Category Archives: alfresco

Connecting Apache Chemistry CMIS Workbench to the Alfresco Cloud

Anyone who’s familiar with CMIS and the Apache Chemistry project will likely be familiar with the CMIS Workbench.  It’s a handy developer-oriented GUI tool that provides a low level view of any CMIS-compliant repository.

With the release of the Alfresco Public API back in October, the Alfresco Cloud is now a CMIS-compliant repository, and can hence be accessed using the CMIS Workbench.  The CMIS Workbench does not yet directly support the OAuth2 authentication mechanism used in the Alfresco Cloud however; this post describes the steps necessary to get it working.

For starters, you’ll need accounts on both the Alfresco Cloud and the Alfresco Developer Portal (signup to both of these services is free).  You’ll then need to download v0.8.0 or newer of the CMIS Workbench and unzip it somewhere convenient on your hard drive.  It also helps to have some understanding of the OAuth2 authentication mechanism, how the various OAuth2 codes and tokens are obtained and used, and how OAuth2 has been implemented in the Alfresco Cloud – if you’re not familiar with these concepts you may find this DevCon 2012 session helpful.

Next you need to obtain an OAuth2 access token from the Alfresco Cloud.  This is best achieved using a pre-built application, such as my Grails sample app (which conveniently dumps the access token to the log).

After that we’re ready to run the CMIS Workbench.  After the “Login” dialog appears, switch to the “Expert” tab and paste in the following text (note: on Mac OSX you need to use the Ctrl key rather than the Command key for select and paste operations):

# Alfresco Cloud (CMIS 1.0 AtomPub)
org.apache.chemistry.opencmis.binding.spi.type=atompub
org.apache.chemistry.opencmis.binding.atompub.url=https://api.alfresco.com/cmis/versions/1.0/atom
org.apache.chemistry.opencmis.binding.auth.http.basic=false

# Please provide a valid OAuth access token in the following property
# Note that Alfresco Cloud access tokens have a limited lifetime (currently 1 hour) and the OpenCMIS Workbench does not auto-refresh the access token when it expires
org.apache.chemistry.opencmis.binding.header.0=Authorization:Bearer ####ACCESS_TOKEN####

# Other optional options - compression etc. - may be provided here

Replace the text “####ACCESS_TOKEN####” with the access token you obtained previously, ensuring there is a single space character between “Bearer” and the access token value.  This should end up looking similar to the following (click to embiggen):

Connection Information for Alfresco Cloud

Click “Load Repositories” and if the settings are correct the Alfresco Networks you are a member of will be displayed in the repositories dropdown.  Pick one (don’t be surprised if you have only one – that’s the normal case), click the Login button and you should be viewing your Alfresco Cloud content using the CMIS Workbench!

Contributor Agreements – Not What You Might Think!

tl;dr

Many open source contributor agreements (including the Alfresco Contributor Agreement) do not involve any reassignment of copyright – instead they grant the project maintainer a license to use, modify and distribute the contribution.

The Full Picture

I was recently chatting with Jennifer Venables (Alfresco’s awesome general counsel) and she mentioned something in passing that I hadn’t realised before, and that I’m guessing many of you may not know either.  I had always been under the impression that most, if not all, contributor agreements (whether for open source projects or not) involved the individual contributor handing over copyright on their contribution to the project maintainer (for example Alfresco Software Inc., in the case of contributions to the open source Alfresco content management system).  If you’re like me, the thought of handing over “your babies” to someone else is not particularly appealing, and in general I’ve made a point of not becoming involved in projects that require me to give up rights to my own creations.

So Jennifer’s off-hand comment took me a little by surprise, and after she patiently explained how contributor agreements typically work, I’m looking at them in a more positive light.  Specifically, the Alfresco Contributor Agreement (and those of some other open source projects) do not involve any reassignment of copyright – you as the creator of a particular contribution retain full ownership of the copyright of that contribution.  Instead, the project maintainer is simply requesting that you license your intellectual property to them, so that they can also use, modify and distribute it – rights you’ve probably granted to the public anyway (at least if you’ve chosen one of the more popular open source licenses).

It’s also worth noting that the Harmony project is an attempt by the wider open source community to try to standardise and clarify contributor agreements, as there seems to be a lot of confusion around them.  Jennifer has been keeping an eye on their progress on behalf of Alfresco, as their initiative would help to clarify what is often (and definitely was for me) a confusing legal mechanism.

<disclaimer aka IANAL>Now I’m about as far from a lawyer as it’s possible to get, so everything I’ve said here you’d be strongly advised to double check with someone who has legal expertise in this area.</disclaimer>

What I can say with certainty is that I had completely misunderstood the intent of Alfresco’s Contributor Agreement and (more importantly) the legal basis upon which it operates, and that misunderstanding has prevented me in the past from contributing to other open source projects.  I guess I’ll chalk this up to “sometimes, you just don’t know what you don’t know”!

