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Subject svn commit: r1375974 - in /ace/site/trunk/content/user-doc: ace_server_ui.png user-guide.mdtext
Date Wed, 22 Aug 2012 10:35:58 GMT
Author: jawi
Date: Wed Aug 22 10:35:57 2012
New Revision: 1375974

Added initial version of the user guide.

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+Title: ACE Users guide
+This article describes how to use ACE and should be a good starting point for new users of
Apache ACE. The remainder of this article assumes you've read and followed the "[Getting Started](/user-doc/getting-started.html)"
guide, meaning that you have an ACE server successfully up and running.
+## Introduction
+Apache ACE is a framework that enables you to provision OSGi software(components) in a controlled
manner. What this means is that you have a central server to which clients, or "targets" in
ACE terminology, connect and fetch their software from. This allows one to control which target
gets which software. 
+The software that is deployed to a target, is composed of one or more distributions. A distribution
is roughly similar to a piece of self-contained software. For example, think of a distribution
as C/C++ Development Tooling that you can install on the Eclipse platform. On its own, distributions
consists of one or more features, that provide pieces of functionality to your software. The
difference between a feature and distribution is that the former is not necessarily fully
self-contained: it might need other features in order to work. Each feature groups one or
more artifacts. An artifact is anything from an OSGi bundle, configuration file or any other
kind of artifact that is needed for the software to work. 
+The artifacts themselves reside on an OBR, which can be either the default one supplied by
ACE, or an external one. Think of an OBR as a kind of Maven repository, storing read-only
versions of artifacts[^1]. As the OBR is the single source for all artifacts, and therefore
the software that is deployed on a target, ACE is able to calculate how to upgrade a target
from one version to another version. This is possible because all changes made to (the metadata
of) ACE are stored in an internal versioned database. 
+## Workflow
+The typical use case for using ACE is where you want to control and manage which software
runs on what target. So, how does one use ACE in practice? To explain the typical workflow
of ACE, let's take the following example.  
+Assume you are working on a large OSGi-based system that provides some kind of service to
your customers (the exact details on what it does isn't relevant for this example). Since
you're trying to make real money out of it, and take development seriously, you want to set
up a DTAP environment. Your developers are working on their development machines, using the
bleeding edge software. They are smart guys that can set up their own environments, so ACE
won't be of much help here.  
+There is also have a tester on your team, responsible for testing all the new features and
bug fixes made by your developers. This tester does not want to have to set up its own environment
and fiddle around with configuration files and such. Instead, he simply wants a working test
environment that runs a recent version of your software. This is were ACE can help you out.
All you need to do is create a testing target, on which a recent software version gets deployed.
That "recent version", can, for example, be a nightly build that comes out of your CI server
that automatically gets pushed to ACE after the nightly build is finished. Alternatively,
the tester also can deploy an older version to its testing target through the ACE server UI,
for example, to do some regression testing.
+Before a new version of your software is put into production, your customers want to do some
acceptance testing to see whether this new version does not break anything. The acceptance
environment should only be updated when a new version is released and after that remains as-is.
In practice, this is most often not the case, as the acceptance environment is, when not used
by any customer, confiscated by your tester for its daily testing purposes, simply, because
ACE allows him to easily deploy other versions to the acceptance environment. When a customer
asks for an acceptance test, he simply deploys the latest greatest official release to the
acceptance environment, and lets the customer do its testing. After that, he can repurpose
it again.
+When all acceptance tests are successful, the new version of your software needs to be deployed
on several production environments, which is done by you, the release manager. As most production
environments only differ in a few details, such as IP addresses and database credentials,
you use the template engine of ACE to make specific configuration files for each production
target. This way, you can easily scale up your production environment by defining new targets
and provide them with the necessary configuration values.
+## Working with ACE Server
+The server UI might look a bit daunting at first, but once you become more familiar with
it, you'll see that it is rather easy to work with.  
+After logging in, the main window consists of two main areas:
+1. The control area at the top of the screen, where you can perform actions like, retrieving
the latest repository changes, revert the changes you've made locally, add new artifacts,
and so on;
+2. The resource area, consisting of (up to) four columns showing the current artifacts, features,
distributions and targets that are known to ACE.
