string is invalid (no matches in the geocoding database) CloseToZip returns False and DistanceToZip returns -1.

§      If the optional distance unit is omitted, the system will use the native measurement unit of the drawing or meters if the drawing is not projected.

§      Distances are great circle distances computed over a WGS84 ellipsoid and are accurate to 1 meter.

§      The geocoding functions cache returned geocoding data between subsequent calls.

§      Functions can be used from IMS as long as the geocoding database is located within the Manifold application installation folder (usually C:\Program Files\Manifold System).

 

Geocoding Function Examples

 

SELECT * FROM Dealers

WHERE CloseToAddress(ID, "330 Lytton Ave, Palo Alto, CA, 94301", 10, "mi")

 

SELECT * FROM Dealers

WHERE DistanceToAddress(ID, "330 Lytton Ave, Palo Alto, CA, 94301", "mi") <= 10

 

SELECT * FROM Dealers

WHERE CloseToZip(ID, "94301", 10, "mi")

 

SELECT * FROM Dealers

WHERE DistanceToZip(ID, "94301", "mi") <= 10

 

All four examples have a similar function. The first query selects all objects in Dealers that are within 10 miles of the given address using the CloseToAddress function, while the second example performs the same task using the DistanceToAddress function. The third and fourth examples perform the same functions using the 94301 ZIP code.

 

To keep the user interface simple and to avoid the complication of dealing with possible user errors when entering address information into forms, many web applications with IMS will use the CloseToZip or DistanceToZip functions since these require the user to merely enter the ZIP code correctly. For many applications, such as locating a dealer, finding the closest objects to the ZIP centroid provides acceptable accuracy.

 

See the Units topic for a list of unit abbreviations that may be used to specify optional distance units.

 

MapPoint and IMS

 

MapPoint geocoding will normally not work from IMS unless we map anonymous Internet connections to a user account that has more enhanced permissions than the default Internet access IUSR_xxx account.

 

To enhance permissions for the Internet access account:

 

1. Create a regular user account with default permissions that is a member of the Users group.

2. Open Control Panel - Administrative Tools - Internet Information Services (or the equivalent dialog in your version of Windows).

3. Right click the folder that contains the published website, select Properties, switch to Directory Security and click Edit under Anonymous access and authentication control.

4. Set the user account used for anonymous access to the account created in step 1 above.

 

See the Geocoding with MapPoint topic for use of MapPoint as an auxiliary geocoder.

 

Tech Tip

 

When developing on one machine and publishing on a different machine, make sure the machine that is actually running the map server is a fully up-to-date Windows machine with all required updates in place just like the machine that was used to create and test the project.

 

For example, Manifold System requires that Microsoft Internet Explorer 5.5 or later (preferably the most recent IE version) has been installed to make sure that all Windows components, including scripting components, have been updated. Occasionally, server machines used as IIS hosts might not have IE installed or might not have the latest version of IE installed because the server is not used interactively to browse the web.

 

In such cases a Manifold project and web page might work fine on the development machine but then not work correctly (queries fail, etc.) when installed on the server. If this happens, check the server machine to make sure Windows is fully updated as required by your Manifold System installation notes.

 

Also make sure to verify that the web server machine has all required Manifold licensing and accessories installed. For example, if an IMS web site uses a project that depends upon Enterprise Edition features the web server machine must also have a license for Enterprise Edition and the project must be correctly configured in the web server so it can connect to the Enterprise server it uses. Likewise, if geocoding queries are used the web server machine must have the Manifold Geocoding Data product installed and be licensed for its use.

 

Troubleshooting

 

See the troubleshooting topic Problems with the Internet Map Server for detailed checklists of what might be wrong.

 

The number one problem with IMS reported to tech support is that users neglect to add the IUSR_ account the IUSR_ account (or, the NETWORK SERVICE account or ASPNET account if applicable) with access permissions to the .map file in use. Using Windows Explorer (do not just depend on the IIS management console or other server management console), right click on the .map file, choose Properties and verify in the Security that the IUSR_ account for the system has necessary read and execute permissions.

 

Take time to think through all permissions issues. The Internet access account must have permissions to get to all the data that is used in the web site. For example, suppose our IMS project uses a linked image. Because linked images use data from the Data Cache folder (the

default), we must also be sure to give the IUSR_ account (or, the NETWORK SERVICE account or ASPNET account if applicable) read permissions to access all files in that folder.

 

Windows security and access permissions can be confusing, but it should be remembered that these issues are Windows issues and not Manifold issues. For example, if an IMS project includes calls to DBMS tables resident in an external DBMS, such as SQL Server, the application will operate using the security context of the ASP or ASPX page comprising the IMS application. Resolving connection issues (such as a failed login to the SQL Server) must be resolved with an informed understanding of Windows integrated authentication.

 

When troubleshooting such problems, the first objective should be to make sure you thoroughly understand all Windows security mechanisms, especially those involved with IIS applications.

 

Note

 

You must be running Manifold System Professional Edition or greater to have the capabilities discussed in this topic. All Manifold editions except Personal Edition include the map server. If you are running Manifold System Personal Edition you will not have the capabilities discussed in this topic.

 

See Also

 

Queries

Map Server Overview

Creating a Web Site

Publishing Multiple Pages

Optimizing Performance

Spatial Extensions

Geocoding Extensions

Street Address Geocoding

Geocoding with MapPoint