Get your social content going with Alfresco and Liferay

By Luis Sala

The fates of Alfresco and Liferay have been intertwined pretty much from the early days, not too long after Alfresco version 1.0 was released in late 2005. There’s a natural, dare I say, “synergy” in combining a robust content repository with a powerful and highly extensible portal.

As an Epicentric [ http://en.wikipedia.org/wiki/Epicentric ] alumnus, my technology career was practically launched working with portal technology. In many respects, Liferay has changed the portal landscape by demonstrating that open source portals are as good, if not superior, to their proprietary counterparts.

I therefore take a great degree of satisfaction and even greater pleasure in seeing that Alfresco and Liferay are partnering to show the world how portals and ECM can work together to give users an unparalleled platform for improved collaboration and social content publishing.
Attendees of this weeks’ Gartner Portal and Collaboration Summit in Los Angeles are getting a first-hand look at our joint success stories along with learning of our roadmap for further collaborations between the two organizations.

The keys to achieving our goals hinge on open standards such as Java Portlets (JSR-286) and CMIS, the Content Management Interoperability Services standard. We also employ other open source components such as the Activiti Business Process Management engine, an Apache-licensed project sponsored by Alfresco, and the Spring Framework, sponsored by VMWare’s SpringSource business unit.

It’s through the interoperability enabled by the aforementioned standards and open source components that joint customers can quickly deploy a solution built on Alfresco and Liferay.

Alfresco recently announced its Social Content Management message which dovetails nicely into Liferay’s social roadmap by facilitating agile collaboration and exposing the functionality through OpenSocial, an industry standard for interoperability among socially-aware applications.

For my part, I’m very excited about the prospect of working closer with Liferay and hope you do too.

You can learn more about our joint efforts by visiting alfresco.com/liferay.

Technical Overview of the Alfresco / Jive Toolkit

Recently I transitioned from my long-standing role leading Alfresco’s Professional Services team to being the in-house technologist for the Business Development team, and one of my first tasks in the new role has been to work on an integration between Alfresco and Jive Engage. This work is being done in partnership with SolutionSet (a partner of both Alfresco and Jive), and I wanted to discuss some of the technical design work that has gone into the Toolkit, ahead of its availability (which will be soon after the Jive 5.0 launch – the version of Jive that the Toolkit is targeting).

Functional Overview, aka “What will it do?”

As announced at Gartner’s Portals, Collaboration & Content Summit this week, the integration (known as the “Jive Toolkit”) is a set of pre-built components that allows Jive to store documents in Alfresco while still offering all of the same social features as “native” Jive documents (commenting, rating, discussions, etc.). While not yet all-encompassing – Jive’s “social” content cannot yet be stored or managed within Alfresco – the Toolkit will provide a foundational level of document-centric integration, allowing implementers to focus on more use-case specific integrations as required (hence the positioning as a “toolkit”, rather than a fully fledged solution).

More specifically, the initial version of the Toolkit will allow users of Alfresco and/or Jive to create “managed” documents in any of the following 3 ways:

  1. By uploading a document to Alfresco, using the Jive UI.
  2. By “publishing” an existing document from Alfresco to Jive, using Alfresco’s Share UI.
  3. By “linking” an existing document stored in Alfresco to Jive, using the Jive UI.

In all 3 cases, the result is the same: the document is visible and accessible via the Jive UI in exactly the same way as any “native” document, but the content of the document is stored and managed in Alfresco only. Jive will maintain some metadata about the document – for example the document’s filename and a pointer to the document in Alfresco – but it will not store the binary content of the document. This approach ensures that the document is a first class citizen in both the Alfresco and Jive worlds, while minimising the risk of synchronisation issues between the two systems.

Here are some screenshots that demonstrate uploading a document to Alfresco using the Jive UI:

Alfresco managedocument step1

Step 1 – Navigating to a community in Jive

Alfresco managedocument step2

Step 2 – Managing a document

Alfresco managedocument step3

Step 3 – Select a file to upload

Alfresco managedocument step4

Step 4 – Select the target space in Alfresco

Alfresco managedocument step5alf

Document details (Alfresco)

Alfresco managedocument step5

Document details (Jive)

Technical Details, aka “Rubber, meet road”

As mentioned above, there are a variety of ways that the initial “linkage” of a document between Alfresco and Jive can be achieved, however all 3 creation mechanisms produce the same end state: Alfresco has the document in its entirety (including the filename, content, etc.) while Jive has a “proxy object” (a structured data-only object that has the filename and a pointer to the document in Alfresco, but does not have the actual binary content).

This means that all downstream events (updates, metadata modifications, deletes) can be handled the same way, irrespective of how the content was linked between the two systems in the first place – a major simplification in the logic for those downstream events.