+![Figure 1: ACE server UI](ace_server_ui.png "Figure 1: The server UI of ACE, showing the
control area at the top, and the resource area below that.")  
+### Uploading artifacts
+To upload one or more artifacts, you click on the "Add artifact…" button. An "Add artifact"
dialogs opened, showing both the artifacts currently in the OBR and a list of uploaded artifacts.
There are two possibilities to upload a file:
+1. Upload the individual artifacts by pressing the "Upload" button and selecting the artifact
from the file chooser dialog, or;
+2. by using drag-and-drop: select all artifacts in an Explorer or Finder and drag them onto
the "Upload artifact" area. This way, you can upload multiple artifacts in one go.
+Once artifacts are uploaded, they appear in the Artifacts listing. For each artifact, you
can edit its properties by double clicking on it. In addition, you can unlink an artifact
from a feature, which will be discussed later on, and remove an artifact. **Note**: removing
an artifact will only remove it from the server's metadata, *not* from the OBR. 
+If you try to upload an artifact that is not recognized by ACE, an error is displayed noting
that that particular artifact is not uploaded. Adding support for particular artifacts in
ACE is discussed in [this article](/dev-doc/adding-artifact-recognizers.html).
+**NOTE**: All changes made through the Web UI need to be stored explicitly by pressing the
"Store" button, otherwise they will not be visible to the ACE server. In case you want to
revert all changes, you can use the "Revert" button. This will ignore all changes and retrieve
the latest state from the server. In case there are no local changes, you can still retrieve
the latest state from the server using the "Retrieve" button.
+### Creating a new feature, distribution and/or target
+Adding features and distributions are very similar. You either click the "Add Feature…"
or "Add Distribution…" buttons. In both cases, you are presented with a dialog that allows
you to enter the (mandatory) name of feature (or distribution) and an optional description.
+There are two ways of adding a target to ACE: either you click the "Add Target…" button
and enter the name of the new target, or let a running target register itself to ACE. The
details on this will be discussed later on.
+After a feature, distribution or target is created, you can edit its properties by double
clicking it. For features and distributions, this means you can alter their description, while
for targets, there are more possibilities to view and alter:
+* On the Management tab, you can change whether or not the target should be automatically
updated to the latest software. If selected, all updates will automatically be approved and
distributed to that target. If not, any update must be explicitly approved prior to being
distributed to the target;
+* On the Info tab, you can view the current state of the target, such as the currently installed
version, or the latest available software version;
+* On the LogViewer tab, you can view the installation log of the target. This allows you
to review the installation of updates on that target;
+* The Tag Editor tab allows you to define tags and their replacement values that will be
replaced in any artifacts that contain those tags. This is useful, for example, to have a
single configuration file that can be used for multiple targets. 
+### Creating associations
+To link artifacts to features, you simply select the artifact and drag it on top of the feature
to which it should be associated. The same principle also apply to associate features to distributions
and distributions to targets.  
+To delete an association once is created, you can click either the left- or the right side
of the association (viz. either the artifact or the feature), and click the "-" on the opposite
side of the association. For example, to delete an association between an feature and distribution,
you can select the feature first, and hit the "-" on the distribution. Alternatively, you
can select the distribution first and hit the "-" on the feature to delete the association.
+Associations can be parameterized, allowing it to be dynamic in what it matches on left-side
and/or right-side of the association. For example, by default an association between a bundle
artifact and a feature will be made to match the *latest* version of the bundle. This way,
if you upload a new version of a bundle, the feature will automatically link to that version.
While this is certainly handy in many situations, there are also situations in which you do
not always want to link to the latest greatest version of a bundle. An example might be the
bundles that should run on your production environment, which should only get an update in
controlled upgrades, not when you upload a new artifact to ACE. To disable the "dynamic" associations
between, uncheck the "Dynamic Links" option in the UI *before* you create the association.
This will create an association that is explicitly bound to the symbolic name and version
of a bundle.
+## Running a target
+As mentioned, a target represents a client on which software can be deployed by ACE. Actually,
a target consists of a small OSGi runtime that runs an management agent that periodically
checks with the ACE server whether or not it is has new software for it. In case new software
is available for a target, it will automatically download it and install it. 
