It is easy
to see if a data source has been linked into the project read-only.
Read-only data sources show a database icon with a lock,
whether they have been opened or not.
Linking a file or a .map project into a Manifold project by default links the file or .map project both for reading and writing, and restricts the use of that file or .map project to only one Manifold session. If we link a file or a .map project read-only into a Manifold project, then other Manifold sessions can also use that same file or .map project so long as they also link that file or .map project into their projects read-only.
The above applies to files that more than one Manifold user might want to use, and it also applies to .map projects that more than one Manifold user may want to use which in turn contain links to files or to other .map projects
Whenever we know that some other Manifold user may want to simultaneously link in a file or use a .map project, it is good to get into the habit to link all such data sources read-only into our projects. Whenever linking a file or a .map project into such .map projects, get into the habit of linking them by dragging and Ctrl-Shift-dropping the file or the .map project into the Project pane.
Drag and Ctrl-Shift-drop is the shortcut way of linking a file read-only. This is a shortcut that is simpler than using File - Create - New Data Source to create a read-only linked data source.
The drag and Ctrl-Shift-drop shortcut also works to add .map projects as read-only data sources into a project. By adding a .map project to another project as a read-only data source, we can share a single .map project for simultaneous use by multiple users on different machines. That's very easy to do and it allows us to keep frequently used data in archived .map files.
It is easy
to see if a data source has been linked into the project read-only.
Read-only data sources show a database icon with a lock,
whether they have been opened or not.
In this example we will use a .map project file called graticules.map that is stored on a machine on our local network called MINI. The project contains a series of drawings that contain graticule lines at various spacings that GIS users in our organization find convenient to use in their cartography. This example shows how many users on many different machines can simultaneously use the graticules.map drawings in their projects.
In this example we use the full File - Create - New Data Source method to create a read-only linked data source.
On our machine, called DESKTOP, we launch Manifold with a new project. To use drawings from the graticules.map project on MINI we begin by creating a new data source for that project.
From main menu we choose File - Create - New Data Source. We can also create a new data source by right-clicking into the Project pane and from the context menu choosing Create - New Data Source.
In the New Data Source dialog, we enter a memorable name, Graticules, for the Name of the new data source. In the Type box we choose File: manifold. We check the Open as read-only box and then we press the picker button for the Source box.
In the Select File dialog, we navigate in the usual Windows way first into the Network choice, then into the MINI machine, then into the Data and cartography folders and finally we click the graticules.map file.
Press the Open button.
That loads the path to the graticules.map project into the Source box. Note that referring to a resource on another machine using \\MINI is standard Windows nomenclature for paths to files on other machines.
Press Create Data Source.
That creates a new data source called Graticules in our project, with the data source cylinder marked with a small lock icon to remind us it is a read-only data source.
We can use any of the drawings in the new data source by dragging and dropping them into maps that we create in our project. However, if we use a drawing from directly within the data source, that drawing cannot be altered in any way, for example, by changing the style. A more convenient approach is to copy the drawing we want to use and to paste it into the main part of the project, outside of the data source.
For example, we can click the 10 degree graticules drawing and then press the Copy button on the Project pane toolbar (or, simply press Ctrl-C, the usual Windows shortcut for Copy. We can then click into the main part of the project and either press the Paste button on the Project pane toolbar press Ctrl-V for Paste.
That creates a copy in our local project of the drawing that is in the remote, read-only Graticules data source. The local copy takes its data from the 10 degree graticules Table that is in the remote, read-only Graticules data source. We will not be able to delete or to add or to edit the geometry of objects shown in that drawing, because the data for those objects comes from a read-only table. However, we will be able to change local properties of that local drawing, such as the Style parameters.
We can fill out our project by importing a drawing called Mexico and creating a map that uses a Bing satellite image server as a background layer with the Mexico drawing and the 10 degree graticules drawing as layers. In the illustration above we have closed the Graticules data source for a simpler display.
The 10 degree graticules drawing in the Graticules data source uses simple black lines for the graticule lines. In the illustration above we have used the Style pane to style the lines in our local 10 degree graticules drawing to be alternating, short, black and bright green dashes.
Suppose a user on a different machine would also like to use the graticules.map project at the same time we are using it. That is easy: simply add the graticules.map project as a read-only data source.
Suppose we are also working on the MINI computer. We have launched Manifold with a new, blank project.
To use the graticules.map project, we choose File - Create - New Data Source. We can also create a new data source by right-clicking into the Project pane and from the context menu choosing Create - New Data Source.
In the New Data Source dialog, we enter Graticules for the Name. There is no need to use the same name as on other computers, but it makes sense to use a short and simple name that describes what is in the data source.
For the Source, we navigate to the .map file we want to use. We check the Open as read-only box.
Press Create Data Source.
A new Graticules data source appears in the project pane. As on the other, DESKTOP machine, we Copy the 10 degree graticules drawing inside the data source and we Paste it into the main part of the project.
We then add the various other components we would like to use in this project. We create labels from the local copy of the 10 degree graticules drawing.
In the map we create, we use a drawing of the pre-2016 regions of France as areas, and we add the local copy of the 10 degree graticules drawing as well as the labels we created from it. We can style the 10 degree graticules layer as we like, since it is a local copy. We use a different style than was used on the DESKTOP machine.
How do we change a project that is used by multiple users? We cannot edit a .map file (that is, to change the .map project) as long as it is opened read-only in a Manifold session. To edit the .map file, all users using that .map file opened in one of their projects must close the projects that use it. We can then edit the .map file in a read/write Manifold session.
File - Create - New Data Source - an absolutely key topic for connecting to many thousands of different web servers.
Example: Project Pane Tutorial - In this example we take an extended tour of the Project pane, engaging in a variety of simple but typical moves that are illustrated step by step.