Integration Mechanism, aka “CMIS, by any other name would smell as sweet…”

Another nice characteristic of this approach is that the calls from Jive to Alfresco (to create content, update and retrieve it) can be accomplished using the CMIS API. This has several benefits, from reduced development effort in the Toolkit itself (due to the ready availability of client-side CMIS libraries), to the potential for portability to other CMIS compliant repositories in the future.

One important thing to note is that the Alfresco-to-Jive API calls are not standards-based – they make use of Jive’s proprietary REST API. Jive does not expose a standards-based API (indeed, no suitable standard exists for social business systems yet), and CMIS doesn’t provide any kind of callback mechanism for clients to be notified when repository events of interest occur (i.e. a mechanism equivalent to Alfresco’s Component Policies).

Tricky Bits, aka “The Devil is in the Details”

As with any integration between complex enterprise applications, there is some trickery in some parts of the integration, and it’s critical to understand these if you’re evaluating the Jive Toolkit.

Deletion

The first piece of trickery involves deletion of the content, specifically deletion in Alfresco. Because Jive maintains a pointer to the document in Alfresco (specifically, the “cmis:id”), rather than the content itself, if the document is deleted in Alfresco without Jive being notified, attempts within Jive to retrieve that content will fail. To prevent this, the Toolkit is currently designed to veto deletes in Alfresco if the document has been socialised in Jive. To delete a document, it will first need to be deleted in Jive at which point it can be deleted from Alfresco too. The reason the Toolkit doesn’t simply synchronise deletes between Jive and Alfresco is that there are common use cases where the document may be removed from Jive, but needs to be retained in Alfresco – replicating deletes between the two systems would have ruled out these use cases.

Full Text Indexing

The second item of trickery revolves around full text indexing of the document in Jive. To accomplish this, Jive will retain a copy of the content of the document just long enough to index it into Jive’s full text index, and once indexing is complete the content of the document will be removed from Jive. As you’d expect, Alfresco will also notify Jive of any updates to the document, so that the content can be re-indexed on the Jive side.

Access Control and Identity

Access control to the documents is also tricky, primarily because the Alfresco and Jive ACL models differ in their level of granularity. Jive’s access control is primarily Community-centric (i.e. defined and enforced at the level of the Community), while Alfresco has a fine grained, per-node (file or folder) ACL mechanism. In this first release, the Toolkit will initially create the document in both systems in such a way that the ACLs are in sync, but modification of those ACLs in either system will not be replicated to the other system. The upshot is that direct manipulation of the document’s ACLs in Alfresco may cause errors in Jive (i.e. users who can see the document in the Jive UI, but are unable to download it).

Furthermore, in order for Alfresco and Jive to agree on the principal set, the initial version of the Toolkit assumes that both Alfresco and Jive are configured to use the same LDAP repository for user identity and authentication. During the design sessions it was felt that this was likely to be a requirement for an integrated solution anyway and hence wouldn’t be an impediment, but we’re keen to have that assumption validated as broadly as possible.

In Conclusion

So there you have it – a whirlwind tour of the upcoming Jive Toolkit! As a v1.0 there are some more sophisticated use cases that the Toolkit doesn’t address yet, including multi-document / library based integration, and capture of Jive’s social content (discussions, ratings, wiki pages, etc.) in Alfresco. The intention with the Toolkit is to initially provide Alfresco+Jive Systems Integrators (such as SolutionSet) with a small but solid base on which such extensions could be built, and if/when common requirements are identified for these more sophisticated use cases they can be rolled back into the Toolkit.

We’re keen to hear your feedback and look forward to your participation in the project!

Alfresco and Groovy, Baby!

For quite a few years now I’ve been a fan of scripted languages that run on the JVM, initially experimenting with the venerable BeanShell, then tinkering with Javascript (via Rhino), JRuby and finally discovering Groovy in late 2007. A significant advantage that Groovy has over most of those other languages (with the possible exception of BeanShell), is that it is basically a superset of Java, so most valid Java code is also valid Groovy code and can therefore be executed by the Groovy “interpreter”1 without requiring compilation, packaging or deployment – three things that significantly drag down one’s productivity with “real” Java.

To that end I decided to see if there was a way to implement Alfresco Web Scripts using Groovy, ideally in the hope of gaining access to the powerful Alfresco Java APIs with all of the productivity benefits of working in a scripting-like interpreted environment.

It turns out that the Spring Framework (a central part of Alfresco) moved in this direction some time ago, with support for what they refer to as dynamic-language-backed beans. Given that a Java backed Web Script is little more than a Spring bean plus a descriptor and some view templates, initially it seemed like Groovy backed Web Scripts might be possible in Alfresco already, merely by adding the Groovy runtime JAR to the Alfresco classpath and then configuring a Java-backed Web Script with a dynamic-language-backed Spring bean.