+ACE provides a fully self-contained management agent, that can be run as plain Java JAR,
named <tt>org.apache.ace.launcher.jar</tt>. This management agent wrapper accepts
the following command line arguments:
+: configures the target to act as multiple management agents: `agent-id,identification,discovery[;agent-id,identification,discovery]*`;
+: point to the properties file containing the authentication credentials for a certain subsystem.
Can be either a directory, file or URL;
+: sets the ACE server to connect to, should be an URL. Defaults to `http://localhost:8080`;
+`id` or `identification`
+: defines the name to identify the target on in the ACE server. Defaults to `defaultTargetID`;
+: adds an additional bundle to be started with this management agent: `bundle=my.fully.qualified.BundleActivator`;
+: sets framework options for the OSGi framework to be created. This argument may be repeated.
For example: `fwOption=org.osgi.framework.system.packages.extra=sun.misc,`.
+An example on how to run the launcher is:
+    :::sh
+    $ java -jar org.apache.ace.launcher.jar id=MyTarget discovery=
+    Adding additional bundle activator: org.apache.ace.managementagent.Activator
+    Started management agent.
+      Target ID    : MyTarget
+      Server       :
+      Sync interval: 2000 ms
+      Unaffected bundles will not be stopped during deployment.
+After the management agent is started, a new target should appear in the ACE server after
you "Retrieve" the latest changes or "Revert" the current changes. If a target is added this
way to the ACE server (instead of adding it through the "Add target…" button), it initially
will be *unregistered*. This means that no metadata is present in the ACE server yet and will
not be created. To register a target, you can double click the target to edit its properties.
On the "Management" tab, you can select the "Registered?" (and optionally the "Auto approve?"
option as well) and close the dialog by pressing "Ok"[^2]. 
+### Using the template engine for targets
+If you want to provision software to multiple targets, those targets probably need to have
their own specific configuration. For example, the IP address on which it should listen for
web requests, or the credentials to access a database. One could create specific configuration
files for each target, however, this can become quite tedious is you have lots of targets.
Aside that, ACE requires that each artifact has an unique name, so you need to create unique
file names for your configuration files for each change you make. Fortunately, ACE provides
an easier way to solve this problem: an template engine.
+All configuration files[^3] can be regarded as templates, in which variables are replaced
with values supplied by ACE. In fact, the values are definable per target, distribution, feature
or artifact. To define variables and their replacement values (or "tags") for, for example,
a distribution, open up its properties dialog by double clicking on it, and selecting the
"Tag Editor" tab. Each line in this editor represents a tag. The key of a tag defines that
(part of) the variable name to be replaced in configuration files, and the value of a tag
the actual replacement value. 
+For example, consider the following configuration file:
+    :::xml
+    <properties>
+      <key>ipAddress</key>
+      <value>${context.address}</value>
+    </properties>
+The <tt>${context.address}</tt> represent the variable that will be replaced.
The "context." part is mandatory, and everything after that is user definable. Suppose we
want to deploy this configuration file to two targets, "Target1", which is supposed to listen
on address and "Target2", which is supposed to listen on address
To make the configuration file specific for both targets, we simply need to define a tag on
"Target1", like: `address` -> ``, and a similar tag on "Target2", like `address`
-> ``.
+**NOTE**: In case a configuration file consists of a variable that cannot be resolved, it
will simply not be replaced, but left as-is. This way, you can still include Velocity-like
templates in your distribution without having them garbled by ACE.
+ACE will scan all configuration files and replace all known variables as soon as a new deployment
is created. This means that for our example, both "Target1" and "Target2" will get their own
copy of the configuration file with their specific content. ACE also automatically versions
these generated files, to aid downgrading software.
+[^1]: Once an artifact is uploaded to the OBR, it cannot be modified anymore. This is necessary
in order to allow both software upgrades as downgrades possible.
+[^2]: Do not forget to store your changes!
+[^3]: In fact any artifact can be considered as an template, but by default ACE only considers
configuration files. 
+*[OBR]: OSGi Bundle Repository
+*[DTAP]: Development, Testing, Acceptance and Production
+*[CI]: Continuous Integration

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