Oh behave!

Unfortunately this approach ran into one small snag: Alfresco requires that Java Web Script beans have a “parent” of “webscript”, as follows:

<bean id="webscript.my.web.script.get"
class="com.acme.MyWebScript"
parent="webscript">
<constructor-arg index="0" ref="ServiceRegistry" />
</bean>

but Spring doesn’t allow dynamic-language-backed beans to have a “parent” clause.

It’s freedom baby, yeah!

There are several ways to work around this issue, but the simplest was to implement a “proxy” Web Script bean in Java that simply delegates to another Spring bean, which itself could be a dynamic-language-backed Spring bean implemented in any of the dynamic languages Spring supports.

This class ends up looking something like (imports and comments removed in the interest of brevity):

public class DelegatingWebScript
extends DeclarativeWebScript
{
private final DynamicDeclarativeWebScript dynamicWebScript;

public DelegatingWebScript(final DynamicDeclarativeWebScript dynamicWebScript)
{
this.dynamicWebScript = dynamicWebScript;
}

@Override
protected Map executeImpl(WebScriptRequest request, Status status, Cache cache)
{
return(dynamicWebScript.execute(request, status, cache));
}
}

While DynamicDeclarativeWebScript looks something like:

public interface DynamicDeclarativeWebScript
{
Map execute(WebScriptRequest request, Status status, Cache cache);
}

This Java interface defines the API the Groovy code needs to implement in order for the DelegatingWebScript to be able to delegate to it correctly when the Web Script is invoked.

The net effect of all this is that a Web Script can now be implemented in Groovy (or any of the dynamic languages Spring supports for beans), by implementing the DynamicDeclarativeWebScript interface in a Groovy class, declaring a Spring bean with the script file containing that Groovy class and then configuring a new DelegatingWebScript instance with that dynamic bean. This may sound complicated, but as you can see in this example, is pretty straightforward:

<lang:groovy id="groovy.myWebScript"
refresh-check-delay="5000"
script-source="classpath:alfresco/extension/groovy/MyWebScript.groovy">
<lang:property name="serviceRegistry" ref="ServiceRegistry" />
</lang:groovy>

<bean id="webscript.groovy.myWebScript"
class="org.alfresco.extension.webscripts.groovy.DynamicDelegatingWebScript"
parent="webscript">
<constructor-arg index="0" ref="groovy.myWebScript" />
</bean>

While a little more work than I’d expected, this approach meets all of my goals of being able to write Groovy backed Web Scripts, and in the interests of sharing I’ve put the code up on the Alfresco forge Google Code.

I demand the sum… …OF 1 MILLION DOLLARS!

But wait – there’s more! Not content with simply providing a framework for developing custom Web Scripts in Groovy, I decided to test out this framework by implementing a “Groovy Shell” Web Script. The idea here is that rather than having to develop and register a new Groovy Web Script each and every time I want to tinker with some Groovy code, instead the Web Script would receive the Groovy code as a parameter and execute whatever is passed to it.

Before we go any further, I should mention one very important thing: this opens up a massive script-injection-attack hole in Alfresco, and as a result this Web Script should NOT be used in any environment where data loss (or worse!) is unacceptable!! It is trivial to upload a script that does extremely nasty things to the machine hosting Alfresco (including, but by no means limited to, formatting all drives attached to the system) so please be extremely cautious about where this Web Script gets deployed!

Getting back on track, I accomplished this using Groovy’s GroovyShell class to evaluate a form POSTed parameter to the Web Script as Groovy code (this is conceptually identical to Javascript’s “eval” function, hence the warning about injection attacks). Effectively we have a Groovy-backed Web Script that interprets an input parameter as Groovy code, and then goes ahead and dynamically executes it! It’s turtles all the way down!

The code also transforms the output of the script into JSON format, since there are existing Java libraries for transforming arbitrary object graphs (as would be returned by an arbitrary Groovy script) into JSON format.

Here’s a screenshot showing the end result:

Alfresco Groovy Shell

Alfresco Groovy Shell - Vanilla Groovy Script

The more observant reader will have noticed the notes in the top right corner, particularly the note referring to a “serviceRegistry” object. Before evaluating the script, the Web Script injects the all important Alfresco ServiceRegistry object into the execution context of the script, in a Groovy variable called “serviceRegistry”. The reason for doing so is obvious – this allows the script to interrogate and manipulate the Alfresco repository:

Alfresco Groovy Shell

Alfresco Groovy Shell - Groovy Script that Interrogates the Alfresco Repository

Sharks with lasers strapped to their heads!

Now if you look carefully at this script, you’ll notice that it (mostly) looks like Java, and this is where the value of this Groovy Shell Web Script starts to become apparent: because most valid Java code is also valid Groovy code, you can use this Web Script to prototype Java code that interacts with the Alfresco repository, without going through the usual Java rigmarole of compiling, packaging, deploying and restarting!

I recently conducted an in-depth custom code review for an Alfresco customer who had used Java extensively, and this Web Script was a godsend – not only did I eliminate the drudgery of compiling, packaging and deploying the customer’s custom code (not to mention restarting Alfresco each time), I also completely avoided the time consuming (and, let’s be honest, painful) task of trying to reverse engineer their build toolchain so that I could build the code in my environment. This alone was worth the price of admission, but coupled with the rapid turnaround on changes (the mythical “edit / test / edit / test” cycle), I was able to diagnose their issues in a much shorter time than would otherwise have been possible.

Conclusion

As always I’m keen to hear of your experiences with this project should you choose to use it, and am keen to have others join me in maintaining and enhancing the code (which is surprisingly little, once all’s said and done).


Technically Groovy does not have an interpreter; rather it compiles source scripts into JVM bytecode on demand. The net effect for the developer however is the same – the developer doesn’t have to build, package or deploy their code prior to execution – a serious productivity boost.

Disabling “Configure Workflow”

By default, the Alfresco WCM UI allows an author to select a different workflow and even reconfigure it at submission time, as shown in the following screenshot:

Configure Workflow at Submit Time

Screenshot: Configure Workflow at Submit Time

The obvious issue is that typically authors should not have the ability to influence the approval process, which, after all, is intended to ensure that any content they submit is appropriate for display on the live site.  As the feature currently exists in Alfresco, it is possible, for example, for the author to set themselves as the approver of their change set, completely circumventing the approval process that has been put in place.

While there is an open enhancement request (ENH-466) requesting that these controls be removed, many implementers need to be able to remove them immediately, on versions of Alfresco where this enhancement request has not yet been implemented.

Luckily there’s a straight forward way of doing this, albeit one that requires modification of a core Alfresco JSP.  The UI for the Submit Items dialog is rendered by a single JSP in the Alfresco Explorer UI:

/jsp/wcm/submit-dialog.jsp

At around line 104 (on Enterprise 3.2r – it may be slightly earlier or later in the file on other versions) the following two <h:panelGrid> blocks appear:

<h:panelGrid columns="1" cellpadding="2" style="padding-top:12px;padding-bottom:4px;"
width="100%" rowClasses="wizardSectionHeading">
<h:outputText value="&nbsp;#{msg.workflow}" escape="false" />
</h:panelGrid>

<h:panelGrid columns="1" cellpadding="2" cellpadding="2" width="100%" style="margin-left:8px">
<h:panelGroup rendered="#{DialogManager.bean.workflowListSize != 0}">
<h:outputText value="#{msg.submit_workflow_selection}" />
<h:panelGrid columns="2" cellpadding="2" cellpadding="2">
<a:selectList id="workflow-list" multiSelect="false" styleClass="noBrColumn" itemStyle="padding-top: 3px;"
value="#{DialogManager.bean.workflowSelectedValue}">
<a:listItems value="#{DialogManager.bean.workflowList}" />
</a:selectList>
<h:commandButton value="#{msg.submit_configure_workflow}" style="margin:4px" styleClass="dialogControls"
action="dialog:submitConfigureWorkflow" actionListener="#{DialogManager.bean.setupConfigureWorkflow}" />
</h:panelGrid>
</h:panelGroup>
<h:panelGroup rendered="#{DialogManager.bean.workflowListSize == 0}">
<f:verbatim><% PanelGenerator.generatePanelStart(out, request.getContextPath(), "yellowInner", "#ffffcc"); %></f:verbatim>
<h:panelGrid columns="2" cellpadding="0" cellpadding="0">
<h:graphicImage url="/images/icons/warning.gif" style="padding-top:2px;padding-right:4px" width="16" height="16"/>
<h:outputText styleClass="mainSubText" value="#{msg.submit_no_workflow_warning}" />
</h:panelGrid>
<f:verbatim><% PanelGenerator.generatePanelEnd(out, request.getContextPath(), "yellowInner"); %></f:verbatim>
</h:panelGroup>
</h:panelGrid>

Removing the ability for authors to select a different workflow and/or reconfigure the selected workflow is as simple as commenting out both of these blocks, using JSP style comment tags (<%– and –%>).  The result appears as follows:

No Ability to Select or Configure Workflow

Screenshot: No Ability to Select or Configure Workflow

As you can see, the entire Workflow section of the Submit Items dialog has now been removed, and the user no longer has the ability to select a different workflow or reconfigure it.

A Note about Packaging

While it may be tempting to simply modify the JSP directly in the exploded Alfresco webapp, it is critically important to understand that doing so is unsafe.  Specifically, Tomcat may choose to re-explode the alfresco.war file at any time, overwriting your changes without warning and thereby reverting the Submit Items dialog to the default behaviour.

A better approach is to package up the modified JSP file into an AMP file, and deploy it to other environments (test, production, etc.) using the apply_amps script or the Module Management Tool.  Packaging the JSP as an AMP file also allows you to “pin” the change to a specific version of Alfresco (via the module.repo.version.min and module.repo.version.max properties, described here), which is also important to prevent someone accidentally installing an older version of the JSP into a newer version of Alfresco (which can create other, difficult-to-track-down issues in Alfresco).

 
Please note that modifying core Alfresco code (even JSPs) will technically invalidate support for the installation if you are a subscriber to Alfresco’s Enterprise Network – this should not be done lightly! In this case, however, the risk of unexpected side effects is minimal and although the change will need to be manually re-applied every time the installation is upgraded, there are ways of pro-actively managing that risk.

Timed Deployment

While Alfresco WCM contains a sophisticated deployment engine, the options for initiating deployment are rather more limited, comprising the manual “Deploy Snapshot” function in the Explorer UI, and the automatic “Auto Deploy” function that can be configured in the Web Project Settings and then requested by an author at submission time.

While these options are useful, they each have their downsides.  Manual deployment is, well, highly manual, and in practice it’s usually unacceptable to dedicate a Content Manager to monitoring promotions and deploying them as they roll in.  Auto-deployment removes the manual step (once authors are trained to check the “auto-deploy” checkbox during submission to workflow), but has the problem that a high rate of concurrent promotion can overwhelm the deployment system (since each and every promotion is auto-deployed individually, despite the deployment engine offering a far more efficient “batch” deployment mode).

A Better Alternative

A better approach is to have deployment initiated automatically on a scheduled basis, picking up the latest snapshot at that point in time (which will automatically include all prior snapshots since the last successful deployment).

So what would be involved in developing this as a customisation?

Not very much, as it turns out.  Alfresco already includes all of the necessary components to provide this functionality:

  1. It includes the Quartz job scheduling engine.
  2. It includes an Action for initiating deployment.

All that’s needed is some glue code to tie these two components together, and thanks to the generosity of a recent Alfresco Enterprise customer, that glue code has now been developed and is available as part of the alfresco-wcm-deployment project on Google Code.

Under the Hood

As it turns out there was one critical detail that made this slightly less straight forward than I’d expected. Specifically, the action responsible for deploying a Web Site (the AVMDeployWebsite action) isn’t responsible for writing deployment reports into the Web Project – that step is performed in the Explorer UI’s JSF code instead (in a private class called org.alfresco.web.bean.wcm.DeployWebsiteDialog).

Given that deployment reports are a critical piece of operational reporting information, it was clear that generating the deployment reports in exactly the same fashion as the OOTB “Deploy Snapshot” and “Auto Deploy” functions was a high priority.  As a result the code doesn’t call the AVMDeployWebsite action directly – instead I copied the relevant block of code out of DeployWebsiteDialog and added it to my own custom class.

Other than that, the code is pretty straight forward.  Following Alfresco’s ubiquitous “in-process SOA” pattern I introduced a new service interface (called WebProjectDeploymentService), wired it into my Quartz job class using Spring, then configured it (with the cron expression that controls how frequently it runs) in a separate “trigger” bean.

As always, if you have any questions or comments, please feel free to reply here.  I would request that any bug reports or enhancement requests get raised in the issue tracker in the Google Code project however – they are far easier to monitor there than in the comments on this post.


Note that this creates upgrade risk, since that code could change in future versions of Alfresco. Given I work with the Alfresco code day-to-day I’m in a better position to detect when such changes have occurred, but if you’re doing something like this yourself I would encourage extra diligence in monitoring changes to the original code to ensure your extension doesn’t break unexpectedly following an upgrade.

Version Baselining

One of the great things about working with Alfresco is the vast number of extension points the system offers to developers.  Some of these stem from the pervasive use of the Spring framework, some of them to a well thought out application architecture, and many of them from a number of guiding principles that are consistently applied even when their potential uses aren’t necessarily known with certainty ahead of time.

I recently had the pleasure of being reminded of this latter case when a customer asked for an extension that allowed their content contributors to control the “baseline” version number of documents in their Alfresco installation.  The idea was to allow their contributors to (optionally) enter a version number along with each document, and have the Alfresco versioning system start with that version number instead of the default of 1.0.

Although I didn’t know how this might be achieved, in less than 10 minutes I had my answer and it relied on a slight variation of a mechanism that I’d used in the past.  The customer was also gracious enough to release the IP, so I’ve made the initial version of the extension available on google code.

Here is a brief overview of its usage:

This extension works by extending Alfresco with a custom content type called “Version Baselined Content” that includes a single property called “Base Version”.  This property is where the content contributor can set the base version to be used if/when versioning is enabled on the document.

In order to create content of this type, “Version Baselined Content” needs to be selected in the “Type” dropdown of the “Add Content Dialog”:

Provided the “Modify all properties when this page closes” checkbox is left checked (the default), the contributor will then be presented with the option to specify the base version number for this document (if/when versioning is enabled):

The default value for this field is “0.1” – if the contributor elects to skip modification of the new content’s properties, this is the base version number it will be assigned automatically.

The base version number must be a valid non-negative decimal number (ie. it must be a number greater than or equal to 0.0).  If an invalid value is entered, an error will be displayed when the user clicks the “OK” button.

Once the version number is populated, it may be edited via the document’s properties as many times as are necessary, up until the time versioning is enabled for the document:

Once versioning is enabled for the document, the initial version number will be set to the value of the “Base Version Number” property at that time:

From this point on, any modifications to the “Base Version Number” property will be ignored as it is not possible to renumber an existing Alfresco version history.

Other than allowing explicit control over the initial version number for a document, this extension does not change any other versioning behavior in the system.  For example creating a new minor revision of a document (via checkout and checkin) will increment the version number by 0.1.  Similarly, creating a new major revision of a document (via checkout and checkin) will increment the major component of the version number by 1, and set the minor component to 0:

While the extension is quite neat and (due to the generosity of the customer) available for anyone to use, refine and extend, what really grabbed me as I developed it was how, despite having no prior experience with this particular extension point, it was familiar enough that I was able to understand it almost immediately and leverage it to achieve the desired goal.

Bulk Import from a Filesystem

The Use Case

In any CMS implementation an almost ubiquitous requirement is to load existing content into the new system. That content may reside in a legacy CMS, on a shared network drive, on individual user’s hard drives or in email, but the requirement is almost always there – to inventory the content that’s out there and bring some or all of it into the CMS with a minimum of effort.

Alfresco provides several mechanisms that can be used to import content, including:

Alfresco is also fortunate to have SI partners such as Technology Services Group who provide specialised content migration services and tools (their open source OpenMigrate tool has proven to be popular amongst Alfresco implementers).

That said, most of these approaches suffer from one or more of the following limitations:

  • They require the content to be massaged into some other format prior to ingestion
  • Orchestration of the ingestion process is performed external (ie. out-of-process) to Alfresco, resulting in excessive chattiness between the orchestrator and Alfresco.
  • They require development or configuration work
  • They’re more general in nature, and so aren’t as performant as a specialised solution

An Opinionated (but High Performance!) Alternative

For that reason I recently set about implementing a bulk filesystem import tool, that focuses on satisfying a single, highly specific use case in the most performant manner possible: to take a set of folders and files on local disk and load them into the repository as quickly and efficiently as possible.

The key assumption that allows this process to be efficient is that the source folders and files must be on disk that is locally accessible to the Alfresco server – typically this will mean a filesystem that is located on a hard drive physically housed in the server Alfresco is running on.  This allows the code to directly stream from disk into the repository, which basically devolves into disk-to-disk streaming – far more efficient than any kind of mechanism that requires network I/O.

How those folders and files got onto the local disk is left as an exercise for the reader, but most OSes provide efficient mechanisms for transferring files across a network (rsync and robocopy, for example).  Alternatively it’s also possible to mount a remote filesystem using an OS-native mechanism (CIFS, NFS, GFS and the like), although doing so reintroduces network I/O overhead.

Another key differentiator of this solution is that all of the logic for ingestion executes in-process within Alfresco.  This completely eliminates expensive network RPCs while ingestion is occurring, and also provides fine grained control of various expensive operations (such as transaction commits / rollbacks).

Which leads into another advantage of this solution: like most transactional systems, there are some general strategies that should be followed when writing large amount of data into the Alfresco repository:

  1. Break up large volumes of writes into multiple batches – long running transactions are problematic for most transactional systems (including Alfresco).
  2. Avoid updating the same objects from different concurrent transactions.  In the case of Alfresco, this is particularly noticeable when writing content into the same folder, as those writes cause updates to the parent folder’s modification timestamp.[EDIT] In recent versions of Alfresco, the automatic update of a folder’s modification timestamp (cm:modified property) has been disabled by default. It can be turned back on (by setting the property “system.enableTimestampPropagation” to true), but the default is false so this is likely to be less of an impact to bulk ingestion than I’d originally thought.

The bulk filesystem import tool implements both of these strategies (something that is not easily accomplished when ingestion is coordinated by a separate process).  It batches the source content by folder, using a separate transaction per folder, and it also breaks up any folder containing more than a specific number of files (1,000 by default) into multiple transactions.  It also creates all of the children of a given folder (both files and sub-folders) as part of the same transaction, so that indirect updates to the parent folder occur from that single transaction.

But What Does this Mean in Real Life?

The benefit of this approach was demonstrated recently when an Alfresco implementation had a bulk ingestion process that regularly loaded large numbers (1,000s) of large image files (several MBs per file) into the repository via CIFS.  In one test, it took approximately an hour to load 1,500 files into the repository via CIFS.  In contrast the bulk filesystem import tool took less than 5 minutes to ingest the same content set.

Now clearly this ignores the time it took to copy the 1,500 files onto the Alfresco server’s hard drive prior to running the bulk filesystem import tool, but in this case it was possible to modify the sourcing process so that it dropped the content directly onto the Alfresco server’s hard drive, providing a substantial (order of magnitude) overall saving.

What Doesn’t it Do (Yet)?

Despite already being in use in production, this tool is not what I would consider complete.  The issue tracker in the Google Code project has details on the functionality that’s currently missing; the most notable gap being the lack of support for population of metadata (folders are created as cm:folder and files are created as cm:content). [EDIT] v0.5 adds a first cut at metadata import functionality.  The “user experience” (I hesitate to call it that) is also very rough and could easily be substantially improved. [EDIT] v0.4 added several UI Web Scripts that significantly improve the usability of the tool (at least for the target audience: Alfresco developers and administrators).

That said, the core logic is sound, and has been in production use for some time.  You may find that it’s worth investigating even in its currently rough state.

[POST EDIT] This tool seems to have attracted quite a bit of interest amongst the Alfresco implementer community. I’m chuffed that that’s the case and would request that any questions or comments you have be raised on the mailing list.  If you believe you’ve found a bug, or wish to request an enhancement to the tool, the issue tracker is the best place. Thanks!

Including a Static XSD in a Web Form

Since their inception, Alfresco WCM Web Forms have supported an inclusion mechanism based on the standard XML Schema include and import constructs.  Originally this mechanism read the included assets from the Web Project where the user was creating the content, but since v2.2SP3 the preferred mechanism has been to reference a Web Script instead (in fact the legacy mechanism may be deprecated in a future release).

One question that this new approach raises is how to support inclusion of static XSDs, as Web Scripts are inherently dynamic and introduce some unnecessary overhead for the simple static case. The good news is that Alfresco ships with a Web Script that simply reads a file from the repository and returns its contents:

/api/path/content{property}/{store_type}/{store_id}/{path}?a={attach?}

An example usage is:

/api/path/content/workspace/SpacesStore/Company Home/Data Dictionary/Presentation Templates/readme.ftl

Using the Web Script inclusion mechanism for Web Forms, we can use this Web Script to include or import any XSD file stored in the DM repository.  For example, if we have a file called “my-include.xsd” in the “Company Home” space that contains the following content:

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:alf="http://www.alfresco.org/"
           targetNamespace="http://www.alfresco.org/"
           elementFormDefault="qualified">
  <xs:complexType abstract="true" name="IncludedComplexType">
    <xs:sequence>
      <xs:element name="Title"
                  type="xs:normalizedString"
                  minOccurs="1"
                  maxOccurs="1" />
      <xs:element name="Summary"
                  type="xs:string"
                  minOccurs="0"
                  maxOccurs="1" />
      <xs:element name="Keyword"
                  type="xs:normalizedString"
                  minOccurs="0"
                  maxOccurs="unbounded" />
    </xs:sequence>
  </xs:complexType>
</xs:schema>

We could include it into a Web Form XSD using an include statement such as the following:

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:alf="http://www.alfresco.org/"
           targetNamespace="http://www.alfresco.org/"
           elementFormDefault="qualified">
  <xs:include schemaLocation="webscript://api/path/content/workspace/SpacesStore/Company Home/my-include.xsd?ticket={ticket}" />
  <xs:complexType name="MyWebFormType">
    <xs:complexContent>
      <xs:extension base="alf:IncludedComplexType">
        <xs:sequence>
          <xs:element name="Body"
                      type="xs:string"
                      minOccurs="1"
                      maxOccurs="1" />
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>
  <xs:element name="MyWebForm" type="alf:MyWebFormType" />
</xs:schema>

This is clearly faster and easier than developing a custom Web Script to either emit the XML Schema shown above, or to return the contents of a specific XSD file from the repository!

This approach also provides a solution to another question: how does one neatly package up a Web Form, along with all of its dependencies, ready for deployment to another Alfresco environment?

By storing included XSD files in Company Home > Data Dictionary > Web Forms, we give ourselves the option to package up the entire Web Forms space as an ACP file and deploy that ACP file to any other Alfresco environment, knowing that we’ve captured not only all of the Web Forms in the source environment, but all dependent XSD files as well.